[clang] [llvm] [SPIRV][HLSL] Add DXC compatibility option for extension (PR #151554)

[Chris B via llvm-commits]

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@@ -173,24 +173,78 @@ bool isLegalValidatorVersion(StringRef ValVersionStr, const Driver &D) {
   return true;
 }
 
+std::string getSpirvExtOperand(llvm::StringRef SpvExtensionArg) {
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llvm-beanz wrote:

nit: I would probably change this to take a `raw_ostream&` to write the operand into, then you could use a SmallString with a big stack allocation, and reduce the likelihood of lots of string re-allocations.

Feel free to take or leave this feedback as the driver isn't generally a performance sensitive part of the compiler since we'll do this like once per compile.

https://github.com/llvm/llvm-project/pull/151554