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From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug debug/54971] New: SRA pessimizes debug info by not creating debug stmts for fields without replacements Date: Thu, 18 Oct 2012 09:48:00 -0000 [thread overview] Message-ID: <bug-54971-4@http.gcc.gnu.org/bugzilla/> (raw) http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54971 Bug #: 54971 Summary: SRA pessimizes debug info by not creating debug stmts for fields without replacements Classification: Unclassified Product: gcc Version: 4.8.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: debug AssignedTo: unassigned@gcc.gnu.org ReportedBy: jakub@gcc.gnu.org CC: jamborm@gcc.gnu.org Consider the testcase in PR54970, or the following one. int main () { int a[] = { 1, 2, 3 }; int *p = a + 2; int *q = a + 1; asm volatile ("nop"); *p += 10; asm volatile ("nop"); *q += 10; asm volatile ("nop"); __builtin_memcpy (&a, (int [3]) { 4, 5, 6 }, sizeof (a)); asm volatile ("nop"); *p += 10; asm volatile ("nop"); *q += 10; asm volatile ("nop"); return 0; } For a[1] and a[2] replacements are created and we eventually get corret debug info, tracking the value changes of those array elements. But for a[0] SRA decides not to create a replacement, as it seems to be only assigned and never read (in PR54970 testcase just once, in the above testcase twice). Would it be possible for MAY_HAVE_DEBUG_STMTS to create also replacements for those fields/elements that are only ever assigned, and at the places they used to be assigned instead of setting the replacement to the value it should have create a debug bind stmt? In the above testcase that would be at the place of former a[0] = 1; add DEBUG a$0 => 1 stmt (where a$0's DECL_DEBUG_EXPR would be a[0]), and at the point of the MEM[&a, 0] = MEM[something, 0] assignment DEBUG a$0 => 4 ?
next reply other threads:[~2012-10-18 9:48 UTC|newest] Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-10-18 9:48 jakub at gcc dot gnu.org [this message] 2012-10-18 13:35 ` [Bug debug/54971] " jakub at gcc dot gnu.org 2012-10-18 17:37 ` jamborm at gcc dot gnu.org 2012-10-19 16:01 ` jamborm at gcc dot gnu.org 2012-10-22 14:56 ` jamborm at gcc dot gnu.org 2012-10-22 15:09 ` jakub at gcc dot gnu.org 2012-10-22 15:14 ` jamborm at gcc dot gnu.org 2012-10-22 16:19 ` jakub at gcc dot gnu.org 2012-10-22 20:00 ` jakub at gcc dot gnu.org 2012-10-26 9:33 ` jamborm at gcc dot gnu.org 2012-10-26 16:13 ` jamborm at gcc dot gnu.org 2012-10-26 19:20 ` jakub at gcc dot gnu.org 2012-10-27 17:30 ` jakub at gcc dot gnu.org 2012-10-29 8:36 ` jakub at gcc dot gnu.org 2012-10-29 15:20 ` rguenth at gcc dot gnu.org 2012-10-29 15:26 ` jakub at gcc dot gnu.org 2012-11-05 14:37 ` jakub at gcc dot gnu.org 2013-01-04 14:41 ` jamborm at gcc dot gnu.org
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