[Bug tree-optimization/65136] [5 Regression] VRP inserts unnecessary constant copy in the loop

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65136

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |uros at gcc dot gnu.org

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
After the patch the assembly difference between 4.9 and 5 is

--- t.s.good    2015-02-20 13:26:52.337186388 +0100
+++ t.s 2015-02-20 13:26:56.769235529 +0100
@@ -21,7 +21,7 @@
        testl   %eax, %eax
        jne     .L3
        xorl    %eax, %eax
-       cmpw    $-1, %di
+       cmpl    $65535, %edi
        sete    %al
        ret
        .cfi_endproc

not sure why we prefer the bigger encoding now.