[clang] [llvm] Adding splitdouble HLSL function (PR #109331)

[Farzon Lotfi via cfe-commits]

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@@ -18843,6 +18843,75 @@ case Builtin::BI__builtin_hlsl_elementwise_isinf: {
         retType, CGM.getHLSLRuntime().getSignIntrinsic(),
         ArrayRef<Value *>{Op0}, nullptr, "hlsl.sign");
   }
+  // This should only be called when targeting DXIL
+  case Builtin::BI__builtin_hlsl_splitdouble: {
+
+    assert((E->getArg(0)->getType()->hasFloatingRepresentation() &&
+            E->getArg(1)->getType()->hasUnsignedIntegerRepresentation() &&
+            E->getArg(2)->getType()->hasUnsignedIntegerRepresentation()) &&
+           "asuint operands types mismatch");
+
+    Value *Op0 = EmitScalarExpr(E->getArg(0));
+    const HLSLOutArgExpr *OutArg1 = dyn_cast<HLSLOutArgExpr>(E->getArg(1));
+    const HLSLOutArgExpr *OutArg2 = dyn_cast<HLSLOutArgExpr>(E->getArg(2));
+
+    auto emitSplitDouble =
+        [](CGBuilderTy *Builder, llvm::Value *arg,
+           llvm::Type *retType) -> std::pair<Value *, Value *> {
+      CallInst *CI =
+          Builder->CreateIntrinsic(retType, llvm::Intrinsic::dx_splitdouble,
+                                   {arg}, nullptr, "hlsl.asuint");
+
+      Value *arg0 = Builder->CreateExtractValue(CI, 0);
+      Value *arg1 = Builder->CreateExtractValue(CI, 1);
+
+      return std::make_pair(arg0, arg1);
+    };
+
+    CallArgList Args;
+    auto [Op1BaseLValue, Op1TmpLValue] =
+        EmitHLSLOutArgExpr(OutArg1, Args, OutArg1->getType());
+    auto [Op2BaseLValue, Op2TmpLValue] =
+        EmitHLSLOutArgExpr(OutArg2, Args, OutArg2->getType());
+
+    llvm::StructType *retType = llvm::StructType::get(Int32Ty, Int32Ty);
+
+    if (!Op0->getType()->isVectorTy()) {
+      auto [arg0, arg1] = emitSplitDouble(&Builder, Op0, retType);
+
+      Builder.CreateStore(arg0, Op1TmpLValue.getAddress());
+      auto *s = Builder.CreateStore(arg1, Op2TmpLValue.getAddress());
+
+      EmitWritebacks(*this, Args);
+      return s;
+    }
+
+    auto *Op0VecTy = E->getArg(0)->getType()->getAs<VectorType>();
+
+    llvm::VectorType *i32VecTy = llvm::VectorType::get(
+        Int32Ty, ElementCount::getFixed(Op0VecTy->getNumElements()));
+
+    std::pair<Value *, Value *> inserts = std::make_pair(nullptr, nullptr);
+
+    for (uint64_t idx = 0; idx < Op0VecTy->getNumElements(); idx++) {
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farzonl wrote:

If we do decide to use the scalarizer pass you would have to add your intrinsic here: llvm/lib/Target/DirectX/DirectXTargetTransformInfo.cpp

https://github.com/llvm/llvm-project/pull/109331