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Date: Thu, 03 Jan 2008 22:32:00 -0000
From: "scox at redhat dot com" <sourceware-bugzilla@sourceware.org>
To: frysk-bugzilla@sourceware.org
Message-ID: <20080103223124.5540.scox@redhat.com>
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Subject: [Bug general/5540] New: location expression DW_OP_breg is sign extended
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There is an intermittent failure caused by the sign extending of DW_OP_breg
values in LocationExpression.java at: long regval = frame.getRegister(register);
The scenario is:
 frysk.stack.Frame.getRegister
 return getRegisterValue(register).asLong()
  frysk.stack.Frame.getRegisterValue
  return new Value(register.getType()
   frysk.value.Value.Value
   where Location might have values such as: -128, 62, -105, -1 
where asLong is:
 frysk.value.Value.asLong
 return 
 ((ArithmeticType)type.getUltimateType()).getBigInteger(location).longValue()
  frysk.value.SignedType.getBigInteger
  return new BigInteger(location.get(order()))

I'm trying to come up with a simple test but here is a small java example
showing what is happening above:

import java.math.BigInteger;
// bigInteger.longValue is -15654349 for bytes = {-1,0x11,0x22,0x33}
// bigInteger.longValue is 4279312947 for bytes = {0,-1,0x11,0x22,0x33}
public class tstbi {
  public static void main(String[] args) {
    BigInteger bigInteger;
    byte [] bytes = {0,-1,0x11,0x22,0x33};
    bigInteger = new BigInteger(bytes);
    System.out.println("bigInteger=" + bigInteger.longValue());
  }
}

-- 
           Summary: location expression DW_OP_breg is sign extended
           Product: frysk
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: general
        AssignedTo: frysk-bugzilla at sourceware dot org
        ReportedBy: scox at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=5540

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