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-rw-r--r--lib/compress.js317
1 files changed, 153 insertions, 164 deletions
diff --git a/lib/compress.js b/lib/compress.js
index a4552e85..3bf54da0 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -668,26 +668,24 @@ merge(Compressor.prototype, {
var CHANGED, max_iter = 10;
do {
CHANGED = false;
- statements = eliminate_spurious_blocks(statements);
+ eliminate_spurious_blocks(statements);
if (compressor.option("dead_code")) {
- statements = eliminate_dead_code(statements, compressor);
+ eliminate_dead_code(statements, compressor);
}
if (compressor.option("if_return")) {
- statements = handle_if_return(statements, compressor);
+ handle_if_return(statements, compressor);
}
if (compressor.sequences_limit > 0) {
- statements = sequencesize(statements, compressor);
+ sequencesize(statements, compressor);
}
if (compressor.option("join_vars")) {
- statements = join_consecutive_vars(statements, compressor);
+ join_consecutive_vars(statements, compressor);
}
if (compressor.option("collapse_vars")) {
- statements = collapse(statements, compressor);
+ collapse(statements, compressor);
}
} while (CHANGED && max_iter-- > 0);
- return statements;
-
// Search from right to left for assignment-like expressions:
// - `var a = x;`
// - `a = x;`
@@ -789,7 +787,6 @@ merge(Compressor.prototype, {
if (replaced && !remove_candidate(candidate)) statements.splice(stat_index, 1);
}
}
- return statements;
function extract_candidates(expr) {
if (expr instanceof AST_Assign && !expr.left.has_side_effects(compressor)
@@ -891,59 +888,60 @@ merge(Compressor.prototype, {
function eliminate_spurious_blocks(statements) {
var seen_dirs = [];
- return statements.reduce(function(a, stat){
+ for (var i = 0; i < statements.length;) {
+ var stat = statements[i];
if (stat instanceof AST_BlockStatement) {
CHANGED = true;
- a.push.apply(a, eliminate_spurious_blocks(stat.body));
+ eliminate_spurious_blocks(stat.body);
+ [].splice.apply(statements, [i, 1].concat(stat.body));
+ i += stat.body.length;
} else if (stat instanceof AST_EmptyStatement) {
CHANGED = true;
+ statements.splice(i, 1);
} else if (stat instanceof AST_Directive) {
if (seen_dirs.indexOf(stat.value) < 0) {
- a.push(stat);
+ i++;
seen_dirs.push(stat.value);
} else {
CHANGED = true;
+ statements.splice(i, 1);
}
- } else {
- a.push(stat);
- }
- return a;
- }, []);
- };
+ } else i++;
+ }
+ }
function handle_if_return(statements, compressor) {
var self = compressor.self();
var multiple_if_returns = has_multiple_if_returns(statements);
var in_lambda = self instanceof AST_Lambda;
- var ret = []; // Optimized statements, build from tail to front
- loop: for (var i = statements.length; --i >= 0;) {
+ for (var i = statements.length; --i >= 0;) {
var stat = statements[i];
- switch (true) {
- case (in_lambda && stat instanceof AST_Return && !stat.value && ret.length == 0):
+ var next = statements[i + 1];
+
+ if (in_lambda && stat instanceof AST_Return && !stat.value && !next) {
CHANGED = true;
- // note, ret.length is probably always zero
- // because we drop unreachable code before this
- // step. nevertheless, it's good to check.
- continue loop;
- case stat instanceof AST_If:
+ statements.length--;
+ continue;
+ }
+
+ if (stat instanceof AST_If) {
var ab = aborts(stat.body);
if (can_merge_flow(ab)) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
- var funs = extract_functions_from_statement_array(ret);
- var body = as_statement_array_with_return(stat.body, ab);
stat = stat.clone();
stat.condition = stat.condition.negate(compressor);
+ var body = as_statement_array_with_return(stat.body, ab);
stat.body = make_node(AST_BlockStatement, stat, {
- body: as_statement_array(stat.alternative).concat(ret)
+ body: as_statement_array(stat.alternative).concat(extract_functions())
});
stat.alternative = make_node(AST_BlockStatement, stat, {
body: body
});
- ret = [ stat.transform(compressor) ].concat(funs);
- continue loop;
+ statements[i] = stat.transform(compressor);
+ continue;
}
var ab = aborts(stat.alternative);
@@ -952,81 +950,71 @@ merge(Compressor.prototype, {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
- var funs = extract_functions_from_statement_array(ret);
stat = stat.clone();
stat.body = make_node(AST_BlockStatement, stat.body, {
- body: as_statement_array(stat.body).concat(ret)
+ body: as_statement_array(stat.body).concat(extract_functions())
});
var body = as_statement_array_with_return(stat.alternative, ab);
stat.alternative = make_node(AST_BlockStatement, stat.alternative, {
body: body
});
- ret = [ stat.transform(compressor) ].concat(funs);
- continue loop;
+ statements[i] = stat.transform(compressor);
+ continue;
}
+ }
- if (stat.body instanceof AST_Return) {
- var value = stat.body.value;
- //---
- // pretty silly case, but:
- // if (foo()) return; return; ==> foo(); return;
- if ((in_lambda && ret.length == 0 || ret[0] instanceof AST_Return && !ret[0].value)
- && !value && !stat.alternative) {
- CHANGED = true;
- var cond = make_node(AST_SimpleStatement, stat.condition, {
- body: stat.condition
- });
- ret.unshift(cond);
- continue loop;
- }
- //---
- // if (foo()) return x; return y; ==> return foo() ? x : y;
- if (ret[0] instanceof AST_Return && value && ret[0].value && !stat.alternative) {
- CHANGED = true;
- stat = stat.clone();
- stat.alternative = ret[0];
- ret[0] = stat.transform(compressor);
- continue loop;
- }
- //---
- // if (foo()) return x; [ return ; ] ==> return foo() ? x : undefined;
- if (multiple_if_returns && (ret.length == 0 || ret[0] instanceof AST_Return)
- && value && !stat.alternative && in_lambda) {
- CHANGED = true;
- stat = stat.clone();
- stat.alternative = ret[0] || make_node(AST_Return, stat, {
- value: null
- });
- ret[0] = stat.transform(compressor);
- continue loop;
- }
- //---
- // if (a) return b; if (c) return d; e; ==> return a ? b : c ? d : void e;
- //
- // if sequences is not enabled, this can lead to an endless loop (issue #866).
- // however, with sequences on this helps producing slightly better output for
- // the example code.
- if (compressor.option("sequences")
- && i > 0 && statements[i - 1] instanceof AST_If && statements[i - 1].body instanceof AST_Return
- && ret.length == 1 && in_lambda && ret[0] instanceof AST_SimpleStatement
- && !stat.alternative) {
- CHANGED = true;
- ret.push(make_node(AST_Return, ret[0], {
- value: null
- }).transform(compressor));
- ret.unshift(stat);
- continue loop;
- }
+ if (stat instanceof AST_If && stat.body instanceof AST_Return) {
+ var value = stat.body.value;
+ //---
+ // pretty silly case, but:
+ // if (foo()) return; return; ==> foo(); return;
+ if (!value && !stat.alternative
+ && (in_lambda && !next || next instanceof AST_Return && !next.value)) {
+ CHANGED = true;
+ statements[i] = make_node(AST_SimpleStatement, stat.condition, {
+ body: stat.condition
+ });
+ continue;
+ }
+ //---
+ // if (foo()) return x; return y; ==> return foo() ? x : y;
+ if (value && !stat.alternative && next instanceof AST_Return && next.value) {
+ CHANGED = true;
+ stat = stat.clone();
+ stat.alternative = next;
+ statements.splice(i, 2, stat.transform(compressor));
+ continue;
+ }
+ //---
+ // if (foo()) return x; [ return ; ] ==> return foo() ? x : undefined;
+ if (multiple_if_returns && in_lambda && value && !stat.alternative
+ && (!next || next instanceof AST_Return)) {
+ CHANGED = true;
+ stat = stat.clone();
+ stat.alternative = next || make_node(AST_Return, stat, {
+ value: null
+ });
+ statements.splice(i, next ? 2 : 1, stat.transform(compressor));
+ continue;
+ }
+ //---
+ // if (a) return b; if (c) return d; e; ==> return a ? b : c ? d : void e;
+ //
+ // if sequences is not enabled, this can lead to an endless loop (issue #866).
+ // however, with sequences on this helps producing slightly better output for
+ // the example code.
+ var prev = statements[i - 1];
+ if (compressor.option("sequences") && in_lambda && !stat.alternative
+ && prev instanceof AST_If && prev.body instanceof AST_Return
+ && i + 2 == statements.length && next instanceof AST_SimpleStatement) {
+ CHANGED = true;
+ statements.push(make_node(AST_Return, next, {
+ value: null
+ }).transform(compressor));
+ continue;
}
-
- ret.unshift(stat);
- break;
- default:
- ret.unshift(stat);
- break;
}
}
- return ret;
function has_multiple_if_returns(statements) {
var n = 0;
@@ -1051,6 +1039,18 @@ merge(Compressor.prototype, {
|| ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct;
}
+ function extract_functions() {
+ var tail = statements.slice(i + 1);
+ statements.length = i + 1;
+ return tail.filter(function(stat) {
+ if (stat instanceof AST_Defun) {
+ statements.push(stat);
+ return false;
+ }
+ return true;
+ });
+ }
+
function as_statement_array_with_return(node, ab) {
var body = as_statement_array(node).slice(0, -1);
if (ab.value) {
@@ -1060,49 +1060,52 @@ merge(Compressor.prototype, {
}
return body;
}
- };
+ }
function eliminate_dead_code(statements, compressor) {
- var has_quit = false;
- var orig = statements.length;
+ var has_quit;
var self = compressor.self();
- statements = statements.reduce(function(a, stat){
- if (has_quit) {
- extract_declarations_from_unreachable_code(compressor, stat, a);
- } else {
- if (stat instanceof AST_LoopControl) {
- var lct = compressor.loopcontrol_target(stat);
- if ((stat instanceof AST_Break
- && !(lct instanceof AST_IterationStatement)
- && loop_body(lct) === self) || (stat instanceof AST_Continue
- && loop_body(lct) === self)) {
- if (stat.label) {
- remove(stat.label.thedef.references, stat);
- }
- } else {
- a.push(stat);
+ for (var i = 0, n = 0, len = statements.length; i < len; i++) {
+ var stat = statements[i];
+ if (stat instanceof AST_LoopControl) {
+ var lct = compressor.loopcontrol_target(stat);
+ if (stat instanceof AST_Break
+ && !(lct instanceof AST_IterationStatement)
+ && loop_body(lct) === self
+ || stat instanceof AST_Continue
+ && loop_body(lct) === self) {
+ if (stat.label) {
+ remove(stat.label.thedef.references, stat);
}
} else {
- a.push(stat);
+ statements[n++] = stat;
}
- if (aborts(stat)) has_quit = true;
+ } else {
+ statements[n++] = stat;
}
- return a;
- }, []);
- CHANGED = statements.length != orig;
- return statements;
- };
+ if (aborts(stat)) {
+ has_quit = statements.slice(i + 1);
+ break;
+ }
+ }
+ statements.length = n;
+ CHANGED = n != len;
+ if (has_quit) has_quit.forEach(function(stat) {
+ extract_declarations_from_unreachable_code(compressor, stat, statements);
+ });
+ }
function sequencesize(statements, compressor) {
- if (statements.length < 2) return statements;
- var seq = [], ret = [];
+ if (statements.length < 2) return;
+ var seq = [], n = 0;
function push_seq() {
if (!seq.length) return;
var body = make_sequence(seq[0], seq);
- ret.push(make_node(AST_SimpleStatement, body, { body: body }));
+ statements[n++] = make_node(AST_SimpleStatement, body, { body: body });
seq = [];
- };
- statements.forEach(function(stat){
+ }
+ for (var i = 0, len = statements.length; i < len; i++) {
+ var stat = statements[i];
if (stat instanceof AST_SimpleStatement) {
if (seq.length >= compressor.sequences_limit) push_seq();
var body = stat.body;
@@ -1110,18 +1113,18 @@ merge(Compressor.prototype, {
if (body) merge_sequence(seq, body);
} else {
push_seq();
- ret.push(stat);
+ statements[n++] = stat;
}
- });
+ }
push_seq();
- ret = sequencesize_2(ret, compressor);
- CHANGED = ret.length != statements.length;
- return ret;
- };
+ statements.length = n;
+ sequencesize_2(statements, compressor);
+ CHANGED = statements.length != len;
+ }
function sequencesize_2(statements, compressor) {
function cons_seq(right) {
- ret.pop();
+ n--;
var left = prev.body;
if (!(left instanceof AST_Sequence)) {
left = make_node(AST_Sequence, left, {
@@ -1131,8 +1134,9 @@ merge(Compressor.prototype, {
merge_sequence(left.expressions, right);
return left.transform(compressor);
};
- var ret = [], prev = null;
- statements.forEach(function(stat){
+ var n = 0, prev;
+ for (var i = 0, len = statements.length; i < len; i++) {
+ var stat = statements[i];
if (prev) {
if (stat instanceof AST_For) {
try {
@@ -1145,7 +1149,7 @@ merge(Compressor.prototype, {
}
else if (!stat.init) {
stat.init = prev.body.drop_side_effect_free(compressor);
- ret.pop();
+ n--;
}
} catch(ex) {
if (ex !== cons_seq) throw ex;
@@ -1167,15 +1171,16 @@ merge(Compressor.prototype, {
stat.expression = cons_seq(stat.expression);
}
}
- ret.push(stat);
+ statements[n++] = stat;
prev = stat instanceof AST_SimpleStatement ? stat : null;
- });
- return ret;
- };
+ }
+ statements.length = n;
+ }
function join_consecutive_vars(statements, compressor) {
- var prev = null;
- return statements.reduce(function(a, stat){
+ for (var i = 0, j = -1, len = statements.length; i < len; i++) {
+ var stat = statements[i];
+ var prev = statements[j];
if (stat instanceof AST_Definitions && prev && prev.TYPE == stat.TYPE) {
prev.definitions = prev.definitions.concat(stat.definitions);
CHANGED = true;
@@ -1184,35 +1189,19 @@ merge(Compressor.prototype, {
&& prev instanceof AST_Var
&& (!stat.init || stat.init.TYPE == prev.TYPE)) {
CHANGED = true;
- a.pop();
if (stat.init) {
stat.init.definitions = prev.definitions.concat(stat.init.definitions);
} else {
stat.init = prev;
}
- a.push(stat);
- prev = stat;
+ statements[j] = stat;
}
else {
- prev = stat;
- a.push(stat);
+ statements[++j] = stat;
}
- return a;
- }, []);
- };
-
- };
-
- function extract_functions_from_statement_array(statements) {
- var funs = [];
- for (var i = statements.length - 1; i >= 0; --i) {
- var stat = statements[i];
- if (stat instanceof AST_Defun) {
- statements.splice(i, 1);
- funs.unshift(stat);
}
- }
- return funs;
+ statements.length = j + 1;
+ };
}
function extract_declarations_from_unreachable_code(compressor, stat, target) {
@@ -1989,12 +1978,12 @@ merge(Compressor.prototype, {
});
OPT(AST_Block, function(self, compressor){
- self.body = tighten_body(self.body, compressor);
+ tighten_body(self.body, compressor);
return self;
});
OPT(AST_BlockStatement, function(self, compressor){
- self.body = tighten_body(self.body, compressor);
+ tighten_body(self.body, compressor);
switch (self.body.length) {
case 1: return self.body[0];
case 0: return make_node(AST_EmptyStatement, self);
@@ -2901,7 +2890,7 @@ merge(Compressor.prototype, {
});
OPT(AST_Try, function(self, compressor){
- self.body = tighten_body(self.body, compressor);
+ tighten_body(self.body, compressor);
if (self.bcatch && self.bfinally && all(self.bfinally.body, is_empty)) self.bfinally = null;
if (all(self.body, is_empty)) {
var body = [];
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