enhance if_return (#5594)
This commit is contained in:
Alex Lam S.L
139
lib/compress.js
139
lib/compress.js
@@ -3451,7 +3451,7 @@ Compressor.prototype.compress = function(node) {
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var changed = false;
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var parent = compressor.parent();
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var self = compressor.self();
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var jump, merge_jump;
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var declare_only, jump, merge_jump;
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var in_iife = in_lambda && parent && parent.TYPE == "Call" && parent.expression === self;
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var chain_if_returns = in_lambda && compressor.option("conditionals") && compressor.option("sequences");
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var multiple_if_returns = has_multiple_if_returns(statements);
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@@ -3460,7 +3460,7 @@ Compressor.prototype.compress = function(node) {
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var j = next_index(i);
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var next = statements[j];
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if (in_lambda && !next && stat instanceof AST_Return
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if (in_lambda && declare_only && !next && stat instanceof AST_Return
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&& !(self instanceof AST_SwitchBranch)
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&& !(in_try && in_try.bfinally && in_async_generator(in_lambda))) {
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var body = stat.value;
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@@ -3493,7 +3493,7 @@ Compressor.prototype.compress = function(node) {
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body: as_statement_array_with_return(stat.body, ab),
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});
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stat.alternative = make_node(AST_BlockStatement, stat, {
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body: as_statement_array(stat.alternative).concat(extract_functions()),
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body: as_statement_array(stat.alternative).concat(extract_functions(merge_jump, jump)),
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});
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statements[i] = stat;
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statements[i] = stat.transform(compressor);
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@@ -3502,15 +3502,17 @@ Compressor.prototype.compress = function(node) {
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if (ab && !stat.alternative && next instanceof AST_Jump) {
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var cond = stat.condition;
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cond = best_of_expression(cond, cond.negate(compressor), stat.body instanceof AST_BlockStatement);
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var preference = i + 1 == j && stat.body instanceof AST_BlockStatement;
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cond = best_of_expression(cond, cond.negate(compressor), preference);
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if (cond !== stat.condition) {
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changed = true;
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stat = stat.clone();
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stat.condition = cond;
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statements[j] = stat.body;
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stat.body = next;
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if (next === jump) jump = null;
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statements[i] = stat;
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var body = stat.body;
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stat.body = make_node(AST_BlockStatement, next, {
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body: extract_functions(true, null, j + 1),
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});
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statements.splice(i, 1, stat, body);
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statements[i] = stat.transform(compressor);
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continue;
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}
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@@ -3522,7 +3524,7 @@ Compressor.prototype.compress = function(node) {
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changed = true;
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stat = stat.clone();
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stat.body = make_node(AST_BlockStatement, stat.body, {
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body: as_statement_array(stat.body).concat(extract_functions()),
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body: as_statement_array(stat.body).concat(extract_functions(merge_jump, jump)),
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});
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stat.alternative = make_node(AST_BlockStatement, stat.alternative, {
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body: as_statement_array_with_return(stat.alternative, alt),
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@@ -3551,38 +3553,26 @@ Compressor.prototype.compress = function(node) {
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if (!stat.alternative && next instanceof AST_Return) {
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changed = true;
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stat = stat.clone();
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stat.alternative = next;
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if (next === jump) jump = null;
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statements.splice(i, 1, stat.transform(compressor));
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statements.splice(j, 1);
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stat.alternative = make_node(AST_BlockStatement, next, {
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body: extract_functions(true, null, j + 1),
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});
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statements[i] = stat;
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statements[i] = stat.transform(compressor);
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continue;
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}
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if (!stat.alternative && !next && in_lambda) {
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// if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
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if (in_bool || value && multiple_if_returns) {
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changed = true;
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stat = stat.clone();
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stat.alternative = make_node(AST_Return, stat, { value: null });
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statements.splice(i, 1, stat.transform(compressor));
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continue;
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}
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// if (foo()) return bar() ? x : void 0; ---> return foo() && bar() ? x : void 0;
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// if (foo()) return bar() ? void 0 : x; ---> return !foo() || bar() ? void 0 : x;
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var or;
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if (value instanceof AST_Conditional
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&& ((or = is_undefined(value.consequent, compressor))
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|| is_undefined(value.alternative, compressor))) {
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changed = true;
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var ret = stat.body.clone();
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ret.value = value.clone();
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ret.value.condition = make_node(AST_Binary, stat, {
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operator: or ? "||" : "&&",
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left: or ? stat.condition.negate(compressor) : stat.condition,
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right: value.condition,
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});
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statements.splice(i, 1, ret.transform(compressor));
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continue;
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}
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// if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
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// if (foo()) return bar() ? x : void 0; ---> return foo() && bar() ? x : void 0;
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// if (foo()) return bar() ? void 0 : x; ---> return !foo() || bar() ? void 0 : x;
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if (in_lambda && declare_only && !next && !stat.alternative && (in_bool
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|| value && multiple_if_returns
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|| value instanceof AST_Conditional && (is_undefined(value.consequent, compressor)
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|| is_undefined(value.alternative, compressor)))) {
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changed = true;
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stat = stat.clone();
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stat.alternative = make_node(AST_Return, stat, { value: null });
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statements[i] = stat;
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statements[i] = stat.transform(compressor);
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continue;
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}
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// if (a) return b; if (c) return d; e; ---> return a ? b : c ? d : void e;
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//
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@@ -3593,22 +3583,17 @@ Compressor.prototype.compress = function(node) {
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if (chain_if_returns && !stat.alternative
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&& (!(prev_stat = statements[prev = prev_index(i)]) && in_iife
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|| prev_stat instanceof AST_If && prev_stat.body instanceof AST_Return)
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&& next_index(j) == statements.length && next instanceof AST_SimpleStatement) {
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&& (!next ? !declare_only
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: next instanceof AST_SimpleStatement && next_index(j) == statements.length)) {
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changed = true;
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var exprs = [];
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var args = prev_stat ? trim_defns(prev, exprs) : [ i, 1 ];
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stat = stat.clone();
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exprs.push(stat.condition);
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stat.condition = make_sequence(stat, exprs);
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stat.alternative = make_node(AST_BlockStatement, next, {
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body: [
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next,
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make_node(AST_Return, next, { value: null }),
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],
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body: extract_functions().concat(make_node(AST_Return, next, { value: null })),
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});
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args.push(stat.transform(compressor));
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statements.splice(j, 1);
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[].splice.apply(statements, args);
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statements[i] = stat.transform(compressor);
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i = prev + 1;
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continue;
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}
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@@ -3703,17 +3688,18 @@ Compressor.prototype.compress = function(node) {
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return true;
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}
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function extract_functions() {
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function extract_functions(mode, stop, end) {
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var defuns = [];
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var lexical = false;
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var start = i + 1;
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var end;
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if (merge_jump) {
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end = statements.lastIndexOf(jump);
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if (end < 0) end = statements.length;
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} else {
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if (!mode) {
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end = statements.length;
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jump = null;
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} else if (stop) {
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end = statements.lastIndexOf(stop);
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} else {
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stop = statements[end];
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if (stop !== jump) jump = null;
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}
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var tail = statements.splice(start, end - start).filter(function(stat) {
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if (stat instanceof AST_LambdaDefinition) {
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@@ -3723,11 +3709,11 @@ Compressor.prototype.compress = function(node) {
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if (is_lexical_definition(stat)) lexical = true;
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return true;
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});
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if (merge_jump === 3) {
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tail.push(make_node(AST_SimpleStatement, jump.value, {
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body: make_sequence(jump.value, jump.value.expressions.slice(0, -1)),
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if (mode === 3) {
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tail.push(make_node(AST_SimpleStatement, stop.value, {
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body: make_sequence(stop.value, stop.value.expressions.slice(0, -1)),
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}));
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jump.value = jump.value.tail_node();
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stop.value = stop.value.tail_node();
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}
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[].push.apply(lexical ? tail : statements, defuns);
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return tail;
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@@ -3758,38 +3744,29 @@ Compressor.prototype.compress = function(node) {
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}
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function next_index(i) {
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for (var j = i + 1; j < statements.length; j++) {
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if (!is_declaration(statements[j])) break;
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declare_only = true;
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for (var j = i; ++j < statements.length;) {
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var stat = statements[j];
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if (is_declaration(stat)) continue;
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if (stat instanceof AST_Var) {
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declare_only = false;
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continue;
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}
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break;
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}
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return j;
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}
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function prev_index(i) {
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for (var j = i; --j >= 0;) {
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if (!(statements[j] instanceof AST_Var)) break;
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var stat = statements[j];
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if (stat instanceof AST_Var) continue;
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if (is_declaration(stat)) continue;
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break;
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}
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return j;
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}
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function trim_defns(j, exprs) {
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var args = [ j + 1, i - j ];
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var var_defs = [];
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while (++j < i) {
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var stat = statements[j];
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stat.remove_initializers(compressor, var_defs);
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stat.definitions.forEach(function(var_def) {
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if (!var_def.value) return;
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exprs.push(make_node(AST_Assign, var_def, {
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operator: "=",
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left: var_def.name.convert_symbol(AST_SymbolRef, process_to_assign),
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right: var_def.value,
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}));
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});
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}
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if (var_defs.length > 0) args.push(make_node(AST_Var, stat, { definitions: var_defs }));
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return args;
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}
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function eliminate_returns(stat, in_block) {
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if (stat instanceof AST_Exit) {
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var mode = match_return(stat, true);
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@@ -9618,7 +9595,7 @@ Compressor.prototype.compress = function(node) {
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}
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if (var_defs.length > 0) body.push(make_node(AST_Var, self, { definitions: var_defs }));
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if (body.length > 0) {
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body.push(self);
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body.push(self.transform(compressor));
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return make_node(AST_BlockStatement, self, { body: body }).optimize(compressor);
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}
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} else if (body_exprs && alt_exprs) {
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