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From: "mikpe at it dot uu.se" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/53016] memcpy optimization can cause unaligned access on ARM
Date: Tue, 17 Apr 2012 08:15:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53016

--- Comment #1 from Mikael Pettersson <mikpe at it dot uu.se> 2012-04-17 08:14:49 UTC ---
Created attachment 27175
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27175
reduced test case

Gets alignment faults with both -mthumb and -marm (+ -march=armv5te -O1) using
gcc 4.4.7 and 4.5.3, but not with 4.6.3 or 4.7.0.

With -marm I get alignment faults that the kernel fixes up.  With -mthumb I get
a fatal SIGBUS and a kernel message like the following:

Alignment trap: a.out (10263) PC=0x0000834e Instr=0xc331ca31 Address=0xbea0b335
FSR 0x001
Alignment trap: not handling instruction c331ca31 at [<0000834e>]
Unhandled fault: alignment exception (0x001) at 0xbea0b335

I'm not sure if that's due to a kernel bug or because I've neglected to enable
some Thumb1-specific support in my kernel (I normally only run pure ARM code).