Re: optimization/3783

[Steve Ellcey <sje at cup dot hp dot com>]

The following reply was made to PR optimization/3783; it has been noted by GNATS.

From: Steve Ellcey <sje@cup.hp.com>
To: wilson@redhat.com, gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org,
	linux-ia64@linuxia64.org, davidm@hpl.hp.com, davidm@hpl.hp.com,
	gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org
Cc:  
Subject: Re: optimization/3783
Date: Wed, 01 Aug 2001 15:02:40 -0700

 FYI:  I have spent a little time looking at this bug, I haven't got a
 fix but I did create a smaller test program that I am including in this
 mail.  Running it on HP-UX IA64 it looks like the optimizer is going
 into an infinite loop in canon_rtx because one of the entries (REG 351
 in my case) is set to be a plus RTX of REG 351 and CONST 1.  How that
 self-referential access got in there, I don't know but it seems to be
 the cause of the problem.  Anyway I thought I would just send off what
 I know and the smaller test case before going off on some vacation.
 
 Steve Ellcey
 sje@cup.hp.com
 
 extern struct buffer_headX *udf_read_taggedX(unsigned short *);
 #pragma pack(1)
 typedef struct {
         unsigned int extLength;
         unsigned int extLocation;
 } extent_adX;
 #pragma pack()
 struct super_blockX {
         unsigned long s_blocksize;
         unsigned char s_blocksize_bits;
         unsigned char s_dirt;
 };
 struct buffer_headX {
         struct buffer_head *b_next;
         unsigned long b_blocknr;
         unsigned short b_size;
         unsigned short b_list;
 };
 static void
 udf_load_logicalvolintX(struct super_blockX *sb, extent_adX loc)
 {
         struct buffer_headX *bh = ((void *)0);
         unsigned short ident;
         while ((bh = udf_read_taggedX(&ident)) && loc.extLength > 0)
         {
                 loc.extLength -= sb->s_blocksize;
                 loc.extLocation ++;
         }
 }
 
 http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view&pr=3783&database=gcc