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Date: Wed, 29 Jul 2009 17:04:00 -0000
Subject: [Bug rtl-optimization/40906]  New: Wrong code generated for push of long double
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From: "mikulas at artax dot karlin dot mff dot cuni dot cz" <gcc-bugzilla@gcc.gnu.org>
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Hi. Try this program:

#include <stdlib.h>

void f(long double a)
{
        if (a != 1.0) abort();
}

int g(long double b)
{
        f(b);
        return 0;
}

int main(void)
{
        g(1.0);
        return 0;
}

Compile it with "-O2 -mpush-args -mno-accumulate-outgoing-args
-fomit-frame-pointer -fno-inline"

In gcc 4.3.2 it works, in gcc-4.4.1 it aborts. If you add -m128bit-long-double,
both gcc 4.3 and 4.4 fail. The reason is that push of long double in the
function "g" is badly generated --- it is pushing value that is already on the
stack and while it is pushing it, the stack pointer changes. Gcc tries to
compensate for it, but the code is buggy and it ends up pushing wrong words.


-- 
           Summary: Wrong code generated for push of long double
           Product: gcc
           Version: 4.4.1
            Status: UNCONFIRMED
          Severity: major
          Priority: P3
         Component: rtl-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: mikulas at artax dot karlin dot mff dot cuni dot cz
 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=40906