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Merge pull request #6756 from ethereum/shiftMulRules

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Add optimizer rules for multiplication and division by left-shifted one.
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chriseth 2019-05-15 12:37:35 +02:00 committed by GitHub
commit ca4b1bc8c4
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1
Changelog.md
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@ -11,6 +11,7 @@ Compiler Features:
* SMTChecker: Inline external function calls to ``this``.
* Assembler: Encode the compiler version in the deployed bytecode.
* Yul Optimizer: Simplify single-run ``for`` loops to ``if`` statements.
* Optimizer: Add rules for multiplication and division by left-shifted one.
Bugfixes:

25
libevmasm/RuleList.h
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@ -391,6 +391,31 @@ std::vector<SimplificationRule<Pattern>> simplificationRuleListPart7(
false
});
rules.push_back({
// MUL(X, SHL(Y, 1)) -> SHL(Y, X)
{Instruction::MUL, {X, {Instruction::SHL, {Y, u256(1)}}}},
[=]() -> Pattern {
return {Instruction::SHL, {Y, X}};
},
false
});
rules.push_back({
// MUL(SHL(X, 1), Y) -> SHL(X, Y)
{Instruction::MUL, {{Instruction::SHL, {X, u256(1)}}, Y}},
[=]() -> Pattern {
return {Instruction::SHL, {X, Y}};
},
false
});
rules.push_back({
// DIV(X, SHL(Y, 1)) -> SHR(Y, X)
{Instruction::DIV, {X, {Instruction::SHL, {Y, u256(1)}}}},
[=]() -> Pattern {
return {Instruction::SHR, {Y, X}};
},
false
});
std::function<bool()> feasibilityFunction = [=]() {
if (B.d() > 256)