[llvm] [DirectX] Add `llvm.dx.resource.getdimensions and lowering (PR #161753)
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Thu Oct 2 16:36:21 PDT 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-backend-directx
Author: Helena Kotas (hekota)
<details>
<summary>Changes</summary>
Introduces LLVM intrinsic `lvm.dx.resource.getdimensions` and its lowering to DXIL op `op.dx.getDimensions`.
The intrinsic will be used to implement various `GetDimension` overload on buffers and textures.
Closes #<!-- -->112982
---
Full diff: https://github.com/llvm/llvm-project/pull/161753.diff
5 Files Affected:
- (modified) llvm/include/llvm/IR/IntrinsicsDirectX.td (+4)
- (modified) llvm/lib/Target/DirectX/DXIL.td (+8)
- (modified) llvm/lib/Target/DirectX/DXILOpBuilder.cpp (+8)
- (modified) llvm/lib/Target/DirectX/DXILOpLowering.cpp (+27)
- (added) llvm/test/CodeGen/DirectX/bufferGetDimensions.ll (+34)
``````````diff
diff --git a/llvm/include/llvm/IR/IntrinsicsDirectX.td b/llvm/include/llvm/IR/IntrinsicsDirectX.td
index 570d6bc35cbd0..38cd3f3e07a87 100644
--- a/llvm/include/llvm/IR/IntrinsicsDirectX.td
+++ b/llvm/include/llvm/IR/IntrinsicsDirectX.td
@@ -77,6 +77,10 @@ def int_dx_resource_updatecounter
: DefaultAttrsIntrinsic<[llvm_i32_ty], [llvm_any_ty, llvm_i8_ty],
[IntrInaccessibleMemOrArgMemOnly]>;
+def int_dx_resource_getdimensions
+ : DefaultAttrsIntrinsic<[llvm_i32_ty, llvm_i32_ty, llvm_i32_ty, llvm_i32_ty], [llvm_any_ty, llvm_i32_ty],
+ [IntrReadMem]>;
+
// Cast between target extension handle types and dxil-style opaque handles
def int_dx_resource_casthandle : Intrinsic<[llvm_any_ty], [llvm_any_ty]>;
diff --git a/llvm/lib/Target/DirectX/DXIL.td b/llvm/lib/Target/DirectX/DXIL.td
index 228114c5c24b2..44c48305f2832 100644
--- a/llvm/lib/Target/DirectX/DXIL.td
+++ b/llvm/lib/Target/DirectX/DXIL.td
@@ -57,6 +57,7 @@ def ResBindTy : DXILOpParamType;
def ResPropsTy : DXILOpParamType;
def SplitDoubleTy : DXILOpParamType;
def BinaryWithCarryTy : DXILOpParamType;
+def DimensionsTy : DXILOpParamType;
class DXILOpClass;
@@ -901,6 +902,13 @@ def CheckAccessFullyMapped : DXILOp<71, checkAccessFullyMapped> {
let attributes = [Attributes<DXIL1_0, [ReadOnly]>];
}
+def GetDimensions : DXILOp<72, getDimensions> {
+ let Doc = "gets the dimensions of a buffer or texture";
+ let arguments = [HandleTy, Int32Ty];
+ let result = DimensionsTy;
+ let stages = [Stages<DXIL1_0, [all_stages]>];
+}
+
def Barrier : DXILOp<80, barrier> {
let Doc = "inserts a memory barrier in the shader";
let intrinsics = [
diff --git a/llvm/lib/Target/DirectX/DXILOpBuilder.cpp b/llvm/lib/Target/DirectX/DXILOpBuilder.cpp
index 1aed8f9867231..944b2e6433988 100644
--- a/llvm/lib/Target/DirectX/DXILOpBuilder.cpp
+++ b/llvm/lib/Target/DirectX/DXILOpBuilder.cpp
@@ -261,6 +261,12 @@ static StructType *getBinaryWithCarryType(LLVMContext &Context) {
return StructType::create({Int32Ty, Int1Ty}, "dx.types.i32c");
}
+static StructType *getDimensionsType(LLVMContext &Ctx) {
+ Type *Int32Ty = Type::getInt32Ty(Ctx);
+ return getOrCreateStructType("dx.types.Dimensions",
+ {Int32Ty, Int32Ty, Int32Ty, Int32Ty}, Ctx);
+}
+
static Type *getTypeFromOpParamType(OpParamType Kind, LLVMContext &Ctx,
Type *OverloadTy) {
switch (Kind) {
@@ -318,6 +324,8 @@ static Type *getTypeFromOpParamType(OpParamType Kind, LLVMContext &Ctx,
return getSplitDoubleType(Ctx);
case OpParamType::BinaryWithCarryTy:
return getBinaryWithCarryType(Ctx);
+ case OpParamType::DimensionsTy:
+ return getDimensionsType(Ctx);
}
llvm_unreachable("Invalid parameter kind");
return nullptr;
diff --git a/llvm/lib/Target/DirectX/DXILOpLowering.cpp b/llvm/lib/Target/DirectX/DXILOpLowering.cpp
index 610d8b63bba27..34bb450bce7d0 100644
--- a/llvm/lib/Target/DirectX/DXILOpLowering.cpp
+++ b/llvm/lib/Target/DirectX/DXILOpLowering.cpp
@@ -627,6 +627,30 @@ class OpLowerer {
});
}
+ [[nodiscard]] bool lowerGetDimensions(Function &F) {
+ IRBuilder<> &IRB = OpBuilder.getIRB();
+ Type *Int32Ty = IRB.getInt32Ty();
+
+ return replaceFunction(F, [&](CallInst *CI) -> Error {
+ IRB.SetInsertPoint(CI);
+ Value *Handle =
+ createTmpHandleCast(CI->getArgOperand(0), OpBuilder.getHandleType());
+ Value *Op1 = CI->getArgOperand(1);
+ if (isa<llvm::PoisonValue>(Op1))
+ Op1 = UndefValue::get(Int32Ty);
+
+ Expected<CallInst *> OpCall = OpBuilder.tryCreateOp(
+ OpCode::GetDimensions, {Handle, Op1}, CI->getName(), Int32Ty);
+ if (Error E = OpCall.takeError())
+ return E;
+ if (Error E = replaceNamedStructUses(CI, *OpCall))
+ return E;
+
+ CI->eraseFromParent();
+ return Error::success();
+ });
+ }
+
[[nodiscard]] bool lowerGetPointer(Function &F) {
// These should have already been handled in DXILResourceAccess, so we can
// just clean up the dead prototype.
@@ -934,6 +958,9 @@ class OpLowerer {
case Intrinsic::dx_resource_updatecounter:
HasErrors |= lowerUpdateCounter(F);
break;
+ case Intrinsic::dx_resource_getdimensions:
+ HasErrors |= lowerGetDimensions(F);
+ break;
case Intrinsic::ctpop:
HasErrors |= lowerCtpopToCountBits(F);
break;
diff --git a/llvm/test/CodeGen/DirectX/bufferGetDimensions.ll b/llvm/test/CodeGen/DirectX/bufferGetDimensions.ll
new file mode 100644
index 0000000000000..7805426181b35
--- /dev/null
+++ b/llvm/test/CodeGen/DirectX/bufferGetDimensions.ll
@@ -0,0 +1,34 @@
+; RUN: opt -S -dxil-op-lower %s | FileCheck %s
+
+target triple = "dxil-pc-shadermodel6.6-compute"
+
+define i32 @test_getdimensions_no_mips() {
+ ; CHECK: [[HANDLE1:%.*]] = call %dx.types.Handle @dx.op.createHandleFromBinding(i32 217,
+ ; CHECK-NEXT: [[ANNOT_HANDLE1:%.*]] = call %dx.types.Handle @dx.op.annotateHandle(i32 216, %dx.types.Handle [[HANDLE1]]
+ %handle1 = call target("dx.TypedBuffer", <4 x float>, 0, 0, 0) @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, ptr null)
+
+ ; CHECK-NEXT: [[RETVAL1:%.*]] = call %dx.types.Dimensions @dx.op.getDimensions(i32 72, %dx.types.Handle [[ANNOT_HANDLE1]], i32 undef)
+ %1 = call { i32, i32, i32, i32 } @llvm.dx.resource.getdimensions.tdx.RawBuffer_i32_1_0t(target("dx.TypedBuffer", <4 x float>, 0, 0, 0) %handle1, i32 poison)
+
+ ; CHECK-NEXT: %[[DIM1:.*]] = extractvalue %dx.types.Dimensions [[RETVAL1]], 0
+ %2 = extractvalue { i32, i32, i32, i32 } %1, 0
+
+ ; CHECK-NEXT: ret i32 %[[DIM1]]
+ ret i32 %2
+}
+
+
+define i32 @test_getdimensions_with_0_mips() {
+ ; CHECK: [[HANDLE2:%.*]] = call %dx.types.Handle @dx.op.createHandleFromBinding(i32 217,
+ ; CHECK-NEXT: [[ANNOT_HANDLE2:%.*]] = call %dx.types.Handle @dx.op.annotateHandle(i32 216, %dx.types.Handle [[HANDLE2]]
+ %handle1 = call target("dx.RawBuffer", float, 0, 0) @llvm.dx.resource.handlefrombinding(i32 0, i32 0, i32 1, i32 0, ptr null)
+
+ ; CHECK-NEXT: [[RETVAL2:%.*]] = call %dx.types.Dimensions @dx.op.getDimensions(i32 72, %dx.types.Handle [[ANNOT_HANDLE2]], i32 0)
+ %1 = call { i32, i32, i32, i32 } @llvm.dx.resource.getdimensions.tdx.RawBuffer_i32_1_0t(target("dx.RawBuffer", float, 0, 0) %handle1, i32 0)
+
+ ; CHECK-NEXT: %[[DIM2:.*]] = extractvalue %dx.types.Dimensions [[RETVAL2]], 0
+ %2 = extractvalue { i32, i32, i32, i32 } %1, 0
+
+ ; CHECK-NEXT: ret i32 %[[DIM2]]
+ ret i32 %2
+}
``````````
</details>
https://github.com/llvm/llvm-project/pull/161753
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