[PATCH] D85257: [X86] Optimize getImpliedDisabledFeatures & getImpliedEnabledFeatures'

[Fangrui Song via Phabricator via llvm-commits]

MaskRay marked an inline comment as done.
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Comment at: llvm/lib/Support/X86TargetParser.cpp:570
+    Prev = Bits;
+    for (unsigned i = CPU_FEATURE_MAX; i;)
+      if (Bits[--i])
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craig.topper wrote:
> Is there something special about going in reverse here?
Backward iteration is more efficient.

If most "implies" edges are forward (i.e. from a smaller index to a larger index; if we organize features from older to newer), one iteration is going to finalize `Bits`. The second iteration will break the loop.


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https://reviews.llvm.org/D85257