[clang] [llvm] [HLSL] Implement the `fwidth` intrinsic for DXIL and SPIR-V target (PR #161378)

[Farzon Lotfi via cfe-commits]

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@@ -2615,6 +2618,15 @@ bool SPIRVInstructionSelector::selectDiscard(Register ResVReg,
       .constrainAllUses(TII, TRI, RBI);
 }
 
+bool SPIRVInstructionSelector::selectFwidth(Register ResVReg,
+                                            const SPIRVType *ResType,
+                                            MachineInstr &I) const {
+  return BuildMI(*I.getParent(), I, I.getDebugLoc(), TII.get(SPIRV::OpFwidth))
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farzonl wrote:

the way this is implemented would imply that this should work with opencl? can you write an opencl spirv test to confirm.

https://github.com/llvm/llvm-project/pull/161378