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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Add $vm debugging tool."
href="https://bugs.webkit.org/show_bug.cgi?id=143809">143809</a>
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<th>Summary</th>
<td>Add $vm debugging tool.
</td>
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>528+ (Nightly build)
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<th>Hardware</th>
<td>Unspecified
</td>
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<th>OS</th>
<td>Unspecified
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
</td>
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<th>Priority</th>
<td>P2
</td>
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<th>Component</th>
<td>JavaScriptCore
</td>
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>mark.lam@apple.com
</td>
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<p>
<div>
<pre>For debugging VM bugs, it would be useful to be able to dump VM data structures from JS code that we instrument. To this end, let's introduce a JS_enableDollarVM option that, if true, installs an $vm property into each JS global object at creation time. The $vm property refers to an object that provides a collection of useful utility functions. For this initial implementation, $vm will have the following:
dfgTrue() - returns true if the current function is DFG compiled, else returns false.
jitTrue() - returns true if the current function is compiled by the baseline JIT, else returns false.
llintTrue() - returns true if the current function is interpreted by the LLINT, else returns false.
gc() - runs a full GC and sweep all dead objects.
fullGC() - runs a full GC but does not sweep dead objects.
edenGC() - runs an eden GC but does not sweep dead objects.
codeBlockForFrame(frameNumber) - gets the codeBlock at the specified frame (0 = current, 1 = caller, etc).
printSourceFor(codeBlock) - prints the source code for the codeBlock.
printByteCodeFor(codeBlock) - prints the bytecode for the codeBlock.
print(str) - prints a string to dataLog output.
printCallFrame() - prints the current CallFrame.
printStack() - prints the JS stack.
printInternal(value) - prints the JSC internal info for the specified value.
With JS_enableDollarVM=true, JS code can use the above functions like so:
$vm.print("Using $vm features\n");</pre>
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