[Bug c++/39823] New: GCC 4.4.0 produces bad code for libstdc++

[Bug c++/39823] New: GCC 4.4.0 produces bad code for libstdc++

[d dot g dot gorbachev at gmail dot com]

GCC 4.4.0 20090414 i686-pc-linux-gnu

Configure options:

--prefix=/usr/local --enable-languages=c,c++
--enable-version-specific-runtime-libs --with-host-libstdcxx='-lstdc++ -lm'
--disable-bootstrap --disable-shared --disable-nls

Libraries: GMP 4.3, MPFR 2.4.1-p5, PPL 0.10.2, CLooG-PPL 0.15.

In std::string::begin() (_ZNSs5beginEv):

  movl    12(%ebp), %ebx
  movl    (%ebx), %eax

or:

  mov    0xc(%ebp),%ebx
  ...
  mov    (%ebx),%edx  // crash here


-- 
           Summary: GCC 4.4.0 produces bad code for libstdc++
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
        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=39823

[Bug c++/39823] GCC 4.4.0 produces bad code for libstdc++

[d dot g dot gorbachev at gmail dot com]

------- Comment #1 from d dot g dot gorbachev at gmail dot com  2009-04-20 19:26 -------
Created an attachment (id=17657)
 --> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=17657&action=view)
Preprocessed source

g++ -S -std=gnu++0x -O1 string-inst.cc


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39823

[Bug middle-end/39823] GCC 4.4.0 produces bad code for libstdc++

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2009-04-20 20:23 -------
Do you have an example where this happens?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39823

[Bug c++/39823] GCC 4.4.0 produces bad code for libstdc++

[d dot g dot gorbachev at gmail dot com]

------- Comment #3 from d dot g dot gorbachev at gmail dot com  2009-04-20 21:24 -------
For example, a ppl-0.10.2 test numberinput1 crashed because of this.
std::string::begin() is called at src/checked.cc:171

  for (i = num.mantissa.begin(); ...


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d dot g dot gorbachev at gmail dot com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|middle-end                  |c++


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39823

[Bug c++/39823] GCC 4.4.0 produces bad code for libstdc++

[jakub at gcc dot gnu dot org]

------- Comment #4 from jakub at gcc dot gnu dot org  2009-04-20 22:09 -------
What makes you think there is a problem on the _ZNSs5beginEv side?
0(%ebp) is saved %ebp, 4(%ebp) is caller IP, 8(%ebp) is address of return value
(returned by invisible reference), 12(%ebp) is this pointer.  If there is a
crash on dereferencing the this pointer, it is a problem in the caller.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39823

[Bug c++/39823] GCC 4.4.0 produces bad code for libstdc++

[d dot g dot gorbachev at gmail dot com]

------- Comment #5 from d dot g dot gorbachev at gmail dot com  2009-04-21 12:24 -------
(In reply to comment #4)

Sorry, my mistake. The problem indeed was in the caller because of different
compiler flags.


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d dot g dot gorbachev at gmail dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39823