This is the mail archive of the
gcc-bugs@gcc.gnu.org
mailing list for the GCC project.
[Bug target/54829] bad optimization: sub followed by cmp w/ zero (x86 & ARM)
- From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Sat, 13 Oct 2012 16:18:03 +0000
- Subject: [Bug target/54829] bad optimization: sub followed by cmp w/ zero (x86 & ARM)
- Auto-submitted: auto-generated
- References: <bug-54829-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54829
--- Comment #6 from Richard Earnshaw <rearnsha at gcc dot gnu.org> 2012-10-13 16:18:03 UTC ---
Note also that flag setting behaviour of the PPC instruction essentially is a
comparison of the result against zero. On ARM the flags are set as if the two
input operands were compared; that's not the same as comparing the result with
zero.