tree 763958d8d02249fa14ae5af020e332216f09380e
parent 9bd6d010c4900e456e49ffa068ff14d918ff9889
author sbarati@apple.com <sbarati@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1575617584 +0000
committer sbarati@apple.com <sbarati@apple.com@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1575617584 +0000

get_by_id ICs should have a structure history used to indicate when we should skip generating an IC
https://bugs.webkit.org/show_bug.cgi?id=204904
<rdar://problem/57631437>

Reviewed by Yusuke Suzuki and Tadeu Zagallo.

I implemented a similar policy for get_by_val for the number of unique seen
identifiers. This allows us to create a heuristic to directly call the slow
path when profiling information tells us if inline caching might not be
profitable. This patch implements a similar policy for get_by_id where we
profile the seen base value structures. If the LLInt observes enough
unique structures, we omit emitting the inline cache in the upper
tiers.

The goal here was to try to speed up Speedometer2. Local testing showed
this patch to repeatedly be 0.5% faster, but all the P values I got were
insignificant. So it appears it's either neutral or slightly faster.

This patch also adjusts the policy of seeing a non-identifier inside
the PointerHistory data structure. Instead of increasing it to reach the
limit when we see a non-identifier, we just treat each execution with
a non-identifier to increment the count by 1.

* JavaScriptCore.xcodeproj/project.pbxproj:
* bytecode/BytecodeList.rb:
* bytecode/GetByValHistory.h: Removed.
* bytecode/PointerHistory.h: Copied from Source/JavaScriptCore/bytecode/GetByValHistory.h.
(JSC::PointerHistory::observe):
(JSC::PointerHistory::observeNull):
(JSC::GetByValHistory::observeNonUID): Deleted.
(JSC::GetByValHistory::observe): Deleted.
(JSC::GetByValHistory::count const): Deleted.
(JSC::GetByValHistory::filter const): Deleted.
(JSC::GetByValHistory::update): Deleted.
* dfg/DFGByteCodeParser.cpp:
(JSC::DFG::ByteCodeParser::parseGetById):
(JSC::DFG::ByteCodeParser::parseBlock):
* dfg/DFGGraph.h:
* dfg/DFGSpeculativeJIT.cpp:
(JSC::DFG::SpeculativeJIT::compileGetById):
* dfg/DFGSpeculativeJIT32_64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* dfg/DFGSpeculativeJIT64.cpp:
(JSC::DFG::SpeculativeJIT::compile):
* ftl/FTLLowerDFGToB3.cpp:
(JSC::FTL::DFG::LowerDFGToB3::compileGetById):
(JSC::FTL::DFG::LowerDFGToB3::compileGetByVal):
* generator/DSL.rb:
* jit/JITPropertyAccess.cpp:
(JSC::JIT::emit_op_try_get_by_id):
(JSC::JIT::emitSlow_op_try_get_by_id):
(JSC::JIT::emit_op_get_by_id_direct):
(JSC::JIT::emitSlow_op_get_by_id_direct):
(JSC::JIT::emit_op_get_by_id):
(JSC::JIT::emitSlow_op_get_by_id):
* llint/LLIntSlowPaths.cpp:
(JSC::LLInt::LLINT_SLOW_PATH_DECL):
* runtime/OptionsList.h:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@253201 268f45cc-cd09-0410-ab3c-d52691b4dbfc