From mboxrd@z Thu Jan  1 00:00:00 1970
From: hjl@lucon.org (H.J. Lu)
To: scox@cygnus.com
Cc: egcs@cygnus.com
Subject: A bug in reg-stack.c
Date: Mon, 16 Mar 1998 20:25:00 -0000
Message-id: <m0yEQiZ-00058gC@ocean.lucon.org>
X-SW-Source: 1998-03/msg00552.html

Hi,

reg-stack.c has quite a few bugs. Here is a test case.

# gcc cc -S -O2 980313-1.c
cc: Internal compiler error: program cc1 got fatal signal 6

The problem is in compare_for_stack_reg (). Around line 2063, there
are

  replace_reg (src1, FIRST_STACK_REG);
   
  if (STACK_REG_P (*src2))
    replace_reg (src2, get_hard_regnum (regstack, *src2));

  if (src1_note)
    {
      CLEAR_HARD_REG_BIT (regstack->reg_set, REGNO (XEXP (src1_note, 0)));
      replace_reg (&XEXP (src1_note, 0), FIRST_STACK_REG);
      regstack->top--;
    }

That is quite bogus since probably REGNO (XEXP (src1_note, 0)) !=
FIRST_STACK_REG. regstack->top-- is not correct to remove the dead
register. Could someone please take a look?

Thanks.


-- 
H.J. Lu (hjl@gnu.org)
---980313-1.c-----
/* { dg-do compile { target i?86-*-* } } */
/* { dg-options "-O2 -mach=pentiumpro" } */

extern __inline  double
__expm1 (double __x)
{
  double __temp;
  __temp -= 1.0;
  return __temp;
}
extern __inline  double
__sgn1 (double __x)
{
  return __x >= 0.0 ? 1.0 : -1.0;
}
double
tanh (double __x)
{
  register double __exm1 = __expm1 (__x);
  return __exm1 / (__exm1 + 2.0) * __sgn1 (-__x);
}