1 use super::operand::OperandRef;
2 use super::operand::OperandValue::{Immediate, Pair, Ref};
3 use super::place::PlaceRef;
4 use super::{CachedLlbb, FunctionCx, LocalRef};
7 use crate::common::{self, IntPredicate};
13 use rustc_ast::{InlineAsmOptions, InlineAsmTemplatePiece};
14 use rustc_hir::lang_items::LangItem;
15 use rustc_index::vec::Idx;
16 use rustc_middle::mir::{self, AssertKind, SwitchTargets};
17 use rustc_middle::ty::layout::{HasTyCtxt, LayoutOf};
18 use rustc_middle::ty::print::{with_no_trimmed_paths, with_no_visible_paths};
19 use rustc_middle::ty::{self, Instance, Ty, TypeVisitable};
20 use rustc_session::config::OptLevel;
21 use rustc_span::source_map::Span;
22 use rustc_span::{sym, Symbol};
23 use rustc_symbol_mangling::typeid::typeid_for_fnabi;
24 use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode, Reg};
25 use rustc_target::abi::{self, HasDataLayout, WrappingRange};
26 use rustc_target::spec::abi::Abi;
28 // Indicates if we are in the middle of merging a BB's successor into it. This
29 // can happen when BB jumps directly to its successor and the successor has no
30 // other predecessors.
31 #[derive(Debug, PartialEq)]
37 /// Used by `FunctionCx::codegen_terminator` for emitting common patterns
38 /// e.g., creating a basic block, calling a function, etc.
39 struct TerminatorCodegenHelper<'tcx> {
41 terminator: &'tcx mir::Terminator<'tcx>,
42 funclet_bb: Option<mir::BasicBlock>,
45 impl<'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>>(
50 fx: &'b mut FunctionCx<'a, 'tcx, Bx>,
51 ) -> Option<&'b Bx::Funclet> {
52 let funclet_bb = self.funclet_bb?;
53 if base::wants_msvc_seh(fx.cx.tcx().sess) {
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);
67 fx.funclets[funclet_bb]
69 .expect("landing_pad_for didn't also create funclets entry"),
76 /// Get a basic block (creating it if necessary), possibly with cleanup
77 /// stuff in it or next to it.
78 fn llbb_with_cleanup<Bx: BuilderMethods<'a, 'tcx>>(
80 fx: &mut FunctionCx<'a, 'tcx, Bx>,
81 target: mir::BasicBlock,
83 let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
84 let mut lltarget = fx.llbb(target);
85 if needs_landing_pad {
86 lltarget = fx.landing_pad_for(target);
89 // MSVC cross-funclet jump - need a trampoline
90 debug_assert!(base::wants_msvc_seh(fx.cx.tcx().sess));
91 debug!("llbb_with_cleanup: creating cleanup trampoline for {:?}", target);
92 let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
93 let trampoline_llbb = Bx::append_block(fx.cx, fx.llfn, name);
94 let mut trampoline_bx = Bx::build(fx.cx, trampoline_llbb);
95 trampoline_bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
102 fn llbb_characteristics<Bx: BuilderMethods<'a, 'tcx>>(
104 fx: &mut FunctionCx<'a, 'tcx, Bx>,
105 target: mir::BasicBlock,
107 let target_funclet = fx.cleanup_kinds[target].funclet_bb(target);
108 let (needs_landing_pad, is_cleanupret) = match (self.funclet_bb, target_funclet) {
109 (None, None) => (false, false),
110 (None, Some(_)) => (true, false),
112 let span = self.terminator.source_info.span;
113 span_bug!(span, "{:?} - jump out of cleanup?", self.terminator);
115 (Some(f), Some(t_f)) => {
116 if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) {
123 (needs_landing_pad, is_cleanupret)
126 fn funclet_br<Bx: BuilderMethods<'a, 'tcx>>(
128 fx: &mut FunctionCx<'a, 'tcx, Bx>,
130 target: mir::BasicBlock,
131 mergeable_succ: bool,
133 let (needs_landing_pad, is_cleanupret) = self.llbb_characteristics(fx, target);
134 if mergeable_succ && !needs_landing_pad && !is_cleanupret {
135 // We can merge the successor into this bb, so no need for a `br`.
138 let mut lltarget = fx.llbb(target);
139 if needs_landing_pad {
140 lltarget = fx.landing_pad_for(target);
143 // micro-optimization: generate a `ret` rather than a jump
145 bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
153 /// Call `fn_ptr` of `fn_abi` with the arguments `llargs`, the optional
154 /// return destination `destination` and the cleanup function `cleanup`.
155 fn do_call<Bx: BuilderMethods<'a, 'tcx>>(
157 fx: &mut FunctionCx<'a, 'tcx, Bx>,
159 fn_abi: &'tcx FnAbi<'tcx, Ty<'tcx>>,
161 llargs: &[Bx::Value],
162 destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
163 cleanup: Option<mir::BasicBlock>,
164 copied_constant_arguments: &[PlaceRef<'tcx, <Bx as BackendTypes>::Value>],
165 mergeable_succ: bool,
167 // If there is a cleanup block and the function we're calling can unwind, then
168 // do an invoke, otherwise do a call.
169 let fn_ty = bx.fn_decl_backend_type(&fn_abi);
171 let unwind_block = if let Some(cleanup) = cleanup.filter(|_| fn_abi.can_unwind) {
172 Some(self.llbb_with_cleanup(fx, cleanup))
173 } else if fx.mir[self.bb].is_cleanup
175 && !base::wants_msvc_seh(fx.cx.tcx().sess)
177 // Exception must not propagate out of the execution of a cleanup (doing so
178 // can cause undefined behaviour). We insert a double unwind guard for
179 // functions that can potentially unwind to protect against this.
181 // This is not necessary for SEH which does not use successive unwinding
182 // like Itanium EH. EH frames in SEH are different from normal function
183 // frames and SEH will abort automatically if an exception tries to
184 // propagate out from cleanup.
185 Some(fx.double_unwind_guard())
190 if let Some(unwind_block) = unwind_block {
191 let ret_llbb = if let Some((_, target)) = destination {
194 fx.unreachable_block()
196 let invokeret = bx.invoke(
205 if fx.mir[self.bb].is_cleanup {
206 bx.do_not_inline(invokeret);
209 if let Some((ret_dest, target)) = destination {
210 bx.switch_to_block(fx.llbb(target));
211 fx.set_debug_loc(bx, self.terminator.source_info);
212 for tmp in copied_constant_arguments {
213 bx.lifetime_end(tmp.llval, tmp.layout.size);
215 fx.store_return(bx, ret_dest, &fn_abi.ret, invokeret);
219 let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &llargs, self.funclet(fx));
220 if fx.mir[self.bb].is_cleanup {
221 // Cleanup is always the cold path. Don't inline
222 // drop glue. Also, when there is a deeply-nested
223 // struct, there are "symmetry" issues that cause
224 // exponential inlining - see issue #41696.
225 bx.do_not_inline(llret);
228 if let Some((ret_dest, target)) = destination {
229 for tmp in copied_constant_arguments {
230 bx.lifetime_end(tmp.llval, tmp.layout.size);
232 fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
233 self.funclet_br(fx, bx, target, mergeable_succ)
241 /// Generates inline assembly with optional `destination` and `cleanup`.
242 fn do_inlineasm<Bx: BuilderMethods<'a, 'tcx>>(
244 fx: &mut FunctionCx<'a, 'tcx, Bx>,
246 template: &[InlineAsmTemplatePiece],
247 operands: &[InlineAsmOperandRef<'tcx, Bx>],
248 options: InlineAsmOptions,
250 destination: Option<mir::BasicBlock>,
251 cleanup: Option<mir::BasicBlock>,
252 instance: Instance<'_>,
253 mergeable_succ: bool,
255 if let Some(cleanup) = cleanup {
256 let ret_llbb = if let Some(target) = destination {
259 fx.unreachable_block()
262 bx.codegen_inline_asm(
268 Some((ret_llbb, self.llbb_with_cleanup(fx, cleanup), self.funclet(fx))),
272 bx.codegen_inline_asm(template, &operands, options, line_spans, instance, None);
274 if let Some(target) = destination {
275 self.funclet_br(fx, bx, target, mergeable_succ)
284 /// Codegen implementations for some terminator variants.
285 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
286 /// Generates code for a `Resume` terminator.
287 fn codegen_resume_terminator(&mut self, helper: TerminatorCodegenHelper<'tcx>, bx: &mut Bx) {
288 if let Some(funclet) = helper.funclet(self) {
289 bx.cleanup_ret(funclet, None);
291 let slot = self.get_personality_slot(bx);
292 let exn0 = slot.project_field(bx, 0);
293 let exn0 = bx.load_operand(exn0).immediate();
294 let exn1 = slot.project_field(bx, 1);
295 let exn1 = bx.load_operand(exn1).immediate();
296 slot.storage_dead(bx);
298 bx.resume(exn0, exn1);
302 fn codegen_switchint_terminator(
304 helper: TerminatorCodegenHelper<'tcx>,
306 discr: &mir::Operand<'tcx>,
307 targets: &SwitchTargets,
309 let discr = self.codegen_operand(bx, &discr);
310 let switch_ty = discr.layout.ty;
311 let mut target_iter = targets.iter();
312 if target_iter.len() == 1 {
313 // If there are two targets (one conditional, one fallback), emit `br` instead of
315 let (test_value, target) = target_iter.next().unwrap();
316 let lltrue = helper.llbb_with_cleanup(self, target);
317 let llfalse = helper.llbb_with_cleanup(self, targets.otherwise());
318 if switch_ty == bx.tcx().types.bool {
319 // Don't generate trivial icmps when switching on bool.
321 0 => bx.cond_br(discr.immediate(), llfalse, lltrue),
322 1 => bx.cond_br(discr.immediate(), lltrue, llfalse),
326 let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
327 let llval = bx.const_uint_big(switch_llty, test_value);
328 let cmp = bx.icmp(IntPredicate::IntEQ, discr.immediate(), llval);
329 bx.cond_br(cmp, lltrue, llfalse);
331 } else if self.cx.sess().opts.optimize == OptLevel::No
332 && target_iter.len() == 2
333 && self.mir[targets.otherwise()].is_empty_unreachable()
335 // In unoptimized builds, if there are two normal targets and the `otherwise` target is
336 // an unreachable BB, emit `br` instead of `switch`. This leaves behind the unreachable
337 // BB, which will usually (but not always) be dead code.
339 // Why only in unoptimized builds?
340 // - In unoptimized builds LLVM uses FastISel which does not support switches, so it
341 // must fall back to the to the slower SelectionDAG isel. Therefore, using `br` gives
342 // significant compile time speedups for unoptimized builds.
343 // - In optimized builds the above doesn't hold, and using `br` sometimes results in
344 // worse generated code because LLVM can no longer tell that the value being switched
345 // on can only have two values, e.g. 0 and 1.
347 let (test_value1, target1) = target_iter.next().unwrap();
348 let (_test_value2, target2) = target_iter.next().unwrap();
349 let ll1 = helper.llbb_with_cleanup(self, target1);
350 let ll2 = helper.llbb_with_cleanup(self, target2);
351 let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
352 let llval = bx.const_uint_big(switch_llty, test_value1);
353 let cmp = bx.icmp(IntPredicate::IntEQ, discr.immediate(), llval);
354 bx.cond_br(cmp, ll1, ll2);
358 helper.llbb_with_cleanup(self, targets.otherwise()),
359 target_iter.map(|(value, target)| (value, helper.llbb_with_cleanup(self, target))),
364 fn codegen_return_terminator(&mut self, bx: &mut Bx) {
365 // Call `va_end` if this is the definition of a C-variadic function.
366 if self.fn_abi.c_variadic {
367 // The `VaList` "spoofed" argument is just after all the real arguments.
368 let va_list_arg_idx = self.fn_abi.args.len();
369 match self.locals[mir::Local::new(1 + va_list_arg_idx)] {
370 LocalRef::Place(va_list) => {
371 bx.va_end(va_list.llval);
373 _ => bug!("C-variadic function must have a `VaList` place"),
376 if self.fn_abi.ret.layout.abi.is_uninhabited() {
377 // Functions with uninhabited return values are marked `noreturn`,
378 // so we should make sure that we never actually do.
379 // We play it safe by using a well-defined `abort`, but we could go for immediate UB
380 // if that turns out to be helpful.
382 // `abort` does not terminate the block, so we still need to generate
383 // an `unreachable` terminator after it.
387 let llval = match &self.fn_abi.ret.mode {
388 PassMode::Ignore | PassMode::Indirect { .. } => {
393 PassMode::Direct(_) | PassMode::Pair(..) => {
394 let op = self.codegen_consume(bx, mir::Place::return_place().as_ref());
395 if let Ref(llval, _, align) = op.val {
396 bx.load(bx.backend_type(op.layout), llval, align)
398 op.immediate_or_packed_pair(bx)
402 PassMode::Cast(cast_ty, _) => {
403 let op = match self.locals[mir::RETURN_PLACE] {
404 LocalRef::Operand(Some(op)) => op,
405 LocalRef::Operand(None) => bug!("use of return before def"),
406 LocalRef::Place(cg_place) => OperandRef {
407 val: Ref(cg_place.llval, None, cg_place.align),
408 layout: cg_place.layout,
410 LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
412 let llslot = match op.val {
413 Immediate(_) | Pair(..) => {
414 let scratch = PlaceRef::alloca(bx, self.fn_abi.ret.layout);
415 op.val.store(bx, scratch);
418 Ref(llval, _, align) => {
419 assert_eq!(align, op.layout.align.abi, "return place is unaligned!");
423 let ty = bx.cast_backend_type(cast_ty);
424 let addr = bx.pointercast(llslot, bx.type_ptr_to(ty));
425 bx.load(ty, addr, self.fn_abi.ret.layout.align.abi)
431 #[tracing::instrument(level = "trace", skip(self, helper, bx))]
432 fn codegen_drop_terminator(
434 helper: TerminatorCodegenHelper<'tcx>,
436 location: mir::Place<'tcx>,
437 target: mir::BasicBlock,
438 unwind: Option<mir::BasicBlock>,
439 mergeable_succ: bool,
441 let ty = location.ty(self.mir, bx.tcx()).ty;
442 let ty = self.monomorphize(ty);
443 let drop_fn = Instance::resolve_drop_in_place(bx.tcx(), ty);
445 if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
446 // we don't actually need to drop anything.
447 return helper.funclet_br(self, bx, target, mergeable_succ);
450 let place = self.codegen_place(bx, location.as_ref());
452 let mut args = if let Some(llextra) = place.llextra {
453 args2 = [place.llval, llextra];
456 args1 = [place.llval];
459 let (drop_fn, fn_abi) = match ty.kind() {
460 // FIXME(eddyb) perhaps move some of this logic into
461 // `Instance::resolve_drop_in_place`?
462 ty::Dynamic(_, _, ty::Dyn) => {
463 // IN THIS ARM, WE HAVE:
464 // ty = *mut (dyn Trait)
465 // which is: exists<T> ( *mut T, Vtable<T: Trait> )
468 // args = ( Data, Vtable )
475 let virtual_drop = Instance {
476 def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
477 substs: drop_fn.substs,
479 debug!("ty = {:?}", ty);
480 debug!("drop_fn = {:?}", drop_fn);
481 debug!("args = {:?}", args);
482 let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
483 let vtable = args[1];
484 // Truncate vtable off of args list
487 meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
488 .get_fn(bx, vtable, ty, &fn_abi),
492 ty::Dynamic(_, _, ty::DynStar) => {
493 // IN THIS ARM, WE HAVE:
494 // ty = *mut (dyn* Trait)
495 // which is: *mut exists<T: sizeof(T) == sizeof(usize)> (T, Vtable<T: Trait>)
508 // WE CAN CONVERT THIS INTO THE ABOVE LOGIC BY DOING
510 // data = &(*args[0]).0 // gives a pointer to Data above (really the same pointer)
511 // vtable = (*args[0]).1 // loads the vtable out
512 // (data, vtable) // an equivalent Rust `*mut dyn Trait`
514 // SO THEN WE CAN USE THE ABOVE CODE.
515 let virtual_drop = Instance {
516 def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
517 substs: drop_fn.substs,
519 debug!("ty = {:?}", ty);
520 debug!("drop_fn = {:?}", drop_fn);
521 debug!("args = {:?}", args);
522 let fn_abi = bx.fn_abi_of_instance(virtual_drop, ty::List::empty());
524 let data_ty = bx.cx().backend_type(place.layout);
526 bx.gep(data_ty, data, &[bx.cx().const_i32(0), bx.cx().const_i32(1)]);
527 let vtable = bx.load(bx.type_i8p(), vtable_ptr, abi::Align::ONE);
528 // Truncate vtable off of args list
530 debug!("args' = {:?}", args);
532 meth::VirtualIndex::from_index(ty::COMMON_VTABLE_ENTRIES_DROPINPLACE)
533 .get_fn(bx, vtable, ty, &fn_abi),
537 _ => (bx.get_fn_addr(drop_fn), bx.fn_abi_of_instance(drop_fn, ty::List::empty())),
545 Some((ReturnDest::Nothing, target)),
552 fn codegen_assert_terminator(
554 helper: TerminatorCodegenHelper<'tcx>,
556 terminator: &mir::Terminator<'tcx>,
557 cond: &mir::Operand<'tcx>,
559 msg: &mir::AssertMessage<'tcx>,
560 target: mir::BasicBlock,
561 cleanup: Option<mir::BasicBlock>,
562 mergeable_succ: bool,
564 let span = terminator.source_info.span;
565 let cond = self.codegen_operand(bx, cond).immediate();
566 let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
568 // This case can currently arise only from functions marked
569 // with #[rustc_inherit_overflow_checks] and inlined from
570 // another crate (mostly core::num generic/#[inline] fns),
571 // while the current crate doesn't use overflow checks.
572 // NOTE: Unlike binops, negation doesn't have its own
573 // checked operation, just a comparison with the minimum
574 // value, so we have to check for the assert message.
575 if !bx.check_overflow() {
576 if let AssertKind::OverflowNeg(_) = *msg {
577 const_cond = Some(expected);
581 // Don't codegen the panic block if success if known.
582 if const_cond == Some(expected) {
583 return helper.funclet_br(self, bx, target, mergeable_succ);
586 // Pass the condition through llvm.expect for branch hinting.
587 let cond = bx.expect(cond, expected);
589 // Create the failure block and the conditional branch to it.
590 let lltarget = helper.llbb_with_cleanup(self, target);
591 let panic_block = bx.append_sibling_block("panic");
593 bx.cond_br(cond, lltarget, panic_block);
595 bx.cond_br(cond, panic_block, lltarget);
598 // After this point, bx is the block for the call to panic.
599 bx.switch_to_block(panic_block);
600 self.set_debug_loc(bx, terminator.source_info);
602 // Get the location information.
603 let location = self.get_caller_location(bx, terminator.source_info).immediate();
605 // Put together the arguments to the panic entry point.
606 let (lang_item, args) = match msg {
607 AssertKind::BoundsCheck { ref len, ref index } => {
608 let len = self.codegen_operand(bx, len).immediate();
609 let index = self.codegen_operand(bx, index).immediate();
610 // It's `fn panic_bounds_check(index: usize, len: usize)`,
611 // and `#[track_caller]` adds an implicit third argument.
612 (LangItem::PanicBoundsCheck, vec![index, len, location])
615 let msg = bx.const_str(msg.description());
616 // It's `pub fn panic(expr: &str)`, with the wide reference being passed
617 // as two arguments, and `#[track_caller]` adds an implicit third argument.
618 (LangItem::Panic, vec![msg.0, msg.1, location])
622 let (fn_abi, llfn) = common::build_langcall(bx, Some(span), lang_item);
624 // Codegen the actual panic invoke/call.
625 let merging_succ = helper.do_call(self, bx, fn_abi, llfn, &args, None, cleanup, &[], false);
626 assert_eq!(merging_succ, MergingSucc::False);
630 fn codegen_abort_terminator(
632 helper: TerminatorCodegenHelper<'tcx>,
634 terminator: &mir::Terminator<'tcx>,
636 let span = terminator.source_info.span;
637 self.set_debug_loc(bx, terminator.source_info);
639 // Obtain the panic entry point.
640 let (fn_abi, llfn) = common::build_langcall(bx, Some(span), LangItem::PanicCannotUnwind);
642 // Codegen the actual panic invoke/call.
643 let merging_succ = helper.do_call(self, bx, fn_abi, llfn, &[], None, None, &[], false);
644 assert_eq!(merging_succ, MergingSucc::False);
647 /// Returns `Some` if this is indeed a panic intrinsic and codegen is done.
648 fn codegen_panic_intrinsic(
650 helper: &TerminatorCodegenHelper<'tcx>,
652 intrinsic: Option<Symbol>,
653 instance: Option<Instance<'tcx>>,
654 source_info: mir::SourceInfo,
655 target: Option<mir::BasicBlock>,
656 cleanup: Option<mir::BasicBlock>,
657 mergeable_succ: bool,
658 ) -> Option<MergingSucc> {
659 // Emit a panic or a no-op for `assert_*` intrinsics.
660 // These are intrinsics that compile to panics so that we can get a message
661 // which mentions the offending type, even from a const context.
662 #[derive(Debug, PartialEq)]
663 enum AssertIntrinsic {
666 MemUninitializedValid,
668 let panic_intrinsic = intrinsic.and_then(|i| match i {
669 sym::assert_inhabited => Some(AssertIntrinsic::Inhabited),
670 sym::assert_zero_valid => Some(AssertIntrinsic::ZeroValid),
671 sym::assert_mem_uninitialized_valid => Some(AssertIntrinsic::MemUninitializedValid),
674 if let Some(intrinsic) = panic_intrinsic {
675 use AssertIntrinsic::*;
677 let ty = instance.unwrap().substs.type_at(0);
678 let layout = bx.layout_of(ty);
679 let do_panic = match intrinsic {
680 Inhabited => layout.abi.is_uninhabited(),
681 ZeroValid => !bx.tcx().permits_zero_init(layout),
682 MemUninitializedValid => !bx.tcx().permits_uninit_init(layout),
685 let msg_str = with_no_visible_paths!({
686 with_no_trimmed_paths!({
687 if layout.abi.is_uninhabited() {
688 // Use this error even for the other intrinsics as it is more precise.
689 format!("attempted to instantiate uninhabited type `{}`", ty)
690 } else if intrinsic == ZeroValid {
691 format!("attempted to zero-initialize type `{}`, which is invalid", ty)
694 "attempted to leave type `{}` uninitialized, which is invalid",
700 let msg = bx.const_str(&msg_str);
702 // Obtain the panic entry point.
704 common::build_langcall(bx, Some(source_info.span), LangItem::PanicNounwind);
706 // Codegen the actual panic invoke/call.
713 target.as_ref().map(|bb| (ReturnDest::Nothing, *bb)),
720 let target = target.unwrap();
721 helper.funclet_br(self, bx, target, mergeable_succ)
728 fn codegen_call_terminator(
730 helper: TerminatorCodegenHelper<'tcx>,
732 terminator: &mir::Terminator<'tcx>,
733 func: &mir::Operand<'tcx>,
734 args: &[mir::Operand<'tcx>],
735 destination: mir::Place<'tcx>,
736 target: Option<mir::BasicBlock>,
737 cleanup: Option<mir::BasicBlock>,
739 mergeable_succ: bool,
741 let source_info = terminator.source_info;
742 let span = source_info.span;
744 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
745 let callee = self.codegen_operand(bx, func);
747 let (instance, mut llfn) = match *callee.layout.ty.kind() {
748 ty::FnDef(def_id, substs) => (
750 ty::Instance::expect_resolve(
752 ty::ParamEnv::reveal_all(),
756 .polymorphize(bx.tcx()),
760 ty::FnPtr(_) => (None, Some(callee.immediate())),
761 _ => bug!("{} is not callable", callee.layout.ty),
763 let def = instance.map(|i| i.def);
765 if let Some(ty::InstanceDef::DropGlue(_, None)) = def {
766 // Empty drop glue; a no-op.
767 let target = target.unwrap();
768 return helper.funclet_br(self, bx, target, mergeable_succ);
771 // FIXME(eddyb) avoid computing this if possible, when `instance` is
772 // available - right now `sig` is only needed for getting the `abi`
773 // and figuring out how many extra args were passed to a C-variadic `fn`.
774 let sig = callee.layout.ty.fn_sig(bx.tcx());
777 // Handle intrinsics old codegen wants Expr's for, ourselves.
778 let intrinsic = match def {
779 Some(ty::InstanceDef::Intrinsic(def_id)) => Some(bx.tcx().item_name(def_id)),
783 let extra_args = &args[sig.inputs().skip_binder().len()..];
784 let extra_args = bx.tcx().mk_type_list(extra_args.iter().map(|op_arg| {
785 let op_ty = op_arg.ty(self.mir, bx.tcx());
786 self.monomorphize(op_ty)
789 let fn_abi = match instance {
790 Some(instance) => bx.fn_abi_of_instance(instance, extra_args),
791 None => bx.fn_abi_of_fn_ptr(sig, extra_args),
794 if intrinsic == Some(sym::transmute) {
795 return if let Some(target) = target {
796 self.codegen_transmute(bx, &args[0], destination);
797 helper.funclet_br(self, bx, target, mergeable_succ)
799 // If we are trying to transmute to an uninhabited type,
800 // it is likely there is no allotted destination. In fact,
801 // transmuting to an uninhabited type is UB, which means
802 // we can do what we like. Here, we declare that transmuting
803 // into an uninhabited type is impossible, so anything following
804 // it must be unreachable.
805 assert_eq!(fn_abi.ret.layout.abi, abi::Abi::Uninhabited);
811 if let Some(merging_succ) = self.codegen_panic_intrinsic(
824 // The arguments we'll be passing. Plus one to account for outptr, if used.
825 let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
826 let mut llargs = Vec::with_capacity(arg_count);
828 // Prepare the return value destination
829 let ret_dest = if target.is_some() {
830 let is_intrinsic = intrinsic.is_some();
831 self.make_return_dest(bx, destination, &fn_abi.ret, &mut llargs, is_intrinsic)
836 if intrinsic == Some(sym::caller_location) {
837 return if let Some(target) = target {
839 self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
841 if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
842 location.val.store(bx, tmp);
844 self.store_return(bx, ret_dest, &fn_abi.ret, location.immediate());
845 helper.funclet_br(self, bx, target, mergeable_succ)
852 None | Some(sym::drop_in_place) => {}
853 Some(sym::copy_nonoverlapping) => unreachable!(),
855 let dest = match ret_dest {
856 _ if fn_abi.ret.is_indirect() => llargs[0],
857 ReturnDest::Nothing => {
858 bx.const_undef(bx.type_ptr_to(bx.arg_memory_ty(&fn_abi.ret)))
860 ReturnDest::IndirectOperand(dst, _) | ReturnDest::Store(dst) => dst.llval,
861 ReturnDest::DirectOperand(_) => {
862 bug!("Cannot use direct operand with an intrinsic call")
866 let args: Vec<_> = args
870 // The indices passed to simd_shuffle* in the
871 // third argument must be constant. This is
872 // checked by const-qualification, which also
873 // promotes any complex rvalues to constants.
874 if i == 2 && intrinsic.as_str().starts_with("simd_shuffle") {
875 if let mir::Operand::Constant(constant) = arg {
876 let c = self.eval_mir_constant(constant);
877 let (llval, ty) = self.simd_shuffle_indices(
880 self.monomorphize(constant.ty()),
884 val: Immediate(llval),
885 layout: bx.layout_of(ty),
888 span_bug!(span, "shuffle indices must be constant");
892 self.codegen_operand(bx, arg)
896 Self::codegen_intrinsic_call(
898 *instance.as_ref().unwrap(),
905 if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
906 self.store_return(bx, ret_dest, &fn_abi.ret, dst.llval);
909 return if let Some(target) = target {
910 helper.funclet_br(self, bx, target, mergeable_succ)
918 // Split the rust-call tupled arguments off.
919 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
920 let (tup, args) = args.split_last().unwrap();
926 let mut copied_constant_arguments = vec![];
927 'make_args: for (i, arg) in first_args.iter().enumerate() {
928 let mut op = self.codegen_operand(bx, arg);
930 if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
932 Pair(data_ptr, meta) => {
933 // In the case of Rc<Self>, we need to explicitly pass a
934 // *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
935 // that is understood elsewhere in the compiler as a method on
937 // To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
938 // we get a value of a built-in pointer type.
940 // This is also relevant for `Pin<&mut Self>`, where we need to peel the `Pin`.
941 'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
942 && !op.layout.ty.is_region_ptr()
944 for i in 0..op.layout.fields.count() {
945 let field = op.extract_field(bx, i);
946 if !field.layout.is_zst() {
947 // we found the one non-zero-sized field that is allowed
948 // now find *its* non-zero-sized field, or stop if it's a
951 continue 'descend_newtypes;
955 span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
958 // now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
959 // data pointer and vtable. Look up the method in the vtable, and pass
960 // the data pointer as the first argument
961 llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
967 llargs.push(data_ptr);
970 Ref(data_ptr, Some(meta), _) => {
971 // by-value dynamic dispatch
972 llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
978 llargs.push(data_ptr);
982 // See comment above explaining why we peel these newtypes
983 'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
984 && !op.layout.ty.is_region_ptr()
986 for i in 0..op.layout.fields.count() {
987 let field = op.extract_field(bx, i);
988 if !field.layout.is_zst() {
989 // we found the one non-zero-sized field that is allowed
990 // now find *its* non-zero-sized field, or stop if it's a
993 continue 'descend_newtypes;
997 span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
1000 // Make sure that we've actually unwrapped the rcvr down
1001 // to a pointer or ref to `dyn* Trait`.
1002 if !op.layout.ty.builtin_deref(true).unwrap().ty.is_dyn_star() {
1003 span_bug!(span, "can't codegen a virtual call on {:#?}", op);
1005 let place = op.deref(bx.cx());
1006 let data_ptr = place.project_field(bx, 0);
1007 let meta_ptr = place.project_field(bx, 1);
1008 let meta = bx.load_operand(meta_ptr);
1009 llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(
1015 llargs.push(data_ptr.llval);
1019 span_bug!(span, "can't codegen a virtual call on {:#?}", op);
1024 // The callee needs to own the argument memory if we pass it
1025 // by-ref, so make a local copy of non-immediate constants.
1026 match (arg, op.val) {
1027 (&mir::Operand::Copy(_), Ref(_, None, _))
1028 | (&mir::Operand::Constant(_), Ref(_, None, _)) => {
1029 let tmp = PlaceRef::alloca(bx, op.layout);
1030 bx.lifetime_start(tmp.llval, tmp.layout.size);
1031 op.val.store(bx, tmp);
1032 op.val = Ref(tmp.llval, None, tmp.align);
1033 copied_constant_arguments.push(tmp);
1038 self.codegen_argument(bx, op, &mut llargs, &fn_abi.args[i]);
1040 let num_untupled = untuple.map(|tup| {
1041 self.codegen_arguments_untupled(bx, tup, &mut llargs, &fn_abi.args[first_args.len()..])
1044 let needs_location =
1045 instance.map_or(false, |i| i.def.requires_caller_location(self.cx.tcx()));
1047 let mir_args = if let Some(num_untupled) = num_untupled {
1048 first_args.len() + num_untupled
1055 "#[track_caller] fn's must have 1 more argument in their ABI than in their MIR: {:?} {:?} {:?}",
1061 self.get_caller_location(bx, mir::SourceInfo { span: fn_span, ..source_info });
1063 "codegen_call_terminator({:?}): location={:?} (fn_span {:?})",
1064 terminator, location, fn_span
1067 let last_arg = fn_abi.args.last().unwrap();
1068 self.codegen_argument(bx, location, &mut llargs, last_arg);
1071 let (is_indirect_call, fn_ptr) = match (llfn, instance) {
1072 (Some(llfn), _) => (true, llfn),
1073 (None, Some(instance)) => (false, bx.get_fn_addr(instance)),
1074 _ => span_bug!(span, "no llfn for call"),
1077 // For backends that support CFI using type membership (i.e., testing whether a given
1078 // pointer is associated with a type identifier).
1079 if bx.tcx().sess.is_sanitizer_cfi_enabled() && is_indirect_call {
1080 // Emit type metadata and checks.
1081 // FIXME(rcvalle): Add support for generalized identifiers.
1082 // FIXME(rcvalle): Create distinct unnamed MDNodes for internal identifiers.
1083 let typeid = typeid_for_fnabi(bx.tcx(), fn_abi);
1084 let typeid_metadata = self.cx.typeid_metadata(typeid);
1086 // Test whether the function pointer is associated with the type identifier.
1087 let cond = bx.type_test(fn_ptr, typeid_metadata);
1088 let bb_pass = bx.append_sibling_block("type_test.pass");
1089 let bb_fail = bx.append_sibling_block("type_test.fail");
1090 bx.cond_br(cond, bb_pass, bb_fail);
1092 bx.switch_to_block(bb_pass);
1093 let merging_succ = helper.do_call(
1099 target.as_ref().map(|&target| (ret_dest, target)),
1101 &copied_constant_arguments,
1104 assert_eq!(merging_succ, MergingSucc::False);
1106 bx.switch_to_block(bb_fail);
1110 return MergingSucc::False;
1119 target.as_ref().map(|&target| (ret_dest, target)),
1121 &copied_constant_arguments,
1126 fn codegen_asm_terminator(
1128 helper: TerminatorCodegenHelper<'tcx>,
1130 terminator: &mir::Terminator<'tcx>,
1131 template: &[ast::InlineAsmTemplatePiece],
1132 operands: &[mir::InlineAsmOperand<'tcx>],
1133 options: ast::InlineAsmOptions,
1134 line_spans: &[Span],
1135 destination: Option<mir::BasicBlock>,
1136 cleanup: Option<mir::BasicBlock>,
1137 instance: Instance<'_>,
1138 mergeable_succ: bool,
1140 let span = terminator.source_info.span;
1142 let operands: Vec<_> = operands
1144 .map(|op| match *op {
1145 mir::InlineAsmOperand::In { reg, ref value } => {
1146 let value = self.codegen_operand(bx, value);
1147 InlineAsmOperandRef::In { reg, value }
1149 mir::InlineAsmOperand::Out { reg, late, ref place } => {
1150 let place = place.map(|place| self.codegen_place(bx, place.as_ref()));
1151 InlineAsmOperandRef::Out { reg, late, place }
1153 mir::InlineAsmOperand::InOut { reg, late, ref in_value, ref out_place } => {
1154 let in_value = self.codegen_operand(bx, in_value);
1156 out_place.map(|out_place| self.codegen_place(bx, out_place.as_ref()));
1157 InlineAsmOperandRef::InOut { reg, late, in_value, out_place }
1159 mir::InlineAsmOperand::Const { ref value } => {
1160 let const_value = self
1161 .eval_mir_constant(value)
1162 .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved"));
1163 let string = common::asm_const_to_str(
1167 bx.layout_of(value.ty()),
1169 InlineAsmOperandRef::Const { string }
1171 mir::InlineAsmOperand::SymFn { ref value } => {
1172 let literal = self.monomorphize(value.literal);
1173 if let ty::FnDef(def_id, substs) = *literal.ty().kind() {
1174 let instance = ty::Instance::resolve_for_fn_ptr(
1176 ty::ParamEnv::reveal_all(),
1181 InlineAsmOperandRef::SymFn { instance }
1183 span_bug!(span, "invalid type for asm sym (fn)");
1186 mir::InlineAsmOperand::SymStatic { def_id } => {
1187 InlineAsmOperandRef::SymStatic { def_id }
1192 helper.do_inlineasm(
1207 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
1208 pub fn codegen_block(&mut self, mut bb: mir::BasicBlock) {
1209 let llbb = match self.try_llbb(bb) {
1213 let bx = &mut Bx::build(self.cx, llbb);
1216 // MIR basic blocks stop at any function call. This may not be the case
1217 // for the backend's basic blocks, in which case we might be able to
1218 // combine multiple MIR basic blocks into a single backend basic block.
1220 let data = &mir[bb];
1222 debug!("codegen_block({:?}={:?})", bb, data);
1224 for statement in &data.statements {
1225 self.codegen_statement(bx, statement);
1228 let merging_succ = self.codegen_terminator(bx, bb, data.terminator());
1229 if let MergingSucc::False = merging_succ {
1233 // We are merging the successor into the produced backend basic
1234 // block. Record that the successor should be skipped when it is
1237 // Note: we must not have already generated code for the successor.
1238 // This is implicitly ensured by the reverse postorder traversal,
1239 // and the assertion explicitly guarantees that.
1240 let mut successors = data.terminator().successors();
1241 let succ = successors.next().unwrap();
1242 assert!(matches!(self.cached_llbbs[succ], CachedLlbb::None));
1243 self.cached_llbbs[succ] = CachedLlbb::Skip;
1248 fn codegen_terminator(
1251 bb: mir::BasicBlock,
1252 terminator: &'tcx mir::Terminator<'tcx>,
1254 debug!("codegen_terminator: {:?}", terminator);
1256 // Create the cleanup bundle, if needed.
1257 let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb);
1258 let helper = TerminatorCodegenHelper { bb, terminator, funclet_bb };
1260 let mergeable_succ = || {
1261 // Note: any call to `switch_to_block` will invalidate a `true` value
1262 // of `mergeable_succ`.
1263 let mut successors = terminator.successors();
1264 if let Some(succ) = successors.next()
1265 && successors.next().is_none()
1266 && let &[succ_pred] = self.mir.basic_blocks.predecessors()[succ].as_slice()
1268 // bb has a single successor, and bb is its only predecessor. This
1269 // makes it a candidate for merging.
1270 assert_eq!(succ_pred, bb);
1277 self.set_debug_loc(bx, terminator.source_info);
1278 match terminator.kind {
1279 mir::TerminatorKind::Resume => {
1280 self.codegen_resume_terminator(helper, bx);
1284 mir::TerminatorKind::Abort => {
1285 self.codegen_abort_terminator(helper, bx, terminator);
1289 mir::TerminatorKind::Goto { target } => {
1290 helper.funclet_br(self, bx, target, mergeable_succ())
1293 mir::TerminatorKind::SwitchInt { ref discr, ref targets } => {
1294 self.codegen_switchint_terminator(helper, bx, discr, targets);
1298 mir::TerminatorKind::Return => {
1299 self.codegen_return_terminator(bx);
1303 mir::TerminatorKind::Unreachable => {
1308 mir::TerminatorKind::Drop { place, target, unwind } => {
1309 self.codegen_drop_terminator(helper, bx, place, target, unwind, mergeable_succ())
1312 mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => self
1313 .codegen_assert_terminator(
1325 mir::TerminatorKind::DropAndReplace { .. } => {
1326 bug!("undesugared DropAndReplace in codegen: {:?}", terminator);
1329 mir::TerminatorKind::Call {
1337 } => self.codegen_call_terminator(
1349 mir::TerminatorKind::GeneratorDrop | mir::TerminatorKind::Yield { .. } => {
1350 bug!("generator ops in codegen")
1352 mir::TerminatorKind::FalseEdge { .. } | mir::TerminatorKind::FalseUnwind { .. } => {
1353 bug!("borrowck false edges in codegen")
1356 mir::TerminatorKind::InlineAsm {
1363 } => self.codegen_asm_terminator(
1379 fn codegen_argument(
1382 op: OperandRef<'tcx, Bx::Value>,
1383 llargs: &mut Vec<Bx::Value>,
1384 arg: &ArgAbi<'tcx, Ty<'tcx>>,
1387 PassMode::Ignore => return,
1388 PassMode::Cast(_, true) => {
1389 // Fill padding with undef value, where applicable.
1390 llargs.push(bx.const_undef(bx.reg_backend_type(&Reg::i32())));
1392 PassMode::Pair(..) => match op.val {
1398 _ => bug!("codegen_argument: {:?} invalid for pair argument", op),
1400 PassMode::Indirect { attrs: _, extra_attrs: Some(_), on_stack: _ } => match op.val {
1401 Ref(a, Some(b), _) => {
1406 _ => bug!("codegen_argument: {:?} invalid for unsized indirect argument", op),
1411 // Force by-ref if we have to load through a cast pointer.
1412 let (mut llval, align, by_ref) = match op.val {
1413 Immediate(_) | Pair(..) => match arg.mode {
1414 PassMode::Indirect { .. } | PassMode::Cast(..) => {
1415 let scratch = PlaceRef::alloca(bx, arg.layout);
1416 op.val.store(bx, scratch);
1417 (scratch.llval, scratch.align, true)
1419 _ => (op.immediate_or_packed_pair(bx), arg.layout.align.abi, false),
1421 Ref(llval, _, align) => {
1422 if arg.is_indirect() && align < arg.layout.align.abi {
1423 // `foo(packed.large_field)`. We can't pass the (unaligned) field directly. I
1424 // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't
1425 // have scary latent bugs around.
1427 let scratch = PlaceRef::alloca(bx, arg.layout);
1437 (scratch.llval, scratch.align, true)
1439 (llval, align, true)
1444 if by_ref && !arg.is_indirect() {
1445 // Have to load the argument, maybe while casting it.
1446 if let PassMode::Cast(ty, _) = &arg.mode {
1447 let llty = bx.cast_backend_type(ty);
1448 let addr = bx.pointercast(llval, bx.type_ptr_to(llty));
1449 llval = bx.load(llty, addr, align.min(arg.layout.align.abi));
1451 // We can't use `PlaceRef::load` here because the argument
1452 // may have a type we don't treat as immediate, but the ABI
1453 // used for this call is passing it by-value. In that case,
1454 // the load would just produce `OperandValue::Ref` instead
1455 // of the `OperandValue::Immediate` we need for the call.
1456 llval = bx.load(bx.backend_type(arg.layout), llval, align);
1457 if let abi::Abi::Scalar(scalar) = arg.layout.abi {
1458 if scalar.is_bool() {
1459 bx.range_metadata(llval, WrappingRange { start: 0, end: 1 });
1462 // We store bools as `i8` so we need to truncate to `i1`.
1463 llval = bx.to_immediate(llval, arg.layout);
1470 fn codegen_arguments_untupled(
1473 operand: &mir::Operand<'tcx>,
1474 llargs: &mut Vec<Bx::Value>,
1475 args: &[ArgAbi<'tcx, Ty<'tcx>>],
1477 let tuple = self.codegen_operand(bx, operand);
1479 // Handle both by-ref and immediate tuples.
1480 if let Ref(llval, None, align) = tuple.val {
1481 let tuple_ptr = PlaceRef::new_sized_aligned(llval, tuple.layout, align);
1482 for i in 0..tuple.layout.fields.count() {
1483 let field_ptr = tuple_ptr.project_field(bx, i);
1484 let field = bx.load_operand(field_ptr);
1485 self.codegen_argument(bx, field, llargs, &args[i]);
1487 } else if let Ref(_, Some(_), _) = tuple.val {
1488 bug!("closure arguments must be sized")
1490 // If the tuple is immediate, the elements are as well.
1491 for i in 0..tuple.layout.fields.count() {
1492 let op = tuple.extract_field(bx, i);
1493 self.codegen_argument(bx, op, llargs, &args[i]);
1496 tuple.layout.fields.count()
1499 fn get_caller_location(
1502 mut source_info: mir::SourceInfo,
1503 ) -> OperandRef<'tcx, Bx::Value> {
1506 let mut span_to_caller_location = |span: Span| {
1507 let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
1508 let caller = tcx.sess.source_map().lookup_char_pos(topmost.lo());
1509 let const_loc = tcx.const_caller_location((
1510 Symbol::intern(&caller.file.name.prefer_remapped().to_string_lossy()),
1512 caller.col_display as u32 + 1,
1514 OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
1517 // Walk up the `SourceScope`s, in case some of them are from MIR inlining.
1518 // If so, the starting `source_info.span` is in the innermost inlined
1519 // function, and will be replaced with outer callsite spans as long
1520 // as the inlined functions were `#[track_caller]`.
1522 let scope_data = &self.mir.source_scopes[source_info.scope];
1524 if let Some((callee, callsite_span)) = scope_data.inlined {
1525 // Stop inside the most nested non-`#[track_caller]` function,
1526 // before ever reaching its caller (which is irrelevant).
1527 if !callee.def.requires_caller_location(tcx) {
1528 return span_to_caller_location(source_info.span);
1530 source_info.span = callsite_span;
1533 // Skip past all of the parents with `inlined: None`.
1534 match scope_data.inlined_parent_scope {
1535 Some(parent) => source_info.scope = parent,
1540 // No inlined `SourceScope`s, or all of them were `#[track_caller]`.
1541 self.caller_location.unwrap_or_else(|| span_to_caller_location(source_info.span))
1544 fn get_personality_slot(&mut self, bx: &mut Bx) -> PlaceRef<'tcx, Bx::Value> {
1546 if let Some(slot) = self.personality_slot {
1549 let layout = cx.layout_of(
1550 cx.tcx().intern_tup(&[cx.tcx().mk_mut_ptr(cx.tcx().types.u8), cx.tcx().types.i32]),
1552 let slot = PlaceRef::alloca(bx, layout);
1553 self.personality_slot = Some(slot);
1558 /// Returns the landing/cleanup pad wrapper around the given basic block.
1559 // FIXME(eddyb) rename this to `eh_pad_for`.
1560 fn landing_pad_for(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1561 if let Some(landing_pad) = self.landing_pads[bb] {
1565 let landing_pad = self.landing_pad_for_uncached(bb);
1566 self.landing_pads[bb] = Some(landing_pad);
1570 // FIXME(eddyb) rename this to `eh_pad_for_uncached`.
1571 fn landing_pad_for_uncached(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1572 let llbb = self.llbb(bb);
1573 if base::wants_msvc_seh(self.cx.sess()) {
1576 match self.mir[bb].terminator.as_ref().map(|t| &t.kind) {
1577 // This is a basic block that we're aborting the program for,
1578 // notably in an `extern` function. These basic blocks are inserted
1579 // so that we assert that `extern` functions do indeed not panic,
1580 // and if they do we abort the process.
1582 // On MSVC these are tricky though (where we're doing funclets). If
1583 // we were to do a cleanuppad (like below) the normal functions like
1584 // `longjmp` would trigger the abort logic, terminating the
1585 // program. Instead we insert the equivalent of `catch(...)` for C++
1586 // which magically doesn't trigger when `longjmp` files over this
1589 // Lots more discussion can be found on #48251 but this codegen is
1590 // modeled after clang's for:
1597 Some(&mir::TerminatorKind::Abort) => {
1599 Bx::append_block(self.cx, self.llfn, &format!("cs_funclet{:?}", bb));
1601 Bx::append_block(self.cx, self.llfn, &format!("cp_funclet{:?}", bb));
1604 let mut cs_bx = Bx::build(self.cx, cs_llbb);
1605 let cs = cs_bx.catch_switch(None, None, &[cp_llbb]);
1607 // The "null" here is actually a RTTI type descriptor for the
1608 // C++ personality function, but `catch (...)` has no type so
1609 // it's null. The 64 here is actually a bitfield which
1610 // represents that this is a catch-all block.
1611 let mut cp_bx = Bx::build(self.cx, cp_llbb);
1612 let null = cp_bx.const_null(
1613 cp_bx.type_i8p_ext(cp_bx.cx().data_layout().instruction_address_space),
1615 let sixty_four = cp_bx.const_i32(64);
1616 funclet = cp_bx.catch_pad(cs, &[null, sixty_four, null]);
1621 Bx::append_block(self.cx, self.llfn, &format!("funclet_{:?}", bb));
1622 ret_llbb = cleanup_llbb;
1623 let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
1624 funclet = cleanup_bx.cleanup_pad(None, &[]);
1625 cleanup_bx.br(llbb);
1628 self.funclets[bb] = Some(funclet);
1631 let cleanup_llbb = Bx::append_block(self.cx, self.llfn, "cleanup");
1632 let mut cleanup_bx = Bx::build(self.cx, cleanup_llbb);
1634 let llpersonality = self.cx.eh_personality();
1635 let (exn0, exn1) = cleanup_bx.cleanup_landing_pad(llpersonality);
1637 let slot = self.get_personality_slot(&mut cleanup_bx);
1638 slot.storage_live(&mut cleanup_bx);
1639 Pair(exn0, exn1).store(&mut cleanup_bx, slot);
1641 cleanup_bx.br(llbb);
1646 fn unreachable_block(&mut self) -> Bx::BasicBlock {
1647 self.unreachable_block.unwrap_or_else(|| {
1648 let llbb = Bx::append_block(self.cx, self.llfn, "unreachable");
1649 let mut bx = Bx::build(self.cx, llbb);
1651 self.unreachable_block = Some(llbb);
1656 fn double_unwind_guard(&mut self) -> Bx::BasicBlock {
1657 self.double_unwind_guard.unwrap_or_else(|| {
1658 assert!(!base::wants_msvc_seh(self.cx.sess()));
1660 let llbb = Bx::append_block(self.cx, self.llfn, "abort");
1661 let mut bx = Bx::build(self.cx, llbb);
1662 self.set_debug_loc(&mut bx, mir::SourceInfo::outermost(self.mir.span));
1664 let llpersonality = self.cx.eh_personality();
1665 bx.cleanup_landing_pad(llpersonality);
1667 let (fn_abi, fn_ptr) = common::build_langcall(&bx, None, LangItem::PanicCannotUnwind);
1668 let fn_ty = bx.fn_decl_backend_type(&fn_abi);
1670 let llret = bx.call(fn_ty, Some(&fn_abi), fn_ptr, &[], None);
1671 bx.do_not_inline(llret);
1675 self.double_unwind_guard = Some(llbb);
1680 /// Get the backend `BasicBlock` for a MIR `BasicBlock`, either already
1681 /// cached in `self.cached_llbbs`, or created on demand (and cached).
1682 // FIXME(eddyb) rename `llbb` and other `ll`-prefixed things to use a
1683 // more backend-agnostic prefix such as `cg` (i.e. this would be `cgbb`).
1684 pub fn llbb(&mut self, bb: mir::BasicBlock) -> Bx::BasicBlock {
1685 self.try_llbb(bb).unwrap()
1688 /// Like `llbb`, but may fail if the basic block should be skipped.
1689 pub fn try_llbb(&mut self, bb: mir::BasicBlock) -> Option<Bx::BasicBlock> {
1690 match self.cached_llbbs[bb] {
1691 CachedLlbb::None => {
1692 // FIXME(eddyb) only name the block if `fewer_names` is `false`.
1693 let llbb = Bx::append_block(self.cx, self.llfn, &format!("{:?}", bb));
1694 self.cached_llbbs[bb] = CachedLlbb::Some(llbb);
1697 CachedLlbb::Some(llbb) => Some(llbb),
1698 CachedLlbb::Skip => None,
1702 fn make_return_dest(
1705 dest: mir::Place<'tcx>,
1706 fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
1707 llargs: &mut Vec<Bx::Value>,
1709 ) -> ReturnDest<'tcx, Bx::Value> {
1710 // If the return is ignored, we can just return a do-nothing `ReturnDest`.
1711 if fn_ret.is_ignore() {
1712 return ReturnDest::Nothing;
1714 let dest = if let Some(index) = dest.as_local() {
1715 match self.locals[index] {
1716 LocalRef::Place(dest) => dest,
1717 LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
1718 LocalRef::Operand(None) => {
1719 // Handle temporary places, specifically `Operand` ones, as
1720 // they don't have `alloca`s.
1721 return if fn_ret.is_indirect() {
1722 // Odd, but possible, case, we have an operand temporary,
1723 // but the calling convention has an indirect return.
1724 let tmp = PlaceRef::alloca(bx, fn_ret.layout);
1725 tmp.storage_live(bx);
1726 llargs.push(tmp.llval);
1727 ReturnDest::IndirectOperand(tmp, index)
1728 } else if is_intrinsic {
1729 // Currently, intrinsics always need a location to store
1730 // the result, so we create a temporary `alloca` for the
1732 let tmp = PlaceRef::alloca(bx, fn_ret.layout);
1733 tmp.storage_live(bx);
1734 ReturnDest::IndirectOperand(tmp, index)
1736 ReturnDest::DirectOperand(index)
1739 LocalRef::Operand(Some(_)) => {
1740 bug!("place local already assigned to");
1746 mir::PlaceRef { local: dest.local, projection: &dest.projection },
1749 if fn_ret.is_indirect() {
1750 if dest.align < dest.layout.align.abi {
1751 // Currently, MIR code generation does not create calls
1752 // that store directly to fields of packed structs (in
1753 // fact, the calls it creates write only to temps).
1755 // If someone changes that, please update this code path
1756 // to create a temporary.
1757 span_bug!(self.mir.span, "can't directly store to unaligned value");
1759 llargs.push(dest.llval);
1762 ReturnDest::Store(dest)
1766 fn codegen_transmute(&mut self, bx: &mut Bx, src: &mir::Operand<'tcx>, dst: mir::Place<'tcx>) {
1767 if let Some(index) = dst.as_local() {
1768 match self.locals[index] {
1769 LocalRef::Place(place) => self.codegen_transmute_into(bx, src, place),
1770 LocalRef::UnsizedPlace(_) => bug!("transmute must not involve unsized locals"),
1771 LocalRef::Operand(None) => {
1772 let dst_layout = bx.layout_of(self.monomorphized_place_ty(dst.as_ref()));
1773 assert!(!dst_layout.ty.has_erasable_regions());
1774 let place = PlaceRef::alloca(bx, dst_layout);
1775 place.storage_live(bx);
1776 self.codegen_transmute_into(bx, src, place);
1777 let op = bx.load_operand(place);
1778 place.storage_dead(bx);
1779 self.locals[index] = LocalRef::Operand(Some(op));
1780 self.debug_introduce_local(bx, index);
1782 LocalRef::Operand(Some(op)) => {
1783 assert!(op.layout.is_zst(), "assigning to initialized SSAtemp");
1787 let dst = self.codegen_place(bx, dst.as_ref());
1788 self.codegen_transmute_into(bx, src, dst);
1792 fn codegen_transmute_into(
1795 src: &mir::Operand<'tcx>,
1796 dst: PlaceRef<'tcx, Bx::Value>,
1798 let src = self.codegen_operand(bx, src);
1800 // Special-case transmutes between scalars as simple bitcasts.
1801 match (src.layout.abi, dst.layout.abi) {
1802 (abi::Abi::Scalar(src_scalar), abi::Abi::Scalar(dst_scalar)) => {
1803 // HACK(eddyb) LLVM doesn't like `bitcast`s between pointers and non-pointers.
1804 let src_is_ptr = src_scalar.primitive() == abi::Pointer;
1805 let dst_is_ptr = dst_scalar.primitive() == abi::Pointer;
1806 if src_is_ptr == dst_is_ptr {
1807 assert_eq!(src.layout.size, dst.layout.size);
1809 // NOTE(eddyb) the `from_immediate` and `to_immediate_scalar`
1810 // conversions allow handling `bool`s the same as `u8`s.
1811 let src = bx.from_immediate(src.immediate());
1812 // LLVM also doesn't like `bitcast`s between pointers in different address spaces.
1813 let src_as_dst = if src_is_ptr {
1814 bx.pointercast(src, bx.backend_type(dst.layout))
1816 bx.bitcast(src, bx.backend_type(dst.layout))
1818 Immediate(bx.to_immediate_scalar(src_as_dst, dst_scalar)).store(bx, dst);
1825 let llty = bx.backend_type(src.layout);
1826 let cast_ptr = bx.pointercast(dst.llval, bx.type_ptr_to(llty));
1827 let align = src.layout.align.abi.min(dst.align);
1828 src.val.store(bx, PlaceRef::new_sized_aligned(cast_ptr, src.layout, align));
1831 // Stores the return value of a function call into it's final location.
1835 dest: ReturnDest<'tcx, Bx::Value>,
1836 ret_abi: &ArgAbi<'tcx, Ty<'tcx>>,
1839 use self::ReturnDest::*;
1843 Store(dst) => bx.store_arg(&ret_abi, llval, dst),
1844 IndirectOperand(tmp, index) => {
1845 let op = bx.load_operand(tmp);
1846 tmp.storage_dead(bx);
1847 self.locals[index] = LocalRef::Operand(Some(op));
1848 self.debug_introduce_local(bx, index);
1850 DirectOperand(index) => {
1851 // If there is a cast, we have to store and reload.
1852 let op = if let PassMode::Cast(..) = ret_abi.mode {
1853 let tmp = PlaceRef::alloca(bx, ret_abi.layout);
1854 tmp.storage_live(bx);
1855 bx.store_arg(&ret_abi, llval, tmp);
1856 let op = bx.load_operand(tmp);
1857 tmp.storage_dead(bx);
1860 OperandRef::from_immediate_or_packed_pair(bx, llval, ret_abi.layout)
1862 self.locals[index] = LocalRef::Operand(Some(op));
1863 self.debug_introduce_local(bx, index);
1869 enum ReturnDest<'tcx, V> {
1870 // Do nothing; the return value is indirect or ignored.
1872 // Store the return value to the pointer.
1873 Store(PlaceRef<'tcx, V>),
1874 // Store an indirect return value to an operand local place.
1875 IndirectOperand(PlaceRef<'tcx, V>, mir::Local),
1876 // Store a direct return value to an operand local place.
1877 DirectOperand(mir::Local),