[clang] [llvm] Remove 3dnow from X86TargetParser. (PR #99352)

[James Y Knight via cfe-commits]

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@@ -171,14 +171,14 @@ constexpr FeatureBitset FeaturesClearwaterforest =
 
 // Geode Processor.
 constexpr FeatureBitset FeaturesGeode =
-    FeatureX87 | FeatureCMPXCHG8B | FeatureMMX | Feature3DNOW | Feature3DNOWA;
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jyknight wrote:

Possibly not?

We didn't enable it before (so, e.g. `__PRFCHW__` isn't and wasn't defined), and while we DID enable the prefetchw instruction in the backend for these targets, we still do now (via implying it in X86.td).

OTOH, maybe it's weird to have that divergence, so I'd also be fine with adding it (and therefore setting the preprocessor define).

https://github.com/llvm/llvm-project/pull/99352