[DirectX] Implement Shader Flags Analysis for ResMayNotAlias #131070

Icohedron · 2025-03-13T03:59:08Z

Completed ACs:

-res-may-alias clang-dxc command-line option added
- It inserts and sets a module metadata flag dx.resmayalias to 1
Shader flag set appropriately:
- The flag IS NOT set if DXIL Version <= 1.6 OR the command-line option -res-may-alias is specified
- Otherwise the flag IS set when:
  - DXIL Version > 1.7 AND function uses UAVs, OR
  - DXIL Version <= 1.7 AND UAVs present globally
Add tests
- Tests for Shader Models 6.6, 6.7, and 6.8 corresponding to DXIL Versions 1.6, 1.7, and 1.8
- Tests (res-may-alias-0.ll/res-may-alias-1.ll) for when the module metadata flag dx.resmayalias is set to 0 or 1 respectively
- A frontend test (res-may-alias.hlsl) for testing that that the command-line option -res-may-alias inserts dx.resmayalias module metadata correctly

github-actions · 2025-03-14T00:33:45Z

✅ With the latest revision this PR passed the C/C++ code formatter.

Icohedron · 2025-03-14T00:34:28Z

clang/include/clang/Driver/Options.td

+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">,


This HelpText matches that found in DXC.
Doesn't the flag only affect whether or not the ResMayNotAlias flag can be set? The logic for setting the RestMayNotAlias flag only takes UAVs into consideration.
Perhaps the mention of SRVs should be removed?

Icohedron · 2025-03-14T00:36:32Z

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll

+
+; dx.resmayalias should never appear with a value of 0.
+; But if it does, ensure that it has no effect.
+!0 = !{i32 1, !"dx.resmayalias", i32 0}


I'm not sure if this test is necessary since the -res-may-alias clang-dxc flag will set this to 1. If the clang-dxc flag is not present, then this metadata would not appear at all. Let me know if I should delete this test.

I think the moment we define some metadata we should expect that some user may set the field manually, so having tests for this should definitely be included

llvmbot · 2025-03-14T00:45:54Z

@llvm/pr-subscribers-hlsl
@llvm/pr-subscribers-clang

@llvm/pr-subscribers-clang-driver

Author: Deric C. (Icohedron)

Changes

Fixes #112270

Completed ACs:

-res-may-alias clang-dxc command-line option added
- It inserts and sets a module metadata flag dx.resmayalias to 1
Shader flag set appropriately:
- CASE 1: command-line option -res-may-alias is NOT specified AND DXIL Version > 1.7 AND function uses UAVs
- CASE 2: command-line option -res-may-alias is NOT specified AND DXIL Version <= 1.7 AND UAVs present globally
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 frontend test (res-may-alias.hlsl) for testing that the command-line option -res-may-alias sets the module metadata flag dx.resmayalias to 1, and does not set the module metadata flag dx.resmayalias if -res-may-alias is not given
- Tests (res-may-alias-0.ll/res-may-alias-1.ll) for when the module metadata flag dx.resmayalias is set to 0 or 1

Full diff: https://github.com/llvm/llvm-project/pull/131070.diff

12 Files Affected:

(modified) clang/include/clang/Basic/CodeGenOptions.def (+3)
(modified) clang/include/clang/Driver/Options.td (+5)
(modified) clang/lib/CodeGen/CGHLSLRuntime.cpp (+3)
(modified) clang/lib/Driver/ToolChains/Clang.cpp (+1)
(added) clang/test/CodeGenHLSL/res-may-alias.hlsl (+7)
(modified) llvm/lib/Target/DirectX/DXILShaderFlags.cpp (+37-6)
(modified) llvm/lib/Target/DirectX/DXILShaderFlags.h (+7-2)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll (+39)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll (+37)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll (+33)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll (+33)
(modified) llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll (+5-4)

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 66ae8f1c7f064..9c5fd2354f95e 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -9043,6 +9043,11 @@ 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 5916fa6183a27..6fd8bc295e8ca 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -283,10 +283,13 @@ 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 fe172d923ac07..9be3939641cfc 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3959,6 +3959,7 @@ 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/clang/test/CodeGenHLSL/res-may-alias.hlsl b/clang/test/CodeGenHLSL/res-may-alias.hlsl
new file mode 100644
index 0000000000000..53ee8ee4935d8
--- /dev/null
+++ b/clang/test/CodeGenHLSL/res-may-alias.hlsl
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -res-may-alias -finclude-default-header -triple dxil-pc-shadermodel6.3-library -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=FLAG
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=NOFLAG
+
+// FLAG-DAG: ![[RMA:.*]] = !{i32 1, !"dx.resmayalias", i32 1}
+// FLAG-DAG: !llvm.module.flags = !{{{.*}}![[RMA]]{{.*}}}
+
+// NOFLAG-NOT: dx.resmayalias
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
index 31fbd66dfaa2d..b05ee53798524 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
@@ -74,7 +74,8 @@ static bool checkWaveOps(Intrinsic::ID IID) {
 /// \param I Instruction to check.
 void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
                                             const Instruction &I,
-                                            DXILResourceTypeMap &DRTM) {
+                                            DXILResourceTypeMap &DRTM,
+                                            const ModuleMetadataInfo &MMDI) {
   if (!CSF.Doubles)
     CSF.Doubles = I.getType()->isDoubleTy();
 
@@ -116,8 +117,17 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
     switch (II->getIntrinsicID()) {
     default:
       break;
-    case Intrinsic::dx_resource_handlefrombinding:
-      switch (DRTM[cast<TargetExtType>(II->getType())].getResourceKind()) {
+    case Intrinsic::dx_resource_handlefrombinding: {
+      dxil::ResourceTypeInfo &RTI = DRTM[cast<TargetExtType>(II->getType())];
+
+      // If -res-may-alias is NOT specified, and DXIL Ver > 1.7.
+      // Then set ResMayNotAlias if function uses UAVs.
+      if (!CSF.ResMayNotAlias && !ResMayAlias &&
+          MMDI.DXILVersion > VersionTuple(1, 7) && RTI.isUAV()) {
+        CSF.ResMayNotAlias = true;
+      }
+
+      switch (RTI.getResourceKind()) {
       case dxil::ResourceKind::StructuredBuffer:
       case dxil::ResourceKind::RawBuffer:
         CSF.EnableRawAndStructuredBuffers = true;
@@ -126,6 +136,7 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
         break;
       }
       break;
+    }
     case Intrinsic::dx_resource_load_typedbuffer: {
       dxil::ResourceTypeInfo &RTI =
           DRTM[cast<TargetExtType>(II->getArgOperand(0)->getType())];
@@ -151,7 +162,17 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
 
 /// Construct ModuleShaderFlags for module Module M
 void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
+                                   DXILBindingMap &DBM,
                                    const ModuleMetadataInfo &MMDI) {
+
+  // Check if -res-may-alias was provided on the command line.
+  // The command line option will set the dx.resmayalias module flag to 1.
+  if (auto *RMA = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("dx.resmayalias"))) {
+    if (RMA->getValue() != 0)
+      ResMayAlias = true;
+  }
+
   CallGraph CG(M);
 
   // Compute Shader Flags Mask for all functions using post-order visit of SCC
@@ -176,10 +197,16 @@ void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
         continue;
       }
 
+      // If -res-may-alias is NOT specified, and DXIL Ver <= 1.7.
+      // Then set ResMayNotAlias to true if there are UAVs present globally.
+      if (!ResMayAlias && MMDI.DXILVersion <= VersionTuple(1, 7)) {
+        SCCSF.ResMayNotAlias = !DBM.uavs().empty();
+      }
+
       ComputedShaderFlags CSF;
       for (const auto &BB : *F)
         for (const auto &I : BB)
-          updateFunctionFlags(CSF, I, DRTM);
+          updateFunctionFlags(CSF, I, DRTM, MMDI);
       // Update combined shader flags mask for all functions in this SCC
       SCCSF.merge(CSF);
 
@@ -249,10 +276,11 @@ AnalysisKey ShaderFlagsAnalysis::Key;
 ModuleShaderFlags ShaderFlagsAnalysis::run(Module &M,
                                            ModuleAnalysisManager &AM) {
   DXILResourceTypeMap &DRTM = AM.getResult<DXILResourceTypeAnalysis>(M);
+  DXILBindingMap &DBM = AM.getResult<DXILResourceBindingAnalysis>(M);
   const ModuleMetadataInfo MMDI = AM.getResult<DXILMetadataAnalysis>(M);
 
   ModuleShaderFlags MSFI;
-  MSFI.initialize(M, DRTM, MMDI);
+  MSFI.initialize(M, DRTM, DBM, MMDI);
 
   return MSFI;
 }
@@ -282,16 +310,19 @@ PreservedAnalyses ShaderFlagsAnalysisPrinter::run(Module &M,
 bool ShaderFlagsAnalysisWrapper::runOnModule(Module &M) {
   DXILResourceTypeMap &DRTM =
       getAnalysis<DXILResourceTypeWrapperPass>().getResourceTypeMap();
+  DXILBindingMap &DBM =
+      getAnalysis<DXILResourceBindingWrapperPass>().getBindingMap();
   const ModuleMetadataInfo MMDI =
       getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
 
-  MSFI.initialize(M, DRTM, MMDI);
+  MSFI.initialize(M, DRTM, DBM, MMDI);
   return false;
 }
 
 void ShaderFlagsAnalysisWrapper::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   AU.addRequiredTransitive<DXILResourceTypeWrapperPass>();
+  AU.addRequiredTransitive<DXILResourceBindingWrapperPass>();
   AU.addRequired<DXILMetadataAnalysisWrapperPass>();
 }
 
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.h b/llvm/lib/Target/DirectX/DXILShaderFlags.h
index abf7cc86259ed..b47c79cb293a5 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.h
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.h
@@ -28,6 +28,7 @@ namespace llvm {
 class Module;
 class GlobalVariable;
 class DXILResourceTypeMap;
+class DXILBindingMap;
 
 namespace dxil {
 
@@ -84,12 +85,16 @@ struct ComputedShaderFlags {
 };
 
 struct ModuleShaderFlags {
-  void initialize(Module &, DXILResourceTypeMap &DRTM,
+  void initialize(Module &, DXILResourceTypeMap &DRTM, DXILBindingMap &DBM,
                   const ModuleMetadataInfo &MMDI);
   const ComputedShaderFlags &getFunctionFlags(const Function *) const;
   const ComputedShaderFlags &getCombinedFlags() const { return CombinedSFMask; }
 
 private:
+  // A bool to indicate if the -res-may-alias flag was passed to clang-dxc.
+  // A module flag "dx.resmayalias" is set to 1 if true.
+  // This bool is used in the logic for setting the flag ResMayNotAlias.
+  bool ResMayAlias = false;
   /// Map of Function-Shader Flag Mask pairs representing properties of each of
   /// the functions in the module. Shader Flags of each function represent both
   /// module-level and function-level flags
@@ -97,7 +102,7 @@ struct ModuleShaderFlags {
   /// Combined Shader Flag Mask of all functions of the module
   ComputedShaderFlags CombinedSFMask{};
   void updateFunctionFlags(ComputedShaderFlags &, const Instruction &,
-                           DXILResourceTypeMap &);
+                           DXILResourceTypeMap &, const ModuleMetadataInfo &);
 };
 
 class ShaderFlagsAnalysis : public AnalysisInfoMixin<ShaderFlagsAnalysis> {
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll
new file mode 100644
index 0000000000000..29901de7f8e37
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll
@@ -0,0 +1,39 @@
+; 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
+}
+
+!llvm.module.flags = !{!0}
+
+; dx.resmayalias should never appear with a value of 0.
+; But if it does, ensure that it has no effect.
+!0 = !{i32 1, !"dx.resmayalias", i32 0}
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll
new file mode 100644
index 0000000000000..98a8dd06f6020
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll
@@ -0,0 +1,37 @@
+; 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
+}
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"dx.resmayalias", i32 1}
+
+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..ab3eea71bf8f0
--- /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 : 0x200000000
+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 : 0x200000010
+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"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
index 060d54f961c70..96f80f531fa32 100644
--- a/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
@@ -8,12 +8,13 @@ target triple = "dxil-pc-shadermodel6.7-library"
 ; CHECK-OBJ:     TypedUAVLoadAdditionalFormats: true
 
 ; CHECK:      Combined Shader Flags for Module
-; CHECK-NEXT: Shader Flags Value: 0x00002000
+; CHECK-NEXT: Shader Flags Value: 0x200002000
 
 ; CHECK: Note: shader requires additional functionality:
 ; CHECK:       Typed UAV Load Additional Formats
+; CHECK:       Any UAV may not alias any other UAV
 
-; CHECK: Function multicomponent : 0x00002000
+; CHECK: Function multicomponent : 0x200002000
 define <4 x float> @multicomponent() #0 {
   %res = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
@@ -23,7 +24,7 @@ define <4 x float> @multicomponent() #0 {
   ret <4 x float> %val
 }
 
-; CHECK: Function onecomponent : 0x00000000
+; CHECK: Function onecomponent : 0x200000000
 define float @onecomponent() #0 {
   %res = call target("dx.TypedBuffer", float, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
@@ -33,7 +34,7 @@ define float @onecomponent() #0 {
   ret float %val
 }
 
-; CHECK: Function noload : 0x00000000
+; CHECK: Function noload : 0x200000000
 define void @noload(<4 x float> %val) #0 {
   %res = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)

llvmbot · 2025-03-14T00:45:54Z

@llvm/pr-subscribers-clang-codegen

Author: Deric C. (Icohedron)

Changes

Fixes #112270

Completed ACs:

-res-may-alias clang-dxc command-line option added
- It inserts and sets a module metadata flag dx.resmayalias to 1
Shader flag set appropriately:
- CASE 1: command-line option -res-may-alias is NOT specified AND DXIL Version > 1.7 AND function uses UAVs
- CASE 2: command-line option -res-may-alias is NOT specified AND DXIL Version <= 1.7 AND UAVs present globally
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 frontend test (res-may-alias.hlsl) for testing that the command-line option -res-may-alias sets the module metadata flag dx.resmayalias to 1, and does not set the module metadata flag dx.resmayalias if -res-may-alias is not given
- Tests (res-may-alias-0.ll/res-may-alias-1.ll) for when the module metadata flag dx.resmayalias is set to 0 or 1

Full diff: https://github.com/llvm/llvm-project/pull/131070.diff

12 Files Affected:

(modified) clang/include/clang/Basic/CodeGenOptions.def (+3)
(modified) clang/include/clang/Driver/Options.td (+5)
(modified) clang/lib/CodeGen/CGHLSLRuntime.cpp (+3)
(modified) clang/lib/Driver/ToolChains/Clang.cpp (+1)
(added) clang/test/CodeGenHLSL/res-may-alias.hlsl (+7)
(modified) llvm/lib/Target/DirectX/DXILShaderFlags.cpp (+37-6)
(modified) llvm/lib/Target/DirectX/DXILShaderFlags.h (+7-2)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll (+39)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll (+37)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.7.ll (+33)
(added) llvm/test/CodeGen/DirectX/ShaderFlags/res-may-not-alias-shadermodel6.8.ll (+33)
(modified) llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll (+5-4)

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 66ae8f1c7f064..9c5fd2354f95e 100644
--- a/clang/include/clang/Driver/Options.td
+++ b/clang/include/clang/Driver/Options.td
@@ -9043,6 +9043,11 @@ 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 5916fa6183a27..6fd8bc295e8ca 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.cpp
+++ b/clang/lib/CodeGen/CGHLSLRuntime.cpp
@@ -283,10 +283,13 @@ 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 fe172d923ac07..9be3939641cfc 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -3959,6 +3959,7 @@ 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/clang/test/CodeGenHLSL/res-may-alias.hlsl b/clang/test/CodeGenHLSL/res-may-alias.hlsl
new file mode 100644
index 0000000000000..53ee8ee4935d8
--- /dev/null
+++ b/clang/test/CodeGenHLSL/res-may-alias.hlsl
@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -res-may-alias -finclude-default-header -triple dxil-pc-shadermodel6.3-library -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=FLAG
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-library -emit-llvm -disable-llvm-passes -o - %s | FileCheck %s --check-prefix=NOFLAG
+
+// FLAG-DAG: ![[RMA:.*]] = !{i32 1, !"dx.resmayalias", i32 1}
+// FLAG-DAG: !llvm.module.flags = !{{{.*}}![[RMA]]{{.*}}}
+
+// NOFLAG-NOT: dx.resmayalias
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
index 31fbd66dfaa2d..b05ee53798524 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.cpp
@@ -74,7 +74,8 @@ static bool checkWaveOps(Intrinsic::ID IID) {
 /// \param I Instruction to check.
 void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
                                             const Instruction &I,
-                                            DXILResourceTypeMap &DRTM) {
+                                            DXILResourceTypeMap &DRTM,
+                                            const ModuleMetadataInfo &MMDI) {
   if (!CSF.Doubles)
     CSF.Doubles = I.getType()->isDoubleTy();
 
@@ -116,8 +117,17 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
     switch (II->getIntrinsicID()) {
     default:
       break;
-    case Intrinsic::dx_resource_handlefrombinding:
-      switch (DRTM[cast<TargetExtType>(II->getType())].getResourceKind()) {
+    case Intrinsic::dx_resource_handlefrombinding: {
+      dxil::ResourceTypeInfo &RTI = DRTM[cast<TargetExtType>(II->getType())];
+
+      // If -res-may-alias is NOT specified, and DXIL Ver > 1.7.
+      // Then set ResMayNotAlias if function uses UAVs.
+      if (!CSF.ResMayNotAlias && !ResMayAlias &&
+          MMDI.DXILVersion > VersionTuple(1, 7) && RTI.isUAV()) {
+        CSF.ResMayNotAlias = true;
+      }
+
+      switch (RTI.getResourceKind()) {
       case dxil::ResourceKind::StructuredBuffer:
       case dxil::ResourceKind::RawBuffer:
         CSF.EnableRawAndStructuredBuffers = true;
@@ -126,6 +136,7 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
         break;
       }
       break;
+    }
     case Intrinsic::dx_resource_load_typedbuffer: {
       dxil::ResourceTypeInfo &RTI =
           DRTM[cast<TargetExtType>(II->getArgOperand(0)->getType())];
@@ -151,7 +162,17 @@ void ModuleShaderFlags::updateFunctionFlags(ComputedShaderFlags &CSF,
 
 /// Construct ModuleShaderFlags for module Module M
 void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
+                                   DXILBindingMap &DBM,
                                    const ModuleMetadataInfo &MMDI) {
+
+  // Check if -res-may-alias was provided on the command line.
+  // The command line option will set the dx.resmayalias module flag to 1.
+  if (auto *RMA = mdconst::extract_or_null<ConstantInt>(
+          M.getModuleFlag("dx.resmayalias"))) {
+    if (RMA->getValue() != 0)
+      ResMayAlias = true;
+  }
+
   CallGraph CG(M);
 
   // Compute Shader Flags Mask for all functions using post-order visit of SCC
@@ -176,10 +197,16 @@ void ModuleShaderFlags::initialize(Module &M, DXILResourceTypeMap &DRTM,
         continue;
       }
 
+      // If -res-may-alias is NOT specified, and DXIL Ver <= 1.7.
+      // Then set ResMayNotAlias to true if there are UAVs present globally.
+      if (!ResMayAlias && MMDI.DXILVersion <= VersionTuple(1, 7)) {
+        SCCSF.ResMayNotAlias = !DBM.uavs().empty();
+      }
+
       ComputedShaderFlags CSF;
       for (const auto &BB : *F)
         for (const auto &I : BB)
-          updateFunctionFlags(CSF, I, DRTM);
+          updateFunctionFlags(CSF, I, DRTM, MMDI);
       // Update combined shader flags mask for all functions in this SCC
       SCCSF.merge(CSF);
 
@@ -249,10 +276,11 @@ AnalysisKey ShaderFlagsAnalysis::Key;
 ModuleShaderFlags ShaderFlagsAnalysis::run(Module &M,
                                            ModuleAnalysisManager &AM) {
   DXILResourceTypeMap &DRTM = AM.getResult<DXILResourceTypeAnalysis>(M);
+  DXILBindingMap &DBM = AM.getResult<DXILResourceBindingAnalysis>(M);
   const ModuleMetadataInfo MMDI = AM.getResult<DXILMetadataAnalysis>(M);
 
   ModuleShaderFlags MSFI;
-  MSFI.initialize(M, DRTM, MMDI);
+  MSFI.initialize(M, DRTM, DBM, MMDI);
 
   return MSFI;
 }
@@ -282,16 +310,19 @@ PreservedAnalyses ShaderFlagsAnalysisPrinter::run(Module &M,
 bool ShaderFlagsAnalysisWrapper::runOnModule(Module &M) {
   DXILResourceTypeMap &DRTM =
       getAnalysis<DXILResourceTypeWrapperPass>().getResourceTypeMap();
+  DXILBindingMap &DBM =
+      getAnalysis<DXILResourceBindingWrapperPass>().getBindingMap();
   const ModuleMetadataInfo MMDI =
       getAnalysis<DXILMetadataAnalysisWrapperPass>().getModuleMetadata();
 
-  MSFI.initialize(M, DRTM, MMDI);
+  MSFI.initialize(M, DRTM, DBM, MMDI);
   return false;
 }
 
 void ShaderFlagsAnalysisWrapper::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
   AU.addRequiredTransitive<DXILResourceTypeWrapperPass>();
+  AU.addRequiredTransitive<DXILResourceBindingWrapperPass>();
   AU.addRequired<DXILMetadataAnalysisWrapperPass>();
 }
 
diff --git a/llvm/lib/Target/DirectX/DXILShaderFlags.h b/llvm/lib/Target/DirectX/DXILShaderFlags.h
index abf7cc86259ed..b47c79cb293a5 100644
--- a/llvm/lib/Target/DirectX/DXILShaderFlags.h
+++ b/llvm/lib/Target/DirectX/DXILShaderFlags.h
@@ -28,6 +28,7 @@ namespace llvm {
 class Module;
 class GlobalVariable;
 class DXILResourceTypeMap;
+class DXILBindingMap;
 
 namespace dxil {
 
@@ -84,12 +85,16 @@ struct ComputedShaderFlags {
 };
 
 struct ModuleShaderFlags {
-  void initialize(Module &, DXILResourceTypeMap &DRTM,
+  void initialize(Module &, DXILResourceTypeMap &DRTM, DXILBindingMap &DBM,
                   const ModuleMetadataInfo &MMDI);
   const ComputedShaderFlags &getFunctionFlags(const Function *) const;
   const ComputedShaderFlags &getCombinedFlags() const { return CombinedSFMask; }
 
 private:
+  // A bool to indicate if the -res-may-alias flag was passed to clang-dxc.
+  // A module flag "dx.resmayalias" is set to 1 if true.
+  // This bool is used in the logic for setting the flag ResMayNotAlias.
+  bool ResMayAlias = false;
   /// Map of Function-Shader Flag Mask pairs representing properties of each of
   /// the functions in the module. Shader Flags of each function represent both
   /// module-level and function-level flags
@@ -97,7 +102,7 @@ struct ModuleShaderFlags {
   /// Combined Shader Flag Mask of all functions of the module
   ComputedShaderFlags CombinedSFMask{};
   void updateFunctionFlags(ComputedShaderFlags &, const Instruction &,
-                           DXILResourceTypeMap &);
+                           DXILResourceTypeMap &, const ModuleMetadataInfo &);
 };
 
 class ShaderFlagsAnalysis : public AnalysisInfoMixin<ShaderFlagsAnalysis> {
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll
new file mode 100644
index 0000000000000..29901de7f8e37
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll
@@ -0,0 +1,39 @@
+; 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
+}
+
+!llvm.module.flags = !{!0}
+
+; dx.resmayalias should never appear with a value of 0.
+; But if it does, ensure that it has no effect.
+!0 = !{i32 1, !"dx.resmayalias", i32 0}
+
+attributes #0 = { convergent norecurse nounwind "hlsl.export"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll
new file mode 100644
index 0000000000000..98a8dd06f6020
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-1.ll
@@ -0,0 +1,37 @@
+; 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
+}
+
+!llvm.module.flags = !{!0}
+
+!0 = !{i32 1, !"dx.resmayalias", i32 1}
+
+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..ab3eea71bf8f0
--- /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 : 0x200000000
+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 : 0x200000010
+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"}
diff --git a/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll b/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
index 060d54f961c70..96f80f531fa32 100644
--- a/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
+++ b/llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll
@@ -8,12 +8,13 @@ target triple = "dxil-pc-shadermodel6.7-library"
 ; CHECK-OBJ:     TypedUAVLoadAdditionalFormats: true
 
 ; CHECK:      Combined Shader Flags for Module
-; CHECK-NEXT: Shader Flags Value: 0x00002000
+; CHECK-NEXT: Shader Flags Value: 0x200002000
 
 ; CHECK: Note: shader requires additional functionality:
 ; CHECK:       Typed UAV Load Additional Formats
+; CHECK:       Any UAV may not alias any other UAV
 
-; CHECK: Function multicomponent : 0x00002000
+; CHECK: Function multicomponent : 0x200002000
 define <4 x float> @multicomponent() #0 {
   %res = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
@@ -23,7 +24,7 @@ define <4 x float> @multicomponent() #0 {
   ret <4 x float> %val
 }
 
-; CHECK: Function onecomponent : 0x00000000
+; CHECK: Function onecomponent : 0x200000000
 define float @onecomponent() #0 {
   %res = call target("dx.TypedBuffer", float, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)
@@ -33,7 +34,7 @@ define float @onecomponent() #0 {
   ret float %val
 }
 
-; CHECK: Function noload : 0x00000000
+; CHECK: Function noload : 0x200000000
 define void @noload(<4 x float> %val) #0 {
   %res = call target("dx.TypedBuffer", <4 x float>, 1, 0, 0)
       @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, i1 false)

inbelic

Nice work, just some minor comments/questions.

As mentioned, we should have a definitive answer to if we need SRV to be included at all here (both in code comments and testcases).

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll

inbelic · 2025-03-17T21:15:22Z

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll

+target triple = "dxil-pc-shadermodel6.8-library"
+
+; CHECK:      Combined Shader Flags for Module
+; CHECK-NEXT: Shader Flags Value: 0x200000010


It seems the ResMayNotAlias flag is what we are checking and is the 2 value. What is the 1 value for?

The 1 is for the structured buffer (SRV) in the same module. It's there so I can test that the function that accesses only an SRV will not get the ResMayNotAlias flag.

llvm/test/CodeGen/DirectX/ShaderFlags/typed-uav-load-additional-formats.ll

llvm/lib/Target/DirectX/DXILShaderFlags.cpp

inbelic · 2025-03-17T21:20:26Z

llvm/test/CodeGen/DirectX/ShaderFlags/res-may-alias-0.ll

+
+; dx.resmayalias should never appear with a value of 0.
+; But if it does, ensure that it has no effect.
+!0 = !{i32 1, !"dx.resmayalias", i32 0}


I think the moment we define some metadata we should expect that some user may set the field manually, so having tests for this should definitely be included

… Formats

clang/test/CodeGenHLSL/res-may-alias.hlsl

…otalias

farzonl

LGTM

…1070) Fixes llvm#112270 Completed ACs: - `-res-may-alias` clang-dxc command-line option added - It inserts and sets a module metadata flag `dx.resmayalias` to 1 - Shader flag set appropriately: - The flag IS NOT set if DXIL Version <= 1.6 OR the command-line option `-res-may-alias` is specified - Otherwise the flag IS set when: - DXIL Version > 1.7 AND function uses UAVs, OR - DXIL Version <= 1.7 AND UAVs present globally - Add tests - Tests for Shader Models 6.6, 6.7, and 6.8 corresponding to DXIL Versions 1.6, 1.7, and 1.8 - Tests (`res-may-alias-0.ll`/`res-may-alias-1.ll`) for when the module metadata flag `dx.resmayalias` is set to 0 or 1 respectively - A frontend test (`res-may-alias.hlsl`) for testing that that the command-line option `-res-may-alias` inserts `dx.resmayalias` module metadata correctly

Icohedron mentioned this pull request Mar 13, 2025

[DirectX] Shader Flags Analysis for ResMayNotAlias #112270

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Implement ResMayNotAlias DXIL shader flag analysis

81196e0

Icohedron force-pushed the shader-flag-resmaynotalias branch from ad5fbee to 81196e0 Compare March 14, 2025 00:30

Icohedron commented Mar 14, 2025

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Apply clang-format

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Icohedron marked this pull request as ready for review March 14, 2025 00:45

github-project-automation bot added this to HLSL Support Mar 14, 2025

Do not set ResMayNotAlias if DXIL Ver <= 1.6

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inbelic reviewed Mar 17, 2025

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Icohedron added 3 commits March 18, 2025 01:10

Remove braces from single-statement if- bodies

7172146

Add comments to tests for clarity of purpose

5c14432

Set dx.resmayalias module flag to only test Typed UAV Load Additional…

a9d6a6a

… Formats

farzonl reviewed Apr 9, 2025

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clang/test/CodeGenHLSL/res-may-alias.hlsl Outdated Show resolved Hide resolved

Icohedron added 6 commits April 9, 2025 18:16

Use clang_dxc instead of clang_cc1

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Merge remote-tracking branch 'upstream/main' into shader-flag-resmayn…

8e4adbe

…otalias

Conform to ResourceBinding* -> Resource* name changes from upstream

bd6b33b

Apply clang-format

71b215e

Add '-Xclang -emit-llvm' to avoid running the DirectX backend

98a4848

Merge remote-tracking branch 'upstream/main' into shader-flag-resmayn…

a63b7f0

…otalias

farzonl approved these changes Apr 10, 2025

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Icohedron merged commit 727f392 into llvm:main Apr 10, 2025
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damyanp moved this to Closed in HLSL Support Apr 25, 2025

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