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From: "ppluzhnikov at google dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug c++/53220] New: g++ mis-compiles compound literals Date: Thu, 03 May 2012 19:50:00 -0000 [thread overview] Message-ID: <bug-53220-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53220 Bug #: 53220 Summary: g++ mis-compiles compound literals Classification: Unclassified Product: gcc Version: unknown Status: UNCONFIRMED Severity: normal Priority: P3 Component: c++ AssignedTo: unassigned@gcc.gnu.org ReportedBy: ppluzhnikov@google.com This appears to be a gcc-4.7 regression. Confirmed in: g++ (GCC) 4.8.0 20120331 (experimental) g++ (GCC) 4.8.0 20120503 (experimental) #include <stdio.h> int main() { for (int *p = (int[]){ 1, 2, 3, 0}; *p; ++p) { printf("%d\n", *p); } return 0; } gcc -std=c99 t2.c && ./a.out 1 2 3 gcc -std=c99 -O2 t2.c && ./a.out 1 2 3 g++ t2.c && ./a.out 1 2 3 g++ -O2 -g t2.c && ./a.out 944127552 32767 AFAICT, g++ completely removes the initializer and reads random garbage off stack: (gdb) disas main Dump of assembler code for function main(): 0x0000000000400600 <+0>: push %rbx 0x0000000000400601 <+1>: sub $0x10,%rsp 0x0000000000400605 <+5>: mov (%rsp),%esi 0x0000000000400608 <+8>: mov %rsp,%rbx 0x000000000040060b <+11>: test %esi,%esi 0x000000000040060d <+13>: je 0x400626 <main()+38> 0x000000000040060f <+15>: nop 0x0000000000400610 <+16>: xor %eax,%eax 0x0000000000400612 <+18>: add $0x4,%rbx 0x0000000000400616 <+22>: mov $0x40071c,%edi 0x000000000040061b <+27>: callq 0x400478 <printf@plt> 0x0000000000400620 <+32>: mov (%rbx),%esi 0x0000000000400622 <+34>: test %esi,%esi 0x0000000000400624 <+36>: jne 0x400610 <main()+16> 0x0000000000400626 <+38>: add $0x10,%rsp 0x000000000040062a <+42>: xor %eax,%eax 0x000000000040062c <+44>: pop %rbx 0x000000000040062d <+45>: retq End of assembler dump. valgrind ./a.out ... ==13572== Conditional jump or move depends on uninitialised value(s) ==13572== at 0x40060D: main (/tmp/t2.c:5) ==13572== ==13572== Use of uninitialised value of size 8 ==13572== at 0x5625E4B: _itoa_word (/build/buildd/eglibc-2.11.1/stdio-common/_itoa.c:195) ==13572== by 0x5628A87: vfprintf (/build/buildd/eglibc-2.11.1/stdio-common/vfprintf.c:1616) ==13572== by 0x5631659: printf (/build/buildd/eglibc-2.11.1/stdio-common/printf.c:35) ==13572== by 0x40061F: main (/tmp/t2.c:6) ==13572== ==13572== Conditional jump or move depends on uninitialised value(s) ==13572== at 0x5625E55: _itoa_word (/build/buildd/eglibc-2.11.1/stdio-common/_itoa.c:195) ==13572== by 0x5628A87: vfprintf (/build/buildd/eglibc-2.11.1/stdio-common/vfprintf.c:1616) ==13572== by 0x5631659: printf (/build/buildd/eglibc-2.11.1/stdio-common/printf.c:35) ==13572== by 0x40061F: main (/tmp/t2.c:6) ==13572== ==13572== Conditional jump or move depends on uninitialised value(s) ==13572== at 0x5627ED2: vfprintf (/build/buildd/eglibc-2.11.1/stdio-common/vfprintf.c:1616) ==13572== by 0x5631659: printf (/build/buildd/eglibc-2.11.1/stdio-common/printf.c:35) ==13572== by 0x40061F: main (/tmp/t2.c:6) ==13572== ==13572== Conditional jump or move depends on uninitialised value(s) ==13572== at 0x5627EF0: vfprintf (/build/buildd/eglibc-2.11.1/stdio-common/vfprintf.c:1616) ==13572== by 0x5631659: printf (/build/buildd/eglibc-2.11.1/stdio-common/printf.c:35) ==13572== by 0x40061F: main (/tmp/t2.c:6) ==13572== -16780368 ==13572== Conditional jump or move depends on uninitialised value(s) ==13572== at 0x400624: main (/tmp/t2.c:5) ==13572== 127 ... Google ref: b/6439133
next reply other threads:[~2012-05-03 19:50 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-05-03 19:50 ppluzhnikov at google dot com [this message] 2012-05-03 19:53 ` [Bug c++/53220] " ppluzhnikov at google dot com 2012-05-03 22:38 ` [Bug c++/53220] [4.7/4.8 Regression] " hjl.tools at gmail dot com 2012-05-04 9:03 ` rguenth at gcc dot gnu.org 2012-05-04 18:53 ` xinliangli at gmail dot com 2012-05-07 14:33 ` jason at gcc dot gnu.org 2012-05-07 16:25 ` xinliangli at gmail dot com 2012-05-07 16:55 ` ppluzhnikov at google dot com 2012-05-07 17:18 ` xinliangli at gmail dot com 2012-05-07 17:55 ` jason at gcc dot gnu.org 2012-05-08 0:34 ` xinliangli at gmail dot com 2012-05-08 2:22 ` jason at gcc dot gnu.org 2012-05-17 0:13 ` ppluzhnikov at google dot com 2012-05-22 17:42 ` jason at gcc dot gnu.org 2012-05-22 17:50 ` ppluzhnikov at google dot com 2012-05-22 18:05 ` ppluzhnikov at google dot com 2012-05-26 21:20 ` jason at gcc dot gnu.org 2012-05-30 14:52 ` jason at gcc dot gnu.org 2012-06-03 4:50 ` jason at gcc dot gnu.org 2012-06-20 1:59 ` ppluzhnikov at google dot com 2012-06-20 7:20 ` jason at gcc dot gnu.org 2013-05-01 9:54 ` superaxioma at hotmail dot com 2013-05-01 19:13 ` jason at gcc dot gnu.org 2023-11-28 21:29 ` cvs-commit at gcc dot gnu.org
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