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From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/66444] [5/6 Regression] Miscompilation of Xen since r211078
Date: Mon, 08 Jun 2015 09:41:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66444

--- Comment #7 from vries at gcc dot gnu.org ---
(In reply to Jakub Jelinek from comment #6)
> The 0xe000000000UL constant is probably not very good for ilp32 targets. 
> Try some < 4GB one if it still reproduces without the patch, or
> conditionalize it on __SIZEOF_POINTER__.

I've tried with 0xe0000000U. The m64 case still reproduces. 

With -m32 -mregparm=1 we get:
...
        .cfi_startproc
        call    bar
        sall    $4, %eax
        leal    -536870912(%eax), %edx
        movl    %edx, %eax
        call    fn1
        movl    %edx, %eax
        call    fn2
        xorl    %eax, %eax
        ret
...
The reload_combine doesn't trigger for this case.