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From: "jakub at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug target/44199] New: ppc64 glibc miscompilation Date: Wed, 19 May 2010 18:27:00 -0000 [thread overview] Message-ID: <bug-44199-87@http.gcc.gnu.org/bugzilla/> (raw) vfscanf is miscompiled by gcc 4.4, here is a shorter testcase that is miscompiled also by 4.6: extern void *alloca (__SIZE_TYPE__); extern void bar (long *, char *); long foo (long x) { long buf[400]; char *p = alloca (x); bar (buf, p); return buf[0]; } at -O2 -m64 results in: ... bl .bar nop addi 1,31,3328 ld 3,112(31) ld 0,16(1) ld 31,-8(1) mtlr 0 blr Note that sched2 swapped incorrectly the stack frame release and ld 3,112(31), so the ld insn reads from memory location 3216 below the stack (which is much lower than 288 bytes of ppc64 red zone). If a signal comes in in between addi and ld and something clobbers the stack, this function (or, with 4.4 vfscanf) will return incorrect value. There is nothing in the epilogue stack release insn that would make it a memory barrier. -- Summary: ppc64 glibc miscompilation Product: gcc Version: 4.6.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: target AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: jakub at gcc dot gnu dot org GCC target triplet: powerpc64-linux http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44199
next reply other threads:[~2010-05-19 18:27 UTC|newest] Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top 2010-05-19 18:27 jakub at gcc dot gnu dot org [this message] 2010-05-19 18:31 ` [Bug target/44199] " pinskia at gcc dot gnu dot org 2010-05-19 19:10 ` jakub at gcc dot gnu dot org 2010-05-19 19:10 ` jakub at gcc dot gnu dot org 2010-05-19 19:24 ` jakub at gcc dot gnu dot org 2010-05-19 19:28 ` jakub at gcc dot gnu dot org 2010-05-19 20:32 ` jakub at gcc dot gnu dot org 2010-05-19 21:53 ` bergner at gcc dot gnu dot org 2010-05-20 4:31 ` amodra at gmail dot com 2010-05-20 16:23 ` pthaugen at gcc dot gnu dot org 2010-05-20 16:32 ` jakub at gcc dot gnu dot org 2010-05-20 18:00 ` pthaugen at gcc dot gnu dot org 2010-05-20 18:24 ` jakub at gcc dot gnu dot org 2010-05-21 2:33 ` pthaugen at gcc dot gnu dot org 2010-05-21 8:08 ` jakub at gcc dot gnu dot org 2010-05-21 19:14 ` bergner at gcc dot gnu dot org 2010-05-21 19:24 ` iains at gcc dot gnu dot org 2010-05-22 13:31 ` dominiq at lps dot ens dot fr 2010-05-26 6:01 ` jakub at gcc dot gnu dot org 2010-05-26 6:03 ` jakub at gcc dot gnu dot org 2010-05-26 6:06 ` jakub at gcc dot gnu dot org 2010-05-26 6:08 ` jakub at gcc dot gnu dot org 2010-05-26 15:52 ` pthaugen at gcc dot gnu dot org 2010-05-26 16:10 ` jakub at gcc dot gnu dot org 2010-05-26 16:10 ` jakub at gcc dot gnu dot org 2010-05-27 16:31 ` bergner at gcc dot gnu dot org 2010-06-02 15:41 ` bergner at gcc dot gnu dot org
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