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[SVE][CodeGen] Fix bug when falling back to DAG ISel

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In an earlier commit 584d0d5c1749c13625a5d322178ccb4121eea610 I
added functionality to allow AArch64 CodeGen support for falling
back to DAG ISel when Global ISel encounters scalable vector
types. However, it seems that we were not falling back early
enough as llvm::getLLTForType was still being invoked for scalable
vector types.

I've added a new fallback function to the call lowering class in
order to catch this problem early enough, rather than wait for
lowerFormalArguments to reject scalable vector types.

Differential Revision: https://reviews.llvm.org/D82524
This commit is contained in:
David Sherwood 2020-06-25 08:19:49 +01:00
parent 204220c193
commit 654ddede3d
5 changed files with 33 additions and 7 deletions
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2
include/llvm/CodeGen/GlobalISel/CallLowering.h
View File

@ -290,6 +290,8 @@ public:
return false;
}
virtual bool fallBackToDAGISel(const Function &F) const { return false; }
/// This hook must be implemented to lower the incoming (formal)
/// arguments, described by \p VRegs, for GlobalISel. Each argument
/// must end up in the related virtual registers described by \p VRegs.

8
lib/CodeGen/GlobalISel/IRTranslator.cpp
View File

@ -2384,6 +2384,14 @@ bool IRTranslator::runOnMachineFunction(MachineFunction &CurMF) {
// Make our arguments/constants entry block fallthrough to the IR entry block.
EntryBB->addSuccessor(&getMBB(F.front()));
if (CLI->fallBackToDAGISel(F)) {
OptimizationRemarkMissed R("gisel-irtranslator", "GISelFailure",
F.getSubprogram(), &F.getEntryBlock());
R << "unable to lower function: " << ore::NV("Prototype", F.getType());
reportTranslationError(*MF, *TPC, *ORE, R);
return false;
}
// Lower the actual args into this basic block.
SmallVector<ArrayRef<Register>, 8> VRegArgs;
for (const Argument &Arg: F.args()) {

11
lib/Target/AArch64/GISel/AArch64CallLowering.cpp
View File

@ -427,6 +427,14 @@ static void handleMustTailForwardedRegisters(MachineIRBuilder &MIRBuilder,
}
}
bool AArch64CallLowering::fallBackToDAGISel(const Function &F) const {
if (isa<ScalableVectorType>(F.getReturnType()))
return true;
return llvm::any_of(F.args(), [](const Argument &A) {
return isa<ScalableVectorType>(A.getType());
});
}
bool AArch64CallLowering::lowerFormalArguments(
MachineIRBuilder &MIRBuilder, const Function &F,
ArrayRef<ArrayRef<Register>> VRegs) const {
@ -438,9 +446,6 @@ bool AArch64CallLowering::lowerFormalArguments(
SmallVector<ArgInfo, 8> SplitArgs;
unsigned i = 0;
for (auto &Arg : F.args()) {
if (isa<ScalableVectorType>(Arg.getType()))
return false;
if (DL.getTypeStoreSize(Arg.getType()).isZero())
continue;

2
lib/Target/AArch64/GISel/AArch64CallLowering.h
View File

@ -37,6 +37,8 @@ public:
ArrayRef<Register> VRegs,
Register SwiftErrorVReg) const override;
bool fallBackToDAGISel(const Function &F) const override;
bool lowerFormalArguments(MachineIRBuilder &MIRBuilder, const Function &F,
ArrayRef<ArrayRef<Register>> VRegs) const override;

17
test/CodeGen/AArch64/GlobalISel/arm64-fallback.ll
View File

@ -220,21 +220,30 @@ entry:
ret void
}
; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower arguments{{.*}}scalable_arg
; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower function{{.*}}scalable_arg
; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_arg
define <vscale x 16 x i8> @scalable_arg(<vscale x 16 x i1> %pred, i8* %addr) #1 {
%res = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
ret <vscale x 16 x i8> %res
}
; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}scalable_call
; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_call
define <vscale x 16 x i8> @scalable_call(i8* %addr) #1 {
; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to lower function{{.*}}scalable_ret
; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_ret
define <vscale x 16 x i8> @scalable_ret(i8* %addr) #1 {
%pred = call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 0)
%res = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
ret <vscale x 16 x i8> %res
}
; FALLBACK-WITH-REPORT-ERR: remark: <unknown>:0:0: unable to translate instruction{{.*}}scalable_call
; FALLBACK-WITH-REPORT-OUT-LABEL: scalable_call
define i8 @scalable_call(i8* %addr) #1 {
%pred = call <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 0)
%vec = call <vscale x 16 x i8> @llvm.aarch64.sve.ld1.nxv16i8(<vscale x 16 x i1> %pred, i8* %addr)
%res = extractelement <vscale x 16 x i8> %vec, i32 0
ret i8 %res
}
attributes #1 = { "target-features"="+sve" }
declare <vscale x 16 x i1> @llvm.aarch64.sve.ptrue.nxv16i1(i32 %pattern)