Add cast after RWByteAddressBuffer atomic compare exchange (microsoft…

…#5295) * Add cast after RWByteAddressBuffer atomic compare exchange The type of the RWByteAddressBuffer is always uint in the SPIR-V representation. This means that the OpAtomicCompareExchange instruction must have parameters and a result of type uint. If the original code used an in for the result, then there is a type mismatch when storing the value. This is fixed by add a cast when appropriate. Fixes microsoft#4741
s-perron · Jun 20, 2023 · e8b1fcb · e8b1fcb
1 parent 0ed5abb
commit e8b1fcb
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Showing 2 changed files with 16 additions and 2 deletions.
diff --git a/tools/clang/lib/SPIRV/SpirvEmitter.cpp b/tools/clang/lib/SPIRV/SpirvEmitter.cpp
@@ -3816,14 +3816,20 @@ SpirvInstruction *SpirvEmitter::processRWByteAddressBufferAtomicMethods(
 
   if (isCompareExchange || isCompareStore) {
     auto *comparator = doExpr(expr->getArg(1));
-    auto *originalVal = spvBuilder.createAtomicCompareExchange(
+    SpirvInstruction *originalVal = spvBuilder.createAtomicCompareExchange(
         astContext.UnsignedIntTy, ptr, spv::Scope::Device,
         spv::MemorySemanticsMask::MaskNone, spv::MemorySemanticsMask::MaskNone,
         doExpr(expr->getArg(2)), comparator, expr->getCallee()->getExprLoc(),
         range);
-    if (isCompareExchange)
+    if (isCompareExchange) {
+      auto *resultAddress = expr->getArg(3);
+      QualType resultType = resultAddress->getType();
+      if (resultType != astContext.UnsignedIntTy)
+        originalVal = castToInt(originalVal, astContext.UnsignedIntTy,
+                                resultType, expr->getArg(3)->getLocStart());
       spvBuilder.createStore(doExpr(expr->getArg(3)), originalVal,
                              expr->getArg(3)->getLocStart(), range);
+    }
   } else {
     auto *value = doExpr(expr->getArg(1));
     SpirvInstruction *originalVal = spvBuilder.createAtomicOp(

diff --git a/tools/clang/test/CodeGenSPIRV/method.rw-byte-address-buffer.atomic.hlsl b/tools/clang/test/CodeGenSPIRV/method.rw-byte-address-buffer.atomic.hlsl
@@ -8,6 +8,7 @@ RWByteAddressBuffer myBuffer;
 float4 main() : SV_Target
 {
     uint originalVal;
+    int  originalValAsInt;
 
 // CHECK:      [[offset:%\d+]] = OpShiftRightLogical %uint %uint_16 %uint_2
 // CHECK-NEXT:    [[ptr:%\d+]] = OpAccessChain %_ptr_Uniform_uint %myBuffer %uint_0 [[offset]]
@@ -102,6 +103,13 @@ float4 main() : SV_Target
 // CHECK-NEXT:                   OpStore %originalVal [[val]]
     myBuffer.InterlockedCompareExchange(/*offset=*/16, /*compare_value=*/30, /*value=*/42, originalVal);
 
+// CHECK:      [[offset:%\d+]] = OpShiftRightLogical %uint %uint_16 %uint_2
+// CHECK-NEXT:    [[ptr:%\d+]] = OpAccessChain %_ptr_Uniform_uint %myBuffer %uint_0 [[offset]]
+// CHECK-NEXT:    [[val:%\d+]] = OpAtomicCompareExchange %uint [[ptr]] %uint_1 %uint_0 %uint_0 %uint_42 %uint_30
+// CHECK-NEXT:   [[cast:%\d+]] = OpBitcast %int [[val]]
+// CHECK-NEXT:                   OpStore %originalValAsInt [[cast]]
+    myBuffer.InterlockedCompareExchange(/*offset=*/16, /*compare_value=*/30, /*value=*/42, originalValAsInt);
+
 // CHECK:      [[offset:%\d+]] = OpShiftRightLogical %uint %uint_16 %uint_2
 // CHECK-NEXT:    [[ptr:%\d+]] = OpAccessChain %_ptr_Uniform_uint %myBuffer %uint_0 [[offset]]
 // CHECK-NEXT:    [[val:%\d+]] = OpAtomicCompareExchange %uint [[ptr]] %uint_1 %uint_0 %uint_0 %uint_42 %uint_30