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Improve robustness of checking tags of allocated memory blocks #4191

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merged 1 commit into from
Jan 8, 2019
Merged

Improve robustness of checking tags of allocated memory blocks #4191

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14 changes: 7 additions & 7 deletions debugtools/DDR_VM/src/com/ibm/j9ddr/vm29/pointer/helper/J9MemTagHelper.java
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
/*******************************************************************************
* Copyright (c) 2010, 2014 IBM Corp. and others
* Copyright (c) 2010, 2019 IBM Corp. and others
*
* This program and the accompanying materials are made available under
* the terms of the Eclipse Public License 2.0 which accompanies this
Expand Down Expand Up @@ -72,9 +72,8 @@ public class J9MemTagHelper
*/
public static IDATA j9mem_check_tags(VoidPointer memoryPointer, long headerEyecatcher, long footerEyecatcher) throws J9MemTagCheckError
{
J9MemTagPointer headerTagAddress, footerTagAddress = J9MemTagPointer.NULL;

headerTagAddress = j9mem_get_header_tag(memoryPointer);
J9MemTagPointer headerTagAddress = j9mem_get_header_tag(memoryPointer);
J9MemTagPointer footerTagAddress = J9MemTagPointer.NULL;

try {
footerTagAddress = j9mem_get_footer_tag(headerTagAddress);
Expand Down Expand Up @@ -266,8 +265,9 @@ public static VoidPointer j9mem_get_footer_padding(J9MemTagPointer headerEyeCatc

public static UDATA ROUNDED_FOOTER_OFFSET(UDATA number)
{
UDATA a = (number.add(ROUNDING_GRANULARITY - 1)).add(J9MemTag.SIZEOF);
UDATA b = new UDATA(ROUNDING_GRANULARITY - 1).bitNot();
UDATA mask = new UDATA(ROUNDING_GRANULARITY - 1);
UDATA a = mask.add(number).add(J9MemTag.SIZEOF);
UDATA b = mask.bitNot();
return a.bitAnd(b);
}

Expand All @@ -294,7 +294,7 @@ public J9MemTagCheckError(J9MemTagPointer memTag,

public J9MemTagPointer getMemTag()
{
return memTag;
return memTag;
}
}
}