[llvm-bugs] [Bug 24888] New: Clang emits badly performing SSE instead of conditional moves for simple function with -O2

[via llvm-bugs]

https://llvm.org/bugs/show_bug.cgi?id=24888

            Bug ID: 24888
           Summary: Clang emits badly performing SSE instead of
                    conditional moves for simple function with -O2
           Product: clang
           Version: 3.7
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: -New Bugs
          Assignee: unassignedclangbugs at nondot.org
          Reporter: OrlandoMarinera at mailinator.com
                CC: llvm-bugs at lists.llvm.org
    Classification: Unclassified

Created attachment 14910
  --> https://llvm.org/bugs/attachment.cgi?id=14910&action=edit
Repro example

Code attached. Tested on core2 cpu, 64bit, with clang 3.7.0.
Compiling with -O1 produces very compact assembly relying on `cmov`.
Switching to -O2 emits a mass of SSE instructions which ends up
being about 2x slower.

compile with -std=c++11

-- 
You are receiving this mail because:
You are on the CC list for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-bugs/attachments/20150921/4cd68e3d/attachment.html>