Initial ResMayNotAlias shader flag implementation

Icohedron · Icohedron · commit ad5fbee6d0d5 · 2025-03-13T03:56:40.000Z
diff --git 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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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
@@ -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"}
