[clang] [llvm] [DirectX] Implement Shader Flags Analysis for ResMayNotAlias (PR #131070)
Deric C. via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 12 20:59:15 PDT 2025
https://github.com/Icohedron created https://github.com/llvm/llvm-project/pull/131070
Fixes #112270
Completed ACs:
- `-res-may-alias` clang-dxc command-line option added
- Shader flag set appropriately:
- CASE 1: command-line option -res-may-alias is NOT specified AND DXIL Version > 1.7 AND function uses UAVs
- Add tests
- A test (`res-may-not-alias-shadermodel6.8.ll`) for CASE 1
- A test (`res-may-not-alias-shadermodel6.7.ll`) for CASE 2
- A test (`res-may-alias.ll`) for the case where the command-line option `-res-may-alias` is specified
ACs left to complete:
- Shader flag set appropriately:
- CASE 2: command-line option -res-may-alias is NOT specified AND DXIL Version <= 1.7 AND UAVs present globally
- This Draft PR currently uses the now-removed `DXILResourceMD` analysis (#130323) to query for global UAVs
- Need to create an alternative implementation for this case
>From ad5fbee6d0d58df1884153bb70e59a1434953659 Mon Sep 17 00:00:00 2001
From: Icohedron <cheung.deric at gmail.com>
Date: Thu, 13 Mar 2025 03:15:39 +0000
Subject: [PATCH] Initial ResMayNotAlias shader flag implementation
---
clang/include/clang/Basic/CodeGenOptions.def | 3 ++
clang/include/clang/Driver/Options.td | 5 +++
clang/lib/CodeGen/CGHLSLRuntime.cpp | 3 ++
clang/lib/Driver/ToolChains/Clang.cpp | 1 +
llvm/lib/Target/DirectX/DXILShaderFlags.cpp | 30 +++++++++++++---
llvm/lib/Target/DirectX/DXILShaderFlags.h | 9 +++--
.../DirectX/ShaderFlags/res-may-alias.ll | 34 +++++++++++++++++++
.../res-may-not-alias-shadermodel6.7.ll | 33 ++++++++++++++++++
.../res-may-not-alias-shadermodel6.8.ll | 33 ++++++++++++++++++
9 files changed, 145 insertions(+), 6 deletions(-)
create mode 100644 llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias.ll
create mode 100644 llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll
create mode 100644 llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll
diff --git a/clang/include/clang/Basic/CodeGenOptions.def b/clang/include/clang/Basic/CodeGenOptions.def
index a7f5f1abbb825..a436c0ec98d5b 100644
--- a/clang/include/clang/Basic/CodeGenOptions.def
+++ b/clang/include/clang/Basic/CodeGenOptions.def
@@ -476,6 +476,9 @@ CODEGENOPT(ImportCallOptimization, 1, 0)
/// (BlocksRuntime) on Windows.
CODEGENOPT(StaticClosure, 1, 0)
+/// Assume that UAVs/SRVs may alias
+CODEGENOPT(ResMayAlias, 1, 0)
+
/// FIXME: Make DebugOptions its own top-level .def file.
#include "DebugOptions.def"
diff --git a/clang/include/clang/Driver/Options.td b/clang/include/clang/Driver/Options.td
index d0414aba35209..9d33994c777d1 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -9044,6 +9044,11 @@ def dxil_validator_version : Option<["/", "-"], "validator-version", KIND_SEPARA
HelpText<"Override validator version for module. Format: <major.minor>;"
"Default: DXIL.dll version or current internal version">,
MarshallingInfoString<TargetOpts<"DxilValidatorVersion">, "\"1.8\"">;
+def res_may_alias : Option<["/", "-"], "res-may-alias", KIND_FLAG>,
+ Group<dxc_Group>, Flags<[HelpHidden]>,
+ Visibility<[DXCOption, ClangOption, CC1Option]>,
+ HelpText<"Assume that UAVs/SRVs may alias">,
+ MarshallingInfoFlag<CodeGenOpts<"ResMayAlias">>;
def target_profile : DXCJoinedOrSeparate<"T">, MetaVarName<"<profile>">,
HelpText<"Set target profile">,
Values<"ps_6_0, ps_6_1, ps_6_2, ps_6_3, ps_6_4, ps_6_5, ps_6_6, ps_6_7,"
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.cpp b/clang/lib/CodeGen/CGHLSLRuntime.cpp
index dc34653e8f497..b6c2cb0bfefc0 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -252,10 +252,13 @@ void CGHLSLRuntime::addHLSLBufferLayoutType(const RecordType *StructType,
void CGHLSLRuntime::finishCodeGen() {
auto &TargetOpts = CGM.getTarget().getTargetOpts();
+ auto &CodeGenOpts = CGM.getCodeGenOpts();
llvm::Module &M = CGM.getModule();
Triple T(M.getTargetTriple());
if (T.getArch() == Triple::ArchType::dxil)
addDxilValVersion(TargetOpts.DxilValidatorVersion, M);
+ if (CodeGenOpts.ResMayAlias)
+ M.setModuleFlag(llvm::Module::ModFlagBehavior::Error, "dx.resmayalias", 1);
generateGlobalCtorDtorCalls();
}
diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 4ebbd241d2f0b..f066e333c6e74 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3960,6 +3960,7 @@ static void RenderOpenCLOptions(const ArgList &Args, ArgStringList &CmdArgs,
static void RenderHLSLOptions(const ArgList &Args, ArgStringList &CmdArgs,
types::ID InputType) {
const unsigned ForwardedArguments[] = {options::OPT_dxil_validator_version,
+ options::OPT_res_may_alias,
options::OPT_D,
options::OPT_I,
options::OPT_O,
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
index 31fbd66dfaa2d..e05ab0cee1102 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "DXILShaderFlags.h"
+#include "DXILResourceAnalysis.h"
#include "DirectX.h"
#include "llvm/ADT/SCCIterator.h"
#include "llvm/ADT/SmallVector.h"
@@ -74,6 +75,7 @@ static bool checkWaveOps(Intrinsic::ID IID) {
/// \param I Instruction to check.
void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
const Instruction &I,
+ const ModuleMetadataInfo &MMDI,
DXILResourceTypeMap &DRTM) {
if (!CSF.Doubles)
CSF.Doubles = I.getType()->isDoubleTy();
@@ -117,6 +119,11 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
default:
break;
case Intrinsic::dx_resource_handlefrombinding:
+ if (!ResMayAlias && !CSF.ResMayNotAlias &&
+ MMDI.DXILVersion > VersionTuple(1, 7) &&
+ DRTM[cast<TargetExtType>(II->getType())].isUAV()) {
+ CSF.ResMayNotAlias = true;
+ }
switch (DRTM[cast<TargetExtType>(II->getType())].getResourceKind()) {
case dxil::ResourceKind::StructuredBuffer:
case dxil::ResourceKind::RawBuffer:
@@ -151,7 +158,14 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
/// Construct ModuleShaderFlags for module Module M
void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
- const ModuleMetadataInfo &MMDI) {
+ const ModuleMetadataInfo &MMDI,
+ const dxil::Resources &MDR) {
+
+ if (mdconst::extract_or_null<ConstantInt>(
+ M.getModuleFlag("dx.resmayalias"))) {
+ ResMayAlias = true;
+ }
+
CallGraph CG(M);
// Compute Shader Flags Mask for all functions using post-order visit of SCC
@@ -176,10 +190,15 @@ void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
continue;
}
+ if (!ResMayAlias && !SCCSF.ResMayNotAlias &&
+ MMDI.DXILVersion <= VersionTuple(1, 7)) {
+ SCCSF.ResMayNotAlias = MDR.hasUAVs();
+ }
+
ComputedShaderFlags CSF;
for (const auto &BB : *F)
for (const auto &I : BB)
- updateFunctionFlags(CSF, I, DRTM);
+ updateFunctionFlags(CSF, I, MMDI, DRTM);
// Update combined shader flags mask for all functions in this SCC
SCCSF.merge(CSF);
@@ -250,9 +269,10 @@ ModuleShaderFlags ShaderFlagsAnalysis::run(Module &M,
ModuleAnalysisManager &AM) {
DXILResourceTypeMap &DRTM = AM.getResult<DXILResourceTypeAnalysis>(M);
const ModuleMetadataInfo MMDI = AM.getResult<DXILMetadataAnalysis>(M);
+ const dxil::Resources &MDR = AM.getResult<DXILResourceMDAnalysis>(M);
ModuleShaderFlags MSFI;
- MSFI.initialize(M, DRTM, MMDI);
+ MSFI.initialize(M, DRTM, MMDI, MDR);
return MSFI;
}
@@ -284,14 +304,16 @@ bool ShaderFlagsAnalysisWrapper::runOnModule(Module &M) {
getAnalysis<DXILResourceTypeWrapperPass>().getResourceTypeMap();
const ModuleMetadataInfo MMDI =
getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
+ dxil::Resources &MDR = getAnalysis<DXILResourceMDWrapper>().getDXILResource();
- MSFI.initialize(M, DRTM, MMDI);
+ MSFI.initialize(M, DRTM, MMDI, MDR);
return false;
}
void ShaderFlagsAnalysisWrapper::getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
AU.addRequiredTransitive<DXILResourceTypeWrapperPass>();
+ AU.addRequired<DXILResourceMDWrapper>();
AU.addRequired<DXILMetadataAnalysisWrapperPass>();
}
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.h b/llvm/lib/Target/DirectX/DXILShaderFlags.h
index abf7cc86259ed..7b395b729e412 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.h
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.h
@@ -14,6 +14,7 @@
#ifndef LLVM_TARGET_DIRECTX_DXILSHADERFLAGS_H
#define LLVM_TARGET_DIRECTX_DXILSHADERFLAGS_H
+#include "DXILResource.h"
#include "llvm/Analysis/DXILMetadataAnalysis.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/PassManager.h"
@@ -85,7 +86,7 @@ struct ComputedShaderFlags {
struct ModuleShaderFlags {
void initialize(Module &, DXILResourceTypeMap &DRTM,
- const ModuleMetadataInfo &MMDI);
+ const ModuleMetadataInfo &MMDI, const dxil::Resources &MDR);
const ComputedShaderFlags &getFunctionFlags(const Function *) const;
const ComputedShaderFlags &getCombinedFlags() const { return CombinedSFMask; }
@@ -97,7 +98,11 @@ struct ModuleShaderFlags {
/// Combined Shader Flag Mask of all functions of the module
ComputedShaderFlags CombinedSFMask{};
void updateFunctionFlags(ComputedShaderFlags &, const Instruction &,
- DXILResourceTypeMap &);
+ const ModuleMetadataInfo &MMDI,
+ DXILResourceTypeMap &DRTM);
+
+ // Set to indicate if the -res-may-alias flag was passed to clang-dxc
+ bool ResMayAlias = false;
};
class ShaderFlagsAnalysis : public AnalysisInfoMixin<ShaderFlagsAnalysis> {
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias.ll
new file mode 100644
index 0000000000000..e5bdbc7012b55
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias.ll
@@ -0,0 +1,34 @@
+; TODO: Figure out an appropriate RUN command for this test. Normally, -res-may-alias is only applicable to clang-dxc
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+
+target triple = "dxil-pc-shadermodel6.8-library"
+
+; CHECK: Combined Shader Flags for Module
+; CHECK-NEXT: Shader Flags Value: 0x00000010
+
+; CHECK: Note: extra DXIL module flags:
+; CHECK: Raw and Structured buffers
+; CHECK-NOT: Any UAV may not alias any other UAV
+;
+
+; CHECK: Function loadUAV : 0x00000000
+define float @loadUAV() #0 {
+ %res = call target("dx.TypedBuffer", float, 1, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.typedbuffer(
+ target("dx.TypedBuffer", float, 1, 0, 0) %res, i32 0)
+ %val = extractvalue {float, i1} %load, 0
+ ret float %val
+}
+
+; CHECK: Function loadSRV : 0x00000010
+define float @loadSRV() #0 {
+ %res = tail call target("dx.RawBuffer", float, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.rawbuffer(
+ target("dx.RawBuffer", float, 0, 0) %res, i32 0, i32 0)
+ %val = extractvalue { float, i1 } %load, 0
+ ret float %val
+}
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll
new file mode 100644
index 0000000000000..3aed93e593e3b
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll
@@ -0,0 +1,33 @@
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+
+target triple = "dxil-pc-shadermodel6.7-library"
+
+; CHECK: Combined Shader Flags for Module
+; CHECK-NEXT: Shader Flags Value: 0x200000010
+
+; CHECK: Note: extra DXIL module flags:
+; CHECK: Raw and Structured buffers
+; CHECK: Any UAV may not alias any other UAV
+;
+
+; CHECK: Function loadUAV : 0x00000000
+define float @loadUAV() #0 {
+ %res = call target("dx.TypedBuffer", float, 1, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.typedbuffer(
+ target("dx.TypedBuffer", float, 1, 0, 0) %res, i32 0)
+ %val = extractvalue {float, i1} %load, 0
+ ret float %val
+}
+
+; CHECK: Function loadSRV : 0x00000010
+define float @loadSRV() #0 {
+ %res = tail call target("dx.RawBuffer", float, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.rawbuffer(
+ target("dx.RawBuffer", float, 0, 0) %res, i32 0, i32 0)
+ %val = extractvalue { float, i1 } %load, 0
+ ret float %val
+}
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll
new file mode 100644
index 0000000000000..fb5e234f0bd93
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll
@@ -0,0 +1,33 @@
+; RUN: opt -S --passes="print-dx-shader-flags" 2>&1 %s | FileCheck %s
+
+target triple = "dxil-pc-shadermodel6.8-library"
+
+; CHECK: Combined Shader Flags for Module
+; CHECK-NEXT: Shader Flags Value: 0x200000010
+
+; CHECK: Note: extra DXIL module flags:
+; CHECK: Raw and Structured buffers
+; CHECK: Any UAV may not alias any other UAV
+;
+
+; CHECK: Function loadUAV : 0x20000000
+define float @loadUAV() #0 {
+ %res = call target("dx.TypedBuffer", float, 1, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.typedbuffer(
+ target("dx.TypedBuffer", float, 1, 0, 0) %res, i32 0)
+ %val = extractvalue {float, i1} %load, 0
+ ret float %val
+}
+
+; CHECK: Function loadSRV : 0x00000010
+define float @loadSRV() #0 {
+ %res = tail call target("dx.RawBuffer", float, 0, 0)
+ @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
+ %load = call {float, i1} @llvm.dx.resource.load.rawbuffer(
+ target("dx.RawBuffer", float, 0, 0) %res, i32 0, i32 0)
+ %val = extractvalue { float, i1 } %load, 0
+ ret float %val
+}
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
More information about the llvm-commits
mailing list