Replace `std::unordered_map` with `absl::flat_hash_map`. [v8/v8 : main]
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Leszek Swirski (Gerrit)
Jan 8, 2026, 9:24:08 AM (21 hours ago) Jan 8
to Jeffrey Yu, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org
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File-level comment, Patchset 4 (Latest):
Leszek Swirski . resolved
thanks, it does look like this marginally improves performance (https://pprof.corp.google.com/?id=93c69790661d3a31eca4f8a09dfdcce4&id0=832c3aac6ab1e13307e50b912eec892f&filter=showfrom:%255Ev8%253A%253Ainternal%253A%253Amaglev%253A%253A,focus:operator%255C%255B%255C%255D&tab=flame)
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Darius Mercadier (Gerrit)
Jan 8, 2026, 9:27:34 AM (21 hours ago) Jan 8
to Jeffrey Yu, Leszek Swirski, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org
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Darius Mercadier . resolved
lgtm
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Jeffrey Yu (Gerrit)
Jan 8, 2026, 11:54:25 AM (18 hours ago) Jan 8
to Darius Mercadier, Leszek Swirski, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org
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V8 LUCI CQ (Gerrit)
Jan 8, 2026, 12:48:39 PM (18 hours ago) Jan 8
to Jeffrey Yu, Darius Mercadier, Leszek Swirski, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org
V8 LUCI CQ submitted the change![]( "Open in Gerrit")
Change information
Commit message:
Replace `std::unordered_map` with `absl::flat_hash_map`.
The Chromium containers guide
(https://chromium.googlesource.com/chromium/src/+/HEAD/base/containers/README.md)
recommends using `absl::flat_hash_map` as a default map choice instead
of `std::unordered_map` when pointer stability isn't needed, and
`absl::node_hash_map` when it is. Both will still generally perform
better and require less overhead than `std::unordered_map`.
Notably, the guide says: "Note that this advice never suggests the use
of `std::unordered_map` and `std::unordered_set`. These containers
provides similar features to the Abseil flat hash containers but with
worse performance. They should only be used if absolutely required for
compatibility with third-party code.
Bug: 473916362
Change-Id: Idb7c2f98b35f65bed053d3009e981fd44f7ef28a
Reviewed-by: Leszek Swirski <les...@chromium.org>
Reviewed-by: Darius Mercadier <dmerc...@chromium.org>
Commit-Queue: Jeffrey Yu <yu...@chromium.org>
Cr-Commit-Position: refs/heads/main@{#104569}
Files:
- M src/maglev/maglev-code-generator.cc
Change size: XS
Delta: 1 file changed, 2 insertions(+), 1 deletion(-)
Branch: refs/heads/main
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Code-Review: +1 by Leszek Swirski, +1 by Darius Mercadier
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Paolo Severini (Gerrit)
Jan 8, 2026, 4:08:12 PM (14 hours ago) Jan 8
to Jeffrey Yu, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org, was...@google.com
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Paolo Severini (Gerrit)
Jan 8, 2026, 4:08:42 PM (14 hours ago) Jan 8
to Jeffrey Yu, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org, was...@google.com
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| Code-Review | +1 |
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Darius Mercadier (Gerrit)
2:33 AM (4 hours ago) 2:33 AM
to Jeffrey Yu, Leszek Swirski, Paolo Severini, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org, was...@google.com
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Jeffrey Yu (Gerrit)
3:04 AM (3 hours ago) 3:04 AM
to Darius Mercadier, Leszek Swirski, Paolo Severini, V8 LUCI CQ, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org, was...@google.com
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Jeffrey Yu voted Commit-Queue+2![]( "Open in Gerrit")
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V8 LUCI CQ (Gerrit)
3:06 AM (3 hours ago) 3:06 AM
to Jeffrey Yu, Darius Mercadier, Leszek Swirski, Paolo Severini, dmercadi...@chromium.org, jgrube...@chromium.org, leszek...@chromium.org, pthier...@chromium.org, v8-re...@googlegroups.com, verwaes...@chromium.org, victorgo...@chromium.org, was...@google.com
V8 LUCI CQ submitted the change![]( "Open in Gerrit")
Change information
Commit message:
Replace `std::unordered_map` with `absl::flat_hash_map`.
The Chromium containers guide
(https://chromium.googlesource.com/chromium/src/+/HEAD/base/containers/README.md)
recommends using `absl::flat_hash_map` as a default map choice instead
of `std::unordered_map` when pointer stability isn't needed, and
`absl::node_hash_map` when it is. Both will still generally perform
better and require less overhead than `std::unordered_map`.
Notably, the guide says: "Note that this advice never suggests the use
of `std::unordered_map` and `std::unordered_set`. These containers
provides similar features to the Abseil flat hash containers but with
worse performance. They should only be used if absolutely required for
compatibility with third-party code.
Bug: 473916362
Change-Id: I3471fb341f3e4058da4f7b03190fb23098401495
Commit-Queue: Jeffrey Yu <yu...@chromium.org>
Reviewed-by: Paolo Severini <paol...@microsoft.com>
Reviewed-by: Darius Mercadier <dmerc...@chromium.org>
Cr-Commit-Position: refs/heads/main@{#104579}
Files:
- M src/wasm/interpreter/wasm-interpreter.h
Change size: S
Delta: 1 file changed, 12 insertions(+), 10 deletions(-)
Branch: refs/heads/main
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Code-Review: +1 by Darius Mercadier, +1 by Paolo Severini
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