[llvm] [SPIRV] Added support for the constrained arithmetic intrinsic (PR #157441)

[Matt Arsenault via llvm-commits]

================
@@ -1038,6 +1044,48 @@ bool SPIRVInstructionSelector::selectOpWithSrcs(Register ResVReg,
   return MIB.constrainAllUses(TII, TRI, RBI);
 }
 
+bool SPIRVInstructionSelector::selectStrictFMulAdd(Register ResVReg,
----------------
arsenm wrote:

This function is asserting too many things that should be verifier errors 

https://github.com/llvm/llvm-project/pull/157441