Breakpoints on blank lines or comments don't break
authorjoepeck@webkit.org <joepeck@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Fri, 30 Sep 2016 19:22:50 +0000 (19:22 +0000)
committerjoepeck@webkit.org <joepeck@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc>
Fri, 30 Sep 2016 19:22:50 +0000 (19:22 +0000)
commitf5165ed4557c7cde7872a43226d5bfb2fa74462c
treed73d3b88aa35daf092717f1e942b4af02cf18f84
parentfa994b8877579421d8fccee4bc432668fa95ca34
Breakpoints on blank lines or comments don't break
https://bugs.webkit.org/show_bug.cgi?id=9885
<rdar://problem/6134406>

Reviewed by Mark Lam.

Source/JavaScriptCore:

This change introduces a way to perform a Debugger Parse of a script.
This debugger parse gathers a list of breakpoint locations, which
the backend uses to resolve breakpoint locations that came from the
Inspector frontend to the exact location we would actually pause.
We gather this information from the parser so that we can eagerly
get this information without requiring the code to have executed (the
real op_debugs are generated during bytecode generation when code
is actually evaluated).

If an input location was on a line with whitespace or a comment, the
resolved breakpoint location would be before the next statement that
will be executed. That may be the next line, or even later. We also
update our policy when setting breakpoints on and around function
statements to better match user expectations.

For example, when resolving breakpoints in:

    1.  // Comment
    2.  before;
    3.
    4.  function foo() {
    5.      inside;
    6.  }
    7.
    8.  after;

A breakpoint on line 1, a comment, resolves to line 2 the next
statement that will execute.

A breakpoint on line 3 or 7, empty lines, resolves to line 8 the next
statement that will execute. This skips past the definition of foo,
just like stepping would have done. The creation of foo would have
been hoisted, which would have happened before execution of the
other statements.

A breakpoint on line 4, a function signature, resolves to line 5,
inside the function. Users would expect to pause inside of a function
when setting a breakpoint on that function's name or opening brace.

A breakpoint on line 6, a function's closing brace, resolves to
line 6. The debugger will pause whenever execution leaves foo due to
a return and not an exception. This matches stepping behavior. An
explicit or implicit return (the implicit return undefined) will
pause on the closing brace as we leave the function, giving users
an opportunity to inspect the final state before leaving.

--

At this point, op_debug's are still emitted at custom locations during
bytecode generation of other statements / expressions. In order to
ensure the generated op_debugs correspond to locations the Parser
determined were breakpoint locations, the Parser sets a "needs debug
hook" flag on the nodes it will use for breakpoint locations, and
we assert during bytecode generation that op_debugs are only emitted
for nodes that were marked as needing debug hooks.

This still leaves open the possibility that the Parser will mark
some nodes that get missed during bytecode generation, so we might
fail to emit some op_debugs. The next step will be eliminating the
custom emitDebugHooks spread across StatementNode and ExpressionNode
subclasses, and instead always generating op_debugs whenever we
emit a flagged node.

--

* CMakeLists.txt:
* JavaScriptCore.xcodeproj/project.pbxproj:
New DebuggerParseData files.

* API/JSScriptRef.cpp:
(OpaqueJSScript::OpaqueJSScript):
* jsc.cpp:
(functionCheckModuleSyntax):
* parser/SourceCode.h:
(JSC::makeSource):
* parser/SourceProvider.cpp:
(JSC::SourceProvider::SourceProvider):
* parser/SourceProvider.h:
(JSC::SourceProvider::sourceType):
(JSC::StringSourceProvider::create):
(JSC::StringSourceProvider::StringSourceProvider):
(JSC::WebAssemblySourceProvider::WebAssemblySourceProvider):
(JSC::SourceProvider::startPosition): Deleted.
Add a new type on SourceProvider to distinguish if its script was
intended to be a Script, Module, or WebAssembly. This information
will be needed to know how to best parse this file when the
debugger decides to lazily parse.

* runtime/Executable.cpp:
(JSC::EvalExecutable::EvalExecutable):
(JSC::ProgramExecutable::ProgramExecutable):
(JSC::ModuleProgramExecutable::ModuleProgramExecutable):
(JSC::WebAssemblyExecutable::WebAssemblyExecutable):
* runtime/ModuleLoaderPrototype.cpp:
(JSC::moduleLoaderPrototypeParseModule):
ASSERT the SourceProvider type matches the executable type we are
creating for it.

* parser/ASTBuilder.h:
(JSC::ASTBuilder::breakpointLocation):
* parser/SyntaxChecker.h:
(JSC::SyntaxChecker::operatorStackPop):
When gathering breakpoint positions, get the position from the
current node. In the SyntaxChecker, return an invalid position.

* parser/Nodes.h:
(JSC::ExpressionNode::needsDebugHook):
(JSC::ExpressionNode::setNeedsDebugHook):
(JSC::StatementNode::needsDebugHook):
(JSC::StatementNode::setNeedsDebugHook):
When gathering breakpoint positions, mark the node as needing
a debug hook. For now we assert op_debugs generated must come
from these nodes. Later we should just generate op_debugs for
these nodes.

* parser/Parser.cpp:
(JSC::Parser<LexerType>::Parser):
(JSC::Parser<LexerType>::parseStatementListItem):
(JSC::Parser<LexerType>::parseDoWhileStatement):
(JSC::Parser<LexerType>::parseWhileStatement):
(JSC::Parser<LexerType>::parseArrowFunctionSingleExpressionBodySourceElements):
(JSC::Parser<LexerType>::parseForStatement):
(JSC::Parser<LexerType>::parseWithStatement):
(JSC::Parser<LexerType>::parseSwitchStatement):
(JSC::Parser<LexerType>::parseStatement):
(JSC::Parser<LexerType>::parseFunctionBody):
(JSC::Parser<LexerType>::parseFunctionInfo):
(JSC::Parser<LexerType>::parseIfStatement):
(JSC::Parser<LexerType>::parseAssignmentExpression):
* parser/Parser.h:
(JSC::parse):
Add an optional DebuggerParseData struct to the Parser. When available
the Parser will gather debugger data, and parse all functions with the
ASTBuilder instead of SyntaxChecking inner functions.

* debugger/DebuggerParseData.cpp: Added.
(JSC::DebuggerPausePositions::breakpointLocationForLineColumn):
(JSC::DebuggerPausePositions::sort):
(JSC::gatherDebuggerParseData):
(JSC::gatherDebuggerParseDataForSource):
* debugger/DebuggerParseData.h: Copied from Source/JavaScriptCore/debugger/DebuggerPrimitives.h.
(JSC::DebuggerPausePositions::DebuggerPausePositions):
(JSC::DebuggerPausePositions::appendPause):
(JSC::DebuggerPausePositions::appendEntry):
(JSC::DebuggerPausePositions::appendLeave):
The DebuggerParseData struct currently only contains a list of pause positions.
Once populated it can resolve an input location to a pause position.

* bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::emitCall):
(JSC::BytecodeGenerator::emitCallVarargs):
(JSC::BytecodeGenerator::emitDebugHook):
(JSC::BytecodeGenerator::emitEnumeration):
* bytecompiler/BytecodeGenerator.h:
* bytecompiler/NodesCodegen.cpp:
(JSC::EmptyStatementNode::emitBytecode):
(JSC::DebuggerStatementNode::emitBytecode):
(JSC::ExprStatementNode::emitBytecode):
(JSC::DeclarationStatement::emitBytecode):
(JSC::IfElseNode::emitBytecode):
(JSC::DoWhileNode::emitBytecode):
(JSC::WhileNode::emitBytecode):
(JSC::ForNode::emitBytecode):
(JSC::ForInNode::emitBytecode):
(JSC::ContinueNode::emitBytecode):
(JSC::BreakNode::emitBytecode):
(JSC::ReturnNode::emitBytecode):
(JSC::WithNode::emitBytecode):
(JSC::SwitchNode::emitBytecode):
(JSC::ThrowNode::emitBytecode):
Emit op_debugs for the nodes themselves. Assert when we do that the
Parser had marked them as needing a debug hook.

* debugger/Breakpoint.h:
(JSC::Breakpoint::Breakpoint):
A breakpoint may be resolved or unresolved. Debugger::resolveBreakpoint
must be used to resolve the breakpoint. Most methods now require a
resolved breakpoint.

* debugger/Debugger.h:
* debugger/Debugger.cpp:
(JSC::Debugger::detach):
(JSC::Debugger::toggleBreakpoint):
(JSC::Debugger::debuggerParseData):
(JSC::Debugger::resolveBreakpoint):
(JSC::Debugger::setBreakpoint):
(JSC::Debugger::clearParsedData):
Provide a public method to resolve a breakpoint location in a script.
This will gather debugger parse data for the script if none is available.
Ensure clients have resolved a breakpoint before attempting to set it.
Currently we allow only a single breakpoint at a location. This may
need to change if multiple breakpoints resolve to the same location
but have different actions.

* inspector/ScriptDebugListener.h:
ScriptDebugServer::Script is effectively duplicating most of the data from
a SourceProvider. We should eliminate this and just use SourceProvider.

* inspector/ScriptDebugServer.cpp:
(Inspector::ScriptDebugServer::setBreakpointActions):
(Inspector::ScriptDebugServer::removeBreakpointActions):
(Inspector::ScriptDebugServer::getActionsForBreakpoint):
(Inspector::ScriptDebugServer::clearBreakpointActions):
(Inspector::ScriptDebugServer::evaluateBreakpointAction):
(Inspector::ScriptDebugServer::dispatchDidParseSource):
(Inspector::ScriptDebugServer::handleBreakpointHit):
(Inspector::ScriptDebugServer::setBreakpoint): Deleted.
(Inspector::ScriptDebugServer::removeBreakpoint): Deleted.
(Inspector::ScriptDebugServer::clearBreakpoints): Deleted.
* inspector/ScriptDebugServer.h:
Reduce ScriptDebugServer's involvement in breakpoints to just handling
breakpoint actions. Eventually we should eliminate it alltogether and
fold breakpoint logic into Debugger or DebugAgent.

* inspector/agents/InspectorDebuggerAgent.h:
* inspector/agents/InspectorDebuggerAgent.cpp:
(Inspector::buildDebuggerLocation):
(Inspector::parseLocation):
(Inspector::InspectorDebuggerAgent::setBreakpointByUrl):
(Inspector::InspectorDebuggerAgent::setBreakpoint):
(Inspector::InspectorDebuggerAgent::didSetBreakpoint):
(Inspector::InspectorDebuggerAgent::resolveBreakpoint):
(Inspector::InspectorDebuggerAgent::removeBreakpoint):
(Inspector::InspectorDebuggerAgent::continueToLocation):
(Inspector::InspectorDebuggerAgent::didParseSource):
(Inspector::InspectorDebuggerAgent::clearDebuggerBreakpointState):
The Inspector can set breakpoints in multiple ways.
Ensure that once we have the Script that we always
resolve the breakpoint location before setting the
breakpoint. The different paths are:

- setBreakpoint(scriptId, location)
  - Here we know the SourceProvider by its SourceID
    - resolve and set

- setBreakpointByURL(url, location)
  - Search for existing Scripts that match the URL
    - resolve in each and set
  - When new Scripts are parsed that match the URL
    - resolve and set

Source/WebCore:

Tests: inspector/debugger/breakpoints/resolved-dump-all-pause-locations.html
       inspector/debugger/breakpoints/resolved-dump-each-line.html

* bindings/js/CachedScriptSourceProvider.h:
(WebCore::CachedScriptSourceProvider::CachedScriptSourceProvider):

LayoutTests:

* inspector/debugger/breakpoints/resolved-dump-all-pause-locations-expected.txt: Added.
* inspector/debugger/breakpoints/resolved-dump-all-pause-locations.html: Added.
* inspector/debugger/breakpoints/resolved-dump-each-line-expected.txt: Added.
* inspector/debugger/breakpoints/resolved-dump-each-line.html: Added.
* inspector/debugger/breakpoints/resources/dump-functions.js: Added.
* inspector/debugger/breakpoints/resources/dump-general.js: Added.
Test for resolved breakpoint locations in all kinds of different source code.

* inspector/debugger/breakpoints/resources/dump.js: Added.
(TestPage.registerInitializer):
(TestPage.registerInitializer.window.addDumpAllPauseLocationsTestCase):
(TestPage.registerInitializer.window.addDumpEachLinePauseLocationTestCase):
Shared code to run different generalized tests for logging all resolved
breakpoint locations or the resolved breakpoint location if a breakpoint
is set on each individual line.

* inspector/debugger/resources/log-pause-location.js:
(TestPage.registerInitializer.insertCaretIntoStringAtIndex):
(TestPage.registerInitializer.window.findScript):
(TestPage.registerInitializer.window.loadLinesFromSourceCode):
(TestPage.registerInitializer.window.loadMainPageContent):
(TestPage.registerInitializer.window.logResolvedBreakpointLinesWithContext):
(TestPage.registerInitializer.window.logLinesWithContext):
Make some more code shared and provide a way to log two locations,
used to see where a breakpoint was set and where it resolved to.

* inspector/debugger/setBreakpoint-expected.txt:
Update error message. Should not include a period.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@206653 268f45cc-cd09-0410-ab3c-d52691b4dbfc
41 files changed:
LayoutTests/ChangeLog
LayoutTests/TestExpectations
LayoutTests/inspector/debugger/breakpoints/resolved-dump-all-pause-locations-expected.txt [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resolved-dump-all-pause-locations.html [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resolved-dump-each-line-expected.txt [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resolved-dump-each-line.html [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resources/dump-functions.js [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resources/dump-general.js [new file with mode: 0644]
LayoutTests/inspector/debugger/breakpoints/resources/dump.js [new file with mode: 0644]
LayoutTests/inspector/debugger/resources/log-pause-location.js
LayoutTests/inspector/debugger/setBreakpoint-expected.txt
Source/JavaScriptCore/API/JSScriptRef.cpp
Source/JavaScriptCore/CMakeLists.txt
Source/JavaScriptCore/ChangeLog
Source/JavaScriptCore/JavaScriptCore.xcodeproj/project.pbxproj
Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp
Source/JavaScriptCore/bytecompiler/BytecodeGenerator.h
Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp
Source/JavaScriptCore/debugger/Breakpoint.h
Source/JavaScriptCore/debugger/Debugger.cpp
Source/JavaScriptCore/debugger/Debugger.h
Source/JavaScriptCore/debugger/DebuggerParseData.cpp [new file with mode: 0644]
Source/JavaScriptCore/debugger/DebuggerParseData.h [new file with mode: 0644]
Source/JavaScriptCore/inspector/ScriptDebugListener.h
Source/JavaScriptCore/inspector/ScriptDebugServer.cpp
Source/JavaScriptCore/inspector/ScriptDebugServer.h
Source/JavaScriptCore/inspector/agents/InspectorDebuggerAgent.cpp
Source/JavaScriptCore/inspector/agents/InspectorDebuggerAgent.h
Source/JavaScriptCore/jsc.cpp
Source/JavaScriptCore/parser/ASTBuilder.h
Source/JavaScriptCore/parser/Nodes.h
Source/JavaScriptCore/parser/Parser.cpp
Source/JavaScriptCore/parser/Parser.h
Source/JavaScriptCore/parser/SourceCode.h
Source/JavaScriptCore/parser/SourceProvider.cpp
Source/JavaScriptCore/parser/SourceProvider.h
Source/JavaScriptCore/parser/SyntaxChecker.h
Source/JavaScriptCore/runtime/Executable.cpp
Source/JavaScriptCore/runtime/ModuleLoaderPrototype.cpp
Source/WebCore/ChangeLog
Source/WebCore/bindings/js/CachedScriptSourceProvider.h