Re: egcs 1.0.2

[Bruno Haible <haible at ilog dot fr>]

H.J.:
> It appears that the patch really came from
>
> Mon Sep 29 08:21:35 1997  Bruno Haible 
> 
>         * i386.c (notice_update_cc): Use reg_overlap_mentioned_p.
> 
> which is not in egcs 1.0.1.

I apologize for having sent that patch to Kenner only, not to this list.
Here it is again.


egcs-1.0.1 has a bug which wasn't present in gcc-2.7.2.
A "testl $64,%eax" or "testb $64,-4(%ebp)" is omitted. This kind of bug
occurs in particular when DImode variables are used. Please find below
a problem report and a fix.

========================= foo.c ======================
typedef struct { int addr; int type; } object;

extern object bar (object);
object foo (object x, object y)
{
  object z = *(object*)(x.addr);
  if (z.type & 64)
    {
      y = *(object*)(z.addr+8);
      z = *(object*)(z.addr);
      if (z.type & 64)
        y = bar(y);
    }
  return y;
}
======================================================
$ ./xgcc -B./ -O -S foo.c && cat foo.s
	.file	"foo.c"
	.version	"01.01"
/ GNU C version egcs-2.90.23 980102 (egcs-1.0.1 release) (i586-pc-linux-gnulibc1) compiled by GNU C version 2.7.2.
/ options passed:  -O
/ options enabled:  -fdefer-pop -fthread-jumps -fpeephole -ffunction-cse
/ -finline -fkeep-static-consts -fpcc-struct-return -fcommon -fverbose-asm
/ -fgnu-linker -falias-check -fargument-alias -m80387 -mhard-float
/ -mno-soft-float -mieee-fp -mfp-ret-in-387 -mschedule-prologue
/ -mcpu=pentium -march=pentium

gcc2_compiled.:
.text
	.align 4
.globl foo
	.type	 foo,@function
foo:
	pushl %ebp
	movl %esp,%ebp
	subl $8,%esp
	pushl %esi
	pushl %ebx
	movl 8(%ebp),%ebx
	movl 12(%ebp),%eax
	movl (%eax),%edx
	movl %edx,-8(%ebp)
	movl 4(%eax),%eax
	movl %eax,-4(%ebp)
	testb $64,-4(%ebp)
	je .L2
	movl 8(%edx),%esi
	movl %esi,20(%ebp)
	movl 12(%edx),%ecx
	movl %ecx,24(%ebp)
	movl (%edx),%eax
	movl %eax,-8(%ebp)
	movl 4(%edx),%eax
	movl %eax,-4(%ebp)
				;; <========== "testl $64,%eax" missing here
	je .L2
	leal 20(%ebp),%eax
	pushl %ecx
	pushl %esi
	pushl %eax
	call bar
.L2:
	movl 20(%ebp),%eax
	movl %eax,(%ebx)
	movl 24(%ebp),%eax
	movl %eax,4(%ebx)
	movl %ebx,%eax
	leal -16(%ebp),%esp
	popl %ebx
	popl %esi
	movl %ebp,%esp
	popl %ebp
	ret $4
.Lfe1:
	.size	 foo,.Lfe1-foo
	.ident	"GCC: (GNU) egcs-2.90.23 980102 (egcs-1.0.1 release)"
===============================================================================

Here is the fix, which is already present in gcc-2.8.0. (Incidentally,
Kenner mutilated my changelog entry when putting in the patch.)

Sun Sep 28 03:45:32 1997  Bruno Haible  <bruno@linuix.mathematik.uni-karlsruhe.de>

        * i386/i386.c (notice_update_cc): Use reg_overlap_mentioned_p, not
        reg_mentioned_p, for cc_status.value1 might be a ZERO_EXTRACT rtx.

===============================================================================
*** egcs-1.0.1/gcc/config/i386/i386.c.bak	Fri Dec 19 09:47:13 1997
--- egcs-1.0.1/gcc/config/i386/i386.c	Mon Feb 16 22:59:43 1998
***************
*** 3408,3418 ****
  	  && (REG_P (SET_SRC (exp))
  	      || GET_RTX_CLASS (GET_CODE (SET_SRC (exp))) == '<'))
  	{
! 	  if (cc_status.value1 && GET_CODE (cc_status.value1) == MEM
! 	      || reg_mentioned_p (SET_DEST (exp), cc_status.value1))
  	    cc_status.value1 = 0;
! 	  if (cc_status.value2 && GET_CODE (cc_status.value2) == MEM
! 	      || reg_mentioned_p (SET_DEST (exp), cc_status.value2))
  	    cc_status.value2 = 0;
  	  return;
  	}
--- 3408,3418 ----
  	  && (REG_P (SET_SRC (exp))
  	      || GET_RTX_CLASS (GET_CODE (SET_SRC (exp))) == '<'))
  	{
! 	  if (cc_status.value1
! 	      && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value1))
  	    cc_status.value1 = 0;
! 	  if (cc_status.value2
! 	      && reg_overlap_mentioned_p (SET_DEST (exp), cc_status.value2))
  	    cc_status.value2 = 0;
  	  return;
  	}
===============================================================================

Can you please put in this patch in the devel branch and later into
egcs-1.0.2 ?

Bruno