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From: "mikpe at it dot uu.se" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c/48090] gcc 4.5.2 miscompilation when building on arm
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48090

Mikael Pettersson <mikpe at it dot uu.se> changed:

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

--- Comment #7 from Mikael Pettersson <mikpe at it dot uu.se> 2011-03-13 15:09:36 UTC ---
The miscompilation on 4.5 branch started with r154181, the PR42031 fix; see
<http://gcc.gnu.org/ml/gcc-patches/2009-11/msg00725.html>.

On the standalone test case, r154181 changed the -march=armv5t -O2 code as
follows:

--- pr48090.s-r154180   2011-03-13 15:39:16.000000000 +0100
+++ pr48090.s-r154181   2011-03-13 15:43:21.000000000 +0100
@@ -81,11 +81,9 @@
        mov     r6, r1
        bl      seek_archive
        cmp     r1, #0
-       mov     r3, r0
-       mov     r4, r1
        blt     .L14
-       rsbs    r1, r3, #0
-       rsc     r2, r4, #0
+       rsbs    r1, r0, #0
+       rsc     r2, r1, #0
        mov     r4, r2, asl #9
        mov     r3, r1, asl #9
        orr     r4, r4, r1, lsr #23

which breaks the second 'rsc' insn since it now reads the updated r1 value
instead of the original one.