[llvm] [DirectX] Legalize lifetime intrinsics for DXIL (PR #148003)
Deric C. via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 11 09:33:59 PDT 2025
https://github.com/Icohedron updated https://github.com/llvm/llvm-project/pull/148003
>From c9fbdbaa9e20b462b2d251d2dfac4c7feb0f21a0 Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Wed, 9 Jul 2025 20:51:39 +0000
Subject: [PATCH 1/4] Legalize lifetime intrinsics for DXIL
This commit legalizes lifetime intrinsics for DXIL by
- Making lifetime intrinsics an exception to Int64Ops shader flag analysis
- Adding a bitcast for the lifetime intrinsics' pointer operand in dxil-prepare to ensure it gets cast to an i8*
- Making the DXIL bitcode writer write the base/demangled name of lifetime intrinsics to the symbol table
---
llvm/lib/Target/DirectX/DXILPrepare.cpp | 24 ++++++++++--
llvm/lib/Target/DirectX/DXILShaderFlags.cpp | 2 +-
.../DirectX/DXILWriter/DXILBitcodeWriter.cpp | 16 +++++++-
.../ShaderFlags/lifetimes-noint64op.ll | 36 ++++++++++++++++++
.../DirectX/legalize-lifetimes-valver-1.6.ll | 25 ++++++++++++
llvm/test/tools/dxil-dis/lifetimes.ll | 38 +++++++++++++++++++
6 files changed, 136 insertions(+), 5 deletions(-)
create mode 100644 llvm/test/CodeGen/DirectX/ShaderFlags/lifetimes-noint64op.ll
create mode 100644 llvm/test/tools/dxil-dis/lifetimes.ll
diff --git a/llvm/lib/Target/DirectX/DXILPrepare.cpp b/llvm/lib/Target/DirectX/DXILPrepare.cpp
index c8866bfefdfc5..d3a8c0bb995c9 100644
--- a/llvm/lib/Target/DirectX/DXILPrepare.cpp
+++ b/llvm/lib/Target/DirectX/DXILPrepare.cpp
@@ -239,6 +239,13 @@ class DXILPrepareModule : public ModulePass {
for (size_t Idx = 0, End = F.arg_size(); Idx < End; ++Idx)
F.removeParamAttrs(Idx, AttrMask);
+ // Match FnAttrs of lifetime intrinsics in LLVM 3.7
+ if (F.isIntrinsic())
+ switch (F.getIntrinsicID())
+ case Intrinsic::lifetime_start:
+ case Intrinsic::lifetime_end:
+ F.removeFnAttr(Attribute::Memory);
+
for (auto &BB : F) {
IRBuilder<> Builder(&BB);
for (auto &I : make_early_inc_range(BB)) {
@@ -247,7 +254,7 @@ class DXILPrepareModule : public ModulePass {
// Emtting NoOp bitcast instructions allows the ValueEnumerator to be
// unmodified as it reserves instruction IDs during contruction.
- if (auto LI = dyn_cast<LoadInst>(&I)) {
+ if (auto *LI = dyn_cast<LoadInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, LI->getPointerOperand(),
LI->getType())) {
@@ -257,7 +264,7 @@ class DXILPrepareModule : public ModulePass {
}
continue;
}
- if (auto SI = dyn_cast<StoreInst>(&I)) {
+ if (auto *SI = dyn_cast<StoreInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, SI->getPointerOperand(),
SI->getValueOperand()->getType())) {
@@ -268,7 +275,7 @@ class DXILPrepareModule : public ModulePass {
}
continue;
}
- if (auto GEP = dyn_cast<GetElementPtrInst>(&I)) {
+ if (auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
if (Value *NoOpBitcast = maybeGenerateBitcast(
Builder, PointerTypes, I, GEP->getPointerOperand(),
GEP->getSourceElementType()))
@@ -280,6 +287,17 @@ class DXILPrepareModule : public ModulePass {
CB->removeRetAttrs(AttrMask);
for (size_t Idx = 0, End = CB->arg_size(); Idx < End; ++Idx)
CB->removeParamAttrs(Idx, AttrMask);
+ // LLVM 3.7 Lifetime intrinics require an i8* pointer operand, so we
+ // insert a bitcast here to ensure that is the case
+ if (isa<LifetimeIntrinsic>(CB)) {
+ Value *PtrOperand = CB->getArgOperand(1);
+ Builder.SetInsertPoint(CB);
+ PointerType *PtrTy = cast<PointerType>(PtrOperand->getType());
+ Value *NoOpBitcast = Builder.Insert(
+ CastInst::Create(Instruction::BitCast, PtrOperand,
+ Builder.getPtrTy(PtrTy->getAddressSpace())));
+ CB->setArgOperand(1, NoOpBitcast);
+ }
continue;
}
}
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
index bd3349d2e18c5..eb4adfea5aed6 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
@@ -152,7 +152,7 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
if (!CSF.Int64Ops)
CSF.Int64Ops = I.getType()->isIntegerTy(64);
- if (!CSF.Int64Ops) {
+ if (!CSF.Int64Ops && !isa<LifetimeIntrinsic>(&I)) {
for (const Value *Op : I.operands()) {
if (Op->getType()->isIntegerTy(64)) {
CSF.Int64Ops = true;
diff --git a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
index 1d79c3018439e..22736bbd559f0 100644
--- a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
+++ b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
@@ -2559,8 +2559,22 @@ void DXILBitcodeWriter::writeFunctionLevelValueSymbolTable(
// to ensure the binary is the same no matter what values ever existed.
SmallVector<const ValueName *, 16> SortedTable;
+ MallocAllocator Allocator;
for (auto &VI : VST) {
- SortedTable.push_back(VI.second->getValueName());
+ ValueName *VN = VI.second->getValueName();
+ // Clang mangles lifetime intrinsic names by appending '.p0' to the end,
+ // making them invalid lifetime intrinsics in LLVM 3.7. We can't
+ // demangle in dxil-prepare because it would result in invalid IR.
+ // Therefore we have to do this in the bitcode writer while writing its
+ // name to the symbol table.
+ if (const Function *Fn = dyn_cast<Function>(VI.getValue());
+ Fn && Fn->isIntrinsic()) {
+ Intrinsic::ID IID = Fn->getIntrinsicID();
+ if (IID == Intrinsic::lifetime_start || IID == Intrinsic::lifetime_end)
+ VN = ValueName::create(Intrinsic::getBaseName(IID), Allocator,
+ VI.second);
+ }
+ SortedTable.push_back(VN);
}
// The keys are unique, so there shouldn't be stability issues.
llvm::sort(SortedTable, [](const ValueName *A, const ValueName *B) {
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/lifetimes-noint64op.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/lifetimes-noint64op.ll
new file mode 100644
index 0000000000000..736c86ebb1299
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/lifetimes-noint64op.ll
@@ -0,0 +1,36 @@
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+; RUN: llc %s --filetype=obj -o - | obj2yaml | FileCheck %s --check-prefix=DXC
+
+target triple = "dxil-pc-shadermodel6.7-library"
+
+; CHECK: ; Combined Shader Flags for Module
+; CHECK-NEXT: ; Shader Flags Value: 0x00000000
+; CHECK-NEXT: ;
+; CHECK-NOT: ; Note: shader requires additional functionality:
+; CHECK-NOT: ; 64-Bit integer
+; CHECK-NOT: ; Note: extra DXIL module flags:
+; CHECK-NOT: ;
+; CHECK-NEXT: ; Shader Flags for Module Functions
+; CHECK-NEXT: ; Function lifetimes : 0x00000000
+
+define void @lifetimes() #0 {
+ %a = alloca [4 x i32], align 8
+ call void @llvm.lifetime.start.p0(i64 16, ptr nonnull %a)
+ call void @llvm.lifetime.end.p0(i64 16, ptr nonnull %a)
+ ret void
+}
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64, ptr) #1
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64, ptr) #1
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
+attributes #1 = { nounwind memory(argmem: readwrite) }
+
+; DXC: - Name: SFI0
+; DXC-NEXT: Size: 8
+; DXC-NOT: Flags:
+; DXC-NOT: Int64Ops: true
+; DXC: ...
diff --git a/llvm/test/CodeGen/DirectX/legalize-lifetimes-valver-1.6.ll b/llvm/test/CodeGen/DirectX/legalize-lifetimes-valver-1.6.ll
index 6552ccddddab4..f77df2d812dfe 100644
--- a/llvm/test/CodeGen/DirectX/legalize-lifetimes-valver-1.6.ll
+++ b/llvm/test/CodeGen/DirectX/legalize-lifetimes-valver-1.6.ll
@@ -1,5 +1,6 @@
; RUN: opt -S -passes='dxil-op-lower' -mtriple=dxil-pc-shadermodel6.3-library %s | FileCheck %s --check-prefixes=CHECK,CHECK-SM63
; RUN: opt -S -passes='dxil-op-lower' -mtriple=dxil-pc-shadermodel6.6-library %s | FileCheck %s --check-prefixes=CHECK,CHECK-SM66
+; RUN: opt -S -dxil-op-lower -dxil-prepare -mtriple=dxil-pc-shadermodel6.6-library %s | FileCheck %s --check-prefixes=CHECK,CHECK-PREPARE
; CHECK-LABEL: define void @test_legal_lifetime() {
;
@@ -15,6 +16,14 @@
; CHECK-SM66-NEXT: store i32 0, ptr [[GEP]], align 4
; CHECK-SM66-NEXT: call void @llvm.lifetime.end.p0(i64 4, ptr nonnull [[ACCUM_I_FLAT]])
;
+; CHECK-PREPARE-NEXT: [[ACCUM_I_FLAT:%.*]] = alloca [1 x i32], align 4
+; CHECK-PREPARE-NEXT: [[GEP:%.*]] = getelementptr i32, ptr [[ACCUM_I_FLAT]], i32 0
+; CHECK-PREPARE-NEXT: [[BITCAST:%.*]] = bitcast ptr [[ACCUM_I_FLAT]] to ptr
+; CHECK-PREPARE-NEXT: call void @llvm.lifetime.start.p0(i64 4, ptr nonnull [[BITCAST]])
+; CHECK-PREPARE-NEXT: store i32 0, ptr [[GEP]], align 4
+; CHECK-PREPARE-NEXT: [[BITCAST:%.*]] = bitcast ptr [[ACCUM_I_FLAT]] to ptr
+; CHECK-PREPARE-NEXT: call void @llvm.lifetime.end.p0(i64 4, ptr nonnull [[BITCAST]])
+;
; CHECK-NEXT: ret void
;
define void @test_legal_lifetime() {
@@ -26,6 +35,22 @@ define void @test_legal_lifetime() {
ret void
}
+; CHECK-PREPARE-DAG: attributes [[LIFETIME_ATTRS:#.*]] = { nounwind }
+
+; CHECK-PREPARE-DAG: ; Function Attrs: nounwind
+; CHECK-PREPARE-DAG: declare void @llvm.lifetime.start.p0(i64, ptr) [[LIFETIME_ATTRS]]
+
+; CHECK-PREPARE-DAG: ; Function Attrs: nounwind
+; CHECK-PREPARE-DAG: declare void @llvm.lifetime.end.p0(i64, ptr) [[LIFETIME_ATTRS]]
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64, ptr) #0
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64, ptr) #0
+
+attributes #0 = { nounwind memory(argmem: readwrite) }
+
; Set the validator version to 1.6
!dx.valver = !{!0}
!0 = !{i32 1, i32 6}
diff --git a/llvm/test/tools/dxil-dis/lifetimes.ll b/llvm/test/tools/dxil-dis/lifetimes.ll
new file mode 100644
index 0000000000000..6be523f50895c
--- /dev/null
+++ b/llvm/test/tools/dxil-dis/lifetimes.ll
@@ -0,0 +1,38 @@
+; RUN: llc --filetype=obj %s -o - | dxil-dis -o - | FileCheck %s
+target triple = "dxil-unknown-shadermodel6.7-library"
+
+define void @test_lifetimes() {
+; CHECK-LABEL: test_lifetimes
+; CHECK-NEXT: [[ALLOCA:%.*]] = alloca [2 x i32], align 4
+; CHECK-NEXT: [[GEP:%.*]] = getelementptr [2 x i32], [2 x i32]* [[ALLOCA]], i32 0, i32 0
+; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
+; CHECK-NEXT: call void @llvm.lifetime.start(i64 4, i8* nonnull [[BITCAST]])
+; CHECK-NEXT: store i32 0, i32* [[GEP]], align 4
+; CHECK-NEXT: [[BITCAST:%.*]] = bitcast [2 x i32]* [[ALLOCA]] to i8*
+; CHECK-NEXT: call void @llvm.lifetime.end(i64 4, i8* nonnull [[BITCAST]])
+; CHECK-NEXT: ret void
+;
+ %a = alloca [2 x i32], align 4
+ %gep = getelementptr i32, ptr %a, i32 0
+ call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %a)
+ store i32 0, ptr %gep, align 4
+ call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %a)
+ ret void
+}
+
+; CHECK-DAG: attributes [[LIFETIME_ATTRS:#.*]] = { nounwind }
+
+; CHECK-DAG: ; Function Attrs: nounwind
+; CHECK-DAG: declare void @llvm.lifetime.start(i64, i8* nocapture) [[LIFETIME_ATTRS]]
+
+; CHECK-DAG: ; Function Attrs: nounwind
+; CHECK-DAG: declare void @llvm.lifetime.end(i64, i8* nocapture) [[LIFETIME_ATTRS]]
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.end.p0(i64, ptr) #0
+
+; Function Attrs: nounwind memory(argmem: readwrite)
+declare void @llvm.lifetime.start.p0(i64, ptr) #0
+
+attributes #0 = { nounwind memory(argmem: readwrite) }
+
>From 7a2ae374cc1a4d6a44f23c5f043b55133a01f97e Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Thu, 10 Jul 2025 17:17:11 +0000
Subject: [PATCH 2/4] Add missing include to resolve LifetimeIntrinsic
---
llvm/lib/Target/DirectX/DXILPrepare.cpp | 1 +
1 file changed, 1 insertion(+)
diff --git a/llvm/lib/Target/DirectX/DXILPrepare.cpp b/llvm/lib/Target/DirectX/DXILPrepare.cpp
index d3a8c0bb995c9..4ef6cdf68628b 100644
--- a/llvm/lib/Target/DirectX/DXILPrepare.cpp
+++ b/llvm/lib/Target/DirectX/DXILPrepare.cpp
@@ -24,6 +24,7 @@
#include "llvm/IR/AttributeMask.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
+#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
>From 94fe78c15ab3837c183db94a1df3da4c09195b49 Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Thu, 10 Jul 2025 17:47:57 +0000
Subject: [PATCH 3/4] Fix GEP in lifetimes dxil-dis test
---
llvm/test/tools/dxil-dis/lifetimes.ll | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/llvm/test/tools/dxil-dis/lifetimes.ll b/llvm/test/tools/dxil-dis/lifetimes.ll
index 6be523f50895c..cb3e6291c7bc0 100644
--- a/llvm/test/tools/dxil-dis/lifetimes.ll
+++ b/llvm/test/tools/dxil-dis/lifetimes.ll
@@ -13,7 +13,7 @@ define void @test_lifetimes() {
; CHECK-NEXT: ret void
;
%a = alloca [2 x i32], align 4
- %gep = getelementptr i32, ptr %a, i32 0
+ %gep = getelementptr [2 x i32], ptr %a, i32 0, i32 0
call void @llvm.lifetime.start.p0(i64 4, ptr nonnull %a)
store i32 0, ptr %gep, align 4
call void @llvm.lifetime.end.p0(i64 4, ptr nonnull %a)
>From 1b0aaef97c305b61be3aa365117d621f7ed39bfa Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Fri, 11 Jul 2025 16:32:41 +0000
Subject: [PATCH 4/4] Destroy temp lifetime ValueNames when done writing
---
llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
index 22736bbd559f0..51771817791fc 100644
--- a/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
+++ b/llvm/lib/Target/DirectX/DXILWriter/DXILBitcodeWriter.cpp
@@ -2560,6 +2560,7 @@ void DXILBitcodeWriter::writeFunctionLevelValueSymbolTable(
SmallVector<const ValueName *, 16> SortedTable;
MallocAllocator Allocator;
+ SmallVector<ValueName *, 2> LifetimeValueNames;
for (auto &VI : VST) {
ValueName *VN = VI.second->getValueName();
// Clang mangles lifetime intrinsic names by appending '.p0' to the end,
@@ -2570,9 +2571,11 @@ void DXILBitcodeWriter::writeFunctionLevelValueSymbolTable(
if (const Function *Fn = dyn_cast<Function>(VI.getValue());
Fn && Fn->isIntrinsic()) {
Intrinsic::ID IID = Fn->getIntrinsicID();
- if (IID == Intrinsic::lifetime_start || IID == Intrinsic::lifetime_end)
+ if (IID == Intrinsic::lifetime_start || IID == Intrinsic::lifetime_end) {
VN = ValueName::create(Intrinsic::getBaseName(IID), Allocator,
VI.second);
+ LifetimeValueNames.push_back(VN);
+ }
}
SortedTable.push_back(VN);
}
@@ -2625,6 +2628,8 @@ void DXILBitcodeWriter::writeFunctionLevelValueSymbolTable(
NameVals.clear();
}
Stream.ExitBlock();
+ for (auto *VN : LifetimeValueNames)
+ VN->Destroy(Allocator);
}
/// Emit a function body to the module stream.
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