Fix non-deterministic DXIL/PDB output for resource arrays (microsoft#8175)

DxilMutateResourceToHandle iterates a DenseSet<Value *> to process
ConstantExpr GEPs on resource array globals. DenseSet iteration order
depends on pointer hash values, which vary across runs due to ASLR. For
each GEP, mutateCandidates() destroys the old ConstantExpr and creates a
new one, prepending it to the global's use list. The non-deterministic
processing order produces a non-deterministic use list, which
TranslateDxilResourceUses later iterates to create named handles -
resulting in different name suffixes across compilations.

The fix is to change MutateValSet from DenseSet<Value *> to
SetVector<Value *>, which preserves insertion order while maintaining
O(1) lookup. Since collectCandidates() traverses the IR in a
deterministic order, the insertion order is stable, producing a
deterministic use list and consistent handle names.

Fixes microsoft#8171

Co-authored-by: Copilot [email protected]

Author: damyanp

docs/ReleaseNotes.md

@@ -37,7 +37,9 @@ line upon naming the release. Refer to previous for appropriate section names.
   - `dx::IsDebuggerPresent()` returns true if a debugger is attached.
   - SPIR-V: `DebugBreak()` emits `NonSemantic.DebugBreak` extended instruction; `IsDebuggerPresent()` is not supported.
 
-#### Other Changes
+#### Bug Fixes
+
+- Fixed non-deterministic DXIL/PDB output when compiling shaders with resource arrays, debug info, and SM 6.6+. [#8171](https://github.com/microsoft/DirectXShaderCompiler/issues/8171)
 - Fixed mesh shader semantics that were incorrectly case sensitive.
 
 ### Version 1.9.2602

lib/HLSL/DxilPromoteResourcePasses.cpp

@@ -16,6 +16,7 @@
 #include "dxc/HLSL/DxilGenerationPass.h"
 #include "dxc/HLSL/HLModule.h"
 #include "llvm/ADT/DenseSet.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/Analysis/AssumptionCache.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/DebugInfo.h"
@@ -313,7 +314,7 @@ class DxilMutateResourceToHandle : public ModulePass {
   hlsl::OP *hlslOP = nullptr;
   Function *createHandleForLibOnHandle = nullptr;
   DxilTypeSystem *pTypeSys;
-  DenseSet<Value *> MutateValSet;
+  SetVector<Value *> MutateValSet;
   DenseMap<Type *, Type *> MutateTypeMap;
 };
 
@@ -613,7 +614,7 @@ void DxilMutateResourceToHandle::collectCandidates(Module &M) {
 
       for (Value *Val : newCandidates) {
         // New candidate find.
-        if (MutateValSet.insert(Val).second) {
+        if (MutateValSet.insert(Val)) {
           WorkList.emplace_back(Val);
         }
       }

tools/clang/test/DXC/deterministic_output_resource_array.hlsl

@@ -0,0 +1,23 @@
+// Test that compiling a shader with resource arrays produces deterministic output.
+// This is a regression test for https://github.com/microsoft/DirectXShaderCompiler/issues/8171
+// where compiling the same shader multiple times with -Zi and SM 6.6+ produced
+// non-identical disassembly due to non-deterministic handle name suffixes.
+
+// RUN: %dxc -T cs_6_6 -E CSMain -Zi -Fc %t1 %s
+// RUN: %dxc -T cs_6_6 -E CSMain -Zi -Fc %t2 %s
+// RUN: diff %t1 %t2
+
+Texture2D<float4> inMaps[16];
+RWTexture2D<float4> Output;
+
+[numthreads(1,1,1)]
+void CSMain(uint3 threadID : SV_DispatchThreadID)
+{
+    Output[threadID.xy] = inMaps[0][threadID.xy];
+    Output[threadID.xy] = inMaps[1][threadID.xy];
+    Output[threadID.xy] = inMaps[2][threadID.xy];
+    Output[threadID.xy] = inMaps[3][threadID.xy];
+    Output[threadID.xy] = inMaps[4][threadID.xy];
+    Output[threadID.xy] = inMaps[5][threadID.xy];
+    Output[threadID.xy] = inMaps[6][threadID.xy];
+}