Re: Reload bug

[Eric Botcazou <ebotcazou at libertysurf dot fr>]

> Thu Oct 17 17:14:07 CEST 2002  Jan Hubicka  <jh at suse dot cz>
>
> 	PR opt/7630
> 	* reload.c (reload_inner_reg_of_subreg): New argument output;
> 	(push_reload): Update call.

This patch is really bogus, at least on the 3.2 branch: sure, GCC doesn't ICE 
when compiling pr7630.c any more but now it silently produces wrong code!

What you have done is to teach the reload pass to silently transform any 
non-accessible part of a multi-word register into the low part.

Please revert on the 3.2 branch or consider applying the correction I posted 
(which of course brings back the ICE for PR opt/7630).

Thanks.

-- 
Eric Botcazou

/* PR optimization/7630 */
/* Originator: Jeremy Buhler <jbuhler at cs dot wustl dot edu> */
/* { dg-do compile { target i?86-*-* x86_64-*-* } } */
/* { dg-options "-O -fPIC -march=pentium4" } */

typedef union {
    double value;
    struct {
        unsigned int lsw;
        unsigned int msw;
    } parts;
} js_ieee_double_shape_type;

#define JSDOUBLE_HI32(x)  ({js_ieee_double_shape_type sh_u;  \
                            sh_u.value = (x);                \
                            sh_u.parts.msw; })


enum JSOp {JSOP_URSH, JSOP_DIV};
struct JSParseNode {
    enum JSOp     pn_op;
    double        dval;
};

int js_FoldConstants(struct JSParseNode *pn)
{
    double d;
   
    switch (pn->pn_op) {
    case JSOP_URSH:
        d = 0;
       
    case JSOP_DIV:
        if (JSDOUBLE_HI32(d) ^ JSDOUBLE_HI32(d))
            d = 0;
        break;
       
    default:;
    }
   
    pn->dval = d;
    return 0;
}

	.file	"pr7630.c"
	.section	.rodata.cst8,"aM",@progbits,8
	.align 8
.LC0:
	.long	0
	.long	0
	.text
.globl js_FoldConstants
	.type	js_FoldConstants,@function
js_FoldConstants:
	fldz
	pushl	%ebp
	movl	%esp, %ebp
	subl	$16, %esp
	movl	%ebx, -4(%ebp)
	call	.LPR0
	addl	$_GLOBAL_OFFSET_TABLE_, %ebx
	movl	8(%ebp), %edx
	movl	(%edx), %eax
	testl	%eax, %eax
	je	.L3
	cmpl	$1, %eax
	je	.L4
	jmp	.L2
.L3:
	fstp	%st(0)
	fldl	 dot LC0 at GOTOFF(%ebx)
.L4:
	fstl	-16(%ebp)
	movsd	-16(%ebp), %xmm0
	movd	%xmm0, %eax
	cmpl	%eax, %eax
	fldl	 dot LC0 at GOTOFF(%ebx)
	fcmove	%st(1), %st
	fstp	%st(1)
.L2:
	fstpl	4(%edx)
	movl	$0, %eax
	movl	-4(%ebp), %ebx
	movl	%ebp, %esp
	popl	%ebp
	ret
.Lfe1:
	.size	js_FoldConstants,.Lfe1-js_FoldConstants
.LPR0:
	movl	(%esp), %ebx
	ret
	.ident	"GCC: (GNU) 3.2.3 20030405 (prerelease)"