[Bug c/43904] New: Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[Bug c/43904] New: Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[tavianator at gmail dot com]

On x86_64, gcc 4.5.0, this code generates bad assembly:

--- C code ---
typedef unsigned long size_t;
void *memcpy(void *dest, const void *src, size_t n);

void
buggy_init(void *ptr, size_t size)
{
  const char *str = "Hello world!";
  memcpy(ptr, &str, size);
}
--------------

Compiled with gcc -O -foptimize-sibling-calls, the generated assembly looks
like this:

--------------
buggy_init:
        movq    %rsi, %rdx
        movq    $.LC0, -16(%rsp)
        leaq    -16(%rsp), %rsi
        jmp     memcpy
--------------

which passes rsp-16 as memcpy's second argument.  memcpy overwrites this part
of the stack, and copies the wrong value, which causes a crash later.


-- 
           Summary: Wrong code with -foptimize-sibling-calls and memcpy on
                    x86_64
           Product: gcc
           Version: 4.5.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: tavianator at gmail dot com
 GCC build triplet: x86_64-unknown-linux-gnu
  GCC host triplet: x86_64-unknown-linux-gnu
GCC target triplet: x86_64-unknown-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43904

[Bug c/43904] Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2010-04-26 23:47 -------


*** This bug has been marked as a duplicate of 43572 ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |DUPLICATE


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43904

[Bug c/43904] Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[tavianator at gmail dot com]

------- Comment #2 from tavianator at gmail dot com  2010-04-26 23:47 -------
Created an attachment (id=20497)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=20497&action=view)
Full testcase

Proper output:

Stored: 0x40071c
Got:    0x40071c
Hello world!

Output with -O -foptimize-sibling-calls:

Stored: 0x40070c
Got:    0x1
[1]    15940 segmentation fault (core dumped)  ./a.out


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43904

[Bug tree-optimization/43904] Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[hjl at gcc dot gnu dot org]

------- Comment #3 from hjl at gcc dot gnu dot org  2010-04-27 00:25 -------
Subject: Bug 43904

Author: hjl
Date: Tue Apr 27 00:25:18 2010
New Revision: 158757

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158757
Log:
Add a run-time testcase for PR tree-optimization/43904.

2010-04-26  H.J. Lu  <hongjiu.lu@intel.com>

        PR tree-optimization/43904
        * gcc.dg/tree-ssa/tailcall-6.c: New.

Added:
    trunk/gcc/testsuite/gcc.dg/tree-ssa/tailcall-6.c
Modified:
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43904

[Bug tree-optimization/43904] Wrong code with -foptimize-sibling-calls and memcpy on x86_64

[hjl at gcc dot gnu dot org]

------- Comment #4 from hjl at gcc dot gnu dot org  2010-04-27 00:30 -------
Subject: Bug 43904

Author: hjl
Date: Tue Apr 27 00:30:00 2010
New Revision: 158758

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=158758
Log:
Backport testcase from mainline.

2010-04-26  H.J. Lu  <hongjiu.lu@intel.com>

        Backport from mainline
        2010-04-26  H.J. Lu  <hongjiu.lu@intel.com>

        PR tree-optimization/43904
        * gcc.dg/tree-ssa/tailcall-6.c: New.

Added:
    branches/gcc-4_5-branch/gcc/testsuite/gcc.dg/tree-ssa/tailcall-6.c
      - copied unchanged from r158757,
trunk/gcc/testsuite/gcc.dg/tree-ssa/tailcall-6.c
Modified:
    branches/gcc-4_5-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43904