[Bug middle-end/70245] [6 Regression] Miscompilation of ICU on i386 with atom tuning starting with r227382

["jakub at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70245

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |wrong-code
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2016-03-15
     Ever confirmed|0                           |1

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
The difference between r227381 and r227382 on the testcase is:
--- r227382-1.s1        2016-03-15 20:34:52.699640513 +0100
+++ r227382-1.s2        2016-03-15 20:35:05.278470114 +0100
@@ -116,7 +116,7 @@ _ZL3barP1BPi:
        movl    24(%esp), %edi
        movl    %eax, 24(%esp)
        movl    %edi, 12(%esp)
-       movl    (%edx), %ecx
+       movl    (%edi), %ecx
        movl    %eax, (%esp)
        addl    %edx, %ecx
        movl    %ebp, 4(%esp)
which is the load of g->d in d's arguments, %edi at this point isn't equal to
g, while %edx is (you can see it a few insns later, g and f are not modified
after assignment and aren't addressable, thus they have the same value, and so
it is actually f + f->d, in the addition it is either correct %edx + (%edx), or
incorrect %edx + (%edi) where %edi happens to point to 0 instead of the right
4.