From mboxrd@z Thu Jan  1 00:00:00 1970
From: "William M. Brack" <wbrack@mmm.com.hk>
To: nobody@gcc.gnu.org
Cc: gcc-prs@gcc.gnu.org
Subject: Re: optimization/3387: GCC 3.0 optimisation -O2 -fPIC produces incorrect code
Date: Fri, 22 Jun 2001 19:56:00 -0000
Message-id: <20010623025605.10340.qmail@sourceware.cygnus.com>
X-SW-Source: 2001-06/msg01009.html
List-Id: <gcc-prs.sourceware.org>

The following reply was made to PR optimization/3387; it has been noted by GNATS.

From: "William M. Brack" <wbrack@mmm.com.hk>
To: <gcc-gnats@gcc.gnu.org>
Cc:  
Subject: Re: optimization/3387: GCC 3.0 optimisation -O2 -fPIC produces incorrect code
Date: Sat, 23 Jun 2001 10:50:59 +0800

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 Looking at the bug database for this report, it appears that the attached
 file was somehow lost during the web submission.  If true, please add it to
 the PR for me; if false, please ignore this (and excuse my ignorance).
 
 W. Brack
 
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 /*=0D
 The following program generates incorrect code (judged by reading the =
 generated=0D
 assembler source) when compiled with flags -O2 and -fPIC.  It seems to =
 compile=0D
 correctly with flags -O1 and -fPIC, as well as with flags -O2 only.=0D
 =0D
 The critical problem is that the routine "f1" modifies the referenced =
 param (str),=0D
 so the restoration of the initial value is required ( "str =3D tmp;" ).  =
 However,=0D
 the generated code deletes that statement.=0D
 =0D
 Please note:  This fragment is completely artificial - it is a VERY =
 reduced excerpt=0D
 from a reasonably complex program in which the problem caused complete =
 failure.=0D
 Any criticism about about "poor coding" will be taken as a personal =
 insult ;>)=0D
 */=0D
 =0D
 int f1(int uri, char **str);=0D
 int f2(int uri, char **str);=0D
 =0D
 int bug(int uri, char *str) {=0D
     int ret;=0D
     char *tmp =3D str;		/* Save the initial value of param str */=0D
 =0D
     ret =3D f1(uri, &str);	/* This routine modifies the value of str =
 */=0D
     if (ret !=3D 0) {=0D
 	str =3D tmp;		/* Restore the initial value of str */=0D
         ret =3D f2(uri, &str);=0D
     }=0D
     if (ret !=3D 0)=0D
 	return(ret);=0D
 =0D
     ret =3D f2(uri, &str);=0D
 =0D
     return(0);=0D
 }=0D
 
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