dead code elimination bug in egcs-2.90.08

[Burkhard Steding]

Hi,

here is a little example that does not get compiled right.
I discovered this problem on sparc, but it does not seem
to be specific to any architecture or operating system.

############################################################

int ts(int a)
{
  if (a < 1000 && a > 2000)
    return 1;
  else
    return 0;
}

int tu(unsigned int a)
{
  if (a < 1000 && a > 2000)
    return 1;
  else
    return 0;
}

############################################################

The unsigned comparison is compiled right (0 is returned),
but the signed case is wrong (1 is returned), see below.

############################################################

	.file	"t.c"
! GNU C version egcs-2.90.08 970917 (gcc2-970802 experimental) (sparc-sun-solaris2.5.1) compiled by GNU C version egcs-2.90.08 970917 (gcc2-970802 experimental).
! options passed:  -O
! options enabled:  -fdefer-pop -fomit-frame-pointer -fthread-jumps
! -fpeephole -ffunction-cse -finline -fkeep-static-consts
! -fpcc-struct-return -fdelayed-branch -fexceptions -fcommon -fverbose-asm
! -fgnu-linker -falias-check -fargument-alias -mepilogue -mapp-regs

gcc2_compiled.:
.section	".text"
	.align 4
	.global ts
	.type	 ts,#function
	.proc	04
ts:
.LLFB1:
	!#PROLOGUE# 0
	!#PROLOGUE# 1
	retl
	mov 1,%o0
.LLFE1:
.LLfe1:
	.size	 ts,.LLfe1-ts
	.align 4
	.global tu
	.type	 tu,#function
	.proc	04
tu:
.LLFB2:
	!#PROLOGUE# 0
	!#PROLOGUE# 1
	retl
	mov 0,%o0
.LLFE2:
.LLfe2:
	.size	 tu,.LLfe2-tu
	.ident	"GCC: (GNU) egcs-2.90.08 970917 (gcc2-970802 experimental)"

############################################################

When compiled without -O, the generated code is correct.
BTW, it would be nice if "egcc -O -Wall ..." produced a warning
in cases like this.

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