rustc_codegen_ssa/mir/
block.rs

1use std::cmp;
2
3use rustc_abi::{Align, BackendRepr, ExternAbi, HasDataLayout, Reg, Size, WrappingRange};
4use rustc_ast as ast;
5use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
6use rustc_data_structures::packed::Pu128;
7use rustc_hir::lang_items::LangItem;
8use rustc_middle::mir::{self, AssertKind, InlineAsmMacro, SwitchTargets, UnwindTerminateReason};
9use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf, ValidityRequirement};
10use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
11use rustc_middle::ty::{self, Instance, Ty};
12use rustc_middle::{bug, span_bug};
13use rustc_session::config::OptLevel;
14use rustc_span::Span;
15use rustc_span::source_map::Spanned;
16use rustc_target::callconv::{ArgAbi, CastTarget, FnAbi, PassMode};
17use tracing::{debug, info};
18
19use super::operand::OperandRef;
20use super::operand::OperandValue::{Immediate, Pair, Ref, ZeroSized};
21use super::place::{PlaceRef, PlaceValue};
22use super::{CachedLlbb, FunctionCx, LocalRef};
23use crate::base::{self, is_call_from_compiler_builtins_to_upstream_monomorphization};
24use crate::common::{self, IntPredicate};
25use crate::errors::CompilerBuiltinsCannotCall;
26use crate::traits::*;
27use crate::{MemFlags, meth};
28
29// Indicates if we are in the middle of merging a BB's successor into it. This
30// can happen when BB jumps directly to its successor and the successor has no
31// other predecessors.
32#[derive(Debug, PartialEq)]
33enum MergingSucc {
34    False,
35    True,
36}
37
38/// Used by `FunctionCx::codegen_terminator` for emitting common patterns
39/// e.g., creating a basic block, calling a function, etc.
40struct TerminatorCodegenHelper<'tcx> {
41    bb: mir::BasicBlock,
42    terminator: &'tcx mir::Terminator<'tcx>,
43}
44
45impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
46    /// Returns the appropriate `Funclet` for the current funclet, if on MSVC,
47    /// either already previously cached, or newly created, by `landing_pad_for`.
48    fn funclet<'b, Bx: BuilderMethods<'a, 'tcx>>(
49        &self,
50        fx: &'b mut FunctionCx<'a, 'tcx, Bx>,
51    ) -> Option<&'b Bx::Funclet> {
52        let cleanup_kinds = fx.cleanup_kinds.as_ref()?;
53        let funclet_bb = cleanup_kinds[self.bb].funclet_bb(self.bb)?;
54        // If `landing_pad_for` hasn't been called yet to create the `Funclet`,
55        // it has to be now. This may not seem necessary, as RPO should lead
56        // to all the unwind edges being visited (and so to `landing_pad_for`
57        // getting called for them), before building any of the blocks inside
58        // the funclet itself - however, if MIR contains edges that end up not
59        // being needed in the LLVM IR after monomorphization, the funclet may
60        // be unreachable, and we don't have yet a way to skip building it in
61        // such an eventuality (which may be a better solution than this).
62        if fx.funclets[funclet_bb].is_none() {
63            fx.landing_pad_for(funclet_bb);
64        }
65        Some(
66            fx.funclets[funclet_bb]
67                .as_ref()
68                .expect("landing_pad_for didn't also create funclets entry"),
69        )
70    }
71
72    /// Get a basic block (creating it if necessary), possibly with cleanup
73    /// stuff in it or next to it.
74    fn llbb_with_cleanup<Bx: BuilderMethods<'a, 'tcx>>(
75        &self,
76        fx: &mut FunctionCx<'a, 'tcx, Bx>,
77        target: mir::BasicBlock,
78    ) -> Bx::BasicBlock {
79        let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
80        let mut lltarget = fx.llbb(target);
81        if needs_landing_pad {
82            lltarget = fx.landing_pad_for(target);
83        }
84        if is_cleanupret {
85            // Cross-funclet jump - need a trampoline
86            assert!(base::wants_new_eh_instructions(fx.cx.tcx().sess));
87            debug!("llbb_with_cleanup: creating cleanup trampoline for {:?}", target);
88            let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
89            let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name);
90            let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb);
91            trampoline_bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
92            trampoline_llbb
93        } else {
94            lltarget
95        }
96    }
97
98    fn llbb_characteristics<Bx: BuilderMethods<'a, 'tcx>>(
99        &self,
100        fx: &mut FunctionCx<'a, 'tcx, Bx>,
101        target: mir::BasicBlock,
102    ) -> (bool, bool) {
103        if let Some(ref cleanup_kinds) = fx.cleanup_kinds {
104            let funclet_bb = cleanup_kinds[self.bb].funclet_bb(self.bb);
105            let target_funclet = cleanup_kinds[target].funclet_bb(target);
106            let (needs_landing_pad, is_cleanupret) = match (funclet_bb, target_funclet) {
107                (None, None) => (false, false),
108                (None, Some(_)) => (true, false),
109                (Some(f), Some(t_f)) => (f != t_f, f != t_f),
110                (Some(_), None) => {
111                    let span = self.terminator.source_info.span;
112                    span_bug!(span, "{:?} - jump out of cleanup?", self.terminator);
113                }
114            };
115            (needs_landing_pad, is_cleanupret)
116        } else {
117            let needs_landing_pad = !fx.mir[self.bb].is_cleanup && fx.mir[target].is_cleanup;
118            let is_cleanupret = false;
119            (needs_landing_pad, is_cleanupret)
120        }
121    }
122
123    fn funclet_br<Bx: BuilderMethods<'a, 'tcx>>(
124        &self,
125        fx: &mut FunctionCx<'a, 'tcx, Bx>,
126        bx: &mut Bx,
127        target: mir::BasicBlock,
128        mergeable_succ: bool,
129    ) -> MergingSucc {
130        let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
131        if mergeable_succ && !needs_landing_pad && !is_cleanupret {
132            // We can merge the successor into this bb, so no need for a `br`.
133            MergingSucc::True
134        } else {
135            let mut lltarget = fx.llbb(target);
136            if needs_landing_pad {
137                lltarget = fx.landing_pad_for(target);
138            }
139            if is_cleanupret {
140                // micro-optimization: generate a `ret` rather than a jump
141                // to a trampoline.
142                bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
143            } else {
144                bx.br(lltarget);
145            }
146            MergingSucc::False
147        }
148    }
149
150    /// Call `fn_ptr` of `fn_abi` with the arguments `llargs`, the optional
151    /// return destination `destination` and the unwind action `unwind`.
152    fn do_call<Bx: BuilderMethods<'a, 'tcx>>(
153        &self,
154        fx: &mut FunctionCx<'a, 'tcx, Bx>,
155        bx: &mut Bx,
156        fn_abi: &'tcx FnAbi<'tcx, Ty<'tcx>>,
157        fn_ptr: Bx::Value,
158        llargs: &[Bx::Value],
159        destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
160        mut unwind: mir::UnwindAction,
161        lifetime_ends_after_call: &[(Bx::Value, Size)],
162        instance: Option<Instance<'tcx>>,
163        mergeable_succ: bool,
164    ) -> MergingSucc {
165        let tcx = bx.tcx();
166        if let Some(instance) = instance
167            && is_call_from_compiler_builtins_to_upstream_monomorphization(tcx, instance)
168        {
169            if destination.is_some() {
170                let caller_def = fx.instance.def_id();
171                let e = CompilerBuiltinsCannotCall {
172                    span: tcx.def_span(caller_def),
173                    caller: with_no_trimmed_paths!(tcx.def_path_str(caller_def)),
174                    callee: with_no_trimmed_paths!(tcx.def_path_str(instance.def_id())),
175                };
176                tcx.dcx().emit_err(e);
177            } else {
178                info!(
179                    "compiler_builtins call to diverging function {:?} replaced with abort",
180                    instance.def_id()
181                );
182                bx.abort();
183                bx.unreachable();
184                return MergingSucc::False;
185            }
186        }
187
188        // If there is a cleanup block and the function we're calling can unwind, then
189        // do an invoke, otherwise do a call.
190        let fn_ty = bx.fn_decl_backend_type(fn_abi);
191
192        let fn_attrs = if bx.tcx().def_kind(fx.instance.def_id()).has_codegen_attrs() {
193            Some(bx.tcx().codegen_fn_attrs(fx.instance.def_id()))
194        } else {
195            None
196        };
197
198        if !fn_abi.can_unwind {
199            unwind = mir::UnwindAction::Unreachable;
200        }
201
202        let unwind_block = match unwind {
203            mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
204            mir::UnwindAction::Continue => None,
205            mir::UnwindAction::Unreachable => None,
206            mir::UnwindAction::Terminate(reason) => {
207                if fx.mir[self.bb].is_cleanup && base::wants_new_eh_instructions(fx.cx.tcx().sess) {
208                    // MSVC SEH will abort automatically if an exception tries to
209                    // propagate out from cleanup.
210
211                    // FIXME(@mirkootter): For wasm, we currently do not support terminate during
212                    // cleanup, because this requires a few more changes: The current code
213                    // caches the `terminate_block` for each function; funclet based code - however -
214                    // requires a different terminate_block for each funclet
215                    // Until this is implemented, we just do not unwind inside cleanup blocks
216
217                    None
218                } else {
219                    Some(fx.terminate_block(reason))
220                }
221            }
222        };
223
224        if let Some(unwind_block) = unwind_block {
225            let ret_llbb = if let Some((_, target)) = destination {
226                fx.llbb(target)
227            } else {
228                fx.unreachable_block()
229            };
230            let invokeret = bx.invoke(
231                fn_ty,
232                fn_attrs,
233                Some(fn_abi),
234                fn_ptr,
235                llargs,
236                ret_llbb,
237                unwind_block,
238                self.funclet(fx),
239                instance,
240            );
241            if fx.mir[self.bb].is_cleanup {
242                bx.apply_attrs_to_cleanup_callsite(invokeret);
243            }
244
245            if let Some((ret_dest, target)) = destination {
246                bx.switch_to_block(fx.llbb(target));
247                fx.set_debug_loc(bx, self.terminator.source_info);
248                for &(tmp, size) in lifetime_ends_after_call {
249                    bx.lifetime_end(tmp, size);
250                }
251                fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
252            }
253            MergingSucc::False
254        } else {
255            let llret =
256                bx.call(fn_ty, fn_attrs, Some(fn_abi), fn_ptr, llargs, self.funclet(fx), instance);
257            if fx.mir[self.bb].is_cleanup {
258                bx.apply_attrs_to_cleanup_callsite(llret);
259            }
260
261            if let Some((ret_dest, target)) = destination {
262                for &(tmp, size) in lifetime_ends_after_call {
263                    bx.lifetime_end(tmp, size);
264                }
265                fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
266                self.funclet_br(fx, bx, target, mergeable_succ)
267            } else {
268                bx.unreachable();
269                MergingSucc::False
270            }
271        }
272    }
273
274    /// Generates inline assembly with optional `destination` and `unwind`.
275    fn do_inlineasm<Bx: BuilderMethods<'a, 'tcx>>(
276        &self,
277        fx: &mut FunctionCx<'a, 'tcx, Bx>,
278        bx: &mut Bx,
279        template: &[InlineAsmTemplatePiece],
280        operands: &[InlineAsmOperandRef<'tcx, Bx>],
281        options: InlineAsmOptions,
282        line_spans: &[Span],
283        destination: Option<mir::BasicBlock>,
284        unwind: mir::UnwindAction,
285        instance: Instance<'_>,
286        mergeable_succ: bool,
287    ) -> MergingSucc {
288        let unwind_target = match unwind {
289            mir::UnwindAction::Cleanup(cleanup) => Some(self.llbb_with_cleanup(fx, cleanup)),
290            mir::UnwindAction::Terminate(reason) => Some(fx.terminate_block(reason)),
291            mir::UnwindAction::Continue => None,
292            mir::UnwindAction::Unreachable => None,
293        };
294
295        if operands.iter().any(|x| matches!(x, InlineAsmOperandRef::Label { .. })) {
296            assert!(unwind_target.is_none());
297            let ret_llbb = if let Some(target) = destination {
298                fx.llbb(target)
299            } else {
300                fx.unreachable_block()
301            };
302
303            bx.codegen_inline_asm(
304                template,
305                operands,
306                options,
307                line_spans,
308                instance,
309                Some(ret_llbb),
310                None,
311            );
312            MergingSucc::False
313        } else if let Some(cleanup) = unwind_target {
314            let ret_llbb = if let Some(target) = destination {
315                fx.llbb(target)
316            } else {
317                fx.unreachable_block()
318            };
319
320            bx.codegen_inline_asm(
321                template,
322                operands,
323                options,
324                line_spans,
325                instance,
326                Some(ret_llbb),
327                Some((cleanup, self.funclet(fx))),
328            );
329            MergingSucc::False
330        } else {
331            bx.codegen_inline_asm(template, operands, options, line_spans, instance, None, None);
332
333            if let Some(target) = destination {
334                self.funclet_br(fx, bx, target, mergeable_succ)
335            } else {
336                bx.unreachable();
337                MergingSucc::False
338            }
339        }
340    }
341}
342
343/// Codegen implementations for some terminator variants.
344impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
345    /// Generates code for a `Resume` terminator.
346    fn codegen_resume_terminator(&mut self, helper: TerminatorCodegenHelper<'tcx>, bx: &mut Bx) {
347        if let Some(funclet) = helper.funclet(self) {
348            bx.cleanup_ret(funclet, None);
349        } else {
350            let slot = self.get_personality_slot(bx);
351            let exn0 = slot.project_field(bx, 0);
352            let exn0 = bx.load_operand(exn0).immediate();
353            let exn1 = slot.project_field(bx, 1);
354            let exn1 = bx.load_operand(exn1).immediate();
355            slot.storage_dead(bx);
356
357            bx.resume(exn0, exn1);
358        }
359    }
360
361    fn codegen_switchint_terminator(
362        &mut self,
363        helper: TerminatorCodegenHelper<'tcx>,
364        bx: &mut Bx,
365        discr: &mir::Operand<'tcx>,
366        targets: &SwitchTargets,
367    ) {
368        let discr = self.codegen_operand(bx, discr);
369        let discr_value = discr.immediate();
370        let switch_ty = discr.layout.ty;
371        // If our discriminant is a constant we can branch directly
372        if let Some(const_discr) = bx.const_to_opt_u128(discr_value, false) {
373            let target = targets.target_for_value(const_discr);
374            bx.br(helper.llbb_with_cleanup(self, target));
375            return;
376        };
377
378        let mut target_iter = targets.iter();
379        if target_iter.len() == 1 {
380            // If there are two targets (one conditional, one fallback), emit `br` instead of
381            // `switch`.
382            let (test_value, target) = target_iter.next().unwrap();
383            let otherwise = targets.otherwise();
384            let lltarget = helper.llbb_with_cleanup(self, target);
385            let llotherwise = helper.llbb_with_cleanup(self, otherwise);
386            let target_cold = self.cold_blocks[target];
387            let otherwise_cold = self.cold_blocks[otherwise];
388            // If `target_cold == otherwise_cold`, the branches have the same weight
389            // so there is no expectation. If they differ, the `target` branch is expected
390            // when the `otherwise` branch is cold.
391            let expect = if target_cold == otherwise_cold { None } else { Some(otherwise_cold) };
392            if switch_ty == bx.tcx().types.bool {
393                // Don't generate trivial icmps when switching on bool.
394                match test_value {
395                    0 => {
396                        let expect = expect.map(|e| !e);
397                        bx.cond_br_with_expect(discr_value, llotherwise, lltarget, expect);
398                    }
399                    1 => {
400                        bx.cond_br_with_expect(discr_value, lltarget, llotherwise, expect);
401                    }
402                    _ => bug!(),
403                }
404            } else {
405                let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
406                let llval = bx.const_uint_big(switch_llty, test_value);
407                let cmp = bx.icmp(IntPredicate::IntEQ, discr_value, llval);
408                bx.cond_br_with_expect(cmp, lltarget, llotherwise, expect);
409            }
410        } else if target_iter.len() == 2
411            && self.mir[targets.otherwise()].is_empty_unreachable()
412            && targets.all_values().contains(&Pu128(0))
413            && targets.all_values().contains(&Pu128(1))
414        {
415            // This is the really common case for `bool`, `Option`, etc.
416            // By using `trunc nuw` we communicate that other values are
417            // impossible without needing `switch` or `assume`s.
418            let true_bb = targets.target_for_value(1);
419            let false_bb = targets.target_for_value(0);
420            let true_ll = helper.llbb_with_cleanup(self, true_bb);
421            let false_ll = helper.llbb_with_cleanup(self, false_bb);
422
423            let expected_cond_value = if self.cx.sess().opts.optimize == OptLevel::No {
424                None
425            } else {
426                match (self.cold_blocks[true_bb], self.cold_blocks[false_bb]) {
427                    // Same coldness, no expectation
428                    (true, true) | (false, false) => None,
429                    // Different coldness, expect the non-cold one
430                    (true, false) => Some(false),
431                    (false, true) => Some(true),
432                }
433            };
434
435            let bool_ty = bx.tcx().types.bool;
436            let cond = if switch_ty == bool_ty {
437                discr_value
438            } else {
439                let bool_llty = bx.immediate_backend_type(bx.layout_of(bool_ty));
440                bx.unchecked_utrunc(discr_value, bool_llty)
441            };
442            bx.cond_br_with_expect(cond, true_ll, false_ll, expected_cond_value);
443        } else if self.cx.sess().opts.optimize == OptLevel::No
444            && target_iter.len() == 2
445            && self.mir[targets.otherwise()].is_empty_unreachable()
446        {
447            // In unoptimized builds, if there are two normal targets and the `otherwise` target is
448            // an unreachable BB, emit `br` instead of `switch`. This leaves behind the unreachable
449            // BB, which will usually (but not always) be dead code.
450            //
451            // Why only in unoptimized builds?
452            // - In unoptimized builds LLVM uses FastISel which does not support switches, so it
453            //   must fall back to the slower SelectionDAG isel. Therefore, using `br` gives
454            //   significant compile time speedups for unoptimized builds.
455            // - In optimized builds the above doesn't hold, and using `br` sometimes results in
456            //   worse generated code because LLVM can no longer tell that the value being switched
457            //   on can only have two values, e.g. 0 and 1.
458            //
459            let (test_value1, target1) = target_iter.next().unwrap();
460            let (_test_value2, target2) = target_iter.next().unwrap();
461            let ll1 = helper.llbb_with_cleanup(self, target1);
462            let ll2 = helper.llbb_with_cleanup(self, target2);
463            let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
464            let llval = bx.const_uint_big(switch_llty, test_value1);
465            let cmp = bx.icmp(IntPredicate::IntEQ, discr_value, llval);
466            bx.cond_br(cmp, ll1, ll2);
467        } else {
468            let otherwise = targets.otherwise();
469            let otherwise_cold = self.cold_blocks[otherwise];
470            let otherwise_unreachable = self.mir[otherwise].is_empty_unreachable();
471            let cold_count = targets.iter().filter(|(_, target)| self.cold_blocks[*target]).count();
472            let none_cold = cold_count == 0;
473            let all_cold = cold_count == targets.iter().len();
474            if (none_cold && (!otherwise_cold || otherwise_unreachable))
475                || (all_cold && (otherwise_cold || otherwise_unreachable))
476            {
477                // All targets have the same weight,
478                // or `otherwise` is unreachable and it's the only target with a different weight.
479                bx.switch(
480                    discr_value,
481                    helper.llbb_with_cleanup(self, targets.otherwise()),
482                    target_iter
483                        .map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
484                );
485            } else {
486                // Targets have different weights
487                bx.switch_with_weights(
488                    discr_value,
489                    helper.llbb_with_cleanup(self, targets.otherwise()),
490                    otherwise_cold,
491                    target_iter.map(|(value, target)| {
492                        (value, helper.llbb_with_cleanup(self, target), self.cold_blocks[target])
493                    }),
494                );
495            }
496        }
497    }
498
499    fn codegen_return_terminator(&mut self, bx: &mut Bx) {
500        // Call `va_end` if this is the definition of a C-variadic function.
501        if self.fn_abi.c_variadic {
502            // The `VaList` "spoofed" argument is just after all the real arguments.
503            let va_list_arg_idx = self.fn_abi.args.len();
504            match self.locals[mir::Local::from_usize(1 + va_list_arg_idx)] {
505                LocalRef::Place(va_list) => {
506                    bx.va_end(va_list.val.llval);
507                }
508                _ => bug!("C-variadic function must have a `VaList` place"),
509            }
510        }
511        if self.fn_abi.ret.layout.is_uninhabited() {
512            // Functions with uninhabited return values are marked `noreturn`,
513            // so we should make sure that we never actually do.
514            // We play it safe by using a well-defined `abort`, but we could go for immediate UB
515            // if that turns out to be helpful.
516            bx.abort();
517            // `abort` does not terminate the block, so we still need to generate
518            // an `unreachable` terminator after it.
519            bx.unreachable();
520            return;
521        }
522        let llval = match &self.fn_abi.ret.mode {
523            PassMode::Ignore | PassMode::Indirect { .. } => {
524                bx.ret_void();
525                return;
526            }
527
528            PassMode::Direct(_) | PassMode::Pair(..) => {
529                let op = self.codegen_consume(bx, mir::Place::return_place().as_ref());
530                if let Ref(place_val) = op.val {
531                    bx.load_from_place(bx.backend_type(op.layout), place_val)
532                } else {
533                    op.immediate_or_packed_pair(bx)
534                }
535            }
536
537            PassMode::Cast { cast: cast_ty, pad_i32: _ } => {
538                let op = match self.locals[mir::RETURN_PLACE] {
539                    LocalRef::Operand(op) => op,
540                    LocalRef::PendingOperand => bug!("use of return before def"),
541                    LocalRef::Place(cg_place) => {
542                        OperandRef { val: Ref(cg_place.val), layout: cg_place.layout }
543                    }
544                    LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
545                };
546                let llslot = match op.val {
547                    Immediate(_) | Pair(..) => {
548                        let scratch = PlaceRef::alloca(bx, self.fn_abi.ret.layout);
549                        op.val.store(bx, scratch);
550                        scratch.val.llval
551                    }
552                    Ref(place_val) => {
553                        assert_eq!(
554                            place_val.align, op.layout.align.abi,
555                            "return place is unaligned!"
556                        );
557                        place_val.llval
558                    }
559                    ZeroSized => bug!("ZST return value shouldn't be in PassMode::Cast"),
560                };
561                load_cast(bx, cast_ty, llslot, self.fn_abi.ret.layout.align.abi)
562            }
563        };
564        bx.ret(llval);
565    }
566
567    #[tracing::instrument(level = "trace", skip(self, helper, bx))]
568    fn codegen_drop_terminator(
569        &mut self,
570        helper: TerminatorCodegenHelper<'tcx>,
571        bx: &mut Bx,
572        source_info: &mir::SourceInfo,
573        location: mir::Place<'tcx>,
574        target: mir::BasicBlock,
575        unwind: mir::UnwindAction,
576        mergeable_succ: bool,
577    ) -> MergingSucc {
578        let ty = location.ty(self.mir, bx.tcx()).ty;
579        let ty = self.monomorphize(ty);
580        let drop_fn = Instance::resolve_drop_in_place(bx.tcx(), ty);
581
582        if let ty::InstanceKind::DropGlue(_, None) = drop_fn.def {
583            // we don't actually need to drop anything.
584            return helper.funclet_br(self, bx, target, mergeable_succ);
585        }
586
587        let place = self.codegen_place(bx, location.as_ref());
588        let (args1, args2);
589        let mut args = if let Some(llextra) = place.val.llextra {
590            args2 = [place.val.llval, llextra];
591            &args2[..]
592        } else {
593            args1 = [place.val.llval];
594            &args1[..]
595        };
596        let (maybe_null, drop_fn, fn_abi, drop_instance) = match ty.kind() {
597            // FIXME(eddyb) perhaps move some of this logic into
598            // `Instance::resolve_drop_in_place`?
599            ty::Dynamic(_, _, ty::Dyn) => {
600                // IN THIS ARM, WE HAVE:
601                // ty = *mut (dyn Trait)
602                // which is: exists<T> ( *mut T,    Vtable<T: Trait> )
603                //                       args[0]    args[1]
604                //
605                // args = ( Data, Vtable )
606                //                  |
607                //                  v
608                //                /-------\
609                //                | ...   |
610                //                \-------/
611                //
612                let virtual_drop = Instance {
613                    def: ty::InstanceKind::Virtual(drop_fn.def_id(), 0), // idx 0: the drop function
614                    args: drop_fn.args,
615                };
616                debug!("ty = {:?}", ty);
617                debug!("drop_fn = {:?}", drop_fn);
618                debug!("args = {:?}", args);
619                let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
620                let vtable = args[1];
621                // Truncate vtable off of args list
622                args = &args[..1];
623                (
624                    true,
625                    meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
626                        .get_optional_fn(bx, vtable, ty, fn_abi),
627                    fn_abi,
628                    virtual_drop,
629                )
630            }
631            ty::Dynamic(_, _, ty::DynStar) => {
632                // IN THIS ARM, WE HAVE:
633                // ty = *mut (dyn* Trait)
634                // which is: *mut exists<T: sizeof(T) == sizeof(usize)> (T, Vtable<T: Trait>)
635                //
636                // args = [ * ]
637                //          |
638                //          v
639                //      ( Data, Vtable )
640                //                |
641                //                v
642                //              /-------\
643                //              | ...   |
644                //              \-------/
645                //
646                //
647                // WE CAN CONVERT THIS INTO THE ABOVE LOGIC BY DOING
648                //
649                // data = &(*args[0]).0    // gives a pointer to Data above (really the same pointer)
650                // vtable = (*args[0]).1   // loads the vtable out
651                // (data, vtable)          // an equivalent Rust `*mut dyn Trait`
652                //
653                // SO THEN WE CAN USE THE ABOVE CODE.
654                let virtual_drop = Instance {
655                    def: ty::InstanceKind::Virtual(drop_fn.def_id(), 0), // idx 0: the drop function
656                    args: drop_fn.args,
657                };
658                debug!("ty = {:?}", ty);
659                debug!("drop_fn = {:?}", drop_fn);
660                debug!("args = {:?}", args);
661                let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
662                let meta_ptr = place.project_field(bx, 1);
663                let meta = bx.load_operand(meta_ptr);
664                // Truncate vtable off of args list
665                args = &args[..1];
666                debug!("args' = {:?}", args);
667                (
668                    true,
669                    meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
670                        .get_optional_fn(bx, meta.immediate(), ty, fn_abi),
671                    fn_abi,
672                    virtual_drop,
673                )
674            }
675            _ => (
676                false,
677                bx.get_fn_addr(drop_fn),
678                bx.fn_abi_of_instance(drop_fn, ty::List::empty()),
679                drop_fn,
680            ),
681        };
682
683        // We generate a null check for the drop_fn. This saves a bunch of relocations being
684        // generated for no-op drops.
685        if maybe_null {
686            let is_not_null = bx.append_sibling_block("is_not_null");
687            let llty = bx.fn_ptr_backend_type(fn_abi);
688            let null = bx.const_null(llty);
689            let non_null =
690                bx.icmp(base::bin_op_to_icmp_predicate(mir::BinOp::Ne, false), drop_fn, null);
691            bx.cond_br(non_null, is_not_null, helper.llbb_with_cleanup(self, target));
692            bx.switch_to_block(is_not_null);
693            self.set_debug_loc(bx, *source_info);
694        }
695
696        helper.do_call(
697            self,
698            bx,
699            fn_abi,
700            drop_fn,
701            args,
702            Some((ReturnDest::Nothing, target)),
703            unwind,
704            &[],
705            Some(drop_instance),
706            !maybe_null && mergeable_succ,
707        )
708    }
709
710    fn codegen_assert_terminator(
711        &mut self,
712        helper: TerminatorCodegenHelper<'tcx>,
713        bx: &mut Bx,
714        terminator: &mir::Terminator<'tcx>,
715        cond: &mir::Operand<'tcx>,
716        expected: bool,
717        msg: &mir::AssertMessage<'tcx>,
718        target: mir::BasicBlock,
719        unwind: mir::UnwindAction,
720        mergeable_succ: bool,
721    ) -> MergingSucc {
722        let span = terminator.source_info.span;
723        let cond = self.codegen_operand(bx, cond).immediate();
724        let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
725
726        // This case can currently arise only from functions marked
727        // with #[rustc_inherit_overflow_checks] and inlined from
728        // another crate (mostly core::num generic/#[inline] fns),
729        // while the current crate doesn't use overflow checks.
730        if !bx.sess().overflow_checks() && msg.is_optional_overflow_check() {
731            const_cond = Some(expected);
732        }
733
734        // Don't codegen the panic block if success if known.
735        if const_cond == Some(expected) {
736            return helper.funclet_br(self, bx, target, mergeable_succ);
737        }
738
739        // Because we're branching to a panic block (either a `#[cold]` one
740        // or an inlined abort), there's no need to `expect` it.
741
742        // Create the failure block and the conditional branch to it.
743        let lltarget = helper.llbb_with_cleanup(self, target);
744        let panic_block = bx.append_sibling_block("panic");
745        if expected {
746            bx.cond_br(cond, lltarget, panic_block);
747        } else {
748            bx.cond_br(cond, panic_block, lltarget);
749        }
750
751        // After this point, bx is the block for the call to panic.
752        bx.switch_to_block(panic_block);
753        self.set_debug_loc(bx, terminator.source_info);
754
755        // Get the location information.
756        let location = self.get_caller_location(bx, terminator.source_info).immediate();
757
758        // Put together the arguments to the panic entry point.
759        let (lang_item, args) = match msg {
760            AssertKind::BoundsCheck { len, index } => {
761                let len = self.codegen_operand(bx, len).immediate();
762                let index = self.codegen_operand(bx, index).immediate();
763                // It's `fn panic_bounds_check(index: usize, len: usize)`,
764                // and `#[track_caller]` adds an implicit third argument.
765                (LangItem::PanicBoundsCheck, vec![index, len, location])
766            }
767            AssertKind::MisalignedPointerDereference { required, found } => {
768                let required = self.codegen_operand(bx, required).immediate();
769                let found = self.codegen_operand(bx, found).immediate();
770                // It's `fn panic_misaligned_pointer_dereference(required: usize, found: usize)`,
771                // and `#[track_caller]` adds an implicit third argument.
772                (LangItem::PanicMisalignedPointerDereference, vec![required, found, location])
773            }
774            AssertKind::NullPointerDereference => {
775                // It's `fn panic_null_pointer_dereference()`,
776                // `#[track_caller]` adds an implicit argument.
777                (LangItem::PanicNullPointerDereference, vec![location])
778            }
779            AssertKind::InvalidEnumConstruction(source) => {
780                let source = self.codegen_operand(bx, source).immediate();
781                // It's `fn panic_invalid_enum_construction(source: u128)`,
782                // `#[track_caller]` adds an implicit argument.
783                (LangItem::PanicInvalidEnumConstruction, vec![source, location])
784            }
785            _ => {
786                // It's `pub fn panic_...()` and `#[track_caller]` adds an implicit argument.
787                (msg.panic_function(), vec![location])
788            }
789        };
790
791        let (fn_abi, llfn, instance) = common::build_langcall(bx, span, lang_item);
792
793        // Codegen the actual panic invoke/call.
794        let merging_succ =
795            helper.do_call(self, bx, fn_abi, llfn, &args, None, unwind, &[], Some(instance), false);
796        assert_eq!(merging_succ, MergingSucc::False);
797        MergingSucc::False
798    }
799
800    fn codegen_terminate_terminator(
801        &mut self,
802        helper: TerminatorCodegenHelper<'tcx>,
803        bx: &mut Bx,
804        terminator: &mir::Terminator<'tcx>,
805        reason: UnwindTerminateReason,
806    ) {
807        let span = terminator.source_info.span;
808        self.set_debug_loc(bx, terminator.source_info);
809
810        // Obtain the panic entry point.
811        let (fn_abi, llfn, instance) = common::build_langcall(bx, span, reason.lang_item());
812
813        // Codegen the actual panic invoke/call.
814        let merging_succ = helper.do_call(
815            self,
816            bx,
817            fn_abi,
818            llfn,
819            &[],
820            None,
821            mir::UnwindAction::Unreachable,
822            &[],
823            Some(instance),
824            false,
825        );
826        assert_eq!(merging_succ, MergingSucc::False);
827    }
828
829    /// Returns `Some` if this is indeed a panic intrinsic and codegen is done.
830    fn codegen_panic_intrinsic(
831        &mut self,
832        helper: &TerminatorCodegenHelper<'tcx>,
833        bx: &mut Bx,
834        intrinsic: ty::IntrinsicDef,
835        instance: Instance<'tcx>,
836        source_info: mir::SourceInfo,
837        target: Option<mir::BasicBlock>,
838        unwind: mir::UnwindAction,
839        mergeable_succ: bool,
840    ) -> Option<MergingSucc> {
841        // Emit a panic or a no-op for `assert_*` intrinsics.
842        // These are intrinsics that compile to panics so that we can get a message
843        // which mentions the offending type, even from a const context.
844        let Some(requirement) = ValidityRequirement::from_intrinsic(intrinsic.name) else {
845            return None;
846        };
847
848        let ty = instance.args.type_at(0);
849
850        let is_valid = bx
851            .tcx()
852            .check_validity_requirement((requirement, bx.typing_env().as_query_input(ty)))
853            .expect("expect to have layout during codegen");
854
855        if is_valid {
856            // a NOP
857            let target = target.unwrap();
858            return Some(helper.funclet_br(self, bx, target, mergeable_succ));
859        }
860
861        let layout = bx.layout_of(ty);
862
863        let msg_str = with_no_visible_paths!({
864            with_no_trimmed_paths!({
865                if layout.is_uninhabited() {
866                    // Use this error even for the other intrinsics as it is more precise.
867                    format!("attempted to instantiate uninhabited type `{ty}`")
868                } else if requirement == ValidityRequirement::Zero {
869                    format!("attempted to zero-initialize type `{ty}`, which is invalid")
870                } else {
871                    format!("attempted to leave type `{ty}` uninitialized, which is invalid")
872                }
873            })
874        });
875        let msg = bx.const_str(&msg_str);
876
877        // Obtain the panic entry point.
878        let (fn_abi, llfn, instance) =
879            common::build_langcall(bx, source_info.span, LangItem::PanicNounwind);
880
881        // Codegen the actual panic invoke/call.
882        Some(helper.do_call(
883            self,
884            bx,
885            fn_abi,
886            llfn,
887            &[msg.0, msg.1],
888            target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)),
889            unwind,
890            &[],
891            Some(instance),
892            mergeable_succ,
893        ))
894    }
895
896    fn codegen_call_terminator(
897        &mut self,
898        helper: TerminatorCodegenHelper<'tcx>,
899        bx: &mut Bx,
900        terminator: &mir::Terminator<'tcx>,
901        func: &mir::Operand<'tcx>,
902        args: &[Spanned<mir::Operand<'tcx>>],
903        destination: mir::Place<'tcx>,
904        target: Option<mir::BasicBlock>,
905        unwind: mir::UnwindAction,
906        fn_span: Span,
907        mergeable_succ: bool,
908    ) -> MergingSucc {
909        let source_info = mir::SourceInfo { span: fn_span, ..terminator.source_info };
910
911        // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
912        let callee = self.codegen_operand(bx, func);
913
914        let (instance, mut llfn) = match *callee.layout.ty.kind() {
915            ty::FnDef(def_id, generic_args) => {
916                let instance = ty::Instance::expect_resolve(
917                    bx.tcx(),
918                    bx.typing_env(),
919                    def_id,
920                    generic_args,
921                    fn_span,
922                );
923
924                let instance = match instance.def {
925                    // We don't need AsyncDropGlueCtorShim here because it is not `noop func`,
926                    // it is `func returning noop future`
927                    ty::InstanceKind::DropGlue(_, None) => {
928                        // Empty drop glue; a no-op.
929                        let target = target.unwrap();
930                        return helper.funclet_br(self, bx, target, mergeable_succ);
931                    }
932                    ty::InstanceKind::Intrinsic(def_id) => {
933                        let intrinsic = bx.tcx().intrinsic(def_id).unwrap();
934                        if let Some(merging_succ) = self.codegen_panic_intrinsic(
935                            &helper,
936                            bx,
937                            intrinsic,
938                            instance,
939                            source_info,
940                            target,
941                            unwind,
942                            mergeable_succ,
943                        ) {
944                            return merging_succ;
945                        }
946
947                        let result_layout =
948                            self.cx.layout_of(self.monomorphized_place_ty(destination.as_ref()));
949
950                        let (result, store_in_local) = if result_layout.is_zst() {
951                            (
952                                PlaceRef::new_sized(bx.const_undef(bx.type_ptr()), result_layout),
953                                None,
954                            )
955                        } else if let Some(local) = destination.as_local() {
956                            match self.locals[local] {
957                                LocalRef::Place(dest) => (dest, None),
958                                LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
959                                LocalRef::PendingOperand => {
960                                    // Currently, intrinsics always need a location to store
961                                    // the result, so we create a temporary `alloca` for the
962                                    // result.
963                                    let tmp = PlaceRef::alloca(bx, result_layout);
964                                    tmp.storage_live(bx);
965                                    (tmp, Some(local))
966                                }
967                                LocalRef::Operand(_) => {
968                                    bug!("place local already assigned to");
969                                }
970                            }
971                        } else {
972                            (self.codegen_place(bx, destination.as_ref()), None)
973                        };
974
975                        if result.val.align < result.layout.align.abi {
976                            // Currently, MIR code generation does not create calls
977                            // that store directly to fields of packed structs (in
978                            // fact, the calls it creates write only to temps).
979                            //
980                            // If someone changes that, please update this code path
981                            // to create a temporary.
982                            span_bug!(self.mir.span, "can't directly store to unaligned value");
983                        }
984
985                        let args: Vec<_> =
986                            args.iter().map(|arg| self.codegen_operand(bx, &arg.node)).collect();
987
988                        match self.codegen_intrinsic_call(bx, instance, &args, result, source_info)
989                        {
990                            Ok(()) => {
991                                if let Some(local) = store_in_local {
992                                    let op = bx.load_operand(result);
993                                    result.storage_dead(bx);
994                                    self.overwrite_local(local, LocalRef::Operand(op));
995                                    self.debug_introduce_local(bx, local);
996                                }
997
998                                return if let Some(target) = target {
999                                    helper.funclet_br(self, bx, target, mergeable_succ)
1000                                } else {
1001                                    bx.unreachable();
1002                                    MergingSucc::False
1003                                };
1004                            }
1005                            Err(instance) => {
1006                                if intrinsic.must_be_overridden {
1007                                    span_bug!(
1008                                        fn_span,
1009                                        "intrinsic {} must be overridden by codegen backend, but isn't",
1010                                        intrinsic.name,
1011                                    );
1012                                }
1013                                instance
1014                            }
1015                        }
1016                    }
1017                    _ => instance,
1018                };
1019
1020                (Some(instance), None)
1021            }
1022            ty::FnPtr(..) => (None, Some(callee.immediate())),
1023            _ => bug!("{} is not callable", callee.layout.ty),
1024        };
1025
1026        // FIXME(eddyb) avoid computing this if possible, when `instance` is
1027        // available - right now `sig` is only needed for getting the `abi`
1028        // and figuring out how many extra args were passed to a C-variadic `fn`.
1029        let sig = callee.layout.ty.fn_sig(bx.tcx());
1030
1031        let extra_args = &args[sig.inputs().skip_binder().len()..];
1032        let extra_args = bx.tcx().mk_type_list_from_iter(extra_args.iter().map(|op_arg| {
1033            let op_ty = op_arg.node.ty(self.mir, bx.tcx());
1034            self.monomorphize(op_ty)
1035        }));
1036
1037        let fn_abi = match instance {
1038            Some(instance) => bx.fn_abi_of_instance(instance, extra_args),
1039            None => bx.fn_abi_of_fn_ptr(sig, extra_args),
1040        };
1041
1042        // The arguments we'll be passing. Plus one to account for outptr, if used.
1043        let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
1044
1045        let mut llargs = Vec::with_capacity(arg_count);
1046
1047        // We still need to call `make_return_dest` even if there's no `target`, since
1048        // `fn_abi.ret` could be `PassMode::Indirect`, even if it is uninhabited,
1049        // and `make_return_dest` adds the return-place indirect pointer to `llargs`.
1050        let return_dest = self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs);
1051        let destination = target.map(|target| (return_dest, target));
1052
1053        // Split the rust-call tupled arguments off.
1054        let (first_args, untuple) = if sig.abi() == ExternAbi::RustCall
1055            && let Some((tup, args)) = args.split_last()
1056        {
1057            (args, Some(tup))
1058        } else {
1059            (args, None)
1060        };
1061
1062        // When generating arguments we sometimes introduce temporary allocations with lifetime
1063        // that extend for the duration of a call. Keep track of those allocations and their sizes
1064        // to generate `lifetime_end` when the call returns.
1065        let mut lifetime_ends_after_call: Vec<(Bx::Value, Size)> = Vec::new();
1066        'make_args: for (i, arg) in first_args.iter().enumerate() {
1067            let mut op = self.codegen_operand(bx, &arg.node);
1068
1069            if let (0, Some(ty::InstanceKind::Virtual(_, idx))) = (i, instance.map(|i| i.def)) {
1070                match op.val {
1071                    Pair(data_ptr, meta) => {
1072                        // In the case of Rc<Self>, we need to explicitly pass a
1073                        // *mut RcInner<Self> with a Scalar (not ScalarPair) ABI. This is a hack
1074                        // that is understood elsewhere in the compiler as a method on
1075                        // `dyn Trait`.
1076                        // To get a `*mut RcInner<Self>`, we just keep unwrapping newtypes until
1077                        // we get a value of a built-in pointer type.
1078                        //
1079                        // This is also relevant for `Pin<&mut Self>`, where we need to peel the
1080                        // `Pin`.
1081                        while !op.layout.ty.is_raw_ptr() && !op.layout.ty.is_ref() {
1082                            let (idx, _) = op.layout.non_1zst_field(bx).expect(
1083                                "not exactly one non-1-ZST field in a `DispatchFromDyn` type",
1084                            );
1085                            op = op.extract_field(self, bx, idx.as_usize());
1086                        }
1087
1088                        // Now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
1089                        // data pointer and vtable. Look up the method in the vtable, and pass
1090                        // the data pointer as the first argument.
1091                        llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
1092                            bx,
1093                            meta,
1094                            op.layout.ty,
1095                            fn_abi,
1096                        ));
1097                        llargs.push(data_ptr);
1098                        continue 'make_args;
1099                    }
1100                    Ref(PlaceValue { llval: data_ptr, llextra: Some(meta), .. }) => {
1101                        // by-value dynamic dispatch
1102                        llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
1103                            bx,
1104                            meta,
1105                            op.layout.ty,
1106                            fn_abi,
1107                        ));
1108                        llargs.push(data_ptr);
1109                        continue;
1110                    }
1111                    Immediate(_) => {
1112                        // See comment above explaining why we peel these newtypes
1113                        while !op.layout.ty.is_raw_ptr() && !op.layout.ty.is_ref() {
1114                            let (idx, _) = op.layout.non_1zst_field(bx).expect(
1115                                "not exactly one non-1-ZST field in a `DispatchFromDyn` type",
1116                            );
1117                            op = op.extract_field(self, bx, idx.as_usize());
1118                        }
1119
1120                        // Make sure that we've actually unwrapped the rcvr down
1121                        // to a pointer or ref to `dyn* Trait`.
1122                        if !op.layout.ty.builtin_deref(true).unwrap().is_dyn_star() {
1123                            span_bug!(fn_span, "can't codegen a virtual call on {:#?}", op);
1124                        }
1125                        let place = op.deref(bx.cx());
1126                        let data_place = place.project_field(bx, 0);
1127                        let meta_place = place.project_field(bx, 1);
1128                        let meta = bx.load_operand(meta_place);
1129                        llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
1130                            bx,
1131                            meta.immediate(),
1132                            op.layout.ty,
1133                            fn_abi,
1134                        ));
1135                        llargs.push(data_place.val.llval);
1136                        continue;
1137                    }
1138                    _ => {
1139                        span_bug!(fn_span, "can't codegen a virtual call on {:#?}", op);
1140                    }
1141                }
1142            }
1143
1144            // The callee needs to own the argument memory if we pass it
1145            // by-ref, so make a local copy of non-immediate constants.
1146            match (&arg.node, op.val) {
1147                (&mir::Operand::Copy(_), Ref(PlaceValue { llextra: None, .. }))
1148                | (&mir::Operand::Constant(_), Ref(PlaceValue { llextra: None, .. })) => {
1149                    let tmp = PlaceRef::alloca(bx, op.layout);
1150                    bx.lifetime_start(tmp.val.llval, tmp.layout.size);
1151                    op.val.store(bx, tmp);
1152                    op.val = Ref(tmp.val);
1153                    lifetime_ends_after_call.push((tmp.val.llval, tmp.layout.size));
1154                }
1155                _ => {}
1156            }
1157
1158            self.codegen_argument(
1159                bx,
1160                op,
1161                &mut llargs,
1162                &fn_abi.args[i],
1163                &mut lifetime_ends_after_call,
1164            );
1165        }
1166        let num_untupled = untuple.map(|tup| {
1167            self.codegen_arguments_untupled(
1168                bx,
1169                &tup.node,
1170                &mut llargs,
1171                &fn_abi.args[first_args.len()..],
1172                &mut lifetime_ends_after_call,
1173            )
1174        });
1175
1176        let needs_location =
1177            instance.is_some_and(|i| i.def.requires_caller_location(self.cx.tcx()));
1178        if needs_location {
1179            let mir_args = if let Some(num_untupled) = num_untupled {
1180                first_args.len() + num_untupled
1181            } else {
1182                args.len()
1183            };
1184            assert_eq!(
1185                fn_abi.args.len(),
1186                mir_args + 1,
1187                "#[track_caller] fn's must have 1 more argument in their ABI than in their MIR: {instance:?} {fn_span:?} {fn_abi:?}",
1188            );
1189            let location = self.get_caller_location(bx, source_info);
1190            debug!(
1191                "codegen_call_terminator({:?}): location={:?} (fn_span {:?})",
1192                terminator, location, fn_span
1193            );
1194
1195            let last_arg = fn_abi.args.last().unwrap();
1196            self.codegen_argument(
1197                bx,
1198                location,
1199                &mut llargs,
1200                last_arg,
1201                &mut lifetime_ends_after_call,
1202            );
1203        }
1204
1205        let fn_ptr = match (instance, llfn) {
1206            (Some(instance), None) => bx.get_fn_addr(instance),
1207            (_, Some(llfn)) => llfn,
1208            _ => span_bug!(fn_span, "no instance or llfn for call"),
1209        };
1210        self.set_debug_loc(bx, source_info);
1211        helper.do_call(
1212            self,
1213            bx,
1214            fn_abi,
1215            fn_ptr,
1216            &llargs,
1217            destination,
1218            unwind,
1219            &lifetime_ends_after_call,
1220            instance,
1221            mergeable_succ,
1222        )
1223    }
1224
1225    fn codegen_asm_terminator(
1226        &mut self,
1227        helper: TerminatorCodegenHelper<'tcx>,
1228        bx: &mut Bx,
1229        asm_macro: InlineAsmMacro,
1230        terminator: &mir::Terminator<'tcx>,
1231        template: &[ast::InlineAsmTemplatePiece],
1232        operands: &[mir::InlineAsmOperand<'tcx>],
1233        options: ast::InlineAsmOptions,
1234        line_spans: &[Span],
1235        targets: &[mir::BasicBlock],
1236        unwind: mir::UnwindAction,
1237        instance: Instance<'_>,
1238        mergeable_succ: bool,
1239    ) -> MergingSucc {
1240        let span = terminator.source_info.span;
1241
1242        let operands: Vec<_> = operands
1243            .iter()
1244            .map(|op| match *op {
1245                mir::InlineAsmOperand::In { reg, ref value } => {
1246                    let value = self.codegen_operand(bx, value);
1247                    InlineAsmOperandRef::In { reg, value }
1248                }
1249                mir::InlineAsmOperand::Out { reg, late, ref place } => {
1250                    let place = place.map(|place| self.codegen_place(bx, place.as_ref()));
1251                    InlineAsmOperandRef::Out { reg, late, place }
1252                }
1253                mir::InlineAsmOperand::InOut { reg, late, ref in_value, ref out_place } => {
1254                    let in_value = self.codegen_operand(bx, in_value);
1255                    let out_place =
1256                        out_place.map(|out_place| self.codegen_place(bx, out_place.as_ref()));
1257                    InlineAsmOperandRef::InOut { reg, late, in_value, out_place }
1258                }
1259                mir::InlineAsmOperand::Const { ref value } => {
1260                    let const_value = self.eval_mir_constant(value);
1261                    let string = common::asm_const_to_str(
1262                        bx.tcx(),
1263                        span,
1264                        const_value,
1265                        bx.layout_of(value.ty()),
1266                    );
1267                    InlineAsmOperandRef::Const { string }
1268                }
1269                mir::InlineAsmOperand::SymFn { ref value } => {
1270                    let const_ = self.monomorphize(value.const_);
1271                    if let ty::FnDef(def_id, args) = *const_.ty().kind() {
1272                        let instance = ty::Instance::resolve_for_fn_ptr(
1273                            bx.tcx(),
1274                            bx.typing_env(),
1275                            def_id,
1276                            args,
1277                        )
1278                        .unwrap();
1279                        InlineAsmOperandRef::SymFn { instance }
1280                    } else {
1281                        span_bug!(span, "invalid type for asm sym (fn)");
1282                    }
1283                }
1284                mir::InlineAsmOperand::SymStatic { def_id } => {
1285                    InlineAsmOperandRef::SymStatic { def_id }
1286                }
1287                mir::InlineAsmOperand::Label { target_index } => {
1288                    InlineAsmOperandRef::Label { label: self.llbb(targets[target_index]) }
1289                }
1290            })
1291            .collect();
1292
1293        helper.do_inlineasm(
1294            self,
1295            bx,
1296            template,
1297            &operands,
1298            options,
1299            line_spans,
1300            if asm_macro.diverges(options) { None } else { targets.get(0).copied() },
1301            unwind,
1302            instance,
1303            mergeable_succ,
1304        )
1305    }
1306
1307    pub(crate) fn codegen_block(&mut self, mut bb: mir::BasicBlock) {
1308        let llbb = match self.try_llbb(bb) {
1309            Some(llbb) => llbb,
1310            None => return,
1311        };
1312        let bx = &mut Bx::build(self.cx, llbb);
1313        let mir = self.mir;
1314
1315        // MIR basic blocks stop at any function call. This may not be the case
1316        // for the backend's basic blocks, in which case we might be able to
1317        // combine multiple MIR basic blocks into a single backend basic block.
1318        loop {
1319            let data = &mir[bb];
1320
1321            debug!("codegen_block({:?}={:?})", bb, data);
1322
1323            for statement in &data.statements {
1324                self.codegen_statement(bx, statement);
1325            }
1326
1327            let merging_succ = self.codegen_terminator(bx, bb, data.terminator());
1328            if let MergingSucc::False = merging_succ {
1329                break;
1330            }
1331
1332            // We are merging the successor into the produced backend basic
1333            // block. Record that the successor should be skipped when it is
1334            // reached.
1335            //
1336            // Note: we must not have already generated code for the successor.
1337            // This is implicitly ensured by the reverse postorder traversal,
1338            // and the assertion explicitly guarantees that.
1339            let mut successors = data.terminator().successors();
1340            let succ = successors.next().unwrap();
1341            assert!(matches!(self.cached_llbbs[succ], CachedLlbb::None));
1342            self.cached_llbbs[succ] = CachedLlbb::Skip;
1343            bb = succ;
1344        }
1345    }
1346
1347    pub(crate) fn codegen_block_as_unreachable(&mut self, bb: mir::BasicBlock) {
1348        let llbb = match self.try_llbb(bb) {
1349            Some(llbb) => llbb,
1350            None => return,
1351        };
1352        let bx = &mut Bx::build(self.cx, llbb);
1353        debug!("codegen_block_as_unreachable({:?})", bb);
1354        bx.unreachable();
1355    }
1356
1357    fn codegen_terminator(
1358        &mut self,
1359        bx: &mut Bx,
1360        bb: mir::BasicBlock,
1361        terminator: &'tcx mir::Terminator<'tcx>,
1362    ) -> MergingSucc {
1363        debug!("codegen_terminator: {:?}", terminator);
1364
1365        let helper = TerminatorCodegenHelper { bb, terminator };
1366
1367        let mergeable_succ = || {
1368            // Note: any call to `switch_to_block` will invalidate a `true` value
1369            // of `mergeable_succ`.
1370            let mut successors = terminator.successors();
1371            if let Some(succ) = successors.next()
1372                && successors.next().is_none()
1373                && let &[succ_pred] = self.mir.basic_blocks.predecessors()[succ].as_slice()
1374            {
1375                // bb has a single successor, and bb is its only predecessor. This
1376                // makes it a candidate for merging.
1377                assert_eq!(succ_pred, bb);
1378                true
1379            } else {
1380                false
1381            }
1382        };
1383
1384        self.set_debug_loc(bx, terminator.source_info);
1385        match terminator.kind {
1386            mir::TerminatorKind::UnwindResume => {
1387                self.codegen_resume_terminator(helper, bx);
1388                MergingSucc::False
1389            }
1390
1391            mir::TerminatorKind::UnwindTerminate(reason) => {
1392                self.codegen_terminate_terminator(helper, bx, terminator, reason);
1393                MergingSucc::False
1394            }
1395
1396            mir::TerminatorKind::Goto { target } => {
1397                helper.funclet_br(self, bx, target, mergeable_succ())
1398            }
1399
1400            mir::TerminatorKind::SwitchInt { ref discr, ref targets } => {
1401                self.codegen_switchint_terminator(helper, bx, discr, targets);
1402                MergingSucc::False
1403            }
1404
1405            mir::TerminatorKind::Return => {
1406                self.codegen_return_terminator(bx);
1407                MergingSucc::False
1408            }
1409
1410            mir::TerminatorKind::Unreachable => {
1411                bx.unreachable();
1412                MergingSucc::False
1413            }
1414
1415            mir::TerminatorKind::Drop { place, target, unwind, replace: _, drop, async_fut } => {
1416                assert!(
1417                    async_fut.is_none() && drop.is_none(),
1418                    "Async Drop must be expanded or reset to sync before codegen"
1419                );
1420                self.codegen_drop_terminator(
1421                    helper,
1422                    bx,
1423                    &terminator.source_info,
1424                    place,
1425                    target,
1426                    unwind,
1427                    mergeable_succ(),
1428                )
1429            }
1430
1431            mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, unwind } => self
1432                .codegen_assert_terminator(
1433                    helper,
1434                    bx,
1435                    terminator,
1436                    cond,
1437                    expected,
1438                    msg,
1439                    target,
1440                    unwind,
1441                    mergeable_succ(),
1442                ),
1443
1444            mir::TerminatorKind::Call {
1445                ref func,
1446                ref args,
1447                destination,
1448                target,
1449                unwind,
1450                call_source: _,
1451                fn_span,
1452            } => self.codegen_call_terminator(
1453                helper,
1454                bx,
1455                terminator,
1456                func,
1457                args,
1458                destination,
1459                target,
1460                unwind,
1461                fn_span,
1462                mergeable_succ(),
1463            ),
1464            mir::TerminatorKind::TailCall { .. } => {
1465                // FIXME(explicit_tail_calls): implement tail calls in ssa backend
1466                span_bug!(
1467                    terminator.source_info.span,
1468                    "`TailCall` terminator is not yet supported by `rustc_codegen_ssa`"
1469                )
1470            }
1471            mir::TerminatorKind::CoroutineDrop | mir::TerminatorKind::Yield { .. } => {
1472                bug!("coroutine ops in codegen")
1473            }
1474            mir::TerminatorKind::FalseEdge { .. } | mir::TerminatorKind::FalseUnwind { .. } => {
1475                bug!("borrowck false edges in codegen")
1476            }
1477
1478            mir::TerminatorKind::InlineAsm {
1479                asm_macro,
1480                template,
1481                ref operands,
1482                options,
1483                line_spans,
1484                ref targets,
1485                unwind,
1486            } => self.codegen_asm_terminator(
1487                helper,
1488                bx,
1489                asm_macro,
1490                terminator,
1491                template,
1492                operands,
1493                options,
1494                line_spans,
1495                targets,
1496                unwind,
1497                self.instance,
1498                mergeable_succ(),
1499            ),
1500        }
1501    }
1502
1503    fn codegen_argument(
1504        &mut self,
1505        bx: &mut Bx,
1506        op: OperandRef<'tcx, Bx::Value>,
1507        llargs: &mut Vec<Bx::Value>,
1508        arg: &ArgAbi<'tcx, Ty<'tcx>>,
1509        lifetime_ends_after_call: &mut Vec<(Bx::Value, Size)>,
1510    ) {
1511        match arg.mode {
1512            PassMode::Ignore => return,
1513            PassMode::Cast { pad_i32: true, .. } => {
1514                // Fill padding with undef value, where applicable.
1515                llargs.push(bx.const_undef(bx.reg_backend_type(&Reg::i32())));
1516            }
1517            PassMode::Pair(..) => match op.val {
1518                Pair(a, b) => {
1519                    llargs.push(a);
1520                    llargs.push(b);
1521                    return;
1522                }
1523                _ => bug!("codegen_argument: {:?} invalid for pair argument", op),
1524            },
1525            PassMode::Indirect { attrs: _, meta_attrs: Some(_), on_stack: _ } => match op.val {
1526                Ref(PlaceValue { llval: a, llextra: Some(b), .. }) => {
1527                    llargs.push(a);
1528                    llargs.push(b);
1529                    return;
1530                }
1531                _ => bug!("codegen_argument: {:?} invalid for unsized indirect argument", op),
1532            },
1533            _ => {}
1534        }
1535
1536        // Force by-ref if we have to load through a cast pointer.
1537        let (mut llval, align, by_ref) = match op.val {
1538            Immediate(_) | Pair(..) => match arg.mode {
1539                PassMode::Indirect { attrs, .. } => {
1540                    // Indirect argument may have higher alignment requirements than the type's
1541                    // alignment. This can happen, e.g. when passing types with <4 byte alignment
1542                    // on the stack on x86.
1543                    let required_align = match attrs.pointee_align {
1544                        Some(pointee_align) => cmp::max(pointee_align, arg.layout.align.abi),
1545                        None => arg.layout.align.abi,
1546                    };
1547                    let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
1548                    bx.lifetime_start(scratch.llval, arg.layout.size);
1549                    op.val.store(bx, scratch.with_type(arg.layout));
1550                    lifetime_ends_after_call.push((scratch.llval, arg.layout.size));
1551                    (scratch.llval, scratch.align, true)
1552                }
1553                PassMode::Cast { .. } => {
1554                    let scratch = PlaceRef::alloca(bx, arg.layout);
1555                    op.val.store(bx, scratch);
1556                    (scratch.val.llval, scratch.val.align, true)
1557                }
1558                _ => (op.immediate_or_packed_pair(bx), arg.layout.align.abi, false),
1559            },
1560            Ref(op_place_val) => match arg.mode {
1561                PassMode::Indirect { attrs, .. } => {
1562                    let required_align = match attrs.pointee_align {
1563                        Some(pointee_align) => cmp::max(pointee_align, arg.layout.align.abi),
1564                        None => arg.layout.align.abi,
1565                    };
1566                    if op_place_val.align < required_align {
1567                        // For `foo(packed.large_field)`, and types with <4 byte alignment on x86,
1568                        // alignment requirements may be higher than the type's alignment, so copy
1569                        // to a higher-aligned alloca.
1570                        let scratch = PlaceValue::alloca(bx, arg.layout.size, required_align);
1571                        bx.lifetime_start(scratch.llval, arg.layout.size);
1572                        bx.typed_place_copy(scratch, op_place_val, op.layout);
1573                        lifetime_ends_after_call.push((scratch.llval, arg.layout.size));
1574                        (scratch.llval, scratch.align, true)
1575                    } else {
1576                        (op_place_val.llval, op_place_val.align, true)
1577                    }
1578                }
1579                _ => (op_place_val.llval, op_place_val.align, true),
1580            },
1581            ZeroSized => match arg.mode {
1582                PassMode::Indirect { on_stack, .. } => {
1583                    if on_stack {
1584                        // It doesn't seem like any target can have `byval` ZSTs, so this assert
1585                        // is here to replace a would-be untested codepath.
1586                        bug!("ZST {op:?} passed on stack with abi {arg:?}");
1587                    }
1588                    // Though `extern "Rust"` doesn't pass ZSTs, some ABIs pass
1589                    // a pointer for `repr(C)` structs even when empty, so get
1590                    // one from an `alloca` (which can be left uninitialized).
1591                    let scratch = PlaceRef::alloca(bx, arg.layout);
1592                    (scratch.val.llval, scratch.val.align, true)
1593                }
1594                _ => bug!("ZST {op:?} wasn't ignored, but was passed with abi {arg:?}"),
1595            },
1596        };
1597
1598        if by_ref && !arg.is_indirect() {
1599            // Have to load the argument, maybe while casting it.
1600            if let PassMode::Cast { cast, pad_i32: _ } = &arg.mode {
1601                // The ABI mandates that the value is passed as a different struct representation.
1602                // Spill and reload it from the stack to convert from the Rust representation to
1603                // the ABI representation.
1604                let scratch_size = cast.size(bx);
1605                let scratch_align = cast.align(bx);
1606                // Note that the ABI type may be either larger or smaller than the Rust type,
1607                // due to the presence or absence of trailing padding. For example:
1608                // - On some ABIs, the Rust layout { f64, f32, <f32 padding> } may omit padding
1609                //   when passed by value, making it smaller.
1610                // - On some ABIs, the Rust layout { u16, u16, u16 } may be padded up to 8 bytes
1611                //   when passed by value, making it larger.
1612                let copy_bytes = cmp::min(cast.unaligned_size(bx).bytes(), arg.layout.size.bytes());
1613                // Allocate some scratch space...
1614                let llscratch = bx.alloca(scratch_size, scratch_align);
1615                bx.lifetime_start(llscratch, scratch_size);
1616                // ...memcpy the value...
1617                bx.memcpy(
1618                    llscratch,
1619                    scratch_align,
1620                    llval,
1621                    align,
1622                    bx.const_usize(copy_bytes),
1623                    MemFlags::empty(),
1624                );
1625                // ...and then load it with the ABI type.
1626                llval = load_cast(bx, cast, llscratch, scratch_align);
1627                bx.lifetime_end(llscratch, scratch_size);
1628            } else {
1629                // We can't use `PlaceRef::load` here because the argument
1630                // may have a type we don't treat as immediate, but the ABI
1631                // used for this call is passing it by-value. In that case,
1632                // the load would just produce `OperandValue::Ref` instead
1633                // of the `OperandValue::Immediate` we need for the call.
1634                llval = bx.load(bx.backend_type(arg.layout), llval, align);
1635                if let BackendRepr::Scalar(scalar) = arg.layout.backend_repr {
1636                    if scalar.is_bool() {
1637                        bx.range_metadata(llval, WrappingRange { start: 0, end: 1 });
1638                    }
1639                    // We store bools as `i8` so we need to truncate to `i1`.
1640                    llval = bx.to_immediate_scalar(llval, scalar);
1641                }
1642            }
1643        }
1644
1645        llargs.push(llval);
1646    }
1647
1648    fn codegen_arguments_untupled(
1649        &mut self,
1650        bx: &mut Bx,
1651        operand: &mir::Operand<'tcx>,
1652        llargs: &mut Vec<Bx::Value>,
1653        args: &[ArgAbi<'tcx, Ty<'tcx>>],
1654        lifetime_ends_after_call: &mut Vec<(Bx::Value, Size)>,
1655    ) -> usize {
1656        let tuple = self.codegen_operand(bx, operand);
1657
1658        // Handle both by-ref and immediate tuples.
1659        if let Ref(place_val) = tuple.val {
1660            if place_val.llextra.is_some() {
1661                bug!("closure arguments must be sized");
1662            }
1663            let tuple_ptr = place_val.with_type(tuple.layout);
1664            for i in 0..tuple.layout.fields.count() {
1665                let field_ptr = tuple_ptr.project_field(bx, i);
1666                let field = bx.load_operand(field_ptr);
1667                self.codegen_argument(bx, field, llargs, &args[i], lifetime_ends_after_call);
1668            }
1669        } else {
1670            // If the tuple is immediate, the elements are as well.
1671            for i in 0..tuple.layout.fields.count() {
1672                let op = tuple.extract_field(self, bx, i);
1673                self.codegen_argument(bx, op, llargs, &args[i], lifetime_ends_after_call);
1674            }
1675        }
1676        tuple.layout.fields.count()
1677    }
1678
1679    pub(super) fn get_caller_location(
1680        &mut self,
1681        bx: &mut Bx,
1682        source_info: mir::SourceInfo,
1683    ) -> OperandRef<'tcx, Bx::Value> {
1684        self.mir.caller_location_span(source_info, self.caller_location, bx.tcx(), |span: Span| {
1685            let const_loc = bx.tcx().span_as_caller_location(span);
1686            OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
1687        })
1688    }
1689
1690    fn get_personality_slot(&mut self, bx: &mut Bx) -> PlaceRef<'tcx, Bx::Value> {
1691        let cx = bx.cx();
1692        if let Some(slot) = self.personality_slot {
1693            slot
1694        } else {
1695            let layout = cx.layout_of(Ty::new_tup(
1696                cx.tcx(),
1697                &[Ty::new_mut_ptr(cx.tcx(), cx.tcx().types.u8), cx.tcx().types.i32],
1698            ));
1699            let slot = PlaceRef::alloca(bx, layout);
1700            self.personality_slot = Some(slot);
1701            slot
1702        }
1703    }
1704
1705    /// Returns the landing/cleanup pad wrapper around the given basic block.
1706    // FIXME(eddyb) rename this to `eh_pad_for`.
1707    fn landing_pad_for(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1708        if let Some(landing_pad) = self.landing_pads[bb] {
1709            return landing_pad;
1710        }
1711
1712        let landing_pad = self.landing_pad_for_uncached(bb);
1713        self.landing_pads[bb] = Some(landing_pad);
1714        landing_pad
1715    }
1716
1717    // FIXME(eddyb) rename this to `eh_pad_for_uncached`.
1718    fn landing_pad_for_uncached(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1719        let llbb = self.llbb(bb);
1720        if base::wants_new_eh_instructions(self.cx.sess()) {
1721            let cleanup_bb = Bx::append_block(self.cx, self.llfn, &format!("funclet_{bb:?}"));
1722            let mut cleanup_bx = Bx::build(self.cx, cleanup_bb);
1723            let funclet = cleanup_bx.cleanup_pad(None, &[]);
1724            cleanup_bx.br(llbb);
1725            self.funclets[bb] = Some(funclet);
1726            cleanup_bb
1727        } else {
1728            let cleanup_llbb = Bx::append_block(self.cx, self.llfn, "cleanup");
1729            let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
1730
1731            let llpersonality = self.cx.eh_personality();
1732            let (exn0, exn1) = cleanup_bx.cleanup_landing_pad(llpersonality);
1733
1734            let slot = self.get_personality_slot(&mut cleanup_bx);
1735            slot.storage_live(&mut cleanup_bx);
1736            Pair(exn0, exn1).store(&mut cleanup_bx, slot);
1737
1738            cleanup_bx.br(llbb);
1739            cleanup_llbb
1740        }
1741    }
1742
1743    fn unreachable_block(&mut self) -> Bx::BasicBlock {
1744        self.unreachable_block.unwrap_or_else(|| {
1745            let llbb = Bx::append_block(self.cx, self.llfn, "unreachable");
1746            let mut bx = Bx::build(self.cx, llbb);
1747            bx.unreachable();
1748            self.unreachable_block = Some(llbb);
1749            llbb
1750        })
1751    }
1752
1753    fn terminate_block(&mut self, reason: UnwindTerminateReason) -> Bx::BasicBlock {
1754        if let Some((cached_bb, cached_reason)) = self.terminate_block
1755            && reason == cached_reason
1756        {
1757            return cached_bb;
1758        }
1759
1760        let funclet;
1761        let llbb;
1762        let mut bx;
1763        if base::wants_new_eh_instructions(self.cx.sess()) {
1764            // This is a basic block that we're aborting the program for,
1765            // notably in an `extern` function. These basic blocks are inserted
1766            // so that we assert that `extern` functions do indeed not panic,
1767            // and if they do we abort the process.
1768            //
1769            // On MSVC these are tricky though (where we're doing funclets). If
1770            // we were to do a cleanuppad (like below) the normal functions like
1771            // `longjmp` would trigger the abort logic, terminating the
1772            // program. Instead we insert the equivalent of `catch(...)` for C++
1773            // which magically doesn't trigger when `longjmp` files over this
1774            // frame.
1775            //
1776            // Lots more discussion can be found on #48251 but this codegen is
1777            // modeled after clang's for:
1778            //
1779            //      try {
1780            //          foo();
1781            //      } catch (...) {
1782            //          bar();
1783            //      }
1784            //
1785            // which creates an IR snippet like
1786            //
1787            //      cs_terminate:
1788            //         %cs = catchswitch within none [%cp_terminate] unwind to caller
1789            //      cp_terminate:
1790            //         %cp = catchpad within %cs [null, i32 64, null]
1791            //         ...
1792
1793            llbb = Bx::append_block(self.cx, self.llfn, "cs_terminate");
1794            let cp_llbb = Bx::append_block(self.cx, self.llfn, "cp_terminate");
1795
1796            let mut cs_bx = Bx::build(self.cx, llbb);
1797            let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
1798
1799            bx = Bx::build(self.cx, cp_llbb);
1800            let null =
1801                bx.const_null(bx.type_ptr_ext(bx.cx().data_layout().instruction_address_space));
1802
1803            // The `null` in first argument here is actually a RTTI type
1804            // descriptor for the C++ personality function, but `catch (...)`
1805            // has no type so it's null.
1806            let args = if base::wants_msvc_seh(self.cx.sess()) {
1807                // This bitmask is a single `HT_IsStdDotDot` flag, which
1808                // represents that this is a C++-style `catch (...)` block that
1809                // only captures programmatic exceptions, not all SEH
1810                // exceptions. The second `null` points to a non-existent
1811                // `alloca` instruction, which an LLVM pass would inline into
1812                // the initial SEH frame allocation.
1813                let adjectives = bx.const_i32(0x40);
1814                &[null, adjectives, null] as &[_]
1815            } else {
1816                // Specifying more arguments than necessary usually doesn't
1817                // hurt, but the `WasmEHPrepare` LLVM pass does not recognize
1818                // anything other than a single `null` as a `catch (...)` block,
1819                // leading to problems down the line during instruction
1820                // selection.
1821                &[null] as &[_]
1822            };
1823
1824            funclet = Some(bx.catch_pad(cs, args));
1825        } else {
1826            llbb = Bx::append_block(self.cx, self.llfn, "terminate");
1827            bx = Bx::build(self.cx, llbb);
1828
1829            let llpersonality = self.cx.eh_personality();
1830            bx.filter_landing_pad(llpersonality);
1831
1832            funclet = None;
1833        }
1834
1835        self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
1836
1837        let (fn_abi, fn_ptr, instance) =
1838            common::build_langcall(&bx, self.mir.span, reason.lang_item());
1839        if is_call_from_compiler_builtins_to_upstream_monomorphization(bx.tcx(), instance) {
1840            bx.abort();
1841        } else {
1842            let fn_ty = bx.fn_decl_backend_type(fn_abi);
1843
1844            let llret = bx.call(fn_ty, None, Some(fn_abi), fn_ptr, &[], funclet.as_ref(), None);
1845            bx.apply_attrs_to_cleanup_callsite(llret);
1846        }
1847
1848        bx.unreachable();
1849
1850        self.terminate_block = Some((llbb, reason));
1851        llbb
1852    }
1853
1854    /// Get the backend `BasicBlock` for a MIR `BasicBlock`, either already
1855    /// cached in `self.cached_llbbs`, or created on demand (and cached).
1856    // FIXME(eddyb) rename `llbb` and other `ll`-prefixed things to use a
1857    // more backend-agnostic prefix such as `cg` (i.e. this would be `cgbb`).
1858    pub fn llbb(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1859        self.try_llbb(bb).unwrap()
1860    }
1861
1862    /// Like `llbb`, but may fail if the basic block should be skipped.
1863    pub(crate) fn try_llbb(&mut self, bb: mir::BasicBlock) -> Option<Bx::BasicBlock> {
1864        match self.cached_llbbs[bb] {
1865            CachedLlbb::None => {
1866                let llbb = Bx::append_block(self.cx, self.llfn, &format!("{bb:?}"));
1867                self.cached_llbbs[bb] = CachedLlbb::Some(llbb);
1868                Some(llbb)
1869            }
1870            CachedLlbb::Some(llbb) => Some(llbb),
1871            CachedLlbb::Skip => None,
1872        }
1873    }
1874
1875    fn make_return_dest(
1876        &mut self,
1877        bx: &mut Bx,
1878        dest: mir::Place<'tcx>,
1879        fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
1880        llargs: &mut Vec<Bx::Value>,
1881    ) -> ReturnDest<'tcx, Bx::Value> {
1882        // If the return is ignored, we can just return a do-nothing `ReturnDest`.
1883        if fn_ret.is_ignore() {
1884            return ReturnDest::Nothing;
1885        }
1886        let dest = if let Some(index) = dest.as_local() {
1887            match self.locals[index] {
1888                LocalRef::Place(dest) => dest,
1889                LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
1890                LocalRef::PendingOperand => {
1891                    // Handle temporary places, specifically `Operand` ones, as
1892                    // they don't have `alloca`s.
1893                    return if fn_ret.is_indirect() {
1894                        // Odd, but possible, case, we have an operand temporary,
1895                        // but the calling convention has an indirect return.
1896                        let tmp = PlaceRef::alloca(bx, fn_ret.layout);
1897                        tmp.storage_live(bx);
1898                        llargs.push(tmp.val.llval);
1899                        ReturnDest::IndirectOperand(tmp, index)
1900                    } else {
1901                        ReturnDest::DirectOperand(index)
1902                    };
1903                }
1904                LocalRef::Operand(_) => {
1905                    bug!("place local already assigned to");
1906                }
1907            }
1908        } else {
1909            self.codegen_place(bx, dest.as_ref())
1910        };
1911        if fn_ret.is_indirect() {
1912            if dest.val.align < dest.layout.align.abi {
1913                // Currently, MIR code generation does not create calls
1914                // that store directly to fields of packed structs (in
1915                // fact, the calls it creates write only to temps).
1916                //
1917                // If someone changes that, please update this code path
1918                // to create a temporary.
1919                span_bug!(self.mir.span, "can't directly store to unaligned value");
1920            }
1921            llargs.push(dest.val.llval);
1922            ReturnDest::Nothing
1923        } else {
1924            ReturnDest::Store(dest)
1925        }
1926    }
1927
1928    // Stores the return value of a function call into it's final location.
1929    fn store_return(
1930        &mut self,
1931        bx: &mut Bx,
1932        dest: ReturnDest<'tcx, Bx::Value>,
1933        ret_abi: &ArgAbi<'tcx, Ty<'tcx>>,
1934        llval: Bx::Value,
1935    ) {
1936        use self::ReturnDest::*;
1937
1938        match dest {
1939            Nothing => (),
1940            Store(dst) => bx.store_arg(ret_abi, llval, dst),
1941            IndirectOperand(tmp, index) => {
1942                let op = bx.load_operand(tmp);
1943                tmp.storage_dead(bx);
1944                self.overwrite_local(index, LocalRef::Operand(op));
1945                self.debug_introduce_local(bx, index);
1946            }
1947            DirectOperand(index) => {
1948                // If there is a cast, we have to store and reload.
1949                let op = if let PassMode::Cast { .. } = ret_abi.mode {
1950                    let tmp = PlaceRef::alloca(bx, ret_abi.layout);
1951                    tmp.storage_live(bx);
1952                    bx.store_arg(ret_abi, llval, tmp);
1953                    let op = bx.load_operand(tmp);
1954                    tmp.storage_dead(bx);
1955                    op
1956                } else {
1957                    OperandRef::from_immediate_or_packed_pair(bx, llval, ret_abi.layout)
1958                };
1959                self.overwrite_local(index, LocalRef::Operand(op));
1960                self.debug_introduce_local(bx, index);
1961            }
1962        }
1963    }
1964}
1965
1966enum ReturnDest<'tcx, V> {
1967    /// Do nothing; the return value is indirect or ignored.
1968    Nothing,
1969    /// Store the return value to the pointer.
1970    Store(PlaceRef<'tcx, V>),
1971    /// Store an indirect return value to an operand local place.
1972    IndirectOperand(PlaceRef<'tcx, V>, mir::Local),
1973    /// Store a direct return value to an operand local place.
1974    DirectOperand(mir::Local),
1975}
1976
1977fn load_cast<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
1978    bx: &mut Bx,
1979    cast: &CastTarget,
1980    ptr: Bx::Value,
1981    align: Align,
1982) -> Bx::Value {
1983    let cast_ty = bx.cast_backend_type(cast);
1984    if let Some(offset_from_start) = cast.rest_offset {
1985        assert!(cast.prefix[1..].iter().all(|p| p.is_none()));
1986        assert_eq!(cast.rest.unit.size, cast.rest.total);
1987        let first_ty = bx.reg_backend_type(&cast.prefix[0].unwrap());
1988        let second_ty = bx.reg_backend_type(&cast.rest.unit);
1989        let first = bx.load(first_ty, ptr, align);
1990        let second_ptr = bx.inbounds_ptradd(ptr, bx.const_usize(offset_from_start.bytes()));
1991        let second = bx.load(second_ty, second_ptr, align.restrict_for_offset(offset_from_start));
1992        let res = bx.cx().const_poison(cast_ty);
1993        let res = bx.insert_value(res, first, 0);
1994        bx.insert_value(res, second, 1)
1995    } else {
1996        bx.load(cast_ty, ptr, align)
1997    }
1998}
1999
2000pub fn store_cast<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>>(
2001    bx: &mut Bx,
2002    cast: &CastTarget,
2003    value: Bx::Value,
2004    ptr: Bx::Value,
2005    align: Align,
2006) {
2007    if let Some(offset_from_start) = cast.rest_offset {
2008        assert!(cast.prefix[1..].iter().all(|p| p.is_none()));
2009        assert_eq!(cast.rest.unit.size, cast.rest.total);
2010        assert!(cast.prefix[0].is_some());
2011        let first = bx.extract_value(value, 0);
2012        let second = bx.extract_value(value, 1);
2013        bx.store(first, ptr, align);
2014        let second_ptr = bx.inbounds_ptradd(ptr, bx.const_usize(offset_from_start.bytes()));
2015        bx.store(second, second_ptr, align.restrict_for_offset(offset_from_start));
2016    } else {
2017        bx.store(value, ptr, align);
2018    };
2019}