[libcxx-commits] [PATCH] D100828: Remove if-else to make branch predictor happy

ppenguin via Phabricator via libcxx-commits libcxx-commits at lists.llvm.org
Tue Apr 20 04:34:14 PDT 2021


prehistoric-penguin updated this revision to Diff 338821.
prehistoric-penguin marked an inline comment as done.
prehistoric-penguin added a comment.

Updating D100828 <https://reviews.llvm.org/D100828>: Remove if-else to make branch predictor happy


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D100828/new/

https://reviews.llvm.org/D100828

Files:
  libcxx/include/bitset


Index: libcxx/include/bitset
===================================================================
--- libcxx/include/bitset
+++ libcxx/include/bitset
@@ -775,10 +775,7 @@
     for (; __i < _Mp; ++__i)
     {
         _CharT __c = __str[_Mp - 1 - __i];
-        if (__c == __zero)
-            (*this)[__i] = false;
-        else
-            (*this)[__i] = true;
+        (*this)[__i] = _Traits::eq(__c, __one);
     }
     _VSTD::fill(base::__make_iter(__i), base::__make_iter(_Size), false);
 }
@@ -803,10 +800,7 @@
     for (; __i < _Mp; ++__i)
     {
         _CharT __c = __str[__pos + _Mp - 1 - __i];
-        if (_Traits::eq(__c, __zero))
-            (*this)[__i] = false;
-        else
-            (*this)[__i] = true;
+        (*this)[__i] = _Traits::eq(__c, __one);
     }
     _VSTD::fill(base::__make_iter(__i), base::__make_iter(_Size), false);
 }


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