Your message dated Tue, 24 Jun 2008 08:16:33 +0200 with message-id <[EMAIL PROTECTED]> and subject line Re: Bug#484784: gcc-4.3: -O2 -O3 - wrong arguments are passing to inlined body of function has caused the Debian Bug report #484784, regarding gcc-4.3: -O2 -O3 - wrong arguments are passing to inlined body of function to be marked as done.
This means that you claim that the problem has been dealt with. If this is not the case it is now your responsibility to reopen the Bug report if necessary, and/or fix the problem forthwith. (NB: If you are a system administrator and have no idea what this message is talking about, this may indicate a serious mail system misconfiguration somewhere. Please contact [EMAIL PROTECTED] immediately.) -- 484784: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=484784 Debian Bug Tracking System Contact [EMAIL PROTECTED] with problems
--- Begin Message ---Subject: gcc-4.3: -O2 -O3 - wrong arguments are passing to inlined body of function Package: gcc-4.3 Version: 4.3.0-5 Severity: important Consider this simple program: ---bug.c--- #define N 100 char array[N]; void inline_asm(int iters) { __asm__ volatile ( #ifdef PRESERVE_ALL_REGS "pushal \n" #endif " xorl %%ebx, %%ebx \n" "0: \n" " movzbl (%%eax), %%edx \n" " addl %%edx, %%ebx \n" " incl %%eax \n" " decl %%ecx \n" " jnz 0b \n" #ifdef PRESERVE_ALL_REGS "popal \n" #endif : /* no output */ : "a" (array), "c" (iters) : "ebx", "edx" ); } int main() { int n = 100; while (n--) inline_asm(N); } ---eof--- Function inline_asm just add all values from array; all modified/input registers are listed in __asm__ statement. When program is compiled without any optimization flag, it works ok. However if compiled with -O3 or -O3 --- segfaults. I quickly analyzed assembly output, and it is clear, that gcc fully inlined procedure, however in a while loop only address is restored (%eax), but inner loop counter (%ecx) isn't. Thus in a second iteration %ecx has value 0, and loop would execute 0xffffffff times, but segfault appear faster. When sample program is compiled with -O3 -DPRESERVE_ALL_REGS all is ok, because pair pushal/popal saves and restores all registers. ---bug.s--- main: # .. snip ... movl $array, %esi pushl %ebx pushl %ecx movl $100, %ecx <-- ERROR: ecx is loaded only once .p2align 4,,7 .p2align 3 #while .L4: movl %esi, %eax <-- OK: eax is reloaded in every while-iteration #APP # 6 "bug.c" 1 xorl %ebx, %ebx 0: movzbl (%eax), %edx addl %edx, %ebx incl %eax decl %ecx jnz 0b # 0 "" 2 #NO_APP addl $1, %edi cmpl $100, %edi jne .L4 #endwhile # ... snip ... ---cut--- -- System Information: Debian Release: lenny/sid APT prefers unstable APT policy: (500, 'unstable'), (500, 'stable') Architecture: i386 (i686) Kernel: Linux 2.6.25-2-686 (SMP w/2 CPU cores) Locale: LANG=pl_PL, LC_CTYPE=pl_PL (charmap=ISO-8859-2) Shell: /bin/sh linked to /bin/bash Versions of packages gcc-4.3 depends on: ii binutils 2.18.1~cvs20080103-6 The GNU assembler, linker and bina ii cpp-4.3 4.3.0-5 The GNU C preprocessor ii gcc-4.3-base 4.3.0-5 The GNU Compiler Collection (base ii libc6 2.7-12 GNU C Library: Shared libraries ii libgcc1 1:4.3.0-5 GCC support library ii libgomp1 4.3.0-5 GCC OpenMP (GOMP) support library Versions of packages gcc-4.3 recommends: ii libc6-dev 2.7-12 GNU C Library: Development Librari
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--- Begin Message ---On Sat, Jun 07, 2008 at 10:16:36AM +0200, Bastian Blank wrote: > No bug. You cheated so the compiler is free to do whatever it wants. Closing. Bastian -- Killing is stupid; useless! -- McCoy, "A Private Little War", stardate 4211.8
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