[clang] [llvm] Adding splitdouble HLSL function (PR #109331)
Tex Riddell via cfe-commits
cfe-commits at lists.llvm.org
Fri Oct 25 17:37:28 PDT 2024
================
@@ -95,6 +99,126 @@ static void initializeAlloca(CodeGenFunction &CGF, AllocaInst *AI, Value *Size,
I->addAnnotationMetadata("auto-init");
}
+static Value *handleHlslSplitdouble(const CallExpr *E, CodeGenFunction *CGF) {
+ Value *Op0 = CGF->EmitScalarExpr(E->getArg(0));
+ const auto *OutArg1 = dyn_cast<HLSLOutArgExpr>(E->getArg(1));
+ const auto *OutArg2 = dyn_cast<HLSLOutArgExpr>(E->getArg(2));
+
+ CallArgList Args;
+ LValue Op1TmpLValue =
+ CGF->EmitHLSLOutArgExpr(OutArg1, Args, OutArg1->getType());
+ LValue Op2TmpLValue =
+ CGF->EmitHLSLOutArgExpr(OutArg2, Args, OutArg2->getType());
+
+ if (CGF->getTarget().getCXXABI().areArgsDestroyedLeftToRightInCallee())
+ Args.reverseWritebacks();
+
+ Value *LowBits = nullptr;
+ Value *HighBits = nullptr;
+
+ if (CGF->CGM.getTarget().getTriple().isDXIL()) {
+
+ llvm::Type *RetElementTy = CGF->Int32Ty;
+ if (auto *Op0VecTy = E->getArg(0)->getType()->getAs<clang::VectorType>())
+ RetElementTy = llvm::VectorType::get(
+ CGF->Int32Ty, ElementCount::getFixed(Op0VecTy->getNumElements()));
+ auto *RetTy = llvm::StructType::get(RetElementTy, RetElementTy);
+
+ CallInst *CI = CGF->Builder.CreateIntrinsic(
+ RetTy, Intrinsic::dx_splitdouble, {Op0}, nullptr, "hlsl.splitdouble");
+
+ LowBits = CGF->Builder.CreateExtractValue(CI, 0);
+ HighBits = CGF->Builder.CreateExtractValue(CI, 1);
+
+ } else {
+ // For Non DXIL targets we generate the instructions.
+ // TODO: This code accounts for known limitations in
+ // SPIR-V and splitdouble. Such should be handled,
+ // in a later compilation stage. After
+ // https://github.com/llvm/llvm-project/issues/113597 is fixed, this shall
+ // be refactored.
+
+ // casts `<2 x double>` to `<4 x i32>`, then shuffles into high and low
+ // `<2 x i32>` vectors.
+ auto EmitDouble2Cast =
+ [](CodeGenFunction &CGF,
+ Value *DoubleVec2) -> std::pair<Value *, Value *> {
+ Value *BC = CGF.Builder.CreateBitCast(
+ DoubleVec2, FixedVectorType::get(CGF.Int32Ty, 4));
+ Value *LB = CGF.Builder.CreateShuffleVector(BC, {0, 2});
+ Value *HB = CGF.Builder.CreateShuffleVector(BC, {1, 3});
+ return std::make_pair(LB, HB);
+ };
+
+ if (!Op0->getType()->isVectorTy()) {
+ FixedVectorType *DestTy = FixedVectorType::get(CGF->Int32Ty, 2);
+ Value *Bitcast = CGF->Builder.CreateBitCast(Op0, DestTy);
+
+ LowBits = CGF->Builder.CreateExtractElement(Bitcast, (uint64_t)0);
+ HighBits = CGF->Builder.CreateExtractElement(Bitcast, 1);
+ } else {
+
+ const auto *TargTy = E->getArg(0)->getType()->getAs<clang::VectorType>();
+
+ int NumElements = TargTy->getNumElements();
+
+ FixedVectorType *UintVec2 = FixedVectorType::get(CGF->Int32Ty, 2);
+
+ switch (NumElements) {
+ case 1: {
+ auto *Bitcast = CGF->Builder.CreateBitCast(Op0, UintVec2);
+
+ LowBits = CGF->Builder.CreateExtractElement(Bitcast, (uint64_t)0);
+ HighBits = CGF->Builder.CreateExtractElement(Bitcast, 1);
+ break;
+ }
+ case 2: {
+ auto [LB, HB] = EmitDouble2Cast(*CGF, Op0);
+ LowBits = LB;
+ HighBits = HB;
+ break;
+ }
+
+ case 3: {
+ auto *Shuff = CGF->Builder.CreateShuffleVector(Op0, {0, 1});
+ auto [LB, HB] = EmitDouble2Cast(*CGF, Shuff);
+
+ auto *EV = CGF->Builder.CreateExtractElement(Op0, 2);
+ auto *ScalarBitcast = CGF->Builder.CreateBitCast(EV, UintVec2);
+
+ LowBits =
+ CGF->Builder.CreateShuffleVector(LB, ScalarBitcast, {0, 1, 2});
+ HighBits =
+ CGF->Builder.CreateShuffleVector(HB, ScalarBitcast, {0, 1, 3});
+ break;
+ }
+ case 4: {
+
+ auto *Shuff1 = CGF->Builder.CreateShuffleVector(Op0, {0, 1});
+ auto [LB1, HB1] = EmitDouble2Cast(*CGF, Shuff1);
+
+ auto *Shuff2 = CGF->Builder.CreateShuffleVector(Op0, {2, 3});
+ auto [LB2, HB2] = EmitDouble2Cast(*CGF, Shuff2);
+
+ LowBits = CGF->Builder.CreateShuffleVector(LB1, LB2, {0, 1, 2, 3});
+ HighBits = CGF->Builder.CreateShuffleVector(HB1, HB2, {0, 1, 3, 3});
+ break;
+ }
+ default: {
+ CGF->CGM.Error(E->getExprLoc(),
+ "splitdouble doesn't support vectors larger than 4.");
+ return nullptr;
+ }
+ }
+ }
----------------
tex3d wrote:
Yup, that's how I felt about it too, hence my earlier comments.
https://github.com/llvm/llvm-project/pull/109331
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