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7887c34a29
Previously these functions would only contain a single CheckStackOverflowInstr
in a backtracking block and that CheckStackOverflowInstr would have a zero
loop_depth - which means it would not be considered eligable for OSR.
This change:
* adds CheckStackOverflowInstr with non-zero loop_depth in two other places
(Boyer-Moore lookahead skip loop and greedy loop) where loops arise in the
generated IL;
* sets non-zero loop depth on the CheckStackOverflowInstr in the backtracking
block;
* adds a flag on CheckStackOverflowInstr that allows optimizing compiler to
optimize away those checks that were inserted solely to serve as OSR entries.
* ensures that IR generated by IRRegExpMacroAssembler is OSR compatible:
* GraphEntryInstr has correct osr_id;
* GraphEntry and normal entry have different block ids (B0 and B1 - instead of B0 and B0);
* unreachable blocks are pruned and GraphEntry is rewired to point to OSR entry;
* IRRegExpMacroAssembler::GrowStack should not assume that stack_array_cell and :stack
are always in sync, because :stack can come from OSR or deoptimization why stack_array_cell
is a constant associated with a particular Code object.
* refactors the way the RegExp stack was growing: instead of having a special instruction
just emit a call to a Dart function;
* refactors the way block pruning for OSR is done by consolidating duplicated code
in a single function.
We allow the optimizing compiler to remove preemption checks from
non-backtracking loops in the regexp code because those loops
unlike backtracking have guaranteed O(input_length) time
complexity.
Performance Implications
------------------------
This change improves performance of regexps in cases where regexp spends a lot
of time in the first invocation (either due to backtracking or due to long non
matching prefix) by allowing VM to optimize the :matcher while :matcher is
running.
For example on regex-redux[1] benchmark it improves Dart performance by 3x
(from ~18s to ~6s on my Mac Book Pro).
CL history
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This relands commit
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| bin | ||
| include | ||
| lib | ||
| observatory | ||
| platform | ||
| tests/vm | ||
| third_party | ||
| tools | ||
| vm | ||
| .gitignore | ||
| BUILD.gn | ||
| codereview.settings | ||
| CPPLINT.cfg | ||
| dart-runtime.gyp | ||
| PRESUBMIT.py | ||
| runtime_args.gni | ||