Re: c/10844: Wrong computation on nan initialized vectors.

[Christian Szegedy <szegedy@or.uni-bonn.de>]

The following reply was made to PR c/10844; it has been noted by GNATS.

From: Christian Szegedy <szegedy@or.uni-bonn.de>
To: ehrhardt@mathematik.uni-ulm.de, gcc-bugs@gcc.gnu.org,
   gcc-gnats@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org, nobody@gcc.gnu.org, szegedy@or.uni-bonn.de
Subject: Re: c/10844: Wrong computation on nan initialized vectors.
Date: Mon, 19 May 2003 12:05:19 +0200

 ehrhardt@mathematik.uni-ulm.de wrote:
 
 >Synopsis: Wrong computation on nan initialized vectors.
 >
 >State-Changed-From-To: open->feedback
 >State-Changed-By: cae
 >State-Changed-When: Sun May 18 17:49:33 2003
 >State-Changed-Why:
 >    I can't reproduce this. Could you tell us the compiler options used
 >    to compile the code, the output of gcc -v and the assemble code
 >    generated for the main function? Additionally your libc version might
 >    be of interest here.
 >    
 >        regards  Christian
 >    
 >
 >http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=10844
 >
 >  
 >
 I just used "gcc -lm bug.c" to compile the code.
 I am at work, but I can reproduce the bug on my SuSe 8.0 box, with
 
 Reading specs from 
 /home/szegedy/extern/gcc-3.2-install/lib/gcc-lib/i686-pc-linux-gnu/3.2/specs
 Configured with: ../gcc-3.2/configure 
 --prefix=/home/szegedy/extern/gcc-3.2-install
 Thread model: posix
 gcc version 3.2
 
 How can I determine the glibc version?
 
 The bug also occurs with the old 2.95 compiler.
 
 The assembler output is:
 
         .file   "bug.c"
         .section        .rodata
 .LC0:
         .string ""
 .LC2:
         .string "%lg\n"
         .text
         .align 2
 .globl main
         .type   main,@function
 main:
         pushl   %ebp
         movl    %esp, %ebp
         pushl   %esi
         pushl   %ebx
         subl    $32, %esp
         andl    $-16, %esp
         movl    $0, %eax
         subl    %eax, %esp
         movl    $10, -16(%ebp)
         movl    -16(%ebp), %eax
         sall    $3, %eax
         movl    %eax, (%esp)
         call    malloc
         movl    %eax, -20(%ebp)
         movl    $0, -12(%ebp)
 .L2:
         movl    -12(%ebp), %eax
         cmpl    -16(%ebp), %eax
         jl      .L5
         jmp     .L3
 .L5:
         movl    -12(%ebp), %eax
         leal    0(,%eax,8), %esi
         movl    -20(%ebp), %ebx
         movl    $.LC0, (%esp)
         call    nan
         pushl   %eax
         fildl   (%esp)
         leal    4(%esp), %esp
         fstpl   (%ebx,%esi)
         leal    -12(%ebp), %eax
         incl    (%eax)
         jmp     .L2
 .L3:
         movl    -20(%ebp), %eax
         movl    $0, (%eax)
         movl    $0, 4(%eax)
         movl    -20(%ebp), %edx
         movl    -20(%ebp), %eax
         fldl    (%eax)
         fldz
         faddp   %st, %st(1)
         fstpl   (%edx)
         movl    $.LC2, (%esp)
         movl    -20(%ebp), %eax
         movl    4(%eax), %edx
         movl    (%eax), %eax
         movl    %eax, 4(%esp)
         movl    %edx, 8(%esp)
         call    printf
         movl    $0, %eax
         leal    -8(%ebp), %esp
         popl    %ebx
         popl    %esi
         popl    %ebp
         ret
 .Lfe1:
         .size   main,.Lfe1-main
         .ident  "GCC: (GNU) 3.2"