2010-08-09 Oliver Hunt <[email protected]>
Reviewed by Gavin Barraclough.
Allow an assembler/macroassembler to compact branches to more concise forms when linking
https://bugs.webkit.org/show_bug.cgi?id=43745
This patch makes it possible for an assembler to convert jumps into a different
(presumably more efficient) form at link time. Currently implemented in the
ARMv7 JIT as that already had logic to delay linking of jumps until the end of
compilation already. The ARMv7 JIT chooses between either a 4 byte short jump
or a full 32-bit offset (and rewrites ITTT instructions as appropriate), so does
not yet produce the most compact form possible. The general design of the linker
should make it relatively simple to introduce new branch types with little effort,
as the linker has no knowledge of the exact form of any of the branches.
- JavaScriptCore.xcodeproj/project.pbxproj:
- assembler/ARMv7Assembler.cpp: Added.
(JSC::):
Record jump sizes
- assembler/ARMv7Assembler.h:
(JSC::ARMv7Assembler::LinkRecord::LinkRecord):
(JSC::ARMv7Assembler::LinkRecord::from):
(JSC::ARMv7Assembler::LinkRecord::setFrom):
(JSC::ARMv7Assembler::LinkRecord::to):
(JSC::ARMv7Assembler::LinkRecord::type):
(JSC::ARMv7Assembler::LinkRecord::linkType):
(JSC::ARMv7Assembler::LinkRecord::setLinkType):
Encapsulate LinkRecord fields so we can compress the values somewhat
(JSC::ARMv7Assembler::JmpSrc::JmpSrc):
Need to record the jump type now
(JSC::ARMv7Assembler::b):
(JSC::ARMv7Assembler::blx):
(JSC::ARMv7Assembler::bx):
Need to pass the jump types
(JSC::ARMv7Assembler::executableOffsetFor):
(JSC::ARMv7Assembler::jumpSizeDelta):
(JSC::ARMv7Assembler::linkRecordSourceComparator):
(JSC::ARMv7Assembler::computeJumpType):
(JSC::ARMv7Assembler::convertJumpTo):
(JSC::ARMv7Assembler::recordLinkOffsets):
(JSC::ARMv7Assembler::jumpsToLink):
(JSC::ARMv7Assembler::link):
(JSC::ARMv7Assembler::unlinkedCode):
Helper functions for the linker
(JSC::ARMv7Assembler::linkJump):
(JSC::ARMv7Assembler::canBeShortJump):
(JSC::ARMv7Assembler::linkLongJump):
(JSC::ARMv7Assembler::linkShortJump):
(JSC::ARMv7Assembler::linkJumpAbsolute):
Moving code around for the various jump linking functions
- assembler/AbstractMacroAssembler.h:
(JSC::AbstractMacroAssembler::beginUninterruptedSequence):
(JSC::AbstractMacroAssembler::endUninterruptedSequence):
We have to track uninterrupted sequences in any assembler that compacts
branches as that's not something we're allowed to do in such sequences.
AbstractMacroAssembler has a nop version of these functions as it makes the
code elsewhere nicer.
- assembler/LinkBuffer.h:
(JSC::LinkBuffer::LinkBuffer):
(JSC::LinkBuffer::link):
(JSC::LinkBuffer::patch):
(JSC::LinkBuffer::locationOf):
(JSC::LinkBuffer::locationOfNearCall):
(JSC::LinkBuffer::returnAddressOffset):
(JSC::LinkBuffer::trampolineAt):
Updated these functions to adjust for any changed offsets in the linked code
(JSC::LinkBuffer::applyOffset):
A helper function to deal with the now potentially moved labels
(JSC::LinkBuffer::linkCode):
The new and mighty linker function
- assembler/MacroAssemblerARMv7.h:
(JSC::MacroAssemblerARMv7::MacroAssemblerARMv7):
(JSC::MacroAssemblerARMv7::beginUninterruptedSequence):
(JSC::MacroAssemblerARMv7::endUninterruptedSequence):
(JSC::MacroAssemblerARMv7::jumpsToLink):
(JSC::MacroAssemblerARMv7::unlinkedCode):
(JSC::MacroAssemblerARMv7::computeJumpType):
(JSC::MacroAssemblerARMv7::convertJumpTo):
(JSC::MacroAssemblerARMv7::recordLinkOffsets):
(JSC::MacroAssemblerARMv7::jumpSizeDelta):
(JSC::MacroAssemblerARMv7::link):
(JSC::MacroAssemblerARMv7::jump):
(JSC::MacroAssemblerARMv7::branchMul32):
(JSC::MacroAssemblerARMv7::breakpoint):
(JSC::MacroAssemblerARMv7::nearCall):
(JSC::MacroAssemblerARMv7::call):
(JSC::MacroAssemblerARMv7::ret):
(JSC::MacroAssemblerARMv7::tailRecursiveCall):
(JSC::MacroAssemblerARMv7::executableOffsetFor):
(JSC::MacroAssemblerARMv7::inUninterruptedSequence):
(JSC::MacroAssemblerARMv7::makeJump):
(JSC::MacroAssemblerARMv7::makeBranch):
All branches need to pass on their type now
- jit/ExecutableAllocator.h:
(JSC::ExecutablePool::returnLastBytes):
We can't know ahead of time how much space will be necessary to
hold the linked code if we're compacting branches, this new
function allows us to return the unused bytes at the end of linking
- jit/JIT.cpp:
(JSC::JIT::JIT):
(JSC::JIT::privateCompile):
- jit/JIT.h:
(JSC::JIT::compile):
The JIT class now needs to take a linker offset so that recompilation
can generate the same jumps when using branch compaction.
- jit/JITArithmetic32_64.cpp:
(JSC::JIT::emitSlow_op_mod):
- jit/JITOpcodes.cpp:
(JSC::JIT::privateCompileCTIMachineTrampolines):
- jit/JITOpcodes32_64.cpp:
(JSC::JIT::privateCompileCTIMachineTrampolines):
(JSC::JIT::privateCompileCTINativeCall):
Update for new trampolineAt changes
- wtf/FastMalloc.cpp:
(WTF::TCMallocStats::):
- wtf/Platform.h:
