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bpo-45753: Make recursion checks more efficient. (GH-29524)

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* Uses recursion remaining, instead of recursion depth to speed up check against recursion limit.
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Mark Shannon 2021-11-16 11:01:57 +00:00 • committed by GitHub
parent 9bf2cbc4c4
commit b931077375
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10 changed files with 50 additions and 43 deletions
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Python/ast.c
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@ -933,8 +933,9 @@ _PyAST_Validate(mod_ty mod)
return 0;
}
/* Be careful here to prevent overflow. */
starting_recursion_depth = (tstate->recursion_depth < INT_MAX / COMPILER_STACK_FRAME_SCALE) ?
tstate->recursion_depth * COMPILER_STACK_FRAME_SCALE : tstate->recursion_depth;
int recursion_depth = tstate->recursion_limit - tstate->recursion_remaining;
starting_recursion_depth = (recursion_depth< INT_MAX / COMPILER_STACK_FRAME_SCALE) ?
recursion_depth * COMPILER_STACK_FRAME_SCALE : recursion_depth;
state.recursion_depth = starting_recursion_depth;
state.recursion_limit = (recursion_limit < INT_MAX / COMPILER_STACK_FRAME_SCALE) ?
recursion_limit * COMPILER_STACK_FRAME_SCALE : recursion_limit;