shylie/llvm-project
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

[TableGen][GISel] Improve dead register handling (#120426)

Browse Source 
A dead implicit def wasn't marked as dead if it is also an implicit use.
The new approach should also be more straightforward and simplifies
future changes for supporting optional defs and physical register defs.

Pull Request: https://github.com/llvm/llvm-project/pull/120426
This commit is contained in:
Sergei Barannikov 2024-12-18 18:58:37 +03:00 committed by GitHub
parent aadf606d90
commit d3750412aa
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
5 changed files with 35 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
llvm/test/CodeGen/X86/GlobalISel/select-intrinsic-x86-flags-read-u32.mir
View File

@ -9,7 +9,7 @@
define void @read_flags() { ret void }
; CHECK-LABEL: name: read_flags
; CHECK: bb.0:
; CHECK: [[RDFLAGS32_:%[0-9]+]]:gr32 = RDFLAGS32 implicit-def $esp, implicit $esp
; CHECK: [[RDFLAGS32_:%[0-9]+]]:gr32 = RDFLAGS32 implicit-def dead $esp, implicit $esp
; CHECK: $eax = COPY [[RDFLAGS32_]]
...

2
llvm/test/TableGen/GlobalISelEmitter-nested-subregs.td
View File

@ -38,11 +38,11 @@ def A0 : RegisterClass<"MyTarget", [i32], 32, (add a0)>;
// CHECK-NEXT: // MIs[0] src
// CHECK-NEXT: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s8,
// CHECK-NEXT: // (anyext:{ *:[i16] } i8:{ *:[i8] }:$src) => (EXTRACT_SUBREG:{ *:[i16] } (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), A0b:{ *:[i8] }:$src, lo8:{ *:[i32] }), lo16:{ *:[i32] })
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::INSERT_SUBREG),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_AddSimpleTempRegister, /*InsnID*/1, /*TempRegID*/1,

2
llvm/test/TableGen/GlobalISelEmitterRegSequence.td
View File

@ -39,12 +39,12 @@ def SUBSOME_INSN : I<(outs SRegs:$dst), (ins SOP:$src), []>;
// CHECK-NEXT: GIM_RootCheckType, /*Op*/1, /*Type*/GILLT_s16,
// CHECK-NEXT: GIM_RootCheckRegBankForClass, /*Op*/1, /*RC*/GIMT_Encode2(Test::SRegsRegClassID),
// CHECK-NEXT: // (sext:{ *:[i32] } SOP:{ *:[i16] }:$src) => (REG_SEQUENCE:{ *:[i32] } DRegs:{ *:[i32] }, (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub0:{ *:[i32] }, (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub1:{ *:[i32] })
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/0, /*OpIdx*/1, // src
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_Copy, /*NewInsnID*/1, /*OldInsnID*/0, /*OpIdx*/1, // src

8
llvm/test/TableGen/GlobalISelEmitterSubreg.td
View File

@ -59,13 +59,13 @@ def : Pat<(sub (complex DOP:$src1, DOP:$src2), 77),
(SOME_INSN2 (EXTRACT_SUBREG DOP:$src1, sub0),
(EXTRACT_SUBREG DOP:$src2, sub1))>;
// CHECK-LABEL: // (sub:{ *:[i32] } (complex:{ *:[i32] } DOP:{ *:[i32] }:$src1, DOP:{ *:[i32] }:$src2), 77:{ *:[i32] }) => (SOME_INSN2:{ *:[i32] } (EXTRACT_SUBREG:{ *:[i32] } DOP:{ *:[i32] }:$src1, sub0:{ *:[i32] }), (EXTRACT_SUBREG:{ *:[i32] } DOP:{ *:[i32] }:$src2, sub1:{ *:[i32] }))
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_ComplexSubOperandSubRegRenderer, /*InsnID*/2, /*RendererID*/GIMT_Encode2(0), /*SubOperand*/1, /*SubRegIdx*/GIMT_Encode2(2), // src2
// CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/2, /*Op*/0, GIMT_Encode2(Test::SRegsRegClassID),
// CHECK-NEXT: GIR_ConstrainOperandRC, /*InsnID*/2, /*Op*/1, GIMT_Encode2(Test::DRegsRegClassID),
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_ComplexSubOperandSubRegRenderer, /*InsnID*/1, /*RendererID*/GIMT_Encode2(0), /*SubOperand*/0, /*SubRegIdx*/GIMT_Encode2(1), // src1
@ -103,11 +103,11 @@ def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (IMPLICIT_DEF)), SOP:$src
// instruction.
def : Pat<(i32 (anyext i16:$src)), (SOME_INSN (INSERT_SUBREG (i32 (IMPLICIT_DEF)), SOP:$src, sub0))>;
// CHECK-LABEL: (anyext:{ *:[i32] } i16:{ *:[i16] }:$src) => (SOME_INSN:{ *:[i32] } (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), SOP:{ *:[i16] }:$src, sub0:{ *:[i32] }))
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::INSERT_SUBREG),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_AddSimpleTempRegister, /*InsnID*/1, /*TempRegID*/1,
@ -138,12 +138,12 @@ def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (COPY_TO_REGCLASS SOP:$sr
// by a subinstruction.
def : Pat<(i32 (anyext i16:$src)), (INSERT_SUBREG (i32 (IMPLICIT_DEF)), (SUBSOME_INSN SOP:$src), sub0)>;
// CHECK-LABEL: (anyext:{ *:[i32] } i16:{ *:[i16] }:$src) => (INSERT_SUBREG:{ *:[i32] } (IMPLICIT_DEF:{ *:[i32] }), (SUBSOME_INSN:{ *:[i16] } SOP:{ *:[i16] }:$src), sub0:{ *:[i32] })
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SUBSOME_INSN),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/0, /*OpIdx*/1, // src
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::IMPLICIT_DEF),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/1,
@ -200,12 +200,12 @@ def : Pat<(i16 (trunc (bitreverse DOP:$src))),
// CHECK-NEXT: GIM_CheckRegBankForClass, /*MI*/1, /*Op*/1, /*RC*/GIMT_Encode2(Test::DRegsRegClassID),
// CHECK-NEXT: GIM_CheckIsSafeToFold, /*NumInsns*/1,
// CHECK-NEXT: // (trunc:{ *:[i16] } (ctpop:{ *:[i32] } DOP:{ *:[i32] }:$src)) => (SUBSOME_INSN2:{ *:[i16] } (EXTRACT_SUBREG:{ *:[i16] } (SOME_INSN:{ *:[i32] } DOP:{ *:[i32] }:$src), sub0:{ *:[i32] }))
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/1, /*TypeID*/GILLT_s32,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/2, /*Opcode*/GIMT_Encode2(MyTarget::SOME_INSN),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/2, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_Copy, /*NewInsnID*/2, /*OldInsnID*/1, /*OpIdx*/1, // src
// CHECK-NEXT: GIR_ConstrainSelectedInstOperands, /*InsnID*/2,
// CHECK-NEXT: GIR_MakeTempReg, /*TempRegID*/0, /*TypeID*/GILLT_s16,
// CHECK-NEXT: GIR_BuildMI, /*InsnID*/1, /*Opcode*/GIMT_Encode2(TargetOpcode::COPY),
// CHECK-NEXT: GIR_AddTempRegister, /*InsnID*/1, /*TempRegID*/0, /*TempRegFlags*/GIMT_Encode2(RegState::Define),
// CHECK-NEXT: GIR_AddTempSubRegister, /*InsnID*/1, /*TempRegID*/1, /*TempRegFlags*/GIMT_Encode2(0), GIMT_Encode2(sub0),

77
llvm/utils/TableGen/GlobalISelEmitter.cpp
View File

@ -324,8 +324,6 @@ public:
void emitTestSimplePredicate(raw_ostream &OS) override;
void emitRunCustomAction(raw_ostream &OS) override;
void postProcessRule(RuleMatcher &M);
const CodeGenTarget &getTarget() const override { return Target; }
StringRef getClassName() const override { return ClassName; }
@ -1410,12 +1408,10 @@ GlobalISelEmitter::createAndImportSubInstructionRenderer(
DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID, true);
// Handle additional (ignored) results.
if (DstMIBuilder.getCGI()->Operands.NumDefs > 1) {
InsertPtOrError = importExplicitDefRenderers(
std::prev(*InsertPtOrError), M, DstMIBuilder, Src, Dst, /*Start=*/1);
if (auto Error = InsertPtOrError.takeError())
return std::move(Error);
}
InsertPtOrError = importExplicitDefRenderers(
std::prev(*InsertPtOrError), M, DstMIBuilder, Src, Dst, /*Start=*/1);
if (auto Error = InsertPtOrError.takeError())
return std::move(Error);
InsertPtOrError = importExplicitUseRenderers(InsertPtOrError.get(), M,
DstMIBuilder, Dst, Src);
@ -1454,25 +1450,26 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
action_iterator InsertPt, RuleMatcher &M, BuildMIAction &DstMIBuilder,
const TreePatternNode &Src, const TreePatternNode &Dst, unsigned Start) {
const CodeGenInstruction *DstI = DstMIBuilder.getCGI();
const unsigned SrcNumDefs = Src.getExtTypes().size();
const unsigned DstNumDefs = DstI->Operands.NumDefs;
if (DstNumDefs == 0)
return InsertPt;
for (unsigned I = Start; I < SrcNumDefs; ++I) {
std::string OpName = getMangledRootDefName(DstI->Operands[I].Name);
// CopyRenderer saves a StringRef, so cannot pass OpName itself -
// let's use a string with an appropriate lifetime.
StringRef PermanentRef = M.getOperandMatcher(OpName).getSymbolicName();
DstMIBuilder.addRenderer<CopyRenderer>(PermanentRef);
}
// Some instructions have multiple defs, but are missing a type entry
// (e.g. s_cc_out operands).
if (Dst.getExtTypes().size() < DstNumDefs)
if (Dst.getExtTypes().size() < DstI->Operands.NumDefs)
return failedImport("unhandled discarded def");
for (unsigned I = SrcNumDefs; I < DstNumDefs; ++I) {
// Process explicit defs. The caller may have already handled the first def.
for (unsigned I = Start, E = DstI->Operands.NumDefs; I != E; ++I) {
std::string OpName = getMangledRootDefName(DstI->Operands[I].Name);
// If the def is used in the source DAG, forward it.
if (M.hasOperand(OpName)) {
// CopyRenderer saves a StringRef, so cannot pass OpName itself -
// let's use a string with an appropriate lifetime.
StringRef PermanentRef = M.getOperandMatcher(OpName).getSymbolicName();
DstMIBuilder.addRenderer<CopyRenderer>(PermanentRef);
continue;
}
// The def is discarded, create a dead virtual register for it.
const TypeSetByHwMode &ExtTy = Dst.getExtType(I);
if (!ExtTy.isMachineValueType())
return failedImport("unsupported typeset");
@ -1484,7 +1481,15 @@ Expected<action_iterator> GlobalISelEmitter::importExplicitDefRenderers(
unsigned TempRegID = M.allocateTempRegID();
InsertPt =
M.insertAction<MakeTempRegisterAction>(InsertPt, *OpTy, TempRegID);
DstMIBuilder.addRenderer<TempRegRenderer>(TempRegID, true, nullptr, true);
DstMIBuilder.addRenderer<TempRegRenderer>(
TempRegID, /*IsDef=*/true, /*SubReg=*/nullptr, /*IsDead=*/true);
}
// Implicit defs are not currently supported, mark all of them as dead.
for (const Record *Reg : DstI->ImplicitDefs) {
std::string OpName = getMangledRootDefName(Reg->getName());
assert(!M.hasOperand(OpName) && "The pattern should've been rejected");
DstMIBuilder.setDeadImplicitDef(Reg);
}
return InsertPt;
@ -2299,31 +2304,6 @@ void GlobalISelEmitter::emitRunCustomAction(raw_ostream &OS) {
<< "}\n";
}
void GlobalISelEmitter::postProcessRule(RuleMatcher &M) {
SmallPtrSet<const Record *, 16> UsedRegs;
// TODO: deal with subregs?
for (auto &A : M.actions()) {
auto *MI = dyn_cast<BuildMIAction>(A.get());
if (!MI)
continue;
for (auto *Use : MI->getCGI()->ImplicitUses)
UsedRegs.insert(Use);
}
for (auto &A : M.actions()) {
auto *MI = dyn_cast<BuildMIAction>(A.get());
if (!MI)
continue;
for (auto *Def : MI->getCGI()->ImplicitDefs) {
if (!UsedRegs.contains(Def))
MI->setDeadImplicitDef(Def);
}
}
}
void GlobalISelEmitter::run(raw_ostream &OS) {
if (!UseCoverageFile.empty()) {
RuleCoverage = CodeGenCoverage();
@ -2383,7 +2363,6 @@ void GlobalISelEmitter::run(raw_ostream &OS) {
"Pattern is not covered by a test");
}
Rules.push_back(std::move(MatcherOrErr.get()));
postProcessRule(Rules.back());
}
// Comparison function to order records by name.