[HLSL] NonUniformResourceIndex implementation (#160430)
Adds HLSL function `NonUniformResourceIndex` to `hlsl_intrinsics.h.` The function calls a builtin `__builtin_hlsl_resource_nonuniformindex` which gets translated to LLVM intrinsic `llvm.{dx|spv}.resource_nonuniformindex`.
Closes #157923diff --git a/clang/include/clang/Basic/Builtins.td b/clang/include/clang/Basic/Builtins.td
index 35d2c3e..9bc70ea 100644
--- a/clang/include/clang/Basic/Builtins.td
+++ b/clang/include/clang/Basic/Builtins.td
@@ -4945,6 +4945,12 @@
let Prototype = "void(...)";
}
+def HLSLResourceNonUniformIndex : LangBuiltin<"HLSL_LANG"> {
+ let Spellings = ["__builtin_hlsl_resource_nonuniformindex"];
+ let Attributes = [NoThrow];
+ let Prototype = "uint32_t(uint32_t)";
+}
+
def HLSLAll : LangBuiltin<"HLSL_LANG"> {
let Spellings = ["__builtin_hlsl_all"];
let Attributes = [NoThrow, Const];
diff --git a/clang/lib/CodeGen/CGHLSLBuiltins.cpp b/clang/lib/CodeGen/CGHLSLBuiltins.cpp
index 7b5b924..9f87afa 100644
--- a/clang/lib/CodeGen/CGHLSLBuiltins.cpp
+++ b/clang/lib/CodeGen/CGHLSLBuiltins.cpp
@@ -352,6 +352,13 @@
SmallVector<Value *> Args{OrderID, SpaceOp, RangeOp, IndexOp, Name};
return Builder.CreateIntrinsic(HandleTy, IntrinsicID, Args);
}
+ case Builtin::BI__builtin_hlsl_resource_nonuniformindex: {
+ Value *IndexOp = EmitScalarExpr(E->getArg(0));
+ llvm::Type *RetTy = ConvertType(E->getType());
+ return Builder.CreateIntrinsic(
+ RetTy, CGM.getHLSLRuntime().getNonUniformResourceIndexIntrinsic(),
+ ArrayRef<Value *>{IndexOp});
+ }
case Builtin::BI__builtin_hlsl_all: {
Value *Op0 = EmitScalarExpr(E->getArg(0));
return Builder.CreateIntrinsic(
diff --git a/clang/lib/CodeGen/CGHLSLRuntime.h b/clang/lib/CodeGen/CGHLSLRuntime.h
index 370f3d5..f4b4106 100644
--- a/clang/lib/CodeGen/CGHLSLRuntime.h
+++ b/clang/lib/CodeGen/CGHLSLRuntime.h
@@ -129,6 +129,8 @@
resource_handlefrombinding)
GENERATE_HLSL_INTRINSIC_FUNCTION(CreateHandleFromImplicitBinding,
resource_handlefromimplicitbinding)
+ GENERATE_HLSL_INTRINSIC_FUNCTION(NonUniformResourceIndex,
+ resource_nonuniformindex)
GENERATE_HLSL_INTRINSIC_FUNCTION(BufferUpdateCounter, resource_updatecounter)
GENERATE_HLSL_INTRINSIC_FUNCTION(GroupMemoryBarrierWithGroupSync,
group_memory_barrier_with_group_sync)
diff --git a/clang/lib/Headers/hlsl/hlsl_intrinsics.h b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
index d9d87c8..5ba5bfb 100644
--- a/clang/lib/Headers/hlsl/hlsl_intrinsics.h
+++ b/clang/lib/Headers/hlsl/hlsl_intrinsics.h
@@ -423,6 +423,30 @@
}
//===----------------------------------------------------------------------===//
+// NonUniformResourceIndex builtin
+//===----------------------------------------------------------------------===//
+
+/// \fn uint NonUniformResourceIndex(uint I)
+/// \brief A compiler hint to indicate that a resource index varies across
+/// threads within a wave (i.e., it is non-uniform).
+/// \param I [in] Resource array index
+///
+/// The return value is the \Index parameter.
+///
+/// When indexing into an array of shader resources (e.g., textures, buffers),
+/// some GPU hardware and drivers require the compiler to know whether the index
+/// is uniform (same for all threads) or non-uniform (varies per thread).
+///
+/// Using NonUniformResourceIndex explicitly marks an index as non-uniform,
+/// disabling certain assumptions or optimizations that could lead to incorrect
+/// behavior when dynamically accessing resource arrays with non-uniform
+/// indices.
+
+constexpr uint32_t NonUniformResourceIndex(uint32_t Index) {
+ return __builtin_hlsl_resource_nonuniformindex(Index);
+}
+
+//===----------------------------------------------------------------------===//
// reflect builtin
//===----------------------------------------------------------------------===//
diff --git a/clang/test/CodeGenHLSL/resources/NonUniformResourceIndex.hlsl b/clang/test/CodeGenHLSL/resources/NonUniformResourceIndex.hlsl
new file mode 100644
index 0000000..ab512ce
--- /dev/null
+++ b/clang/test/CodeGenHLSL/resources/NonUniformResourceIndex.hlsl
@@ -0,0 +1,38 @@
+// RUN: %clang_cc1 -finclude-default-header -triple dxil-pc-shadermodel6.3-compute -emit-llvm -disable-llvm-passes -o - %s \
+// RUN: | llvm-cxxfilt | FileCheck %s --check-prefixes=CHECK,DXIL
+// RUN: %clang_cc1 -finclude-default-header -triple spirv-pc-vulkan1.3-compute -emit-llvm -disable-llvm-passes -o - %s \
+// RUN: | llvm-cxxfilt | FileCheck %s --check-prefixes=CHECK,SPV
+
+RWBuffer<float> A[10];
+
+[numthreads(4,1,1)]
+void main(uint GI : SV_GroupID) {
+ // CHECK: %[[GI:.*]] = load i32, ptr %GI.addr
+ // CHECK: %[[NURI_1:.*]] = call {{.*}} i32 @hlsl::NonUniformResourceIndex(unsigned int)(i32 noundef %[[GI]])
+ // CHECK: call void @hlsl::RWBuffer<float>::__createFromImplicitBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+ // CHECK-SAME: (ptr {{.*}}, i32 noundef 0, i32 noundef 0, i32 noundef 10, i32 noundef %[[NURI_1]], ptr noundef @A.str)
+ float a = A[NonUniformResourceIndex(GI)][0];
+
+ // CHECK: %[[GI:.*]] = load i32, ptr %GI.addr
+ // CHECK: %[[ADD:.*]] = add i32 %[[GI]], 1
+ // CHECK: %[[NURI_2:.*]] = call {{.*}} i32 @hlsl::NonUniformResourceIndex(unsigned int)(i32 noundef %[[ADD]])
+ // CHECK: %[[MOD:.*]] = urem i32 %[[NURI_2]], 10
+ // CHECK: call void @hlsl::RWBuffer<float>::__createFromImplicitBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+ // CHECK-SAME: (ptr {{.*}}, i32 noundef 0, i32 noundef 0, i32 noundef 10, i32 noundef %[[MOD]], ptr noundef @A.str)
+ float b = A[NonUniformResourceIndex(GI + 1) % 10][0];
+
+ // CHECK: %[[GI:.*]] = load i32, ptr %GI.addr
+ // CHECK: %[[NURI_3:.*]] = call {{.*}} i32 @hlsl::NonUniformResourceIndex(unsigned int)(i32 noundef %[[GI]])
+ // CHECK: %[[MUL:.*]] = mul i32 3, %[[NURI_3]]
+ // CHECK: %[[ADD2:.*]] = add i32 10, %[[MUL]]
+ // CHECK: call void @hlsl::RWBuffer<float>::__createFromImplicitBinding(unsigned int, unsigned int, int, unsigned int, char const*)
+ // CHECK-SAME: (ptr {{.*}}, i32 noundef 0, i32 noundef 0, i32 noundef 10, i32 noundef %[[ADD2]], ptr noundef @A.str)
+ float c = A[10 + 3 * NonUniformResourceIndex(GI)][0];
+ A[0][0] = a + b + c;
+}
+
+// CHECK: define {{.*}} i32 @hlsl::NonUniformResourceIndex(unsigned int)(i32 noundef %Index)
+// CHECK: %[[INDEX1:.*]] = load i32, ptr %Index.addr, align 4
+// DXIL: %[[INDEX2:.*]] = call i32 @llvm.dx.resource.nonuniformindex(i32 %[[INDEX1]])
+// SPV: %[[INDEX2:.*]] = call i32 @llvm.spv.resource.nonuniformindex(i32 %[[INDEX1]])
+// CHECK: ret i32 %[[INDEX2]]
