[HARMONY-2141] [drlvm][jit][opt] ABCD removes low bound check if certain constraint exists before array access with a negative index

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 5.0M10
• Component/s: DRLVM
• Environment: Any
• Assignee: Unassigned
• Reporter: Elena Sayapina
• Created: 10/Nov/06 09:28
• Updated: 22/Apr/09 21:42
• Resolved: 06/Jun/07 07:54

Description

ABCD optimization removes low bound check if certain constraint exists before array access with a negative index.

ArrayIndexOutOfBoundsException must be thrown if array alement with negative index is accessed.
But harmony doesn't throw the Exception if abcd pass is turned on in the following case:
Array elements are accessed inside a loop and array index depends on the loop control variable.
A call to an array element with negative index occurred if
control loop variable satisfies some linear constraint.

Please, see the code example below.

Code for reproducing:

public class abcdTest {

public static void main(String[] args) {
System.out.println("Start Test ...");
int i = 0;
int arr[] = new int[300000];
try {
for(i=0; i<100000; i++) {
while(i<3)

{ arr[i-1] = 1; i++; }

}
System.out.println("TEST 1 FAILED: " +
"ArrayIndexOutOfBoundsException wasn't thrown");
} catch (ArrayIndexOutOfBoundsException ae)

{ System.out.println("TEST 1 PASSED"); }

i = 0;
try {
for(i=0; i<100000; i++) {
if (i>5)

{ arr[i-100] = 1; i++; }

}
System.out.println("TEST 2 FAILED: " +
"ArrayIndexOutOfBoundsException wasn't thrown");
} catch (ArrayIndexOutOfBoundsException ae)

{ System.out.println("TEST 2 PASSED"); }

}
}

Steps to Reproduce:
Compile abcdTest class and run it on harmony with '-Xem:server_static'.

Note:
If remove loop variable constraints 'while(i<3)' , 'if(i>5)' in test1, test2 correspondingly, then abcdTest passes.

Windows output:
Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Foundation or its licensors,
as applicable.
java version "1.5.0"
pre-alpha : not complete or compatible
svn = r473012, (Nov 10 2006), Windows/ia32/msvc 1310, release build
http://incubator.apache.org/harmony
Start Test ...
TEST 1 FAILED: ArrayIndexOutOfBoundsException wasn't thrown
TEST 2 FAILED: ArrayIndexOutOfBoundsException wasn't thrown

Linux output:
Apache Harmony Launcher : (c) Copyright 1991, 2006 The Apache Software Foundation or its licensors, as applicable.
java version "1.5.0"
pre-alpha : not complete or compatible
svn = r473012, (Nov 10 2006), Linux/ia32/icc 900, release build
http://incubator.apache.org/harmony
Start Test ...
TEST 1 FAILED: ArrayIndexOutOfBoundsException wasn't thrown
TEST 2 FAILED: ArrayIndexOutOfBoundsException wasn't thrown

Output on RI:
Start Test ...
TEST 1 PASSED
TEST 2 PASSED