122844 2013-10-15 10:49:10 -0700 Implement a cheaper and faster Debugger Running mode 2014-01-22 10:10:34 -0800 1 1 1 Unclassified WebKit JavaScriptCore 528+ (Nightly build) Unspecified Unspecified RESOLVED DUPLICATE 122836 InRadar P2 Normal --- 122847 1 mark.lam mark.lam fpizlo ggaren joepeck mhahnenberg msaboff oliver timothy webkit-bug-importer oldest_to_newest 940025 0 mark.lam 2013-10-15 10:49:10 -0700 With https://bugs.webkit.org/show_bug.cgi?id=122836, when in the Debugger Running mode, the LLINT and baseline JIT generated code needs to call a slow path to check if the Debugger needs to switch to Stepping mode. We can do better. This is how: 1. In Running mode, only call the slow path for op_debug if the op_debug "needBreaks" flag is set i.e. we need to handle a breakpoint. 2. In Stepping mode, before taking a step, the Debugger should: 2.1 decorate the next op_debug instruction's needBreaks with a "isStepping" bit. e.g bit 0 == have breakpoint set here, bit 1 == stepping to this bytecode. 2.2. for call opcodes, fix up the CallLinkInfo to force a call to the slow path. 2.2.1 in the call slow paths, decorate the first op_debug instruction's needBreaks flag with an "isStepping" bit. 2.3 when handling exceptions, decorate the exception handler's first op_debug instruction's needBreaks flag with an "isStepping" bit. With this change, the debugger should be able to achieve approximately a 3x speed up over shipping Safari on the Octane benchmark. Note: the DFG is still not enabled for the debugger i.e. the DFG will see the op_debug opcode and fail compilation. 940026 1 webkit-bug-importer 2013-10-15 10:49:18 -0700 <rdar://problem/15232333> 970736 2 mark.lam 2014-01-22 10:10:34 -0800 This work has been folded into <https://webkit.org/b/122836>. *** This bug has been marked as a duplicate of bug 122836 ***