Timestamp:
Apr 16, 2015, 5:25:14 PM (10 years ago)
Author:
[email protected]
Message:

Add $vm debugging tool.
​https://bugs.webkit.org/show_bug.cgi?id=143809

Reviewed by Geoffrey Garen.

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:

crash() - trigger an intentional crash.

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.
edenGC() - runs an eden GC.

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");

(JSC::CodeBlock::printCallOp):

  • FTL compiled functions don't like it when we try to compute the CallLinkStatus. Hence, we skip this step if we're dumping an FTL codeBlock.
  • heap/Heap.cpp:

(JSC::Heap::collectAndSweep):
(JSC::Heap::collectAllGarbage): Deleted.

  • heap/Heap.h:

(JSC::Heap::collectAllGarbage):

  • Add ability to do an Eden collection and sweep.
  • interpreter/StackVisitor.cpp:

(JSC::printIndents):
(JSC::log):
(JSC::logF):
(JSC::StackVisitor::Frame::print):
(JSC::jitTypeName): Deleted.
(JSC::printif): Deleted.

  • Modernize the implementation of StackVisitor::Frame::print(), and remove some now redundant code.
  • Also fix it so that it downgrades gracefully when encountering inlined DFG and compiled FTL functions.

(DebugPrintFrameFunctor::DebugPrintFrameFunctor): Deleted.
(DebugPrintFrameFunctor::operator()): Deleted.
(debugPrintCallFrame): Deleted.
(debugPrintStack): Deleted.

  • these have been moved into JSDollarVMPrototype.cpp.
  • interpreter/StackVisitor.h:
  • StackVisitor::Frame::print() is now enabled for release builds as well so that we can call it from $vm.
  • runtime/JSGlobalObject.cpp:

(JSC::JSGlobalObject::init):
(JSC::JSGlobalObject::visitChildren):

  • runtime/JSGlobalObject.h:
  • Added the $vm instance to global objects conditional on the JSC_enableDollarVM option.
  • runtime/Options.h:
  • Added the JSC_enableDollarVM option.
  • tools/JSDollarVM.cpp: Added.
  • tools/JSDollarVM.h: Added.

(JSC::JSDollarVM::createStructure):
(JSC::JSDollarVM::create):
(JSC::JSDollarVM::JSDollarVM):

  • tools/JSDollarVMPrototype.cpp: Added.
  • This file contains 2 sets of functions:
  1. a C++ implementation of debugging utility functions that are callable when doing debugging from lldb. To the extent possible, these functions try to be cautious and not cause unintended crashes should the user call them with the wrong info. Hence, they are designed to be robust rather than speedy.
  1. the native implementations of JS functions in the $vm object. Where there is overlapping functionality, these are built on top of the C++ functions above to do the work.

Note: it does not make sense for all of the $vm functions to have a C++
counterpart for lldb debugging. For example, the $vm.dfgTrue() function is
only useful for JS code, and works via the DFG intrinsics mechanism.
When doing debugging via lldb, the optimization level of the currently
executing JS function can be gotten by dumping the current CallFrame instead.

(JSC::currentThreadOwnsJSLock):
(JSC::ensureCurrentThreadOwnsJSLock):
(JSC::JSDollarVMPrototype::addFunction):
(JSC::functionCrash): - $vm.crash()
(JSC::functionDFGTrue): - $vm.dfgTrue()
(JSC::CallerFrameJITTypeFunctor::CallerFrameJITTypeFunctor):
(JSC::CallerFrameJITTypeFunctor::operator()):
(JSC::CallerFrameJITTypeFunctor::jitType):
(JSC::functionLLintTrue): - $vm.llintTrue()
(JSC::functionJITTrue): - $vm.jitTrue()
(JSC::gc):
(JSC::functionGC): - $vm.gc()
(JSC::edenGC):
(JSC::functionEdenGC): - $vm.edenGC()
(JSC::isValidCodeBlock):
(JSC::codeBlockForFrame):
(JSC::functionCodeBlockForFrame): - $vm.codeBlockForFrame(frameNumber)
(JSC::codeBlockFromArg):
(JSC::functionPrintSourceFor): - $vm.printSourceFor(codeBlock)
(JSC::functionPrintByteCodeFor): - $vm.printBytecodeFor(codeBlock)
(JSC::functionPrint): - $vm.print(str)
(JSC::PrintFrameFunctor::PrintFrameFunctor):
(JSC::PrintFrameFunctor::operator()):
(JSC::printCallFrame):
(JSC::printStack):
(JSC::functionPrintCallFrame): - $vm.printCallFrame()
(JSC::functionPrintStack): - $vm.printStack()
(JSC::printValue):
(JSC::functionPrintValue): - $vm.printValue()
(JSC::JSDollarVMPrototype::finishCreation):

  • tools/JSDollarVMPrototype.h: Added.

(JSC::JSDollarVMPrototype::create):
(JSC::JSDollarVMPrototype::createStructure):
(JSC::JSDollarVMPrototype::JSDollarVMPrototype):

File:
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