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enhance reduce_vars (#4088)

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This commit is contained in:
Alex Lam S.L
2020-09-02 04:30:46 +01:00
committed by GitHub
parent 2f0da2ff05
commit 2500930234
1 changed files with 36 additions and 30 deletions
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66
lib/compress.js
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@@ -325,22 +325,22 @@ merge(Compressor.prototype, {
} }
var lhs = is_lhs(node, parent); var lhs = is_lhs(node, parent);
if (lhs) return lhs; if (lhs) return lhs;
if (!immutable if (parent instanceof AST_Array) return is_modified(compressor, tw, parent, parent, level + 1);
&& parent instanceof AST_Call if (parent instanceof AST_Call) {
&& parent.expression === node return !immutable
&& !parent.is_expr_pure(compressor) && parent.expression === node
&& (!(value instanceof AST_Function) && !parent.is_expr_pure(compressor)
|| !(parent instanceof AST_New) && value.contains_this())) { && (!(value instanceof AST_Function)
return true; || !(parent instanceof AST_New) && value.contains_this());
} }
if (parent instanceof AST_Array) { if (parent instanceof AST_ForIn) return parent.init === node;
return is_modified(compressor, tw, parent, parent, level + 1); if (parent instanceof AST_ObjectKeyVal) {
} if (parent.value !== node) return;
if (parent instanceof AST_ObjectKeyVal && node === parent.value) {
var obj = tw.parent(level + 1); var obj = tw.parent(level + 1);
return is_modified(compressor, tw, obj, obj, level + 2); return is_modified(compressor, tw, obj, obj, level + 2);
} }
if (parent instanceof AST_PropAccess && parent.expression === node) { if (parent instanceof AST_PropAccess) {
if (parent.expression !== node) return;
var prop = read_property(value, parent); var prop = read_property(value, parent);
return (!immutable || recursive) && is_modified(compressor, tw, parent, prop, level + 1); return (!immutable || recursive) && is_modified(compressor, tw, parent, prop, level + 1);
} }
@@ -514,33 +514,41 @@ merge(Compressor.prototype, {
|| value instanceof AST_This; || value instanceof AST_This;
} }
function has_escaped(d, node, parent) {
if (parent instanceof AST_Assign) return parent.operator == "=" && parent.right === node;
if (parent instanceof AST_Call) return parent.expression !== node || parent instanceof AST_New;
if (parent instanceof AST_Exit) return parent.value === node && node.scope !== d.scope;
if (parent instanceof AST_VarDef) return parent.value === node;
}
function value_in_use(node, parent) {
if (parent instanceof AST_Array) return true;
if (parent instanceof AST_Binary) return lazy_op[parent.operator];
if (parent instanceof AST_Conditional) return parent.condition !== node;
if (parent instanceof AST_Sequence) return parent.tail_node() === node;
}
function mark_escaped(tw, d, scope, node, value, level, depth) { function mark_escaped(tw, d, scope, node, value, level, depth) {
var parent = tw.parent(level); var parent = tw.parent(level);
if (value && value.is_constant()) return; if (value && value.is_constant()) return;
if (parent instanceof AST_Assign && parent.operator == "=" && node === parent.right if (has_escaped(d, node, parent)) {
|| parent instanceof AST_Call && (node !== parent.expression || parent instanceof AST_New)
|| parent instanceof AST_Exit && node === parent.value && node.scope !== d.scope
|| parent instanceof AST_VarDef && node === parent.value) {
d.escaped.push(parent); d.escaped.push(parent);
if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1; if (depth > 1 && !(value && value.is_constant_expression(scope))) depth = 1;
if (!d.escaped.depth || d.escaped.depth > depth) d.escaped.depth = depth; if (!d.escaped.depth || d.escaped.depth > depth) d.escaped.depth = depth;
return; return;
} else if (parent instanceof AST_Array } else if (value_in_use(node, parent)) {
|| parent instanceof AST_Binary && lazy_op[parent.operator]
|| parent instanceof AST_Conditional && node !== parent.condition
|| parent instanceof AST_Sequence && node === parent.tail_node()) {
mark_escaped(tw, d, scope, parent, parent, level + 1, depth); mark_escaped(tw, d, scope, parent, parent, level + 1, depth);
} else if (parent instanceof AST_ObjectKeyVal && node === parent.value) { } else if (parent instanceof AST_ObjectKeyVal && parent.value === node) {
var obj = tw.parent(level + 1); var obj = tw.parent(level + 1);
mark_escaped(tw, d, scope, obj, obj, level + 2, depth); mark_escaped(tw, d, scope, obj, obj, level + 2, depth);
} else if (parent instanceof AST_PropAccess && node === parent.expression) { } else if (parent instanceof AST_PropAccess && parent.expression === node) {
value = read_property(value, parent); value = read_property(value, parent);
mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1); mark_escaped(tw, d, scope, parent, value, level + 1, depth + 1);
if (value) return; if (value) return;
} }
if (level > 0) return; if (level > 0) return;
if (parent instanceof AST_Call && node === parent.expression) return; if (parent instanceof AST_Call && parent.expression === node) return;
if (parent instanceof AST_Sequence && node !== parent.tail_node()) return; if (parent instanceof AST_Sequence && parent.tail_node() !== node) return;
if (parent instanceof AST_SimpleStatement) return; if (parent instanceof AST_SimpleStatement) return;
if (parent instanceof AST_Unary && !unary_side_effects[parent.operator]) return; if (parent instanceof AST_Unary && !unary_side_effects[parent.operator]) return;
d.direct_access = true; d.direct_access = true;
@@ -739,13 +747,11 @@ merge(Compressor.prototype, {
push(tw); push(tw);
var init = this.init; var init = this.init;
init.walk(tw); init.walk(tw);
if (init instanceof AST_Var) { if (init instanceof AST_SymbolRef) {
init = init.definitions[0].name; init.definition().fixed = false;
} else while (init instanceof AST_PropAccess) { } else if (init instanceof AST_Var) {
init = init.expression.tail_node(); init.definitions[0].name.definition().fixed = false;
} }
var def = init.definition();
if (def) def.fixed = false;
this.body.walk(tw); this.body.walk(tw);
pop(tw); pop(tw);
tw.in_loop = saved_loop; tw.in_loop = saved_loop;