[PIX] Fix render-state visualization passes by damyanp · Pull Request #8850 · microsoft/DirectXShaderCompiler

Damyan Pepper (damyanp) · 2026-08-27T23:43:35Z

Part 9 of 14 in the PIX instrumentation stack. It targets users/damyanp/pix-fixes-08. Its content depends on PR 2 for the declaration cleanup helper.

dx.op.storeOutput has four legal overloads: f16, f32, i16, and i32. DxilOutputColorBecomesConstant looks only for f32 and i32. A shader that writes SV_Target0 as min16float, min16int, half, or int16_t gets no constant-color instrumentation. The pass then asserts that the outputs are not mixed, and that assertion cannot tell "both types present" from "neither type recognised".

The pass builds a constant buffer for the colour, but it does not give that buffer a layout ValidateCBuffer can reach. The validator therefore refuses the instrumented module.

DxilReduceMSAAToSingleSample does not look through annotateHandle, and it does not accept a 16-bit texture load.

Only one overload can write SV_Target0, so there is no mixed case to resolve. PIX always uploads four 32-bit components, so the shader narrows them when the output is 16 bits. The upload format does not change.

Assisted-by: Copilot

This changes only the PIX instrumentation, so it needs no release note.

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Copilot

Pull request overview

Fixes PIX render-state visualization for 16-bit outputs, valid constant-buffer metadata, and modern MSAA handles.

Changes:

Supports all legal storeOutput overloads and 16-bit narrowing.
Adds valid constant-buffer layout annotations.
Handles SM 6.6 annotated resources and f16 MSAA loads.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
`lib/DxilPIXPasses/DxilOutputColorBecomesConstant.cpp`	Adds 16-bit output support and valid buffer metadata.
`lib/DxilPIXPasses/DxilReduceMSAAToSingleSample.cpp`	Recognizes annotated handles and all load overloads.
`tools/clang/unittests/HLSL/PixTest.cpp`	Adds validation and MSAA regression tests.
`tools/clang/test/HLSLFileCheck/pix/constantcolorminprecisionMRT.hlsl`	Tests min-precision MRT output.
`tools/clang/test/HLSLFileCheck/pix/constantcolorminprecisionint.hlsl`	Tests min-precision integer output.
`tools/clang/test/HLSLFileCheck/pix/constantcolorminprecisionFromCB.hlsl`	Tests min-precision buffer narrowing.
`tools/clang/test/HLSLFileCheck/pix/constantcolorminprecision.hlsl`	Tests min-precision float literals.
`tools/clang/test/HLSLFileCheck/pix/constantcolorint16.hlsl`	Tests native 16-bit integer output.
`tools/clang/test/HLSLFileCheck/pix/constantcolorhalfMRTOnRTV1.hlsl`	Tests half output on RTV1.
`tools/clang/test/HLSLFileCheck/pix/constantcolorhalfMRT.hlsl`	Tests half output on RTV0.
`tools/clang/test/HLSLFileCheck/pix/constantcolorhalfFromCB.hlsl`	Tests native-half buffer narrowing.
`tools/clang/test/HLSLFileCheck/pix/constantcolorhalf.hlsl`	Tests native-half literal replacement.

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+                : Builder.CreateTrunc(ReplacementColors[ChannelIndex],
+                                      OutputValueType,
+                                      NarrowedNames[ChannelIndex]);


+
+    unsigned RangeId =
+        cast<ConstantInt>(CreateHandle.get_rangeId())->getLimitedValue();
+    auto Resource = DM.GetSRV(RangeId);


Copilot

Copilot review overview

🟡 Changes recommended

Cleanup does not report all module mutations, and the integer constant-buffer narrowing branch lacks regression coverage.

Review effort: Balanced
Findings: 2 · 5

Open (7)

Propagate cleanup modifications in pass result · New
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit annotation pointer type · New
Use explicit pointer type · New
Use explicit return types · New
Use explicit vector and element types · New
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

+    std::array<Function *, 4> &OutputFunctions;
+    ~EraseUnusedOutputFunctionsOnExit() {
+      for (Function *OutputFunction : OutputFunctions) {
+        PIXPassHelpers::eraseIfUnused(DM, OutputFunction);


-    pCBuf->SetSize(4);
+    pCBuf->SetSize(ConstantColorCBufferSizeInBytes);
+
+    auto *StructAnnotation = DM.GetTypeSystem().GetStructAnnotation(CBStructTy);


-bool DxilReduceMSAAToSingleSample::runOnModule(Module &M) {
-  DxilModule &DM = M.GetOrCreateDxilModule();
+static bool IsMultisampledSRVHandle(Value *TextureHandle, DxilModule &DM) {
+  auto *TextureHandleInst = dyn_cast<CallInst>(TextureHandle);


+  auto compiled = Compile(m_dllSupport, source, L"ps_6_0", {L"-Od"});
+  auto output = runSinglePass(compiled, L"-hlsl-dxil-constantColor,mod-mode=1");


+  auto lines = Tokenize(Disassemble(pNewContainer).c_str(), "\n");
+  bool foundConstantColorCBuffer = false;
+  for (auto const &line : lines) {


Copilot

Copilot review overview

🔵 Needs a closer look

The newly introduced 16-bit integer constant-buffer truncation branch lacks direct regression coverage.

Review effort: Balanced
Findings: 2 · 5

Open (7)

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

Copilot

Copilot review overview

🟡 Changes recommended

The new i16 constant-buffer truncation path lacks coverage, and several additions violate the explicit-type convention.

Review effort: Balanced
Findings: 2 · 8

Open (10)

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit field-annotation reference type · New
Use explicit types for short inferred locals · New
Use explicit const string reference element type · New
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

+        auto &FieldAnnotation =
+            StructAnnotation->GetFieldAnnotation(ComponentIndex);


      auto &FunctionUse = *FI++;
-      auto FunctionUser = FunctionUse.getUser();
-      auto instruction = cast<Instruction>(FunctionUser);
-      DxilInst_TextureLoad LoadInstruction(instruction);
-      auto TextureHandle = LoadInstruction.get_srv();
-      auto TextureHandleInst = cast<CallInst>(TextureHandle);
-      DxilInst_CreateHandle createHandle(TextureHandleInst);
-      // Dynamic rangeId is not supported
-      if (isa<ConstantInt>(createHandle.get_rangeId())) {
-        unsigned rangeId =
-            cast<ConstantInt>(createHandle.get_rangeId())->getLimitedValue();
-        if (static_cast<DXIL::ResourceClass>(
-                createHandle.get_resourceClass_val()) ==
-            DXIL::ResourceClass::SRV) {
-          auto Resource = DM.GetSRV(rangeId);
-          if (Resource.GetKind() == DXIL::ResourceKind::Texture2DMS ||
-              Resource.GetKind() == DXIL::ResourceKind::Texture2DMSArray) {
-            // "2" is the mip-level/sample-index operand index:
-            // https://github.com/Microsoft/DirectXShaderCompiler/blob/master/docs/DXIL.rst#textureload
-            instruction->setOperand(2, HlslOP->GetI32Const(0));
-            Modified = true;
-          }
-        }
+      auto *InstructionUser = dyn_cast<Instruction>(FunctionUse.getUser());


+                               const char *textureLoadOverload,
+                               const char *originalSampleIndex) {
+  bool foundTextureLoad = false;
+  for (auto const &line : lines) {


Copilot

Copilot review overview

🔵 Needs a closer look

The no-target path incorrectly reports no module mutation, and the new integer narrowing branch lacks coverage.

Review effort: Balanced
Findings: 2 · 8

Open (10)

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit const string reference element type
Use explicit types for short inferred locals
Use explicit field-annotation reference type
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

Copilot

Copilot review overview

🔵 Needs a closer look

Cleanup reports an incorrect modification result, and the new integer narrowing path lacks coverage.

Review effort: Balanced
Findings: 2 · 8

Open (10)

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit const string reference element type
Use explicit types for short inferred locals
Use explicit field-annotation reference type
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

Copilot

Copilot review overview

🟡 Changes recommended

The newly added integer 16-bit constant-buffer narrowing path lacks regression coverage, alongside several convention issues.

Review effort: Balanced
Findings: 2 · 9

Open (11)

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Use explicit types for helper results · New
Use explicit const string reference element type
Use explicit types for short inferred locals
Use explicit field-annotation reference type
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

+  auto compiled = Compile(m_dllSupport, source, L"ps_6_6", {L"-Od"});
+  auto output = runSinglePass(compiled, L"-hlsl-dxil-reduce-msaa-to-single");
+  auto lines = Tokenize(Disassemble(output.Module).c_str(), "\n");


Copilot

🟡 Changes recommended

The no-target path mutates the module during scope cleanup while incorrectly reporting that no modification occurred.

12 open findings

Propagate cleanup modifications in pass result
The new integer narrowing branch is not exercised. The added FromCB tests cover f16…
Add release note for 16-bit instrumentation fix · New
Use explicit types for helper results
Use explicit const string reference element type
Use explicit types for short inferred locals
Use explicit field-annotation reference type
Use explicit vector and element types
Use explicit return types
Use explicit pointer type
Use explicit annotation pointer type
GetSRV returns a reference, so plain auto copies the entire resource and also conflicts with…

🧠 Review effort: Balanced

+  // dx.op.storeOutput has four legal overloads: f16, f32, i16 and i32.
+  // A min16float or min16int SV_Target lowers through the f16 or i16 form,
+  // as does a native half or int16_t target under -enable-16bit-types.


DxilOutputColorBecomesConstant handles all storeOutput overloads (including 16-bit), gives its constant buffer a layout the validator accepts, and DxilReduceMSAAToSingleSample looks through annotateHandle and accepts 16-bit texture loads. Co-authored-by: Copilot App <[email protected]> Copilot-Session: 40dc9de3-617e-4caf-ab0d-fba0a033ed93

Copilot

🔵 Needs a closer look

The constant-color pass can remove declarations while incorrectly reporting that the module was unmodified.

12 open findings

🧠 Review effort: Balanced

github-project-automation Bot added this to HLSL Roadmap Aug 27, 2026

github-project-automation Bot moved this to New in HLSL Roadmap Aug 27, 2026

Damyan Pepper (damyanp) requested a review from Austin Kinross (austinkinross) August 27, 2026 23:43

Damyan Pepper (damyanp) marked this pull request as ready for review August 27, 2026 23:45

Copilot AI balanced review requested due to automatic review settings August 27, 2026 23:45

Austin Kinross (austinkinross) approved these changes Aug 27, 2026

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Copilot AI balanced review requested due to automatic review settings October 1, 2026 22:01

Damyan Pepper (damyanp) force-pushed the users/damyanp/pix-fixes-09 branch from 95eca4e to ddc1237 Compare October 1, 2026 22:01

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Copilot AI balanced review requested due to automatic review settings October 1, 2026 23:11

Damyan Pepper (damyanp) force-pushed the users/damyanp/pix-fixes-09 branch from ddc1237 to 6c1b3a6 Compare October 1, 2026 23:11

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Copilot AI balanced review requested due to automatic review settings October 6, 2026 21:00

Damyan Pepper (damyanp) force-pushed the users/damyanp/pix-fixes-09 branch from 6c1b3a6 to 2f1e63e Compare October 6, 2026 21:00

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Comment thread tools/clang/unittests/HLSL/PixTest.cpp

Comment on lines +4115 to +4117

auto compiled = Compile(m_dllSupport, source, L"ps_6_6", {L"-Od"});

auto output = runSinglePass(compiled, L"-hlsl-dxil-reduce-msaa-to-single");

auto lines = Tokenize(Disassemble(output.Module).c_str(), "\n");

Copilot AI balanced review requested due to automatic review settings October 7, 2026 18:20

Damyan Pepper (damyanp) force-pushed the users/damyanp/pix-fixes-09 branch from 2f1e63e to 5565bfb Compare October 7, 2026 18:20

Copilot started reviewing on behalf of Damyan Pepper (damyanp) October 7, 2026 18:21

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Copilot AI balanced review requested due to automatic review settings October 9, 2026 17:06

Damyan Pepper (damyanp) force-pushed the users/damyanp/pix-fixes-09 branch from 5565bfb to 78d27d7 Compare October 9, 2026 17:06

Copilot started reviewing on behalf of Damyan Pepper (damyanp) October 9, 2026 17:07

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[PIX] Fix render-state visualization passes - #8850

[PIX] Fix render-state visualization passes#8850
Damyan Pepper (damyanp) wants to merge 1 commit into
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Damyan Pepper (damyanp) commented Aug 27, 2026 •

edited

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		auto compiled = Compile(m_dllSupport, source, L"ps_6_0", {L"-Od"});
		auto output = runSinglePass(compiled, L"-hlsl-dxil-constantColor,mod-mode=1");

		auto &FieldAnnotation =
		StructAnnotation->GetFieldAnnotation(ComponentIndex);

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Damyan Pepper (damyanp) commented Aug 27, 2026 •

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