[Bug debug/36728] [stack]: gdb doesn't work with stack alignment

["hjl dot tools at gmail dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #1 from hjl dot tools at gmail dot com  2008-07-04 13:17 -------
Created an attachment (id=15852)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=15852&action=view)
A testcase with drap 

[hjl@gnu-6 stack-10]$
/export/build/gnu/gcc-stack-internal/build-x86_64-linux/gcc/xgcc
-B/export/build/gnu/gcc-stack-internal/build-x86_64-linux/gcc/ -m32 foo.c -g
[hjl@gnu-6 stack-10]$ gdb a.out 
GNU gdb 6.8.50.20080605-cvs
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-unknown-linux-gnu"...
(gdb) b foo
Breakpoint 1 at 0x80483a8: file foo.c, line 7.
(gdb) r
Starting program: /export/home/hjl/bugs/gcc/stack-10/a.out 

Breakpoint 1, foo (dummy1=-5725018, dummy2=0, dummy3=-5724977, 
    dummy4=-5724952, dummy5=-5724933, dummy6=-5724905, size=-5724890)
    at foo.c:7
7       {
(gdb) next
8         volatile char * ptr=__builtin_alloca(size);
(gdb) 
11        xxx = 2;
(gdb) 
12        ptr [1]= 30;
(gdb) 
13        printf ("%d: %d\n", xxx, ptr [1]);
(gdb) p xxx
$1 = 0
(gdb) p ptr [1]
$2 = 0 '\0'
(gdb)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36728