[libc-commits] [PATCH] D148717: [libc] Improve memcmp latency and codegen

[Tue Ly via Phabricator via libc-commits]

lntue added inline comments.


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Comment at: libc/src/string/memory_utils/utils.h:198-201
+  //   cmp     rdi, rsi         <- serializing
+  //   mov     ecx, -5          <- can be done in parallel
+  //   mov     eax, 5           <- can be done in parallel
+  //   cmovb   eax, ecx         <- serializing
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I wonder what's the tradeoffs between this and what is generated for 1 and -1?  If this is better, then the compiler should just use this for 1 and -1 also, right?


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D148717/new/

https://reviews.llvm.org/D148717