Skip to content
  • mark.lam@apple.com's avatar
    Fix 30% JSBench regression (caused by adding column numbers to stack traces). · 5b45f90a
    mark.lam@apple.com authored
    https://bugs.webkit.org/show_bug.cgi?id=118481.
    
    Reviewed by Mark Hahnenberg and Geoffrey Garen.
    
    Source/JavaScriptCore: 
    
    Previously, we already capture ExpressionRangeInfo that provides a divot for
    each bytecode that can potentially throw an exception (and therefore generate
    a stack trace). On first attempt to compute column numbers, we then do a walk
    of the source string to record all line start positions in a table associated
    with the SourceProvider. The column number can then be computed as
        divot - lineStartFor(bytecodeOffset).
    
    The computation of this lineStarts table is the source of the 30% JSBench
    performance regression.
    
    The new code now records lineStarts as the lexer and parser scans the source
    code. These lineStarts are then used to compute the column number for the
    given divot, and stored in the ExpressionRangeInfo. Similarly, we also capture
    the line number at the divot point and store that in the ExpressionRangeInfo.
    Hence, to look up line and column numbers, we now lookup the ExpressionRangeInfo
    for the bytecodeOffset, and then compute the line and column from the values
    stored in the expression info.
    
    The strategy:
    1. We want to minimize perturbations to the lexer and parser. Specifically,
       the changes added should not change how it scans code, and generate bytecode.
    2. We regard the divot as the source character position we are interested
       in. As such, we'll capture line and lineStart (for column) at the point
       when we capture the divot information. This ensures that the 3 values are
       consistent.
    
    How the change is done:
    1. Change the lexer to track lineStarts.
    2. Change the parser to capture line and lineStarts at the point of capturing
       divots.
    3. Change the parser and associated code to plumb these values all the way to
       the point that the correspoinding ExpressionRangeInfo is emitted.
    4. Propagate and record SourceCode firstLine and firstLineColumnOffset to the
       the necessary places so that we can add them as needed when reifying
       UnlinkedCodeBlocks into CodeBlocks.
    5. Compress the line and column number values in the ExpressionRangeInfo. In
       practice, we seldom have both large line and column numbers. Hence, we can
       encode both in an uint32_t most of the time. For the times when we encounter
       both large line and column numbers, we have a fallback to store the "fat"
       position info.
    6. Emit an ExpressionRangeInfo for UnaryOp nodes to get more line and column
       number coverage.
    7. Change the interpreter to use the new way of computing line and column.
    8. Delete old line and column computation code that is now unused.
    
    Misc details:
    - the old lexer was tracking both a startOffset and charPosition where
      charPosition equals startOffset - SourceCode.startOffset. We now use
      startOffset exclusively throughout the system for consistency.
      All offset values (including lineStart) are relative to the start of the
      SourceProvider string. These values will only be converted to be relative
      to the SourceCode.startOffset at the very last minute i.e. when the divot
      is stored into the ExpressionRangeInfo.
    
      This change to use the same offset system everywhere reduces confusion
      from having to convert back and forth between the 2 systems. It also
      enables a lot of assertions to be used.
    
    - Also fixed some bugs in the choice of divot positions to use. For example,
      both Eval and Function expressions previously used column numbers from
      the start of the expression but used the line number at the end of the
      expression. This is now fixed to use either the start or end positions
      as appropriate, but not a mix of line and columns from both.
    
    - Why use ints instead of unsigneds for offsets and lineStarts inside the
      lexer and parser?
      Some tests (e.g. fast/js/call-base-resolution.html and
      fast/js/eval-cross-window.html) has shown that lineStart offsets can be
      prior to the SourceCode.startOffset. Keeping the lexer offsets as ints
      simplifies computations and makes it easier to maintain the assertions
      that (startOffset >= lineStartOffset).
    
      However, column and line numbers are always unsigned when we publish
      them to the ExpressionRangeInfo. The ints are only used inside the
      lexer and parser ... well, and bytecode generator.
    
    - For all cases, lineStart is always captured where the divot is captured.
      However, some sputnik conformance tests have shown that we cannot honor
      line breaks for assignment statements like the following:
    
          eval("x\u000A*=\u000A-1;");
    
      In this case, the lineStart is expected to be captured at the start of
      the assignment expression instead of at the divot point in the middle.
      The assignment expression is the only special case for this.
    
    This patch has been tested against the full layout tests both with release
    and debug builds with no regression.
    
    * API/JSContextRef.cpp:
    (JSContextCreateBacktrace):
      - Updated to use the new StackFrame::computeLineAndColumn().
    * bytecode/CodeBlock.cpp:
    (JSC::CodeBlock::CodeBlock):
      - Added m_firstLineColumnOffset initialization.
      - Plumbed the firstLineColumnOffset into the SourceCode.
      - Initialized column for op_debug using the new way.
    (JSC::CodeBlock::lineNumberForBytecodeOffset):
      - Changed to compute line number using the ExpressionRangeInfo.
    (JSC::CodeBlock::columnNumberForBytecodeOffset): Added
      - Changed to compute column number using the ExpressionRangeInfo.
    (JSC::CodeBlock::expressionRangeForBytecodeOffset):
    * bytecode/CodeBlock.h:
    (JSC::CodeBlock::firstLineColumnOffset):
    (JSC::GlobalCodeBlock::GlobalCodeBlock):
      - Plumbed firstLineColumnOffset through to the super class.
    (JSC::ProgramCodeBlock::ProgramCodeBlock):
      - Plumbed firstLineColumnOffset through to the super class.
    (JSC::EvalCodeBlock::EvalCodeBlock):
      - Plumbed firstLineColumnOffset through to the super class.
        But for EvalCodeBlocks, the firstLineColumnOffset is always 1
        because we're starting with a new source string with no start
        offset.
    (JSC::FunctionCodeBlock::FunctionCodeBlock):
      - Plumbed firstLineColumnOffset through to the super class.
    
    * bytecode/ExpressionRangeInfo.h:
      - Added modes for encoding line and column into a single 30-bit
        unsigned. The encoding is in 1 of 3 modes:
        1. FatLineMode: 22-bit line, 8-bit column
        2. FatColumnMode: 8-bit line, 22-bit column
        3. FatLineAndColumnMode: 32-bit line, 32-bit column
    (JSC::ExpressionRangeInfo::encodeFatLineMode): Added.
      - Encodes line and column into the 30-bit position using FatLine mode.
    (JSC::ExpressionRangeInfo::encodeFatColumnMode): Added.
      - Encodes line and column into the 30-bit position using FatColumn mode.
    (JSC::ExpressionRangeInfo::decodeFatLineMode): Added.
      - Decodes the FatLine mode 30-bit position into line and column.
    (JSC::ExpressionRangeInfo::decodeFatColumnMode): Added.
      - Decodes the FatColumn mode 30-bit position into line and column.
    
    * bytecode/UnlinkedCodeBlock.cpp:
    (JSC::UnlinkedFunctionExecutable::UnlinkedFunctionExecutable):
      - Plumbed startColumn through.
    (JSC::UnlinkedFunctionExecutable::link):
      - Plumbed startColumn through.
    (JSC::UnlinkedCodeBlock::lineNumberForBytecodeOffset):
      - Computes a line number using the new way.
    (JSC::UnlinkedCodeBlock::expressionRangeForBytecodeOffset):
      - Added decoding of line and column.
      - Added handling of the case when we do not find a fitting expression
        range info for a specified bytecodeOffset. This only happens if the
        bytecodeOffset is below the first expression range info. In that
        case, we'll use the first expression range info entry.
    (JSC::UnlinkedCodeBlock::addExpressionInfo):
      - Added encoding of line and column.
    
    * bytecode/UnlinkedCodeBlock.h:
      - Added m_expressionInfoFatPositions in RareData.
    (JSC::UnlinkedFunctionExecutable::functionStartColumn):
    (JSC::UnlinkedCodeBlock::shrinkToFit):
      - Removed obsoleted m_lineInfo.
    * bytecompiler/BytecodeGenerator.cpp:
    (JSC::BytecodeGenerator::emitCall): Plumbed line and lineStart through.
    (JSC::BytecodeGenerator::emitCallEval): Plumbed line and lineStart through.
    (JSC::BytecodeGenerator::emitCallVarargs): Plumbed line and lineStart through.
    (JSC::BytecodeGenerator::emitConstruct): Plumbed line and lineStart through.
    (JSC::BytecodeGenerator::emitDebugHook): Plumbed lineStart through.
    * bytecompiler/BytecodeGenerator.h:
    (JSC::BytecodeGenerator::emitNode):
    (JSC::BytecodeGenerator::emitNodeInConditionContext):
      - Removed obsoleted m_lineInfo.
    (JSC::BytecodeGenerator::emitExpressionInfo):
      - Plumbed line and lineStart through.
      - Compute the line and column to be added to the expression range info.
    * bytecompiler/NodesCodegen.cpp:
    (JSC::ThrowableExpressionData::emitThrowReferenceError):
    (JSC::ResolveNode::emitBytecode):
    (JSC::ArrayNode::toArgumentList):
    (JSC::BracketAccessorNode::emitBytecode):
    (JSC::DotAccessorNode::emitBytecode):
    (JSC::NewExprNode::emitBytecode):
    (JSC::EvalFunctionCallNode::emitBytecode):
    (JSC::FunctionCallValueNode::emitBytecode):
    (JSC::FunctionCallResolveNode::emitBytecode):
    (JSC::FunctionCallBracketNode::emitBytecode):
    (JSC::FunctionCallDotNode::emitBytecode):
    (JSC::CallFunctionCallDotNode::emitBytecode):
    (JSC::ApplyFunctionCallDotNode::emitBytecode):
    (JSC::PostfixNode::emitResolve):
    (JSC::PostfixNode::emitBracket):
    (JSC::PostfixNode::emitDot):
    (JSC::DeleteResolveNode::emitBytecode):
    (JSC::DeleteBracketNode::emitBytecode):
    (JSC::DeleteDotNode::emitBytecode):
    (JSC::PrefixNode::emitResolve):
    (JSC::PrefixNode::emitBracket):
    (JSC::PrefixNode::emitDot):
      - Plumbed line and lineStart through the above as needed.
    
    (JSC::UnaryOpNode::emitBytecode):
      - Added emission of an ExpressionRangeInfo for the UnaryOp node.
    
    (JSC::BinaryOpNode::emitStrcat):
    (JSC::ThrowableBinaryOpNode::emitBytecode):
    (JSC::InstanceOfNode::emitBytecode):
    (JSC::emitReadModifyAssignment):
    (JSC::ReadModifyResolveNode::emitBytecode):
    (JSC::AssignResolveNode::emitBytecode):
    (JSC::AssignDotNode::emitBytecode):
    (JSC::ReadModifyDotNode::emitBytecode):
    (JSC::AssignBracketNode::emitBytecode):
    (JSC::ReadModifyBracketNode::emitBytecode):
      - Plumbed line and lineStart through the above as needed.
    
    (JSC::ConstStatementNode::emitBytecode):
    (JSC::EmptyStatementNode::emitBytecode):
    (JSC::DebuggerStatementNode::emitBytecode):
    (JSC::ExprStatementNode::emitBytecode):
    (JSC::VarStatementNode::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::LabelNode::emitBytecode):
    (JSC::ThrowNode::emitBytecode):
    (JSC::TryNode::emitBytecode):
    (JSC::ProgramNode::emitBytecode):
    (JSC::EvalNode::emitBytecode):
    (JSC::FunctionBodyNode::emitBytecode):
      - Plumbed line and lineStart through the above as needed.
    
    * interpreter/Interpreter.cpp:
    (JSC::appendSourceToError):
      - Added line and column arguments for expressionRangeForBytecodeOffset().
    (JSC::StackFrame::computeLineAndColumn):
      - Replaces StackFrame::line() and StackFrame::column().
    (JSC::StackFrame::expressionInfo):
      - Added line and column arguments.
    (JSC::StackFrame::toString):
      - Changed to use the new StackFrame::computeLineAndColumn().
    (JSC::Interpreter::getStackTrace):
      - Added the needed firstLineColumnOffset arg for the StackFrame.
    
    * interpreter/Interpreter.h:
    * parser/ASTBuilder.h:
    (JSC::ASTBuilder::BinaryOpInfo::BinaryOpInfo):
    (JSC::ASTBuilder::AssignmentInfo::AssignmentInfo):
    (JSC::ASTBuilder::createResolve):
    (JSC::ASTBuilder::createBracketAccess):
    (JSC::ASTBuilder::createDotAccess):
    (JSC::ASTBuilder::createRegExp):
    (JSC::ASTBuilder::createNewExpr):
    (JSC::ASTBuilder::createAssignResolve):
    (JSC::ASTBuilder::createFunctionExpr):
    (JSC::ASTBuilder::createFunctionBody):
    (JSC::ASTBuilder::createGetterOrSetterProperty):
    (JSC::ASTBuilder::createFuncDeclStatement):
    (JSC::ASTBuilder::createBlockStatement):
    (JSC::ASTBuilder::createExprStatement):
    (JSC::ASTBuilder::createIfStatement):
    (JSC::ASTBuilder::createForLoop):
    (JSC::ASTBuilder::createForInLoop):
    (JSC::ASTBuilder::createVarStatement):
    (JSC::ASTBuilder::createReturnStatement):
    (JSC::ASTBuilder::createBreakStatement):
    (JSC::ASTBuilder::createContinueStatement):
    (JSC::ASTBuilder::createTryStatement):
    (JSC::ASTBuilder::createSwitchStatement):
    (JSC::ASTBuilder::createWhileStatement):
    (JSC::ASTBuilder::createDoWhileStatement):
    (JSC::ASTBuilder::createLabelStatement):
    (JSC::ASTBuilder::createWithStatement):
    (JSC::ASTBuilder::createThrowStatement):
    (JSC::ASTBuilder::createDebugger):
    (JSC::ASTBuilder::createConstStatement):
    (JSC::ASTBuilder::appendBinaryExpressionInfo):
    (JSC::ASTBuilder::appendUnaryToken):
    (JSC::ASTBuilder::unaryTokenStackLastStart):
    (JSC::ASTBuilder::unaryTokenStackLastLineStartPosition): Added.
    (JSC::ASTBuilder::assignmentStackAppend):
    (JSC::ASTBuilder::createAssignment):
    (JSC::ASTBuilder::setExceptionLocation):
    (JSC::ASTBuilder::makeDeleteNode):
    (JSC::ASTBuilder::makeFunctionCallNode):
    (JSC::ASTBuilder::makeBinaryNode):
    (JSC::ASTBuilder::makeAssignNode):
    (JSC::ASTBuilder::makePrefixNode):
    (JSC::ASTBuilder::makePostfixNode):.
      - Plumbed line, lineStart, and startColumn through the above as needed.
    
    * parser/Lexer.cpp:
    (JSC::::currentSourcePtr):
    (JSC::::setCode):
      - Added tracking for sourceoffset and lineStart.
    (JSC::::internalShift):
    (JSC::::parseIdentifier):
      - Added tracking for lineStart.
    (JSC::::parseIdentifierSlowCase):
    (JSC::::parseString):
      - Added tracking for lineStart.
    (JSC::::parseStringSlowCase):
    (JSC::::lex):
      - Added tracking for sourceoffset.
    (JSC::::sourceCode):
    * parser/Lexer.h:
    (JSC::Lexer::currentOffset):
    (JSC::Lexer::currentLineStartOffset):
    (JSC::Lexer::setOffset):
      - Added tracking for lineStart.
    (JSC::Lexer::offsetFromSourcePtr): Added. conversion function.
    (JSC::Lexer::sourcePtrFromOffset): Added. conversion function.
    (JSC::Lexer::setOffsetFromSourcePtr):
    (JSC::::lexExpectIdentifier):
      - Added tracking for sourceoffset and lineStart.
    
    * parser/NodeConstructors.h:
    (JSC::Node::Node):
    (JSC::ResolveNode::ResolveNode):
    (JSC::EvalFunctionCallNode::EvalFunctionCallNode):
    (JSC::FunctionCallValueNode::FunctionCallValueNode):
    (JSC::FunctionCallResolveNode::FunctionCallResolveNode):
    (JSC::FunctionCallBracketNode::FunctionCallBracketNode):
    (JSC::FunctionCallDotNode::FunctionCallDotNode):
    (JSC::CallFunctionCallDotNode::CallFunctionCallDotNode):
    (JSC::ApplyFunctionCallDotNode::ApplyFunctionCallDotNode):
    (JSC::PostfixNode::PostfixNode):
    (JSC::DeleteResolveNode::DeleteResolveNode):
    (JSC::DeleteBracketNode::DeleteBracketNode):
    (JSC::DeleteDotNode::DeleteDotNode):
    (JSC::PrefixNode::PrefixNode):
    (JSC::ReadModifyResolveNode::ReadModifyResolveNode):
    (JSC::ReadModifyBracketNode::ReadModifyBracketNode):
    (JSC::AssignBracketNode::AssignBracketNode):
    (JSC::AssignDotNode::AssignDotNode):
    (JSC::ReadModifyDotNode::ReadModifyDotNode):
    (JSC::AssignErrorNode::AssignErrorNode):
    (JSC::WithNode::WithNode):
    (JSC::ForInNode::ForInNode):
      - Plumbed line and lineStart through the above as needed.
    * parser/Nodes.cpp:
    (JSC::StatementNode::setLoc): Plumbed lineStart.
    (JSC::ScopeNode::ScopeNode): Plumbed lineStart.
    (JSC::ProgramNode::ProgramNode): Plumbed startColumn.
    (JSC::ProgramNode::create): Plumbed startColumn.
    (JSC::EvalNode::create):
    (JSC::FunctionBodyNode::FunctionBodyNode): Plumbed startColumn.
    (JSC::FunctionBodyNode::create): Plumbed startColumn.
    * parser/Nodes.h:
    (JSC::Node::startOffset):
    (JSC::Node::lineStartOffset): Added.
    (JSC::StatementNode::firstLine):
    (JSC::StatementNode::lastLine):
    (JSC::ThrowableExpressionData::ThrowableExpressionData):
    (JSC::ThrowableExpressionData::setExceptionSourceCode):
    (JSC::ThrowableExpressionData::divotStartOffset):
    (JSC::ThrowableExpressionData::divotEndOffset):
    (JSC::ThrowableExpressionData::divotLine):
    (JSC::ThrowableExpressionData::divotLineStart):
    (JSC::ThrowableSubExpressionData::ThrowableSubExpressionData):
    (JSC::ThrowableSubExpressionData::setSubexpressionInfo):
    (JSC::ThrowableSubExpressionData::subexpressionDivot):
    (JSC::ThrowableSubExpressionData::subexpressionStartOffset):
    (JSC::ThrowableSubExpressionData::subexpressionEndOffset):
    (JSC::ThrowableSubExpressionData::subexpressionLine):
    (JSC::ThrowableSubExpressionData::subexpressionLineStart):
    (JSC::ThrowablePrefixedSubExpressionData::ThrowablePrefixedSubExpressionData):
    (JSC::ThrowablePrefixedSubExpressionData::setSubexpressionInfo):
    (JSC::ThrowablePrefixedSubExpressionData::subexpressionDivot):
    (JSC::ThrowablePrefixedSubExpressionData::subexpressionStartOffset):
    (JSC::ThrowablePrefixedSubExpressionData::subexpressionEndOffset):
    (JSC::ThrowablePrefixedSubExpressionData::subexpressionLine):
    (JSC::ThrowablePrefixedSubExpressionData::subexpressionLineStart):
    (JSC::ScopeNode::startStartOffset):
    (JSC::ScopeNode::startLineStartOffset):
    (JSC::ProgramNode::startColumn):
    (JSC::EvalNode::startColumn):
    (JSC::FunctionBodyNode::startColumn):
      - Plumbed line and lineStart through the above as needed.
    * parser/Parser.cpp:
    (JSC::::Parser):
    (JSC::::parseSourceElements):
    (JSC::::parseVarDeclarationList):
    (JSC::::parseConstDeclarationList):
    (JSC::::parseForStatement):
    (JSC::::parseBreakStatement):
    (JSC::::parseContinueStatement):
    (JSC::::parseReturnStatement):
    (JSC::::parseThrowStatement):
    (JSC::::parseWithStatement):
      - Plumbed line and lineStart through the above as needed.
    (JSC::::parseFunctionBody):
      - Plumbed startColumn.
    (JSC::::parseFunctionInfo):
    (JSC::::parseFunctionDeclaration):
    (JSC::LabelInfo::LabelInfo):
    (JSC::::parseExpressionOrLabelStatement):
    (JSC::::parseAssignmentExpression):
    (JSC::::parseBinaryExpression):
    (JSC::::parseProperty):
    (JSC::::parseObjectLiteral):
    (JSC::::parsePrimaryExpression):
    (JSC::::parseMemberExpression):
    (JSC::::parseUnaryExpression):
      - Plumbed line, lineStart, startColumn through the above as needed.
    * parser/Parser.h:
    (JSC::Parser::next):
    (JSC::Parser::nextExpectIdentifier):
    (JSC::Parser::tokenStart):
    (JSC::Parser::tokenColumn):
    (JSC::Parser::tokenEnd):
    (JSC::Parser::tokenLineStart):
    (JSC::Parser::lastTokenLine):
    (JSC::Parser::lastTokenLineStart):
    (JSC::::parse):
    * parser/ParserTokens.h:
    (JSC::JSTokenLocation::JSTokenLocation):
      - Plumbed lineStart.
    (JSC::JSTokenLocation::lineStartPosition):
    (JSC::JSTokenLocation::startPosition):
    (JSC::JSTokenLocation::endPosition):
    * parser/SourceCode.h:
    (JSC::SourceCode::SourceCode):
    (JSC::SourceCode::startColumn):
    (JSC::makeSource):
    (JSC::SourceCode::subExpression):
    * parser/SourceProvider.cpp: delete old code.
    * parser/SourceProvider.h: delete old code.
    * parser/SourceProviderCacheItem.h:
    (JSC::SourceProviderCacheItem::closeBraceToken):
    (JSC::SourceProviderCacheItem::SourceProviderCacheItem):
      - Plumbed lineStart.
    * parser/SyntaxChecker.h:
    (JSC::SyntaxChecker::makeFunctionCallNode):
    (JSC::SyntaxChecker::makeAssignNode):
    (JSC::SyntaxChecker::makePrefixNode):
    (JSC::SyntaxChecker::makePostfixNode):
    (JSC::SyntaxChecker::makeDeleteNode):
    (JSC::SyntaxChecker::createResolve):
    (JSC::SyntaxChecker::createBracketAccess):
    (JSC::SyntaxChecker::createDotAccess):
    (JSC::SyntaxChecker::createRegExp):
    (JSC::SyntaxChecker::createNewExpr):
    (JSC::SyntaxChecker::createAssignResolve):
    (JSC::SyntaxChecker::createFunctionExpr):
    (JSC::SyntaxChecker::createFunctionBody):
    (JSC::SyntaxChecker::createFuncDeclStatement):
    (JSC::SyntaxChecker::createForInLoop):
    (JSC::SyntaxChecker::createReturnStatement):
    (JSC::SyntaxChecker::createBreakStatement):
    (JSC::SyntaxChecker::createContinueStatement):
    (JSC::SyntaxChecker::createWithStatement):
    (JSC::SyntaxChecker::createLabelStatement):
    (JSC::SyntaxChecker::createThrowStatement):
    (JSC::SyntaxChecker::createGetterOrSetterProperty):
    (JSC::SyntaxChecker::appendBinaryExpressionInfo):
    (JSC::SyntaxChecker::operatorStackPop):
      - Made SyntaxChecker prototype changes to match ASTBuilder due to new
        args added for plumbing line, lineStart, and startColumn.
    * runtime/CodeCache.cpp:
    (JSC::CodeCache::generateBytecode):
    (JSC::CodeCache::getCodeBlock):
      - Plumbed startColumn.
    * runtime/Executable.cpp:
    (JSC::FunctionExecutable::FunctionExecutable):
    (JSC::ProgramExecutable::compileInternal):
    (JSC::FunctionExecutable::produceCodeBlockFor):
    (JSC::FunctionExecutable::fromGlobalCode):
      - Plumbed startColumn.
    * runtime/Executable.h:
    (JSC::ScriptExecutable::startColumn):
    (JSC::ScriptExecutable::recordParse):
    (JSC::FunctionExecutable::create):
      - Plumbed startColumn.
    
    Source/WebCore: 
    
    Test: fast/js/line-column-numbers.html
    
    Updated the bindings to use StackFrame::computeLineAndColumn(). The old
    StackFrame::line() and StackFrame::column() has been removed. The new
    algorithm always computes the 2 values together anyway. Hence it is more
    efficient to return them as a pair instead of doing the same computation
    twice for each half of the result.
    
    * bindings/js/ScriptCallStackFactory.cpp:
    (WebCore::createScriptCallStack):
    (WebCore::createScriptCallStackFromException):
    * bindings/js/ScriptSourceCode.h:
    (WebCore::ScriptSourceCode::ScriptSourceCode):
    
    LayoutTests: 
    
    The fix now computes line and column numbers more accurately. As a result,
    some of the test results need to be re-baselined. Among other fixes, one
    major source of difference is that the old code was incorrectly computing
    0-based column numbers. This has now been fixed to be 1-based.
    Note: line numbers were always 1-based.
    
    Also added a new test: fast/js/line-column-numbers.html, which tests line
    and column numbers for source code in various configurations.
    
    * editing/execCommand/outdent-blockquote-test1-expected.txt:
    * editing/execCommand/outdent-blockquote-test2-expected.txt:
    * editing/execCommand/outdent-blockquote-test3-expected.txt:
    * editing/execCommand/outdent-blockquote-test4-expected.txt:
    * editing/pasteboard/copy-paste-float-expected.txt:
    * editing/pasteboard/paste-blockquote-before-blockquote-expected.txt:
    * editing/pasteboard/paste-double-nested-blockquote-before-blockquote-expected.txt:
    * fast/dom/Window/window-resize-contents-expected.txt:
    * fast/events/remove-target-with-shadow-in-drag-expected.txt:
    * fast/js/line-column-numbers-expected.txt: Added.
    * fast/js/line-column-numbers.html: Added.
    * fast/js/script-tests/line-column-numbers.js: Added.
    (try.doThrow4b):
    (doThrow5b.try.innerFunc):
    (doThrow5b):
    (doThrow6b.try.innerFunc):
    (doThrow6b):
    (catch):
    (try.doThrow11b):
    (try.doThrow14b):
    * fast/js/stack-trace-expected.txt:
    * inspector/console/console-url-line-column-expected.txt:
    
    
    
    git-svn-id: http://svn.webkit.org/repository/webkit/trunk@152494 268f45cc-cd09-0410-ab3c-d52691b4dbfc
    5b45f90a