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Stephan Herhut f25656aee2 [wasm] Avoid zero extension after truncate
In wasm code, we sometimes see the pattern

<some 64 bit expression>
i32.wrap/i64
i32.load

where we generate an instruction to extend the 32 bit offset into a zero
extended 64 bit value for the actual load. However, the preceeding
truncate already yields a zero extended 32 bit value, so the extra
instruction is not needed. Even more, it might get in the way of
munching more computation into the final load.

This change adds information about the zero extending behavior to
the existing optimization that avoids the zero extension.

Bug: chromium:853685
Change-Id: Iab9179379923ecb88651df6091b3d9408341cf4c
Reviewed-on: https://chromium-review.googlesource.com/c/1421839
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Jaroslav Sevcik <jarin@chromium.org>
Commit-Queue: Stephan Herhut <herhut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58998}
2019-01-22 15:42:04 +00:00
benchmarks [test] Ensure random generator in JSTests does not use float arithmetic 2018-12-17 10:05:08 +00:00
build_overrides [ndk] Change android ndk root for v8 2018-01-11 08:10:33 +00:00
custom_deps [build] Add common directory for custom deps 2018-06-08 19:23:02 +00:00
docs [Docs] Removed unused docs because they are moved to GitHub 2015-11-19 10:23:30 +00:00
gni [gn] Update link to v8 blog 2019-01-02 10:29:47 +00:00
include [global-handles] Deprecate unused methods 2019-01-21 19:50:04 +00:00
infra [build][test] Add build and test configs for new ubsan builders 2019-01-18 10:08:57 +00:00
samples Add a sample that uses the JS API to create wasm 2018-06-07 23:43:38 +00:00
src [wasm] Avoid zero extension after truncate 2019-01-22 15:42:04 +00:00
test [Compile] Move decision of whether an IIFE is oneshot into parser. 2019-01-22 15:19:39 +00:00
testing Remove dummy files created for rolling googletest. 2018-03-27 05:55:56 +00:00
third_party Update V8 DEPS. 2019-01-22 14:49:04 +00:00
tools [torque] add "struct" keyword to VS Code plugin 2019-01-21 16:42:33 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.clang-tidy [tool] Remove unfixed clang-tidy warnings to ease use. 2018-10-26 07:40:32 +00:00
.editorconfig Add .editorconfig 2017-07-28 13:39:24 +00:00
.git-blame-ignore-revs [build] Add DEPS formatting to hyper-blame 2017-10-09 14:08:45 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore Revert "Reland "[build] Pull binutils via DEPS"" 2018-12-13 12:05:58 +00:00
.gn [test] Remove obsolete test262 archive extract 2018-03-28 13:52:15 +00:00
.vpython [tools] Correctly identify and report test crashes and infra failures 2018-10-30 15:05:40 +00:00
.ycm_extra_conf.py [ycm] Switch from gnu++11 to gnu++14 2017-11-27 07:48:21 +00:00
AUTHORS [objects] Correctly Object.isSeal for TypedArray 2019-01-17 10:46:29 +00:00
BUILD.gn [build][torque] remove workarounds for clang bug 2019-01-22 13:38:46 +00:00
ChangeLog [release] Merge ChangeLog back to master 2018-12-07 15:41:59 +00:00
CODE_OF_CONDUCT.md Explicitly state that the Chromium Code of Conduct also applies to V8 2016-03-02 09:51:24 +00:00
codereview.settings Make Gerrit the default code review for V8 2017-06-30 17:37:37 +00:00
DEPS Update V8 DEPS. 2019-01-22 14:49:04 +00:00
LICENSE Add antlr4 runtime library to support Torque 2018-04-10 10:01:01 +00:00
LICENSE.fdlibm Add LICENSE.fdlibm for all the fdlibm imported sources. 2016-06-09 07:17:03 +00:00
LICENSE.strongtalk Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.v8 Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.valgrind Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
OWNERS Reduce wasm OWNERS to current team members 2018-10-15 14:47:49 +00:00
PRESUBMIT.py Optionally use halfsiphash for integer hashing. 2019-01-09 15:20:51 +00:00
README.md [Docs] Removed unused docs because they are moved to GitHub 2015-11-19 10:23:30 +00:00
snapshot_toolchain.gni Reland "Add Windows ARM64 ABI support to V8" 2018-10-24 19:46:36 +00:00
WATCHLISTS Update WATCHLIST wrt yangguo 2018-11-23 08:29:12 +00:00

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://github.com/v8/v8/wiki

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned on the V8 wiki.