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From: srg@quick.com (Spencer Garrett)
Newsgroups: gnu.gcc.bug
Subject: alloca provokes optimizer bug
Message-ID: <8912121006.AA18083@quick.com>
Date: 12 Dec 89 10:06:38 GMT
Sender: daemon@tut.cis.ohio-state.edu
Distribution: gnu
Organization: GNUs Not Usenet
Lines: 35

gcc 1.36 on Sun 3/50  flags -S -O
unoptimized code appears to be correct.
the optimized code gets b and c confused when
generating the call to sub2().

sub(n)
	int		n;
{
	char		a[3];
	char		b[n + 3];
	char		c;

	sub2(a, b, c);
}

#NO_APP
gcc_compiled.:
.text
	.even
.globl _sub
_sub:
	link a6,#-4
	movel a6@(8),d0
	addql #4,d0
	moveq #-2,d1
	andl d1,d0
	subl d0,sp
	movel sp,d0		| "alloca" results are correct
	extbl d0		| forgot to load c
	movel d0,sp@-
	movel d0,sp@-		| clobbered address of b
	pea a6@(-4)
	jbsr _sub2
	unlk a6
	rts