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enhance unsafe_math (#3603)

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This commit is contained in:
Alex Lam S.L
2019-11-25 21:14:13 +08:00
committed by GitHub
parent 81caadb709
commit 48a0f6fe41
2 changed files with 60 additions and 5 deletions
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29
lib/compress.js
View File

@@ -5811,15 +5811,16 @@ merge(Compressor.prototype, {
self.right = tmp;
}
}
if (commutativeOperators[self.operator] && self.right.is_constant() && !self.left.is_constant()) {
if (commutativeOperators[self.operator]
&& self.right.is_constant()
&& !self.left.is_constant()
&& !(self.left instanceof AST_Binary
&& PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
// if right is a constant, whatever side effects the
// left side might have could not influence the
// result. hence, force switch.
if (!(self.left instanceof AST_Binary
&& PRECEDENCE[self.left.operator] >= PRECEDENCE[self.operator])) {
reverse();
}
}
self = self.lift_sequences(compressor);
if (compressor.option("assignments") && lazy_op[self.operator]) {
var assign = self.right;
@@ -6129,6 +6130,26 @@ merge(Compressor.prototype, {
});
break;
}
// (a + b) + 3 => 3 + (a + b)
if (compressor.option("unsafe_math")
&& self.left instanceof AST_Binary
&& PRECEDENCE[self.left.operator] == PRECEDENCE[self.operator]
&& self.right.is_constant()
&& (self.right.is_boolean(compressor) || self.right.is_number(compressor))
&& self.left.is_number(compressor)
&& !self.left.right.is_constant()
&& (self.left.left.is_boolean(compressor) || self.left.left.is_number(compressor))) {
self = make_node(AST_Binary, self, {
operator: self.left.operator,
left: make_node(AST_Binary, self, {
operator: self.operator,
left: self.right,
right: self.left.left
}),
right: self.left.right
});
break;
}
case "-":
// a - -b => a + b
if (self.right instanceof AST_UnaryPrefix

34
test/compress/numbers.js
View File

@@ -945,3 +945,37 @@ issue_3593: {
}
expect_stdout: "-2"
}
unsafe_math_swap_constant: {
options = {
evaluate: true,
unsafe_math: true,
}
input: {
var a = 1, b = 2;
console.log(
a++ + b-- + 3,
a++ + b + 3,
a + b-- + 3,
a + b + 3,
a++ - b-- + 3,
a++ - b + 3,
a - b-- + 3,
a - b + 3
);
}
expect: {
var a = 1, b = 2;
console.log(
3 + a++ + b--,
a++ + b + 3,
a + b-- + 3,
a + b + 3,
3 + a++ - b--,
3 + a++ - b,
a - b-- + 3,
a - b + 3
);
}
expect_stdout: "6 6 7 6 6 8 9 10"
}