[Mingw-notify] [ mingw-Bugs-2834786 ] gcc 4.4.0 Error code generation with -O3

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Bugs item #2834786, was opened at 2009-08-10 21:12
Message generated for change (Comment added) made by dannysmith
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Category: gcc
Group: Waiting User Response
Status: Pending
Resolution: None
Priority: 5
Private: No
Submitted By: Alexandr Zamaraev (shura_zam)
Assigned to: Nobody/Anonymous (nobody)
Summary: gcc 4.4.0 Error code generation with -O3

Initial Comment:
I tried to compile Qt 4.5.2 on mingw gcc 4.4.0.
Options optimization release:
    QMAKE_CFLAGS_RELEASE = -O3 -march=pentium3 -mtune=pentium3

To build without errors, but when you start assistant.exe get an error 
in QtCode4.dll.
The same error I get when running assistant_adp.exe when you try to 
click on a link.

Running under gdb assistant.exe of shows at the function inflate 
(inflate.c) and inflate_table (inftrees.c) from the directory 
qt4/src/3rdparty/zlib (copy of zlib 1.2.3)

Disasembler line in gdb:
movaps %xmm0,-0x28(%ebp)

After the change -O3 to -O2 and rebuilding QtCode4.dll error disappeared.
However, there are similar errors in other modules.
For example in QtGui4.dll (gdb log tail):
[code]
...
(no debugging symbols found)

Program received signal SIGSEGV, Segmentation fault.
0x679f3c68 in ZNK12QCommonStyle18drawComplexControlEN6QStyle14ComplexControlEPK19QStyleOptionComplexP8QPainterPK7QWidget ()
   from C:\Lang\qt\qt4\bin\QtGui4.dll
(gdb) display/i $pc
1: x/i $pc
0x679f3c68 <ZNK12QCommonStyle18drawComplexControlEN6QStyle14ComplexControlEPK19QStyleOptionComplexP8QPainterPK7QWidget+73448>:  movaps %xmm0,-0x278(%ebp)
(gdb) p $ebp
$1 = (void *) 0x21ca94
(gdb)
[/code]

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>Comment By: Danny Smith (dannysmith)
Date: 2009-08-13 17:35

Message:
This looks like a problem with (un)aligned common.  Try adding -fno-common
to  compile options. 

See also: 
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37216

and try

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Comment By: Alexandr Zamaraev (shura_zam)
Date: 2009-08-13 16:13

Message:
As far as I can judge, in the code where the fault is with the
floating-point computations are not used (zlib 1.2.3).
The compiler inserts instructions sse to optimize the initialization of
local variables.

Can you suggest a search for the minimum reproducible test?

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Comment By: Earnie Boyd (earnie)
Date: 2009-08-11 00:44

Message:
And what makes this a GCC bug instead of a bug in the code that doesn't
know how to handle the additional optimizations?  Find a smaller test case
that proves the bug and attach it to this issue.

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