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improve compress performance (#3348)

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fixes #3174
This commit is contained in:
Alex Lam S.L
2019-03-20 02:53:04 +08:00
committed by GitHub
parent c520e99eda
commit b9615f7a62
2 changed files with 60 additions and 25 deletions
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56
lib/compress.js
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@@ -1101,10 +1101,10 @@ merge(Compressor.prototype, {
stop_if_hit = parent;
}
// Replace variable with assignment when found
var hit_lhs, hit_rhs;
var hit_rhs;
if (can_replace
&& !(node instanceof AST_SymbolDeclaration)
&& (scan_lhs && (hit_lhs = lhs.equivalent_to(node))
&& (scan_lhs && lhs.equivalent_to(node)
|| scan_rhs && (hit_rhs = scan_rhs(node, this)))) {
if (stop_if_hit && (hit_rhs || !lhs_local || !replace_all)) {
abort = true;
@@ -1194,10 +1194,9 @@ merge(Compressor.prototype, {
var stop_after = null;
var stop_if_hit = null;
var lhs = get_lhs(candidate);
var rhs = get_rhs(candidate);
var side_effects = lhs && lhs.has_side_effects(compressor);
var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs);
var scan_rhs = rhs && foldable(rhs);
var scan_rhs = foldable(get_rhs(candidate));
if (!scan_lhs && !scan_rhs) continue;
// Locate symbols which may execute code outside of scanning range
var lvalues = get_lvalues(candidate);
@@ -1524,6 +1523,7 @@ merge(Compressor.prototype, {
}
function foldable(expr) {
if (!expr) return false;
if (expr instanceof AST_SymbolRef) {
var value = expr.evaluate(compressor);
if (value === expr) return rhs_exact_match;
@@ -1545,10 +1545,10 @@ merge(Compressor.prototype, {
}
}));
return !circular && rhs_exact_match;
}
function rhs_exact_match(node) {
return rhs.equivalent_to(node);
function rhs_exact_match(node) {
return expr.equivalent_to(node);
}
}
function rhs_fuzzy_match(value, fallback) {
@@ -4073,19 +4073,6 @@ merge(Compressor.prototype, {
def(AST_Function, function(compressor) {
return this.name && compressor.option("ie8") ? this : null;
});
def(AST_Unary, function(compressor, first_in_statement) {
if (unary_side_effects[this.operator]) {
this.write_only = !this.expression.has_side_effects(compressor);
return this;
}
if (this.operator == "typeof" && this.expression instanceof AST_SymbolRef) return null;
var expression = this.expression.drop_side_effect_free(compressor, first_in_statement);
if (first_in_statement && expression && is_iife_call(expression)) {
if (expression === this.expression && this.operator == "!") return this;
return expression.negate(compressor, first_in_statement);
}
return expression;
});
def(AST_Object, function(compressor, first_in_statement) {
var values = trim(this.properties, compressor, first_in_statement);
return values && make_sequence(this, values);
@@ -4110,9 +4097,27 @@ merge(Compressor.prototype, {
return make_sequence(this, [ expression, property ]);
});
def(AST_SymbolRef, function(compressor) {
return this.is_declared(compressor) ? null : this;
if (!this.is_declared(compressor)) return this;
this.definition().replaced++;
return null;
});
def(AST_This, return_null);
def(AST_Unary, function(compressor, first_in_statement) {
if (unary_side_effects[this.operator]) {
this.write_only = !this.expression.has_side_effects(compressor);
return this;
}
if (this.operator == "typeof" && this.expression instanceof AST_SymbolRef) {
this.expression.definition().replaced++;
return null;
}
var expression = this.expression.drop_side_effect_free(compressor, first_in_statement);
if (first_in_statement && expression && is_iife_call(expression)) {
if (expression === this.expression && this.operator == "!") return this;
return expression.negate(compressor, first_in_statement);
}
return expression;
});
})(function(node, func) {
node.DEFMETHOD("drop_side_effect_free", func);
});
@@ -4607,9 +4612,7 @@ merge(Compressor.prototype, {
});
OPT(AST_Definitions, function(self, compressor) {
if (self.definitions.length == 0)
return make_node(AST_EmptyStatement, self);
return self;
return self.definitions.length ? self : make_node(AST_EmptyStatement, self);
});
AST_Call.DEFMETHOD("lift_sequences", function(compressor) {
@@ -5855,6 +5858,7 @@ merge(Compressor.prototype, {
value = fixed.optimize(compressor);
if (value === fixed) value = fixed.clone(true);
}
def.replaced++;
return value;
}
if (fixed && def.should_replace === undefined) {
@@ -5897,7 +5901,9 @@ merge(Compressor.prototype, {
}
}
if (def.should_replace) {
return def.should_replace();
var value = def.should_replace();
def.replaced++;
return value;
}
}
return self;