[clang-tools-extra] [Clang] Support target attr specifying CPU (PR #68678)

[Aaron Ballman via cfe-commits]

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@@ -2420,11 +2420,11 @@ command line.
 
 The current set of options correspond to the existing "subtarget features" for
 the target with or without a "-mno-" in front corresponding to the absence
-of the feature, as well as ``arch="CPU"`` which will change the default "CPU"
-for the function.
+of the feature, as well as ``arch="CPU"`` and ``cpu="CPU"`` which will change
+the default "CPU" for the function.
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AaronBallman wrote:

These docs confuse me a bit because I'm left wondering what the difference is between using `-arch="whatever"` and `-cpu="whatever"`; it sounds like they both do the same thing. If they indeed are identical, we should document that more clearly (but it certainly begs the question of "why do we have both?").

https://github.com/llvm/llvm-project/pull/68678