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* [Bug ipa/66424] New: wrong code at -O2 and -O3 on x86_64-linux-gnu in 32-bit mode
@ 2015-06-04 22:43 su at cs dot ucdavis.edu
  2015-06-05  6:16 ` [Bug ipa/66424] " jakub at gcc dot gnu.org
                   ` (9 more replies)
  0 siblings, 10 replies; 11+ messages in thread
From: su at cs dot ucdavis.edu @ 2015-06-04 22:43 UTC (permalink / raw)
  To: gcc-bugs

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66424

            Bug ID: 66424
           Summary: wrong code at -O2 and -O3 on x86_64-linux-gnu in
                    32-bit mode
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: ipa
          Assignee: unassigned at gcc dot gnu.org
          Reporter: su at cs dot ucdavis.edu
  Target Milestone: ---

The current gcc trunk (and 5.1.x) miscompiles the following code on
x86_64-linux at -O2 and -O3 in 32-bit mode (but not in 64-bit mode).  

This is a regression from 4.9.x.


$ gcc-trunk -v
Using built-in specs.
COLLECT_GCC=gcc-trunk
COLLECT_LTO_WRAPPER=/usr/local/gcc-trunk/libexec/gcc/x86_64-unknown-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc-trunk/configure --prefix=/usr/local/gcc-trunk
--enable-languages=c,c++ --disable-werror --enable-multilib
Thread model: posix
gcc version 6.0.0 20150604 (experimental) [trunk revision 224114] (GCC) 
$ 
$ gcc-trunk -m32 -Os small.c; ./a.out
small.c: In function ‘fn1’:
small.c:7:1: warning: type of ‘p’ defaults to ‘int’ [-Wimplicit-int]
 fn1 (p)
 ^
$ gcc-trunk -m64 -O2 small.c; ./a.out
small.c: In function ‘fn1’:
small.c:7:1: warning: type of ‘p’ defaults to ‘int’ [-Wimplicit-int]
 fn1 (p)
 ^
$ gcc-4.9.2 -m32 -O2 small.c; ./a.out
$ 
$ gcc-trunk -m32 -O2 small.c
small.c: In function ‘fn1’:
small.c:7:1: warning: type of ‘p’ defaults to ‘int’ [-Wimplicit-int]
 fn1 (p)
 ^
$ ./a.out
Aborted (core dumped)
$ 


---------------------------------------


int a, b, c, d, e[2], f, l, m, n, o;
long long g = 1, j;
static unsigned int h;
static int i, k;

void
fn1 (p)
{
  f = 1 ^ e[f ^ (p & 1)];
}

static void
fn2 (long long p)
{
  f = 1 ^ e[(f ^ 1) & 1];
  fn1 (p >> 1 & 1);
  fn1 (p >> 32 & 1);
}

void
fn3 (int p)
{
  g |= j = p;
}

int
main ()
{
  e[0] = 1;
  char p = l;
  h = --g;
  i = o = c;
  m = d ? 1 / d : 0;
  fn3 (l || 0);
  b = a;
  n = j++;
  k--;
  fn2 (g);
  fn2 (h);
  fn2 (i);

  if (k + f)
    __builtin_abort ();

  return 0;
}
>From gcc-bugs-return-488129-listarch-gcc-bugs=gcc.gnu.org@gcc.gnu.org Thu Jun 04 23:26:46 2015
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From: "dje at google dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/65669] Don't emit debug info for fake_ostream version of cerr (and others)
Date: Thu, 04 Jun 2015 23:26:00 -0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?ide669

--- Comment #3 from Doug Evans <dje at google dot com> ---
(In reply to Doug Evans from comment #2)
> I was wondering if one could just do a strip --strip-debug of globals_io.o
> in the Makefile.

This doesn't work, as is, because gdb ignores the DIE with the real type (from
ios_init.cc) because it's a declaration.


^ permalink raw reply	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2015-09-30 14:44 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2015-06-04 22:43 [Bug ipa/66424] New: wrong code at -O2 and -O3 on x86_64-linux-gnu in 32-bit mode su at cs dot ucdavis.edu
2015-06-05  6:16 ` [Bug ipa/66424] " jakub at gcc dot gnu.org
2015-06-05 17:44 ` su at cs dot ucdavis.edu
2015-06-05 18:03 ` joseph at codesourcery dot com
2015-06-05 19:23 ` [Bug ipa/66424] [5/6 Regression] " jakub at gcc dot gnu.org
2015-06-22 12:03 ` rguenth at gcc dot gnu.org
2015-07-16  9:17 ` rguenth at gcc dot gnu.org
2015-07-21 19:55 ` vmakarov at gcc dot gnu.org
2015-09-29 16:38 ` vmakarov at gcc dot gnu.org
2015-09-29 18:26 ` doko at gcc dot gnu.org
2015-09-30 14:44 ` aurelien at aurel32 dot net

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