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Benedikt Meurer authored
Following up on https://crrev.com/c/2689185, this CL significantly simplifies the whole implementation of the stack trace capturing. Before this CL, capturing any stack trace (for the purpose of the API or Error.stack) would roughly work like this: 1. The CaptureStackTrace() function uses the StackFrameIterator to walk the system stack. For each native frame it uses the FrameSummary abstraction to get all (including potentially inlined) frames. For each of those it appends a record consisting of six elements to a FrameArray (this holds pointers to the actual closures and receivers). 2. Afterwards the FrameArray is shrinked to the required size, and a new FixedArray is allocated, and initialized with new StackTraceFrame objects where each holds a reference to the FrameArray, the index of the frame, and an initially uninitialized StackFrameInfo reference. This new FixedArray is then returned from CaptureStackTrace() and either stored on a message object or provided to the API as v8::StackTrace. The new approach removes a lot of the machinery in between and directly creates a FixedArray of StackFrameInfo objects in CaptureStackTrace(). These StackFrameInfo objects are directly exposed as v8::StackFrame on the public API, and they hold the six fields that were previously stored flat in the FrameArray. This not only avoids a lot of copying around of data and creation of temporary objects and handles, but most importantly unifies and simplifies the stack frame function inside StackFrameInfo, so you no longer need to wonder which function / object might be responsible for a certain API. There's still a lot of room for improvement. In particular we currently don't cache the source position for a given StackFrameInfo (or globally), but rather recompute it every time. This is still very fast, significantly faster than the previous approach. There are some notable (potentially user visible) changes: - The CallSite#GetPosition() method now consistently returns the Wasm module relative bytecode offset for all Wasm frames (previously it'd return the function relative bytecode offset for non-asm.js Wasm frames). - The column and line numbers returned from StackFrameInfo methods are consistently 1-based now, instead of sometimes being 0-based (Wasm) and sometimes being 1-based (JS and asm.js Wasm). The only potentially noticable difference is that for CallSite#GetLineNumber() no longer returns 0 for Wasm frames, but that was wrong and useless anyways. - CallSite#GetThis() would sometimes return the_hole, another bug flushed out by this CL. The CL also contains some other not noteworthy drive-by-cleanups. Fixed: chromium:1057211 Bug: chromium:1077657, chromium:1069425, v8:8742 Bug: chromium:1127391, chromium:1098530, chromium:981541 Change-Id: Iff12f6838a4d99080db8dd96bccc14440affc5a5 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2689183 Commit-Queue: Benedikt Meurer <bmeurer@chromium.org> Reviewed-by: Yang Guo <yangguo@chromium.org> Reviewed-by: Simon Zünd <szuend@chromium.org> Reviewed-by: Jakob Kummerow <jkummerow@chromium.org> Cr-Commit-Position: refs/heads/master@{#72694}
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