The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/28c11f51b7b91165ea4c108afceb1ac30e066c35

commit 28c11f51b7b91165ea4c108afceb1ac30e066c35
Author: meade <meade@chromium.org>
Date: Fri May 13 08:39:57 2016

Factor and simplify generation of the lookup trie used for HTMLLookupTrie.

This is in preparation for making more classes use the lookup trie.

Difference before and after for HTMLElementLookupTrie.cpp is here:
https://www.diffchecker.com/lqhiueko

BUG=606695

Review-Url: https://codereview.chromium.org/1978703002
Cr-Commit-Position: refs/heads/master@{#393478}

[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/make_element_lookup_trie.py
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/scripts.gni
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/scripts.gypi
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/templates/ElementLookupTrie.cpp.tmpl
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/templates/macros.tmpl
[add] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/build/scripts/trie_builder.py
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/core/BUILD.gn
[modify] https://crrev.com/28c11f51b7b91165ea4c108afceb1ac30e066c35/third_party/WebKit/Source/core/core_generated.gyp

FWIW I tested using the trie generator on CSS property names and it's noticeably faster but increases binary size by ~200KB (for the unit type trie the binary size change is small).

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a753d727f2d92f67b594312a6710c931b37a49b3

commit a753d727f2d92f67b594312a6710c931b37a49b3
Author: timloh <timloh@chromium.org>
Date: Wed May 25 10:02:34 2016

Avoid string allocation when parsing CSSPrimitiveValue::UnitType

Currently the CSSPrimitiveValue::fromName function, which parses strings
to unit types, takes a String argument. This means that the CSS parser
needs to allocate a String (since it would only otherwise have a
CSSParserString). This patch avoids this allocation using a generated
switch-statement trie instead.

Generated file: http://paste.ubuntu.com/16652358/

This improves performance of the inline-transform-benchmark test from
https://bugs.chromium.org/p/chromium/issues/detail?id=605792, reducing
the time spent in CSSParserImpl::parseValue by 10%.

Patch originally written by meade@chromium.org:
https://codereview.chromium.org/1938343002

BUG=605792,606695

Review-Url: https://codereview.chromium.org/2002383002
Cr-Commit-Position: refs/heads/master@{#395849}

[add] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/build/scripts/make_css_primitive_value_unit_trie.py
[add] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/build/scripts/templates/CSSPrimitiveValueUnitTrie.cpp.tmpl
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/BUILD.gn
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/CoreInitializer.cpp
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/core.gypi
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/core_generated.gyp
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/core_generated.gypi
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/CSSPrimitiveValue.cpp
[add] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/CSSPrimitiveValueUnitTrie.h
[add] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/CSSPrimitiveValueUnits.in
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/cssom/CSSAngleValue.cpp
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/cssom/CSSLengthValue.cpp
[modify] https://crrev.com/a753d727f2d92f67b594312a6710c931b37a49b3/third_party/WebKit/Source/core/css/parser/CSSParserToken.cpp

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/e22ff8c96ff8b3fa85e1f51b98daf27d5e68a09d

commit e22ff8c96ff8b3fa85e1f51b98daf27d5e68a09d
Author: meade <meade@chromium.org>
Date: Fri Jun 03 12:01:40 2016

Delete remaining unused function definitionss from CSSPrimitiveValue header

These functions were removed from the cpp file in
https://codereview.chromium.org/2002383002.

BUG=605792,606695

Review-Url: https://codereview.chromium.org/2036923002
Cr-Commit-Position: refs/heads/master@{#397686}

[modify] https://crrev.com/e22ff8c96ff8b3fa85e1f51b98daf27d5e68a09d/third_party/WebKit/Source/core/css/CSSPrimitiveValue.h

I don't have time to work on this right now, so here's the status of this bug: Tim and I updated CSSPrimitiveValue::UnitType to use a trie thing. We decided not to change the ones using gperf as it regressed the binary size too much, which leaves updating CSSSelector::PseudoType for someone with some free time :)

- CSSValueKeyword, ~800 values, uses gperf (CSSValueKeywords.in, make_css_value_keywords.py)
- CSSPropertyID, ~500 values, uses gperf (CSSProperties.in, make_css_property_names.py)
-> CSSPrimitiveValue::UnitType, uses generated switch-statement trie (make_element_lookup_trie.py)
- CSSSelector::PseudoType, ~80 values, binary search over (string, enum) pairs
- lookupHTMLTag, ~500 values, uses a generated switch-statement trie (make_element_lookup_trie.py), input is already lower-case

I'm interested in this.

The switch-statement trie doesn't look optimal since it uses indirect branches and large jump tables.

I wonder if it would be possible to come up with either a perfect hash solution that's fast and simple, or if one could generate table-driven tries that are faster and smaller.

We still use gperf in CSSValueKeyword and CSSPropertyID, is this the kind of thing you were thinking? 
e.g. https://cs.chromium.org/chromium/src/out/Debug/gen/blink/core/CSSValueKeywords.cpp?

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