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LibJS/Bytecode: Add peephole optimization pass and fuse compare+jump

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This patch adds a new "Peephole" pass for performing small, local
optimizations to bytecode.

We also introduce the first such optimization, fusing a sequence of
some comparison instruction FooCompare followed by a JumpIf into a
new set of JumpFooCompare instructions.

This gives a ~50% speed-up on the following microbenchmark:

    for (let i = 0; i < 10_000_000; ++i) {
    }

But more traditional benchmarks see a pretty sizable speed-up as well,
for example 15% on Kraken/ai-astar.js and 16% on Kraken/audio-dft.js :^)
This commit is contained in:
Andreas Kling 2024-03-03 14:56:33 +01:00
parent acd29e064c
commit 4438ec481c
8 changed files with 214 additions and 24 deletions
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34
Userland/Libraries/LibJS/Bytecode/Op.h
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@ -1123,6 +1123,40 @@ private:
Operand m_condition;
};
// NOTE: The raw operator is used for comparing two Int32 values.
#define JS_ENUMERATE_FUSABLE_BINARY_OPS(X) \
X(GreaterThan, >, greater_than) \
X(GreaterThanEquals, >=, greater_than_equals) \
X(LessThan, <, less_than) \
X(LessThanEquals, <=, less_than_equals) \
X(LooselyEquals, ==, loosely_equals) \
X(LooselyInequals, !=, loosely_inequals) \
X(StrictlyEquals, ==, strict_equals) \
X(StrictlyInequals, !=, strict_inequals)
#define JS_DECLARE_FUSED_JUMP(PreOp, ...) \
class Jump##PreOp final : public Jump { \
public: \
explicit Jump##PreOp(Operand lhs, Operand rhs, Label true_target, Label false_target) \
: Jump(Type::Jump##PreOp, move(true_target), move(false_target), sizeof(*this)) \
, m_lhs(lhs) \
, m_rhs(rhs) \
{ \
} \
ThrowCompletionOr<void> execute_impl(Bytecode::Interpreter&) const; \
ByteString to_byte_string_impl(Bytecode::Executable const&) const; \
\
Operand lhs() const { return m_lhs; } \
Operand rhs() const { return m_rhs; } \
\
private: \
Operand m_lhs; \
Operand m_rhs; \
};
JS_ENUMERATE_FUSABLE_BINARY_OPS(JS_DECLARE_FUSED_JUMP)
#undef JS_DECLARE_FUSED_JUMP
class JumpNullish final : public Jump {
public:
explicit JumpNullish(Operand condition, Label true_target, Label false_target)