[PATCH] D53994: Fixing lower bound regression in certain situations.

Louis Dionne via Phabricator reviews at reviews.llvm.org
Wed Nov 14 05:12:42 PST 2018


ldionne added a reviewer: jfb.
ldionne added a subscriber: jfb.
ldionne added inline comments.


================
Comment at: include/algorithm:3231
     {
-        difference_type __l2 = __len / 2;
+        difference_type __l2 = _VSTD::__half_positive(__len);
         _ForwardIterator __m = __first;
----------------
I'll admit to being extremely surprised this makes any difference whatsoever. In my experience, Clang always emits the same instruction no matter what: `shr`. Adding @jfb to take a look. If he's OK with this, I'm OK with this.


https://reviews.llvm.org/D53994





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