Ignore:
Timestamp:
Aug 8, 2019, 11:23:18 AM (6 years ago)
Author:
Ross Kirsling
Message:

[JSC] Add "jump if (not) undefined or null" bytecode ops
​https://bugs.webkit.org/show_bug.cgi?id=200480

Reviewed by Saam Barati.

JSTests:

  • stress/destructuring-assignment-require-object-coercible.js:
  • stress/nullish-coalescing.js:

Source/JavaScriptCore:

This patch introduces fused jumps for op_is_undefined_or_null, which ignores "masquerade as undefined" behavior.

This lets us fix a edge-case bug in RequireObjectCoercible (where ({ length } = document.all) was a TypeError)
and moreover provides a very useful optimization for the new ?. and ?? operators, which have semantics centered
around op_jundefined_or_null and op_jnundefined_or_null, respectively.

  • bytecode/BytecodeList.rb:
  • bytecode/BytecodeUseDef.h:

(JSC::computeUsesForBytecodeOffset):
(JSC::computeDefsForBytecodeOffset):

  • bytecode/Opcode.h:

(JSC::isBranch):

  • bytecode/PreciseJumpTargetsInlines.h:
  • bytecompiler/BytecodeGenerator.cpp:

(JSC::Label::setLocation):
(JSC::BytecodeGenerator::emitJumpIfTrue):
(JSC::BytecodeGenerator::emitJumpIfFalse):
(JSC::BytecodeGenerator::emitRequireObjectCoercible):

  • dfg/DFGByteCodeParser.cpp:

(JSC::DFG::ByteCodeParser::parseBlock):

  • dfg/DFGCapabilities.cpp:

(JSC::DFG::capabilityLevel):

  • jit/JIT.cpp:

(JSC::JIT::privateCompileMainPass):

  • jit/JIT.h:
  • jit/JITOpcodes.cpp:

(JSC::JIT::emit_op_jundefined_or_null): Added.
(JSC::JIT::emit_op_jnundefined_or_null): Added.

  • jit/JITOpcodes32_64.cpp:

(JSC::JIT::emit_op_jundefined_or_null): Added.
(JSC::JIT::emit_op_jnundefined_or_null): Added.

  • llint/LowLevelInterpreter32_64.asm:
  • llint/LowLevelInterpreter64.asm:
File:
1 edited

Legend:

Unmodified
Added
Removed

  • trunk/Source/JavaScriptCore/jit/JIT.cpp

    r244865 r248426  
    365365        DEFINE_OP(op_jmp)
    366366        DEFINE_OP(op_jneq_null)
     367        DEFINE_OP(op_jundefined_or_null)
     368        DEFINE_OP(op_jnundefined_or_null)
    367369        DEFINE_OP(op_jneq_ptr)
    368370        DEFINE_OP(op_jless)
Note: See TracChangeset for help on using the changeset viewer.