[clang] [llvm] [HLSL][DXIL] Implement `refract` intrinsic (PR #136026)

[Farzon Lotfi via cfe-commits]

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@@ -3087,6 +3087,8 @@ bool SPIRVInstructionSelector::selectIntrinsic(Register ResVReg,
     return selectExtInst(ResVReg, ResType, I, CL::fract, GL::Fract);
   case Intrinsic::spv_normalize:
     return selectExtInst(ResVReg, ResType, I, CL::normalize, GL::Normalize);
+  case Intrinsic::spv_refract:
+    return selectExtInst(ResVReg, ResType, I, GL::Refract);
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farzonl wrote:

if you are using the `GL `selectExtInst` overload then add an OpenCL test to confirm we error see `llvm/test/CodeGen/SPIRV/opencl/reflect-error.ll`

https://github.com/llvm/llvm-project/pull/136026