1 use super::operand::OperandRef;
2 use super::operand::OperandValue::{Immediate, Pair, Ref};
3 use super::place::PlaceRef;
4 use super::{FunctionCx, LocalRef};
7 use crate::common::{self, IntPredicate};
13 use rustc_hir::lang_items::LangItem;
14 use rustc_index::vec::Idx;
15 use rustc_middle::mir::interpret::ConstValue;
16 use rustc_middle::mir::AssertKind;
17 use rustc_middle::mir::{self, SwitchTargets};
18 use rustc_middle::ty::layout::{FnAbiExt, HasTyCtxt};
19 use rustc_middle::ty::print::with_no_trimmed_paths;
20 use rustc_middle::ty::{self, Instance, Ty, TypeFoldable};
21 use rustc_span::source_map::Span;
22 use rustc_span::{sym, Symbol};
23 use rustc_target::abi::call::{ArgAbi, FnAbi, PassMode};
24 use rustc_target::abi::{self, LayoutOf};
25 use rustc_target::spec::abi::Abi;
27 /// Used by `FunctionCx::codegen_terminator` for emitting common patterns
28 /// e.g., creating a basic block, calling a function, etc.
29 struct TerminatorCodegenHelper<'tcx> {
31 terminator: &'tcx mir::Terminator<'tcx>,
32 funclet_bb: Option<mir::BasicBlock>,
35 impl<'a, 'tcx> TerminatorCodegenHelper<'tcx> {
36 /// Returns the associated funclet from `FunctionCx::funclets` for the
37 /// `funclet_bb` member if it is not `None`.
38 fn funclet<'b, Bx: BuilderMethods<'a, 'tcx>>(
40 fx: &'b FunctionCx<'a, 'tcx, Bx>,
41 ) -> Option<&'b Bx::Funclet> {
42 self.funclet_bb.and_then(|funcl| fx.funclets[funcl].as_ref())
45 fn lltarget<Bx: BuilderMethods<'a, 'tcx>>(
47 fx: &mut FunctionCx<'a, 'tcx, Bx>,
48 target: mir::BasicBlock,
49 ) -> (Bx::BasicBlock, bool) {
50 let span = self.terminator.source_info.span;
51 let lltarget = fx.blocks[target];
52 let target_funclet = fx.cleanup_kinds[target].funclet_bb(target);
53 match (self.funclet_bb, target_funclet) {
54 (None, None) => (lltarget, false),
55 (Some(f), Some(t_f)) if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) => {
58 // jump *into* cleanup - need a landing pad if GNU
59 (None, Some(_)) => (fx.landing_pad_to(target), false),
60 (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", self.terminator),
61 (Some(_), Some(_)) => (fx.landing_pad_to(target), true),
65 /// Create a basic block.
66 fn llblock<Bx: BuilderMethods<'a, 'tcx>>(
68 fx: &mut FunctionCx<'a, 'tcx, Bx>,
69 target: mir::BasicBlock,
71 let (lltarget, is_cleanupret) = self.lltarget(fx, target);
73 // MSVC cross-funclet jump - need a trampoline
75 debug!("llblock: creating cleanup trampoline for {:?}", target);
76 let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
77 let mut trampoline = fx.new_block(name);
78 trampoline.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
85 fn funclet_br<Bx: BuilderMethods<'a, 'tcx>>(
87 fx: &mut FunctionCx<'a, 'tcx, Bx>,
89 target: mir::BasicBlock,
91 let (lltarget, is_cleanupret) = self.lltarget(fx, target);
93 // micro-optimization: generate a `ret` rather than a jump
95 bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
101 /// Call `fn_ptr` of `fn_abi` with the arguments `llargs`, the optional
102 /// return destination `destination` and the cleanup function `cleanup`.
103 fn do_call<Bx: BuilderMethods<'a, 'tcx>>(
105 fx: &mut FunctionCx<'a, 'tcx, Bx>,
107 fn_abi: FnAbi<'tcx, Ty<'tcx>>,
109 llargs: &[Bx::Value],
110 destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
111 cleanup: Option<mir::BasicBlock>,
113 // If there is a cleanup block and the function we're calling can unwind, then
114 // do an invoke, otherwise do a call.
115 if let Some(cleanup) = cleanup.filter(|_| fn_abi.can_unwind) {
116 let ret_bx = if let Some((_, target)) = destination {
119 fx.unreachable_block()
122 bx.invoke(fn_ptr, &llargs, ret_bx, self.llblock(fx, cleanup), self.funclet(fx));
123 bx.apply_attrs_callsite(&fn_abi, invokeret);
125 if let Some((ret_dest, target)) = destination {
126 let mut ret_bx = fx.build_block(target);
127 fx.set_debug_loc(&mut ret_bx, self.terminator.source_info);
128 fx.store_return(&mut ret_bx, ret_dest, &fn_abi.ret, invokeret);
131 let llret = bx.call(fn_ptr, &llargs, self.funclet(fx));
132 bx.apply_attrs_callsite(&fn_abi, llret);
133 if fx.mir[self.bb].is_cleanup {
134 // Cleanup is always the cold path. Don't inline
135 // drop glue. Also, when there is a deeply-nested
136 // struct, there are "symmetry" issues that cause
137 // exponential inlining - see issue #41696.
138 bx.do_not_inline(llret);
141 if let Some((ret_dest, target)) = destination {
142 fx.store_return(bx, ret_dest, &fn_abi.ret, llret);
143 self.funclet_br(fx, bx, target);
151 /// Codegen implementations for some terminator variants.
152 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
153 /// Generates code for a `Resume` terminator.
154 fn codegen_resume_terminator(&mut self, helper: TerminatorCodegenHelper<'tcx>, mut bx: Bx) {
155 if let Some(funclet) = helper.funclet(self) {
156 bx.cleanup_ret(funclet, None);
158 let slot = self.get_personality_slot(&mut bx);
159 let lp0 = slot.project_field(&mut bx, 0);
160 let lp0 = bx.load_operand(lp0).immediate();
161 let lp1 = slot.project_field(&mut bx, 1);
162 let lp1 = bx.load_operand(lp1).immediate();
163 slot.storage_dead(&mut bx);
165 let mut lp = bx.const_undef(self.landing_pad_type());
166 lp = bx.insert_value(lp, lp0, 0);
167 lp = bx.insert_value(lp, lp1, 1);
172 fn codegen_switchint_terminator(
174 helper: TerminatorCodegenHelper<'tcx>,
176 discr: &mir::Operand<'tcx>,
178 targets: &SwitchTargets,
180 let discr = self.codegen_operand(&mut bx, &discr);
181 // `switch_ty` is redundant, sanity-check that.
182 assert_eq!(discr.layout.ty, switch_ty);
183 let mut target_iter = targets.iter();
184 if target_iter.len() == 1 {
185 // If there are two targets (one conditional, one fallback), emit br instead of switch
186 let (test_value, target) = target_iter.next().unwrap();
187 let lltrue = helper.llblock(self, target);
188 let llfalse = helper.llblock(self, targets.otherwise());
189 if switch_ty == bx.tcx().types.bool {
190 // Don't generate trivial icmps when switching on bool
192 0 => bx.cond_br(discr.immediate(), llfalse, lltrue),
193 1 => bx.cond_br(discr.immediate(), lltrue, llfalse),
197 let switch_llty = bx.immediate_backend_type(bx.layout_of(switch_ty));
198 let llval = bx.const_uint_big(switch_llty, test_value);
199 let cmp = bx.icmp(IntPredicate::IntEQ, discr.immediate(), llval);
200 bx.cond_br(cmp, lltrue, llfalse);
205 helper.llblock(self, targets.otherwise()),
206 target_iter.map(|(value, target)| (value, helper.llblock(self, target))),
211 fn codegen_return_terminator(&mut self, mut bx: Bx) {
212 // Call `va_end` if this is the definition of a C-variadic function.
213 if self.fn_abi.c_variadic {
214 // The `VaList` "spoofed" argument is just after all the real arguments.
215 let va_list_arg_idx = self.fn_abi.args.len();
216 match self.locals[mir::Local::new(1 + va_list_arg_idx)] {
217 LocalRef::Place(va_list) => {
218 bx.va_end(va_list.llval);
220 _ => bug!("C-variadic function must have a `VaList` place"),
223 if self.fn_abi.ret.layout.abi.is_uninhabited() {
224 // Functions with uninhabited return values are marked `noreturn`,
225 // so we should make sure that we never actually do.
226 // We play it safe by using a well-defined `abort`, but we could go for immediate UB
227 // if that turns out to be helpful.
229 // `abort` does not terminate the block, so we still need to generate
230 // an `unreachable` terminator after it.
234 let llval = match self.fn_abi.ret.mode {
235 PassMode::Ignore | PassMode::Indirect { .. } => {
240 PassMode::Direct(_) | PassMode::Pair(..) => {
241 let op = self.codegen_consume(&mut bx, mir::Place::return_place().as_ref());
242 if let Ref(llval, _, align) = op.val {
243 bx.load(llval, align)
245 op.immediate_or_packed_pair(&mut bx)
249 PassMode::Cast(cast_ty) => {
250 let op = match self.locals[mir::RETURN_PLACE] {
251 LocalRef::Operand(Some(op)) => op,
252 LocalRef::Operand(None) => bug!("use of return before def"),
253 LocalRef::Place(cg_place) => OperandRef {
254 val: Ref(cg_place.llval, None, cg_place.align),
255 layout: cg_place.layout,
257 LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
259 let llslot = match op.val {
260 Immediate(_) | Pair(..) => {
261 let scratch = PlaceRef::alloca(&mut bx, self.fn_abi.ret.layout);
262 op.val.store(&mut bx, scratch);
265 Ref(llval, _, align) => {
266 assert_eq!(align, op.layout.align.abi, "return place is unaligned!");
270 let addr = bx.pointercast(llslot, bx.type_ptr_to(bx.cast_backend_type(&cast_ty)));
271 bx.load(addr, self.fn_abi.ret.layout.align.abi)
277 fn codegen_drop_terminator(
279 helper: TerminatorCodegenHelper<'tcx>,
281 location: mir::Place<'tcx>,
282 target: mir::BasicBlock,
283 unwind: Option<mir::BasicBlock>,
285 let ty = location.ty(self.mir, bx.tcx()).ty;
286 let ty = self.monomorphize(ty);
287 let drop_fn = Instance::resolve_drop_in_place(bx.tcx(), ty);
289 if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
290 // we don't actually need to drop anything.
291 helper.funclet_br(self, &mut bx, target);
295 let place = self.codegen_place(&mut bx, location.as_ref());
297 let mut args = if let Some(llextra) = place.llextra {
298 args2 = [place.llval, llextra];
301 args1 = [place.llval];
304 let (drop_fn, fn_abi) = match ty.kind() {
305 // FIXME(eddyb) perhaps move some of this logic into
306 // `Instance::resolve_drop_in_place`?
308 let virtual_drop = Instance {
309 def: ty::InstanceDef::Virtual(drop_fn.def_id(), 0),
310 substs: drop_fn.substs,
312 let fn_abi = FnAbi::of_instance(&bx, virtual_drop, &[]);
313 let vtable = args[1];
315 (meth::DESTRUCTOR.get_fn(&mut bx, vtable, &fn_abi), fn_abi)
317 _ => (bx.get_fn_addr(drop_fn), FnAbi::of_instance(&bx, drop_fn, &[])),
325 Some((ReturnDest::Nothing, target)),
330 fn codegen_assert_terminator(
332 helper: TerminatorCodegenHelper<'tcx>,
334 terminator: &mir::Terminator<'tcx>,
335 cond: &mir::Operand<'tcx>,
337 msg: &mir::AssertMessage<'tcx>,
338 target: mir::BasicBlock,
339 cleanup: Option<mir::BasicBlock>,
341 let span = terminator.source_info.span;
342 let cond = self.codegen_operand(&mut bx, cond).immediate();
343 let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
345 // This case can currently arise only from functions marked
346 // with #[rustc_inherit_overflow_checks] and inlined from
347 // another crate (mostly core::num generic/#[inline] fns),
348 // while the current crate doesn't use overflow checks.
349 // NOTE: Unlike binops, negation doesn't have its own
350 // checked operation, just a comparison with the minimum
351 // value, so we have to check for the assert message.
352 if !bx.check_overflow() {
353 if let AssertKind::OverflowNeg(_) = *msg {
354 const_cond = Some(expected);
358 // Don't codegen the panic block if success if known.
359 if const_cond == Some(expected) {
360 helper.funclet_br(self, &mut bx, target);
364 // Pass the condition through llvm.expect for branch hinting.
365 let cond = bx.expect(cond, expected);
367 // Create the failure block and the conditional branch to it.
368 let lltarget = helper.llblock(self, target);
369 let panic_block = self.new_block("panic");
371 bx.cond_br(cond, lltarget, panic_block.llbb());
373 bx.cond_br(cond, panic_block.llbb(), lltarget);
376 // After this point, bx is the block for the call to panic.
378 self.set_debug_loc(&mut bx, terminator.source_info);
380 // Get the location information.
381 let location = self.get_caller_location(&mut bx, terminator.source_info).immediate();
383 // Put together the arguments to the panic entry point.
384 let (lang_item, args) = match msg {
385 AssertKind::BoundsCheck { ref len, ref index } => {
386 let len = self.codegen_operand(&mut bx, len).immediate();
387 let index = self.codegen_operand(&mut bx, index).immediate();
388 // It's `fn panic_bounds_check(index: usize, len: usize)`,
389 // and `#[track_caller]` adds an implicit third argument.
390 (LangItem::PanicBoundsCheck, vec![index, len, location])
393 let msg_str = Symbol::intern(msg.description());
394 let msg = bx.const_str(msg_str);
395 // It's `pub fn panic(expr: &str)`, with the wide reference being passed
396 // as two arguments, and `#[track_caller]` adds an implicit third argument.
397 (LangItem::Panic, vec![msg.0, msg.1, location])
401 // Obtain the panic entry point.
402 let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
403 let instance = ty::Instance::mono(bx.tcx(), def_id);
404 let fn_abi = FnAbi::of_instance(&bx, instance, &[]);
405 let llfn = bx.get_fn_addr(instance);
407 // Codegen the actual panic invoke/call.
408 helper.do_call(self, &mut bx, fn_abi, llfn, &args, None, cleanup);
411 /// Returns `true` if this is indeed a panic intrinsic and codegen is done.
412 fn codegen_panic_intrinsic(
414 helper: &TerminatorCodegenHelper<'tcx>,
416 intrinsic: Option<Symbol>,
417 instance: Option<Instance<'tcx>>,
418 source_info: mir::SourceInfo,
419 destination: &Option<(mir::Place<'tcx>, mir::BasicBlock)>,
420 cleanup: Option<mir::BasicBlock>,
422 // Emit a panic or a no-op for `assert_*` intrinsics.
423 // These are intrinsics that compile to panics so that we can get a message
424 // which mentions the offending type, even from a const context.
425 #[derive(Debug, PartialEq)]
426 enum AssertIntrinsic {
431 let panic_intrinsic = intrinsic.and_then(|i| match i {
432 sym::assert_inhabited => Some(AssertIntrinsic::Inhabited),
433 sym::assert_zero_valid => Some(AssertIntrinsic::ZeroValid),
434 sym::assert_uninit_valid => Some(AssertIntrinsic::UninitValid),
437 if let Some(intrinsic) = panic_intrinsic {
438 use AssertIntrinsic::*;
439 let ty = instance.unwrap().substs.type_at(0);
440 let layout = bx.layout_of(ty);
441 let do_panic = match intrinsic {
442 Inhabited => layout.abi.is_uninhabited(),
443 // We unwrap as the error type is `!`.
444 ZeroValid => !layout.might_permit_raw_init(bx, /*zero:*/ true).unwrap(),
445 // We unwrap as the error type is `!`.
446 UninitValid => !layout.might_permit_raw_init(bx, /*zero:*/ false).unwrap(),
449 let msg_str = with_no_trimmed_paths(|| {
450 if layout.abi.is_uninhabited() {
451 // Use this error even for the other intrinsics as it is more precise.
452 format!("attempted to instantiate uninhabited type `{}`", ty)
453 } else if intrinsic == ZeroValid {
454 format!("attempted to zero-initialize type `{}`, which is invalid", ty)
456 format!("attempted to leave type `{}` uninitialized, which is invalid", ty)
459 let msg = bx.const_str(Symbol::intern(&msg_str));
460 let location = self.get_caller_location(bx, source_info).immediate();
462 // Obtain the panic entry point.
463 // FIXME: dedup this with `codegen_assert_terminator` above.
465 common::langcall(bx.tcx(), Some(source_info.span), "", LangItem::Panic);
466 let instance = ty::Instance::mono(bx.tcx(), def_id);
467 let fn_abi = FnAbi::of_instance(bx, instance, &[]);
468 let llfn = bx.get_fn_addr(instance);
470 // Codegen the actual panic invoke/call.
476 &[msg.0, msg.1, location],
477 destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
482 let target = destination.as_ref().unwrap().1;
483 helper.funclet_br(self, bx, target)
491 fn codegen_call_terminator(
493 helper: TerminatorCodegenHelper<'tcx>,
495 terminator: &mir::Terminator<'tcx>,
496 func: &mir::Operand<'tcx>,
497 args: &[mir::Operand<'tcx>],
498 destination: &Option<(mir::Place<'tcx>, mir::BasicBlock)>,
499 cleanup: Option<mir::BasicBlock>,
502 let source_info = terminator.source_info;
503 let span = source_info.span;
505 // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
506 let callee = self.codegen_operand(&mut bx, func);
508 let (instance, mut llfn) = match *callee.layout.ty.kind() {
509 ty::FnDef(def_id, substs) => (
511 ty::Instance::resolve(bx.tcx(), ty::ParamEnv::reveal_all(), def_id, substs)
514 .polymorphize(bx.tcx()),
518 ty::FnPtr(_) => (None, Some(callee.immediate())),
519 _ => bug!("{} is not callable", callee.layout.ty),
521 let def = instance.map(|i| i.def);
523 if let Some(ty::InstanceDef::DropGlue(_, None)) = def {
524 // Empty drop glue; a no-op.
525 let &(_, target) = destination.as_ref().unwrap();
526 helper.funclet_br(self, &mut bx, target);
530 // FIXME(eddyb) avoid computing this if possible, when `instance` is
531 // available - right now `sig` is only needed for getting the `abi`
532 // and figuring out how many extra args were passed to a C-variadic `fn`.
533 let sig = callee.layout.ty.fn_sig(bx.tcx());
536 // Handle intrinsics old codegen wants Expr's for, ourselves.
537 let intrinsic = match def {
538 Some(ty::InstanceDef::Intrinsic(def_id)) => Some(bx.tcx().item_name(def_id)),
542 let extra_args = &args[sig.inputs().skip_binder().len()..];
543 let extra_args = extra_args
546 let op_ty = op_arg.ty(self.mir, bx.tcx());
547 self.monomorphize(op_ty)
549 .collect::<Vec<_>>();
551 let fn_abi = match instance {
552 Some(instance) => FnAbi::of_instance(&bx, instance, &extra_args),
553 None => FnAbi::of_fn_ptr(&bx, sig, &extra_args),
556 if intrinsic == Some(sym::transmute) {
557 if let Some(destination_ref) = destination.as_ref() {
558 let &(dest, target) = destination_ref;
559 self.codegen_transmute(&mut bx, &args[0], dest);
560 helper.funclet_br(self, &mut bx, target);
562 // If we are trying to transmute to an uninhabited type,
563 // it is likely there is no allotted destination. In fact,
564 // transmuting to an uninhabited type is UB, which means
565 // we can do what we like. Here, we declare that transmuting
566 // into an uninhabited type is impossible, so anything following
567 // it must be unreachable.
568 assert_eq!(fn_abi.ret.layout.abi, abi::Abi::Uninhabited);
574 if self.codegen_panic_intrinsic(
586 // The arguments we'll be passing. Plus one to account for outptr, if used.
587 let arg_count = fn_abi.args.len() + fn_abi.ret.is_indirect() as usize;
588 let mut llargs = Vec::with_capacity(arg_count);
590 // Prepare the return value destination
591 let ret_dest = if let Some((dest, _)) = *destination {
592 let is_intrinsic = intrinsic.is_some();
593 self.make_return_dest(&mut bx, dest, &fn_abi.ret, &mut llargs, is_intrinsic)
598 if intrinsic == Some(sym::caller_location) {
599 if let Some((_, target)) = destination.as_ref() {
601 .get_caller_location(&mut bx, mir::SourceInfo { span: fn_span, ..source_info });
603 if let ReturnDest::IndirectOperand(tmp, _) = ret_dest {
604 location.val.store(&mut bx, tmp);
606 self.store_return(&mut bx, ret_dest, &fn_abi.ret, location.immediate());
607 helper.funclet_br(self, &mut bx, *target);
613 None | Some(sym::drop_in_place) => {}
614 Some(sym::copy_nonoverlapping) => unreachable!(),
616 let dest = match ret_dest {
617 _ if fn_abi.ret.is_indirect() => llargs[0],
618 ReturnDest::Nothing => {
619 bx.const_undef(bx.type_ptr_to(bx.arg_memory_ty(&fn_abi.ret)))
621 ReturnDest::IndirectOperand(dst, _) | ReturnDest::Store(dst) => dst.llval,
622 ReturnDest::DirectOperand(_) => {
623 bug!("Cannot use direct operand with an intrinsic call")
627 let args: Vec<_> = args
631 // The indices passed to simd_shuffle* in the
632 // third argument must be constant. This is
633 // checked by const-qualification, which also
634 // promotes any complex rvalues to constants.
635 if i == 2 && intrinsic.as_str().starts_with("simd_shuffle") {
636 if let mir::Operand::Constant(constant) = arg {
637 let c = self.eval_mir_constant(constant);
639 self.simd_shuffle_indices(&bx, constant.span, constant.ty(), c);
641 val: Immediate(llval),
642 layout: bx.layout_of(ty),
645 span_bug!(span, "shuffle indices must be constant");
649 self.codegen_operand(&mut bx, arg)
653 Self::codegen_intrinsic_call(
655 *instance.as_ref().unwrap(),
662 if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
663 self.store_return(&mut bx, ret_dest, &fn_abi.ret, dst.llval);
666 if let Some((_, target)) = *destination {
667 helper.funclet_br(self, &mut bx, target);
676 // Split the rust-call tupled arguments off.
677 let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
678 let (tup, args) = args.split_last().unwrap();
684 'make_args: for (i, arg) in first_args.iter().enumerate() {
685 let mut op = self.codegen_operand(&mut bx, arg);
687 if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
688 if let Pair(..) = op.val {
689 // In the case of Rc<Self>, we need to explicitly pass a
690 // *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
691 // that is understood elsewhere in the compiler as a method on
693 // To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
694 // we get a value of a built-in pointer type
695 'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
696 && !op.layout.ty.is_region_ptr()
698 for i in 0..op.layout.fields.count() {
699 let field = op.extract_field(&mut bx, i);
700 if !field.layout.is_zst() {
701 // we found the one non-zero-sized field that is allowed
702 // now find *its* non-zero-sized field, or stop if it's a
705 continue 'descend_newtypes;
709 span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
712 // now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
713 // data pointer and vtable. Look up the method in the vtable, and pass
714 // the data pointer as the first argument
716 Pair(data_ptr, meta) => {
718 meth::VirtualIndex::from_index(idx).get_fn(&mut bx, meta, &fn_abi),
720 llargs.push(data_ptr);
723 other => bug!("expected a Pair, got {:?}", other),
725 } else if let Ref(data_ptr, Some(meta), _) = op.val {
726 // by-value dynamic dispatch
727 llfn = Some(meth::VirtualIndex::from_index(idx).get_fn(&mut bx, meta, &fn_abi));
728 llargs.push(data_ptr);
731 span_bug!(span, "can't codegen a virtual call on {:?}", op);
735 // The callee needs to own the argument memory if we pass it
736 // by-ref, so make a local copy of non-immediate constants.
737 match (arg, op.val) {
738 (&mir::Operand::Copy(_), Ref(_, None, _))
739 | (&mir::Operand::Constant(_), Ref(_, None, _)) => {
740 let tmp = PlaceRef::alloca(&mut bx, op.layout);
741 op.val.store(&mut bx, tmp);
742 op.val = Ref(tmp.llval, None, tmp.align);
747 self.codegen_argument(&mut bx, op, &mut llargs, &fn_abi.args[i]);
749 if let Some(tup) = untuple {
750 self.codegen_arguments_untupled(
754 &fn_abi.args[first_args.len()..],
759 instance.map_or(false, |i| i.def.requires_caller_location(self.cx.tcx()));
764 "#[track_caller] fn's must have 1 more argument in their ABI than in their MIR",
767 self.get_caller_location(&mut bx, mir::SourceInfo { span: fn_span, ..source_info });
769 "codegen_call_terminator({:?}): location={:?} (fn_span {:?})",
770 terminator, location, fn_span
773 let last_arg = fn_abi.args.last().unwrap();
774 self.codegen_argument(&mut bx, location, &mut llargs, last_arg);
777 let fn_ptr = match (llfn, instance) {
778 (Some(llfn), _) => llfn,
779 (None, Some(instance)) => bx.get_fn_addr(instance),
780 _ => span_bug!(span, "no llfn for call"),
789 destination.as_ref().map(|&(_, target)| (ret_dest, target)),
794 fn codegen_asm_terminator(
796 helper: TerminatorCodegenHelper<'tcx>,
798 terminator: &mir::Terminator<'tcx>,
799 template: &[ast::InlineAsmTemplatePiece],
800 operands: &[mir::InlineAsmOperand<'tcx>],
801 options: ast::InlineAsmOptions,
803 destination: Option<mir::BasicBlock>,
805 let span = terminator.source_info.span;
807 let operands: Vec<_> = operands
809 .map(|op| match *op {
810 mir::InlineAsmOperand::In { reg, ref value } => {
811 let value = self.codegen_operand(&mut bx, value);
812 InlineAsmOperandRef::In { reg, value }
814 mir::InlineAsmOperand::Out { reg, late, ref place } => {
815 let place = place.map(|place| self.codegen_place(&mut bx, place.as_ref()));
816 InlineAsmOperandRef::Out { reg, late, place }
818 mir::InlineAsmOperand::InOut { reg, late, ref in_value, ref out_place } => {
819 let in_value = self.codegen_operand(&mut bx, in_value);
821 out_place.map(|out_place| self.codegen_place(&mut bx, out_place.as_ref()));
822 InlineAsmOperandRef::InOut { reg, late, in_value, out_place }
824 mir::InlineAsmOperand::Const { ref value } => {
825 if let mir::Operand::Constant(constant) = value {
826 let const_value = self
827 .eval_mir_constant(constant)
828 .unwrap_or_else(|_| span_bug!(span, "asm const cannot be resolved"));
829 let ty = constant.ty();
830 let size = bx.layout_of(ty).size;
831 let scalar = match const_value {
832 ConstValue::Scalar(s) => s,
835 "expected Scalar for promoted asm const, but got {:#?}",
839 let value = scalar.assert_bits(size);
840 let string = match ty.kind() {
841 ty::Uint(_) => value.to_string(),
843 match int_ty.normalize(bx.tcx().sess.target.pointer_width) {
844 ty::IntTy::I8 => (value as i8).to_string(),
845 ty::IntTy::I16 => (value as i16).to_string(),
846 ty::IntTy::I32 => (value as i32).to_string(),
847 ty::IntTy::I64 => (value as i64).to_string(),
848 ty::IntTy::I128 => (value as i128).to_string(),
849 ty::IntTy::Isize => unreachable!(),
852 ty::Float(ty::FloatTy::F32) => f32::from_bits(value as u32).to_string(),
853 ty::Float(ty::FloatTy::F64) => f64::from_bits(value as u64).to_string(),
854 _ => span_bug!(span, "asm const has bad type {}", ty),
856 InlineAsmOperandRef::Const { string }
858 span_bug!(span, "asm const is not a constant");
861 mir::InlineAsmOperand::SymFn { ref value } => {
862 let literal = self.monomorphize(value.literal);
863 if let ty::FnDef(def_id, substs) = *literal.ty().kind() {
864 let instance = ty::Instance::resolve_for_fn_ptr(
866 ty::ParamEnv::reveal_all(),
871 InlineAsmOperandRef::SymFn { instance }
873 span_bug!(span, "invalid type for asm sym (fn)");
876 mir::InlineAsmOperand::SymStatic { def_id } => {
877 InlineAsmOperandRef::SymStatic { def_id }
882 bx.codegen_inline_asm(template, &operands, options, line_spans);
884 if let Some(target) = destination {
885 helper.funclet_br(self, &mut bx, target);
892 impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
893 pub fn codegen_block(&mut self, bb: mir::BasicBlock) {
894 let mut bx = self.build_block(bb);
898 debug!("codegen_block({:?}={:?})", bb, data);
900 for statement in &data.statements {
901 bx = self.codegen_statement(bx, statement);
904 self.codegen_terminator(bx, bb, data.terminator());
907 fn codegen_terminator(
911 terminator: &'tcx mir::Terminator<'tcx>,
913 debug!("codegen_terminator: {:?}", terminator);
915 // Create the cleanup bundle, if needed.
916 let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb);
917 let helper = TerminatorCodegenHelper { bb, terminator, funclet_bb };
919 self.set_debug_loc(&mut bx, terminator.source_info);
920 match terminator.kind {
921 mir::TerminatorKind::Resume => self.codegen_resume_terminator(helper, bx),
923 mir::TerminatorKind::Abort => {
925 // `abort` does not terminate the block, so we still need to generate
926 // an `unreachable` terminator after it.
930 mir::TerminatorKind::Goto { target } => {
932 // This is an unconditional branch back to this same basic block. That means we
933 // have something like a `loop {}` statement. LLVM versions before 12.0
934 // miscompile this because they assume forward progress. For older versions
935 // try to handle just this specific case which comes up commonly in practice
936 // (e.g., in embedded code).
938 // NB: the `sideeffect` currently checks for the LLVM version used internally.
942 helper.funclet_br(self, &mut bx, target);
945 mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref targets } => {
946 self.codegen_switchint_terminator(helper, bx, discr, switch_ty, targets);
949 mir::TerminatorKind::Return => {
950 self.codegen_return_terminator(bx);
953 mir::TerminatorKind::Unreachable => {
957 mir::TerminatorKind::Drop { place, target, unwind } => {
958 self.codegen_drop_terminator(helper, bx, place, target, unwind);
961 mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
962 self.codegen_assert_terminator(
963 helper, bx, terminator, cond, expected, msg, target, cleanup,
967 mir::TerminatorKind::DropAndReplace { .. } => {
968 bug!("undesugared DropAndReplace in codegen: {:?}", terminator);
971 mir::TerminatorKind::Call {
979 self.codegen_call_terminator(
990 mir::TerminatorKind::GeneratorDrop | mir::TerminatorKind::Yield { .. } => {
991 bug!("generator ops in codegen")
993 mir::TerminatorKind::FalseEdge { .. } | mir::TerminatorKind::FalseUnwind { .. } => {
994 bug!("borrowck false edges in codegen")
997 mir::TerminatorKind::InlineAsm {
1004 self.codegen_asm_terminator(
1018 fn codegen_argument(
1021 op: OperandRef<'tcx, Bx::Value>,
1022 llargs: &mut Vec<Bx::Value>,
1023 arg: &ArgAbi<'tcx, Ty<'tcx>>,
1025 // Fill padding with undef value, where applicable.
1026 if let Some(ty) = arg.pad {
1027 llargs.push(bx.const_undef(bx.reg_backend_type(&ty)))
1030 if arg.is_ignore() {
1034 if let PassMode::Pair(..) = arg.mode {
1041 _ => bug!("codegen_argument: {:?} invalid for pair argument", op),
1043 } else if arg.is_unsized_indirect() {
1045 Ref(a, Some(b), _) => {
1050 _ => bug!("codegen_argument: {:?} invalid for unsized indirect argument", op),
1054 // Force by-ref if we have to load through a cast pointer.
1055 let (mut llval, align, by_ref) = match op.val {
1056 Immediate(_) | Pair(..) => match arg.mode {
1057 PassMode::Indirect { .. } | PassMode::Cast(_) => {
1058 let scratch = PlaceRef::alloca(bx, arg.layout);
1059 op.val.store(bx, scratch);
1060 (scratch.llval, scratch.align, true)
1062 _ => (op.immediate_or_packed_pair(bx), arg.layout.align.abi, false),
1064 Ref(llval, _, align) => {
1065 if arg.is_indirect() && align < arg.layout.align.abi {
1066 // `foo(packed.large_field)`. We can't pass the (unaligned) field directly. I
1067 // think that ATM (Rust 1.16) we only pass temporaries, but we shouldn't
1068 // have scary latent bugs around.
1070 let scratch = PlaceRef::alloca(bx, arg.layout);
1080 (scratch.llval, scratch.align, true)
1082 (llval, align, true)
1087 if by_ref && !arg.is_indirect() {
1088 // Have to load the argument, maybe while casting it.
1089 if let PassMode::Cast(ty) = arg.mode {
1090 let addr = bx.pointercast(llval, bx.type_ptr_to(bx.cast_backend_type(&ty)));
1091 llval = bx.load(addr, align.min(arg.layout.align.abi));
1093 // We can't use `PlaceRef::load` here because the argument
1094 // may have a type we don't treat as immediate, but the ABI
1095 // used for this call is passing it by-value. In that case,
1096 // the load would just produce `OperandValue::Ref` instead
1097 // of the `OperandValue::Immediate` we need for the call.
1098 llval = bx.load(llval, align);
1099 if let abi::Abi::Scalar(ref scalar) = arg.layout.abi {
1100 if scalar.is_bool() {
1101 bx.range_metadata(llval, 0..2);
1104 // We store bools as `i8` so we need to truncate to `i1`.
1105 llval = bx.to_immediate(llval, arg.layout);
1112 fn codegen_arguments_untupled(
1115 operand: &mir::Operand<'tcx>,
1116 llargs: &mut Vec<Bx::Value>,
1117 args: &[ArgAbi<'tcx, Ty<'tcx>>],
1119 let tuple = self.codegen_operand(bx, operand);
1121 // Handle both by-ref and immediate tuples.
1122 if let Ref(llval, None, align) = tuple.val {
1123 let tuple_ptr = PlaceRef::new_sized_aligned(llval, tuple.layout, align);
1124 for i in 0..tuple.layout.fields.count() {
1125 let field_ptr = tuple_ptr.project_field(bx, i);
1126 let field = bx.load_operand(field_ptr);
1127 self.codegen_argument(bx, field, llargs, &args[i]);
1129 } else if let Ref(_, Some(_), _) = tuple.val {
1130 bug!("closure arguments must be sized")
1132 // If the tuple is immediate, the elements are as well.
1133 for i in 0..tuple.layout.fields.count() {
1134 let op = tuple.extract_field(bx, i);
1135 self.codegen_argument(bx, op, llargs, &args[i]);
1140 fn get_caller_location(
1143 mut source_info: mir::SourceInfo,
1144 ) -> OperandRef<'tcx, Bx::Value> {
1147 let mut span_to_caller_location = |span: Span| {
1148 let topmost = span.ctxt().outer_expn().expansion_cause().unwrap_or(span);
1149 let caller = tcx.sess.source_map().lookup_char_pos(topmost.lo());
1150 let const_loc = tcx.const_caller_location((
1151 Symbol::intern(&caller.file.name.to_string()),
1153 caller.col_display as u32 + 1,
1155 OperandRef::from_const(bx, const_loc, bx.tcx().caller_location_ty())
1158 // Walk up the `SourceScope`s, in case some of them are from MIR inlining.
1159 // If so, the starting `source_info.span` is in the innermost inlined
1160 // function, and will be replaced with outer callsite spans as long
1161 // as the inlined functions were `#[track_caller]`.
1163 let scope_data = &self.mir.source_scopes[source_info.scope];
1165 if let Some((callee, callsite_span)) = scope_data.inlined {
1166 // Stop inside the most nested non-`#[track_caller]` function,
1167 // before ever reaching its caller (which is irrelevant).
1168 if !callee.def.requires_caller_location(tcx) {
1169 return span_to_caller_location(source_info.span);
1171 source_info.span = callsite_span;
1174 // Skip past all of the parents with `inlined: None`.
1175 match scope_data.inlined_parent_scope {
1176 Some(parent) => source_info.scope = parent,
1181 // No inlined `SourceScope`s, or all of them were `#[track_caller]`.
1182 self.caller_location.unwrap_or_else(|| span_to_caller_location(source_info.span))
1185 fn get_personality_slot(&mut self, bx: &mut Bx) -> PlaceRef<'tcx, Bx::Value> {
1187 if let Some(slot) = self.personality_slot {
1190 let layout = cx.layout_of(
1191 cx.tcx().intern_tup(&[cx.tcx().mk_mut_ptr(cx.tcx().types.u8), cx.tcx().types.i32]),
1193 let slot = PlaceRef::alloca(bx, layout);
1194 self.personality_slot = Some(slot);
1199 /// Returns the landing-pad wrapper around the given basic block.
1201 /// No-op in MSVC SEH scheme.
1202 fn landing_pad_to(&mut self, target_bb: mir::BasicBlock) -> Bx::BasicBlock {
1203 if let Some(block) = self.landing_pads[target_bb] {
1207 let block = self.blocks[target_bb];
1208 let landing_pad = self.landing_pad_uncached(block);
1209 self.landing_pads[target_bb] = Some(landing_pad);
1213 fn landing_pad_uncached(&mut self, target_bb: Bx::BasicBlock) -> Bx::BasicBlock {
1214 if base::wants_msvc_seh(self.cx.sess()) {
1215 span_bug!(self.mir.span, "landing pad was not inserted?")
1218 let mut bx = self.new_block("cleanup");
1220 let llpersonality = self.cx.eh_personality();
1221 let llretty = self.landing_pad_type();
1222 let lp = bx.landing_pad(llretty, llpersonality, 1);
1225 let slot = self.get_personality_slot(&mut bx);
1226 slot.storage_live(&mut bx);
1227 Pair(bx.extract_value(lp, 0), bx.extract_value(lp, 1)).store(&mut bx, slot);
1233 fn landing_pad_type(&self) -> Bx::Type {
1235 cx.type_struct(&[cx.type_i8p(), cx.type_i32()], false)
1238 fn unreachable_block(&mut self) -> Bx::BasicBlock {
1239 self.unreachable_block.unwrap_or_else(|| {
1240 let mut bx = self.new_block("unreachable");
1242 self.unreachable_block = Some(bx.llbb());
1247 pub fn new_block(&self, name: &str) -> Bx {
1248 Bx::new_block(self.cx, self.llfn, name)
1251 pub fn build_block(&self, bb: mir::BasicBlock) -> Bx {
1252 let mut bx = Bx::with_cx(self.cx);
1253 bx.position_at_end(self.blocks[bb]);
1257 fn make_return_dest(
1260 dest: mir::Place<'tcx>,
1261 fn_ret: &ArgAbi<'tcx, Ty<'tcx>>,
1262 llargs: &mut Vec<Bx::Value>,
1264 ) -> ReturnDest<'tcx, Bx::Value> {
1265 // If the return is ignored, we can just return a do-nothing `ReturnDest`.
1266 if fn_ret.is_ignore() {
1267 return ReturnDest::Nothing;
1269 let dest = if let Some(index) = dest.as_local() {
1270 match self.locals[index] {
1271 LocalRef::Place(dest) => dest,
1272 LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
1273 LocalRef::Operand(None) => {
1274 // Handle temporary places, specifically `Operand` ones, as
1275 // they don't have `alloca`s.
1276 return if fn_ret.is_indirect() {
1277 // Odd, but possible, case, we have an operand temporary,
1278 // but the calling convention has an indirect return.
1279 let tmp = PlaceRef::alloca(bx, fn_ret.layout);
1280 tmp.storage_live(bx);
1281 llargs.push(tmp.llval);
1282 ReturnDest::IndirectOperand(tmp, index)
1283 } else if is_intrinsic {
1284 // Currently, intrinsics always need a location to store
1285 // the result, so we create a temporary `alloca` for the
1287 let tmp = PlaceRef::alloca(bx, fn_ret.layout);
1288 tmp.storage_live(bx);
1289 ReturnDest::IndirectOperand(tmp, index)
1291 ReturnDest::DirectOperand(index)
1294 LocalRef::Operand(Some(_)) => {
1295 bug!("place local already assigned to");
1301 mir::PlaceRef { local: dest.local, projection: &dest.projection },
1304 if fn_ret.is_indirect() {
1305 if dest.align < dest.layout.align.abi {
1306 // Currently, MIR code generation does not create calls
1307 // that store directly to fields of packed structs (in
1308 // fact, the calls it creates write only to temps).
1310 // If someone changes that, please update this code path
1311 // to create a temporary.
1312 span_bug!(self.mir.span, "can't directly store to unaligned value");
1314 llargs.push(dest.llval);
1317 ReturnDest::Store(dest)
1321 fn codegen_transmute(&mut self, bx: &mut Bx, src: &mir::Operand<'tcx>, dst: mir::Place<'tcx>) {
1322 if let Some(index) = dst.as_local() {
1323 match self.locals[index] {
1324 LocalRef::Place(place) => self.codegen_transmute_into(bx, src, place),
1325 LocalRef::UnsizedPlace(_) => bug!("transmute must not involve unsized locals"),
1326 LocalRef::Operand(None) => {
1327 let dst_layout = bx.layout_of(self.monomorphized_place_ty(dst.as_ref()));
1328 assert!(!dst_layout.ty.has_erasable_regions());
1329 let place = PlaceRef::alloca(bx, dst_layout);
1330 place.storage_live(bx);
1331 self.codegen_transmute_into(bx, src, place);
1332 let op = bx.load_operand(place);
1333 place.storage_dead(bx);
1334 self.locals[index] = LocalRef::Operand(Some(op));
1335 self.debug_introduce_local(bx, index);
1337 LocalRef::Operand(Some(op)) => {
1338 assert!(op.layout.is_zst(), "assigning to initialized SSAtemp");
1342 let dst = self.codegen_place(bx, dst.as_ref());
1343 self.codegen_transmute_into(bx, src, dst);
1347 fn codegen_transmute_into(
1350 src: &mir::Operand<'tcx>,
1351 dst: PlaceRef<'tcx, Bx::Value>,
1353 let src = self.codegen_operand(bx, src);
1355 // Special-case transmutes between scalars as simple bitcasts.
1356 match (&src.layout.abi, &dst.layout.abi) {
1357 (abi::Abi::Scalar(src_scalar), abi::Abi::Scalar(dst_scalar)) => {
1358 // HACK(eddyb) LLVM doesn't like `bitcast`s between pointers and non-pointers.
1359 if (src_scalar.value == abi::Pointer) == (dst_scalar.value == abi::Pointer) {
1360 assert_eq!(src.layout.size, dst.layout.size);
1362 // NOTE(eddyb) the `from_immediate` and `to_immediate_scalar`
1363 // conversions allow handling `bool`s the same as `u8`s.
1364 let src = bx.from_immediate(src.immediate());
1365 let src_as_dst = bx.bitcast(src, bx.backend_type(dst.layout));
1366 Immediate(bx.to_immediate_scalar(src_as_dst, dst_scalar)).store(bx, dst);
1373 let llty = bx.backend_type(src.layout);
1374 let cast_ptr = bx.pointercast(dst.llval, bx.type_ptr_to(llty));
1375 let align = src.layout.align.abi.min(dst.align);
1376 src.val.store(bx, PlaceRef::new_sized_aligned(cast_ptr, src.layout, align));
1379 // Stores the return value of a function call into it's final location.
1383 dest: ReturnDest<'tcx, Bx::Value>,
1384 ret_abi: &ArgAbi<'tcx, Ty<'tcx>>,
1387 use self::ReturnDest::*;
1391 Store(dst) => bx.store_arg(&ret_abi, llval, dst),
1392 IndirectOperand(tmp, index) => {
1393 let op = bx.load_operand(tmp);
1394 tmp.storage_dead(bx);
1395 self.locals[index] = LocalRef::Operand(Some(op));
1396 self.debug_introduce_local(bx, index);
1398 DirectOperand(index) => {
1399 // If there is a cast, we have to store and reload.
1400 let op = if let PassMode::Cast(_) = ret_abi.mode {
1401 let tmp = PlaceRef::alloca(bx, ret_abi.layout);
1402 tmp.storage_live(bx);
1403 bx.store_arg(&ret_abi, llval, tmp);
1404 let op = bx.load_operand(tmp);
1405 tmp.storage_dead(bx);
1408 OperandRef::from_immediate_or_packed_pair(bx, llval, ret_abi.layout)
1410 self.locals[index] = LocalRef::Operand(Some(op));
1411 self.debug_introduce_local(bx, index);
1417 enum ReturnDest<'tcx, V> {
1418 // Do nothing; the return value is indirect or ignored.
1420 // Store the return value to the pointer.
1421 Store(PlaceRef<'tcx, V>),
1422 // Store an indirect return value to an operand local place.
1423 IndirectOperand(PlaceRef<'tcx, V>, mir::Local),
1424 // Store a direct return value to an operand local place.
1425 DirectOperand(mir::Local),