[llvm] [DXIL] Add sign intrinsic part 2 (PR #101988)

[Farzon Lotfi via llvm-commits]

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@@ -293,6 +295,36 @@ static bool expandClampIntrinsic(CallInst *Orig, Intrinsic::ID ClampIntrinsic) {
   return true;
 }
 
+static bool expandSignIntrinsic(CallInst *Orig) {
+  IRBuilder<> Builder(Orig->getParent());
+  Value *X = Orig->getOperand(0);
+  Type *Ty = X->getType();
+  Type *ScalarTy = Ty->getScalarType();
+  Type *RetTy = Orig->getType();
+  Constant *Zero = Constant::getNullValue(Ty);
+  Builder.SetInsertPoint(Orig);
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farzonl wrote:

i'm not opposed to doing a high level operation for unsigned  `sign` cases, however  for reference this is what DXC does: https://github.com/microsoft/DirectXShaderCompiler/blob/0e7591a6ee94c8c8eb0d536ce7815fd56a776451/lib/HLSL/HLOperationLower.cpp#L2703C1-L2714C2

https://github.com/llvm/llvm-project/pull/101988