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Bug 6855 - An egcc optimizer bug
Summary: An egcc optimizer bug
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: egcs
Version: 6.0
Hardware: i386
OS: Linux
Target Milestone: ---
Assignee: Cristian Gafton
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 1999-11-09 18:16 UTC by ezharkov
Modified: 2008-05-01 15:37 UTC (History)
1 user (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2000-02-05 18:59:46 UTC

Attachments (Terms of Use)

Description ezharkov 1999-11-09 18:16:21 UTC
The following program:

tcsh> cat bug.c
#include <stdio.h>
#include <stdlib.h>

union u {
  unsigned i;
  struct {
    unsigned low : 16;
    unsigned high : 16;
  } s;

static void cvt (unsigned *v) {
  union u u;
  u.i = *v;
  u.s.low = 3;
  memcpy (v, &u.i, sizeof (unsigned));

int main () {
  unsigned i = 0x00010002;
  cvt (&i);
  printf ("res = %08x\n", i);
  return EXIT_SUCCESS;

Compiled on:

tcsh> uname -a
Linux hostname 2.2.12 #3 SMP Thu Sep 2 03:34:03 MDT 1999
i586 unknown

Using cc:

tcsh> cc --version

With the command:

tcsh> cc -O1 -o bug bug.c

Produces the following result:

tcsh> ./bug
res = 00000003

I would prefer it to produce a "00010003" result.

Comment 1 Jim Kingdon 1999-11-09 21:52:59 UTC
At first glance this looks like the same bug as 5184 (also see, which for reference concerns
the "addressof" feature within GCC.

Comment 2 Bill Nottingham 2000-02-05 18:59:59 UTC
Fixed in the egcs currently in Raw Hide.

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