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deps: V8: cherry-pick 7ae0b77628f6
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Original commit message:

    [interpreter] Stop jump-table optimizing switch stms when spread overflows

    Bug: v8:12389
    Change-Id: I53c728ab0c8ba38c7dd96c7e1089f771ba44b9f0
    Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3289227
    Reviewed-by: Leszek Swirski <[email protected]>
    Commit-Queue: Leszek Swirski <[email protected]>
    Cr-Commit-Position: refs/heads/main@{#77995}

Refs: v8/v8@7ae0b77

PR-URL: #40882
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: James M Snell <[email protected]>
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rayw000 authored and targos committed Nov 21, 2021
1 parent 522a30f commit a612ecb
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Showing 2 changed files with 23 additions and 12 deletions.
2 changes: 1 addition & 1 deletion common.gypi
Original file line number Diff line number Diff line change
Expand Up @@ -36,7 +36,7 @@

# Reset this number to 0 on major V8 upgrades.
# Increment by one for each non-official patch applied to deps/v8.
'v8_embedder_string': '-node.13',
'v8_embedder_string': '-node.14',

##### V8 defaults for Node.js #####

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33 changes: 22 additions & 11 deletions deps/v8/src/interpreter/bytecode-generator.cc
Original file line number Diff line number Diff line change
Expand Up @@ -1889,17 +1889,28 @@ bool IsSwitchOptimizable(SwitchStatement* stmt, SwitchInfo* info) {
}

// GCC also jump-table optimizes switch statements with 6 cases or more.
if (!(static_cast<int>(info->covered_cases.size()) >=
FLAG_switch_table_min_cases &&
IsSpreadAcceptable(info->MaxCase() - info->MinCase(),
cases->length()))) {
// Invariant- covered_cases has all cases and only cases that will go in the
// jump table.
info->covered_cases.clear();
return false;
} else {
return true;
}
if (static_cast<int>(info->covered_cases.size()) >=
FLAG_switch_table_min_cases) {
// Due to case spread will be used as the size of jump-table,
// we need to check if it doesn't overflow by casting its
// min and max bounds to int64_t, and calculate if the difference is less
// than or equal to INT_MAX.
int64_t min = static_cast<int64_t>(info->MinCase());
int64_t max = static_cast<int64_t>(info->MaxCase());
int64_t spread = max - min + 1;

DCHECK_GT(spread, 0);

// Check if casted spread is acceptable and doesn't overflow.
if (spread <= INT_MAX &&
IsSpreadAcceptable(static_cast<int>(spread), cases->length())) {
return true;
}
}
// Invariant- covered_cases has all cases and only cases that will go in the
// jump table.
info->covered_cases.clear();
return false;
}

} // namespace
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