[clang] [clang] Enable descriptions for --print-supported-extensions (PR #66715)

[Balint Cristian via cfe-commits]

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@@ -22,7 +23,8 @@ struct RISCVExtensionInfo {
   unsigned MinorVersion;
 };
 
-void riscvExtensionsHelp();
+void getAllExtensions(StringMap<RISCVExtensionInfo> &Features);
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cbalint13 wrote:

Regarding accesors see [these lines]
(https://github.com/cbalint13/tvm/blob/4c17af1a187dee450ab89107df18623e8edadede/src/target/llvm/llvm_module.cc#L90-L107) in an external project.

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The info desired there would be usefull in super simple queries like: "Is true that user desired CPU X have feature X", e.g. a concrete example, a user have a ```casadelake``` and check up if it is ```avx512bw``` capable, and also LLVM backend have it implemented or not (if it is older).

https://github.com/llvm/llvm-project/pull/66715