[clang] [HIP] Pass `-O0` by default for HIP no-RDC compilations (PR #211790)

[Fangrui Song via cfe-commits]

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@@ -9896,6 +9892,12 @@ void LinkerWrapper::ConstructJob(Compilation &C, const JobAction &JA,
         }
       }
 
+      // If no optimization level was requested we default to `-O0` for no-RDC
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MaskRay wrote:

My only question is why the default (where?) is not O0 and requires an override here.

https://github.com/llvm/llvm-project/pull/211790