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recover lost opportunities from #2574 (#2584)

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This commit is contained in:
Alex Lam S.L
2017-12-13 18:20:53 +08:00
committed by GitHub
parent 04cc395c35
commit 7f418978c9
2 changed files with 59 additions and 10 deletions
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23
lib/compress.js
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@@ -863,6 +863,7 @@ merge(Compressor.prototype, {
if (scope.uses_eval || scope.uses_with) return statements;
var args;
var candidates = [];
var in_try = compressor.self() instanceof AST_Try;
var stat_index = statements.length;
var scanner = new TreeTransformer(function(node, descend) {
if (abort) return node;
@@ -956,7 +957,8 @@ merge(Compressor.prototype, {
|| side_effects && !references_in_scope(node.definition()))
|| (sym = lhs_or_def(node))
&& (sym instanceof AST_PropAccess || sym.name in lvalues)
|| may_throw && node.has_side_effects(compressor)
|| may_throw
&& (in_try ? node.has_side_effects(compressor) : side_effects_external(node))
|| (side_effects || !replace_all)
&& (parent instanceof AST_Binary && lazy_op(parent.operator)
|| parent instanceof AST_Conditional
@@ -1192,6 +1194,25 @@ merge(Compressor.prototype, {
return ref.scope === scope;
});
}
function side_effects_external(node, lhs) {
if (node instanceof AST_Assign) {
return side_effects_external(node.left, true)
|| side_effects_external(node.right);
}
if (node instanceof AST_Definitions) return false;
if (node instanceof AST_Unary) return side_effects_external(node.expression, true);
if (node instanceof AST_VarDef) return node.value && side_effects_external(node.value);
if (lhs) {
if (node instanceof AST_Dot) return side_effects_external(node.expression, true);
if (node instanceof AST_Sub) {
return side_effects_external(node.expression, true)
|| side_effects_external(node.property);
}
if (node instanceof AST_SymbolRef) return node.definition().scope !== scope;
}
return node.has_side_effects(compressor);
}
}
function eliminate_spurious_blocks(statements) {