aarch64 backend assertion failure during legalization with -mgeneral-regs-only: "Does Vec not start with size 1?"

[jwf]

Bugzilla Link	48825
Version	trunk
OS	All
CC	@aemerson,@Arnaud-de-Grandmaison-ARM,@DougGregor,@jwf,@ornata,@zygoloid,@smeenai,@smithp35

Extended Description

// clang -c boom.c -target aarch64-unknown-linux-gnu -mgeneral-regs-only
#include <stdbool.h>
bool foo(void);
bool boom() {
return foo();
}

Note that if you instead do

#include <stdbool.h>
bool foo(void);
bool boom() {
bool f = foo();
return f;
}

it compiles fine.

[zygoloid]

lib/CodeGen/GlobalISel/LegalizerInfo.cpp:573: static LegalizerInfo::SizeAndAction llvm::LegalizerInfo::findAction(const llvm::LegalizerInfo::SizeAndActionsVec &, const uint32_t): Assertion `It != Vec.begin() && "Does Vec not start with size 1?"' failed.

#​10 0x000000000a0a2bcc llvm::LegalizerInfo::findAction(std::__1::vector<std::__1::pair<unsigned short, llvm::LegalizeActions::LegalizeAction>, std::__1::allocator<std::__1::pair<unsigned short, llvm::LegalizeActions::LegalizeAction> > > const&, unsigned int) lib/CodeGen/GlobalISel/LegalizerInfo.cpp:574:21
#​11 0x000000000a0a17ad llvm::LegalizerInfo::findScalarLegalAction(llvm::InstrAspect const&) const lib/CodeGen/GlobalISel/LegalizerInfo.cpp:644:24
#​12 0x000000000a0a1464 llvm::LegalizerInfo::getAspectAction(llvm::InstrAspect const&) const lib/CodeGen/GlobalISel/LegalizerInfo.cpp:394:12
#​13 0x000000000a0a20fb llvm::LegalizerInfo::getAction(llvm::LegalityQuery const&) const lib/CodeGen/GlobalISel/LegalizerInfo.cpp:473:19
#​14 0x000000000a0a257b llvm::LegalizerInfo::getAction(llvm::MachineInstr const&, llvm::MachineRegisterInfo const&) const lib/CodeGen/GlobalISel/LegalizerInfo.cpp:513:10
#​15 0x000000000a06d7cb llvm::LegalizerHelper::legalizeInstrStep(llvm::MachineInstr&) lib/CodeGen/GlobalISel/LegalizerHelper.cpp:111:18
#​16 0x000000000a063e4c llvm::Legalizer::legalizeMachineFunction(llvm::MachineFunction&, llvm::LegalizerInfo const&, llvm::ArrayRefllvm::GISelChangeObserver*, llvm::LostDebugLocObserver&, llvm::MachineIRBuilder&) lib/CodeGen/GlobalISel/Legalizer.cpp:233:12

[c-rhodes]

fixed (since LLVM 13): https://godbolt.org/z/6ajM4Gfoh