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* [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm @ 2012-01-24 22:41 jakub at gcc dot gnu.org 2012-01-24 22:53 ` [Bug tree-optimization/51987] " jakub at gcc dot gnu.org ` (3 more replies) 0 siblings, 4 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-24 22:41 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51987 Bug #: 51987 Summary: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm Classification: Unclassified Product: gcc Version: 4.7.0 Status: UNCONFIRMED Keywords: wrong-code Severity: normal Priority: P3 Component: tree-optimization AssignedTo: jakub@gcc.gnu.org ReportedBy: jakub@gcc.gnu.org On s390 (31-bit) gcc 4.7 miscompiles _itoa.o and _itoa.os in glibc (which leads to e.g. cc1 itself when using that glibc to crash on startup). Here is a reduced testcase (for x86_64): extern void abort (void); union U { unsigned long l; struct { unsigned int l, h; } i; }; __attribute__((noinline, noclone)) void foo (char *x, char *y) { int i; for (i = 0; i < 64; i++) { union U u; asm ("movl %1, %k0; salq $32, %0" : "=r" (u.l) : "r" (i)); x[i] = u.i.h; union U v; asm ("movl %1, %k0; salq $32, %0" : "=r" (v.l) : "r" (i)); y[i] = v.i.h; } } int main () { char a[64], b[64]; int i; foo (a, b); for (i = 0; i < 64; i++) if (a[i] != i || b[i] != i) abort (); return 0; } This is miscompiled at -O3, predictive commoning ignores the references in the inline-asm and happily moves loads of u.i.h and v.i.h before the loop, even when it is initialized only by the inline asm inside of the loop. The problem is that tree-data-ref.c (get_references_in_stmt) gives up on GIMPLE_ASM only if it is volatile, and for non-volatile GIMPLE_ASM it just (incorrectly) assumes it doesn't have any references. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51987] [4.7 Regression] Predictive commoning wrong-code with non-volatile asm 2012-01-24 22:41 [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm jakub at gcc dot gnu.org @ 2012-01-24 22:53 ` jakub at gcc dot gnu.org 2012-01-24 23:17 ` jakub at gcc dot gnu.org ` (2 subsequent siblings) 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-24 22:53 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51987 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2012-01-24 Target Milestone|--- |4.7.0 Ever Confirmed|0 |1 ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51987] [4.7 Regression] Predictive commoning wrong-code with non-volatile asm 2012-01-24 22:41 [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm jakub at gcc dot gnu.org 2012-01-24 22:53 ` [Bug tree-optimization/51987] " jakub at gcc dot gnu.org @ 2012-01-24 23:17 ` jakub at gcc dot gnu.org 2012-01-25 16:13 ` jakub at gcc dot gnu.org 2012-01-25 16:40 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-24 23:17 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51987 --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-24 22:40:11 UTC --- Created attachment 26449 --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26449 gcc47-pr51987.patch Untested fix. ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51987] [4.7 Regression] Predictive commoning wrong-code with non-volatile asm 2012-01-24 22:41 [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm jakub at gcc dot gnu.org 2012-01-24 22:53 ` [Bug tree-optimization/51987] " jakub at gcc dot gnu.org 2012-01-24 23:17 ` jakub at gcc dot gnu.org @ 2012-01-25 16:13 ` jakub at gcc dot gnu.org 2012-01-25 16:40 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-25 16:13 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51987 --- Comment #2 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-25 15:38:57 UTC --- Author: jakub Date: Wed Jan 25 15:38:51 2012 New Revision: 183524 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=183524 Log: PR tree-optimization/51987 * tree-data-ref.c (get_references_in_stmt): Handle references in non-volatile GIMPLE_ASM. * gcc.target/i386/pr51987.c: New test. Added: trunk/gcc/testsuite/gcc.target/i386/pr51987.c Modified: trunk/gcc/ChangeLog trunk/gcc/testsuite/ChangeLog trunk/gcc/tree-data-ref.c ^ permalink raw reply [flat|nested] 5+ messages in thread
* [Bug tree-optimization/51987] [4.7 Regression] Predictive commoning wrong-code with non-volatile asm 2012-01-24 22:41 [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm jakub at gcc dot gnu.org ` (2 preceding siblings ...) 2012-01-25 16:13 ` jakub at gcc dot gnu.org @ 2012-01-25 16:40 ` jakub at gcc dot gnu.org 3 siblings, 0 replies; 5+ messages in thread From: jakub at gcc dot gnu.org @ 2012-01-25 16:40 UTC (permalink / raw) To: gcc-bugs http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51987 Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|ASSIGNED |RESOLVED Resolution| |FIXED --- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> 2012-01-25 16:22:35 UTC --- Fixed. ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2012-01-25 16:23 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2012-01-24 22:41 [Bug tree-optimization/51987] New: [4.7 Regression] Predictive commoning wrong-code with non-volatile asm jakub at gcc dot gnu.org 2012-01-24 22:53 ` [Bug tree-optimization/51987] " jakub at gcc dot gnu.org 2012-01-24 23:17 ` jakub at gcc dot gnu.org 2012-01-25 16:13 ` jakub at gcc dot gnu.org 2012-01-25 16:40 ` jakub at gcc dot gnu.org
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