Package: gcc
Version: 4:4.1.1-15
GCC miscompiles the following code :-
extern void extfunc(void);
extern unsigned extvar;
static void inner(char *a, unsigned b)
{
if (b)
extfunc();
else
extvar = (unsigned) a;
}
void outer(unsigned a, unsigned b)
{
char c;
c = a;
inner(&c, b);
}
/*
* with Debian Etch gcc
*
* gcc -O2 -c -o test.o test.c
*
* objdump -d test.o
*
* the initialisation of "c" that is needed
* for the assignment to "extvar" is done
* in the wrong leg of the if() !!
*
test.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <outer>:
0: e52de004 str lr, [sp, #-4]!
4: e3510000 cmp r1, #0 ; 0x0
8: e24dd004 sub sp, sp, #4 ; 0x4
c: 059f301c ldreq r3, [pc, #28] ; 30 <.text+0x30>
10: 028d2003 addeq r2, sp, #3 ; 0x3
14: 05832000 streq r2, [r3]
18: 1a000001 bne 24 <outer+0x24>
1c: e28dd004 add sp, sp, #4 ; 0x4
20: e8bd8000 ldmia sp!, {pc}
24: e5cd0003 strb r0, [sp, #3]
28: ebfffffe bl 0 <extfunc>
2c: eafffffa b 1c <outer+0x1c>
30: 00000000 andeq r0, r0, r0
*/
/*
Using built-in specs.
Target: arm-linux-gnu
Configured with: ../src/configure -v
--enable-languages=c,c++,fortran,objc,obj-c++,treelang --prefix=/usr
--enable-shared --with-system-zlib --libexecdir=/usr/lib
--without-included-gettext --enable-threads=posix --enable-nls
--program-suffix=-4.1 --enable-__cxa_atexit --enable-clocale=gnu
--enable-libstdcxx-debug --enable-mpfr --enable-checking=release
arm-linux-gnu
Thread model: posix
gcc version 4.1.2 20061115 (prerelease) (Debian 4.1.1-21)
*/
/*
* same but with Debian Etch gcc-3.4
*
* this one is correct
*
test.o: file format elf32-littlearm
Disassembly of section .text:
00000000 <outer>:
0: e52de004 str lr, [sp, #-4]!
4: e3510000 cmp r1, #0 ; 0x0
8: 059f3020 ldreq r3, [pc, #32] ; 30 <.text+0x30>
c: e24dd004 sub sp, sp, #4 ; 0x4
10: e28d2004 add r2, sp, #4 ; 0x4
14: e5620001 strb r0, [r2, #-1]!
18: 05832000 streq r2, [r3]
1c: 1a000001 bne 28 <outer+0x28>
20: e28dd004 add sp, sp, #4 ; 0x4
24: e8bd8000 ldmia sp!, {pc}
28: ebfffffe bl 0 <extfunc>
2c: eafffffb b 20 <outer+0x20>
30: 00000000 andeq r0, r0, r0
*/
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