[llvm] [LoopUnrollPass] Don't use clang specific syntax in optimization remarks (PR #182430)

[Aiden Grossman via llvm-commits]

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@@ -1060,9 +1060,8 @@ bool llvm::computeUnrollCount(
             return OptimizationRemarkMissed(DEBUG_TYPE,
                                             "UnrollAsDirectedTooLarge",
                                             L->getStartLoc(), L->getHeader())
-                   << "Unable to unroll loop as directed by unroll(enable) "
-                      "pragma "
-                      "because unrolled size is too large.";
+                   << "unable to unroll loop as directed by enable unroll "
+                      "pragma because unrolled size is too large";
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boomanaiden154 wrote:

Yeah, looking through the diagnostic handling code, Clang can do whatever it wants in its own `DiagnosticHandler`. Given that and that this might come up in other languages (like Rust which doesn't have pragmas), I think metadata is more appropriate.

I guess this is a slight regression in UX for those who don't understand compiler internals, which is unfortunate, but I would expect most users looking at optimization remarks to be able to infer that metadata came from the pragma.

https://github.com/llvm/llvm-project/pull/182430