[Bug other/41340] New: [4.5 Regression] G++ produces different code with and without -g option

[Bug other/41340] New: [4.5 Regression] G++ produces different code with and without -g option

[d dot g dot gorbachev at gmail dot com]

GCC 4.5.0 20090903, 20090910: bootstrap with `--enable-build-with-cxx' failed.

cc1plus -O2 -g rtl.ii


-- 
           Summary: [4.5 Regression] G++ produces different code with and
                    without -g option
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: d dot g dot gorbachev at gmail dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug other/41340] [4.5 Regression] G++ produces different code with and without -g option

[d dot g dot gorbachev at gmail dot com]

------- Comment #1 from d dot g dot gorbachev at gmail dot com  2009-09-11 21:33 -------
Created an attachment (id=18567)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18567&action=view)
gzipped preprocessed source file


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug other/41340] [4.5 Regression] G++ produces different code with and without -g option

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[rguenth at gcc dot gnu dot org]

-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|other                       |debug
           Keywords|                            |build
           Priority|P3                          |P2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[davek at gcc dot gnu dot org]

------- Comment #2 from davek at gcc dot gnu dot org  2009-09-19 09:20 -------
Unsurprisingly, adding -g0 to the build line results in an expr.o without the
undefined reference.

/gnu/gcc/obj.no.pr41357/./prev-gcc/xgcc -B/gnu/gcc/obj.no.pr41357/./prev-gcc/
-B/opt/gcc-tools/i686-pc-cygwin/bin/ -B/opt/gcc-tools/i686-pc-cygwin/bin/
-B/opt/gcc-tools/i686-pc-cygwin/lib/ -isystem
/opt/gcc-tools/i686-pc-cygwin/include -isystem
/opt/gcc-tools/i686-pc-cygwin/sys-include    -c  -g -O2 -DIN_GCC   -W -Wall
-Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes
-Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros
-Wno-overlength-strings -Werror -Wold-style-definition -Wc++-compat -fno-common
 -DHAVE_CONFIG_H -I ../gcc -Ijava -I/gnu/gcc/gcc-unpatched/gcc
-I/gnu/gcc/gcc-unpatched/gcc/java -I/gnu/gcc/gcc-unpatched/gcc/../include
-I/gnu/gcc/gcc-unpatched/gcc/../libcpp/include -I/usr/include -I/usr/include
-I/gnu/gcc/gcc-unpatched/gcc/../libdecnumber
-I/gnu/gcc/gcc-unpatched/gcc/../libdecnumber/dpd -I../libdecnumber   
/gnu/gcc/gcc-unpatched/gcc/java/expr.c -o java/expr.o --save-temps -g0


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[davek at gcc dot gnu dot org]

------- Comment #3 from davek at gcc dot gnu dot org  2009-09-19 09:21 -------
(In reply to comment #2)
> Unsurprisingly, 

Oops, sorry, wrong PR!  I was on the wrong browser tab.  Apologies.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[aoliva at gcc dot gnu dot org]

------- Comment #4 from aoliva at gcc dot gnu dot org  2009-10-15 18:17 -------
Is this just because of the use of random number generators to name symbols
with internal linkage, or is there some actual difference that -fcompare-debug
detects?  (-fcompare-debug uses -frandom-seed to avoid the differences).


-- 

aoliva at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[d dot g dot gorbachev at gmail dot com]

------- Comment #5 from d dot g dot gorbachev at gmail dot com  2009-10-16 20:09 -------
There is a real difference, i.e.

- 179:  mov    0x8(%ebp),%edx
- 17c:  movzwl (%edx),%eax
+ 179:  mov    0x8(%ebp),%esi
+ 17c:  movzwl (%esi),%eax

[...]

- 1a0:  mov    %edx,(%esp)
- 1a3:  mov    %edx,-0x24(%ebp)
- 1a6:  call   1a7 <_Z8copy_rtxP7rtx_def+0x37>
- 1ab:  mov    %eax,%ecx
- 1ad:  movzbl 0x3(%eax),%eax
- 1b1:  mov    %eax,%esi
- 1b3:  and    $0xffffffdf,%eax

[...]

+ 1a0:  mov    %esi,(%esp)
+ 1a3:  call   1a4 <_Z8copy_rtxP7rtx_def+0x34>
+ 1a8:  mov    %eax,%edi
+ 1aa:  movzbl 0x3(%eax),%eax
+ 1ae:  mov    %eax,%ecx
+ 1b0:  and    $0xffffffdf,%eax
+ 1b3:  mov    %al,0x3(%edi)

etc.

-fcompare-debug produces  -fcompare-debug failure (length)


-- 

d dot g dot gorbachev at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |UNCONFIRMED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[d dot g dot gorbachev at gmail dot com]

------- Comment #6 from d dot g dot gorbachev at gmail dot com  2009-10-16 20:12 -------
Created an attachment (id=18813)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18813&action=view)
gzipped preprocessed source file

Another case. Compile with:

cc1 -O3 -march=i686 -g tree-eh.i


-    2fb6:      sub    $0xdc,%esp
+    2fb6:      sub    $0xcc,%esp

[...]

-    38f2:      mov    $0x1,%edi
-    38f7:      movb   $0x0,-0x98(%ebp)
-    38fe:      mov    %edx,-0x9c(%ebp)
-    3904:      cmp    %eax,(%ecx)
-    3906:      jne    3ad9 <execute_cleanup_eh+0xb29>

[...]

+    38f2:      xor    %edi,%edi
+    38f4:      cmp    %eax,(%ecx)
+    38f6:      jne    3ac3 <execute_cleanup_eh+0xb13>
+    38fc:      mov    0x0,%eax
+    3901:      xor    %esi,%esi


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #7 from jakub at gcc dot gnu dot org  2009-10-19 17:05 -------
Confirmed, for -m32 -march=i686 -O3 -g vs. -g0 generates different code on:
typedef struct { int t; } *T;
struct S1 { unsigned s1; };
struct S2 { struct S1 s2; };
struct S3 { unsigned s3; struct S2 **s4; };
struct S5 { struct S2 *s5; };

extern void fn0 (void) __attribute__ ((__noreturn__));
T fn6 (struct S3);
void fn7 (void);

int
fn1 (const struct S1 *x)
{
  return x->s1;
}

int
fn2 (const struct S1 *x, unsigned y)
{
  if (y >= x->s1)
    fn0 ();
  return 0;
}

int
fn3 (struct S3 x)
{
  return (x.s3 == fn1 (*x.s4 ? &(*x.s4)->s2 : 0));
}

int
fn4 (struct S3 x)
{
  return fn2 (&(*x.s4)->s2, x.s3);
}

int
fn5 (struct S3 x, T *y)
{
  if (!fn3 (x))
    {
      *y = (T) (long) fn4 (x);
      return 1;
    }
  return 0;
}

void
test (struct S5 *x)
{
  struct S3 a;
  T b;
  unsigned char c = 0;
  a.s4 = &x->s5;
  while (fn5 (a, &b))
    if (!(b->t & 8))
      c = 1;
  a.s4 = &x->s5;
  while ((b = fn6 (a)))
    ;
  if (!c)
    fn7 ();
}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #8 from jakub at gcc dot gnu dot org  2009-10-19 17:14 -------
NONDEBUG_INSN_P differences start appearing in DSE1, looking into it.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|UNCONFIRMED                 |ASSIGNED
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2009-10-19 17:14:34
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #9 from jakub at gcc dot gnu dot org  2009-10-19 18:35 -------
Actually, it is not DSE1 but already loop-invariant.c, and the difference is in
max_reg_pressure of the current loop (4 vs. 5 for one of the classes).


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |vmakarov at gcc dot gnu dot
                   |                            |org
         AssignedTo|jakub at gcc dot gnu dot org|unassigned at gcc dot gnu
                   |                            |dot org
             Status|ASSIGNED                    |NEW


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #10 from jakub at gcc dot gnu dot org  2009-10-20 09:39 -------
Created an attachment (id=18832)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=18832&action=view)
gcc45-pr41340.patch

Patch I'm going to bootstrap/regtest.


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |jakub at gcc dot gnu dot org
                   |dot org                     |
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #11 from jakub at gcc dot gnu dot org  2009-10-20 13:29 -------
Subject: Bug 41340

Author: jakub
Date: Tue Oct 20 13:29:08 2009
New Revision: 153011

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=153011
Log:
        PR debug/41340
        * loop-invariant.c (calculate_loop_reg_pressure): Don't count regs
        referenced just in DEBUG_INSNs.

        * gcc.dg/pr41340.c: New test.

Added:
    trunk/gcc/testsuite/gcc.dg/pr41340.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/loop-invariant.c
    trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] G++ produces different code with and without -g option

[jakub at gcc dot gnu dot org]

------- Comment #12 from jakub at gcc dot gnu dot org  2009-10-20 14:32 -------
The original rtl.ii.gz testcase compiles just fine with -fcompare-debug too
(though, it surely used to be something different, as those loop-invariant.c
changes are from end of September).


-- 

jakub at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340

[Bug debug/41340] [4.5 Regression] GCC produces different code with and without -g option

[d dot g dot gorbachev at gmail dot com]

------- Comment #13 from d dot g dot gorbachev at gmail dot com  2009-10-23 09:15 -------
The original testcase still fails with -fcompare-debug with GCC 4.5.0 20091022.
This bug is now tracked here: bug 41806.

The second bug is indeed fixed.


-- 

d dot g dot gorbachev at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[4.5 Regression] G++        |[4.5 Regression] GCC
                   |produces different code with|produces different code with
                   |and without -g option       |and without -g option


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=41340