optimization/4822: Bad code with optimization

[ake at purdue dot edu]

>Number:         4822
>Category:       optimization
>Synopsis:       Bad code with optimization
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Nov 07 09:26:00 PST 2001
>Closed-Date:
>Last-Modified:
>Originator:     Antonio Ake
>Release:        unknown-1.0
>Organization:
>Environment:
linux x86 and alpha 21164 tru64 unix
>Description:
This program doesn't work with -O1 and -O2 flags. But when it is
compiled with -O0, then the program runs succesfully.
I have done more testing and this is also a problem with gcc and a C
program.
>How-To-Repeat:
Compile with -02 or -01 and it will show "ERROR". Compile with -O0 and it will work.
This is the Java file and the in the attachment, it is the C file.
public class Test {
    public static void main(String [] args) {
        int i,jjnewStateCnt,startsAt,curPos;
        curPos=1;
        i=67;
        startsAt=67;
        jjnewStateCnt=0;
 
        if ((i = jjnewStateCnt) == (startsAt = 67 - (jjnewStateCnt = startsAt))){
            System.err.println("OK "+ "\n");
            return;
 
        }
        System.out.println("\nERROR\n");
        return;
 
 
 
    }
  }
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
----gnatsweb-attachment----
Content-Type: application/octet-stream; name="test.c"
Content-Transfer-Encoding: base64
Content-Disposition: attachment; filename="test.c"

I2luY2x1ZGUgPG1hdGguaD4KaW50IG1haW4oKXsKCQoJaW50IGksampuZXdTdGF0ZUNudCxzdGFy
dHNBdCxjdXJQb3M7CgljdXJQb3M9MTsKCWk9Njc7CglzdGFydHNBdD02NzsKCWpqbmV3U3RhdGVD
bnQ9MDsKICAgICAgIAoJaWYgKChpID0gampuZXdTdGF0ZUNudCkgPT0gKHN0YXJ0c0F0ID0gNjcg
LSAoampuZXdTdGF0ZUNudCA9IHN0YXJ0c0F0KSkpewoJICAgIHByaW50ZigiT0tcbiIpOwoJICAg
IHJldHVybjsKCSAgICAKCX0KCXByaW50ZigiXG5FUlJPUlxuIik7CglyZXR1cm47Cn0K