[Pkg-javascript-commits] [uglifyjs] 12/491: clean up `collapse_vars` (#1826)
Jonas Smedegaard
dr at jones.dk
Wed Feb 14 19:51:17 UTC 2018
This is an automated email from the git hooks/post-receive script.
js pushed a commit to annotated tag debian/3.3.10-1
in repository uglifyjs.
commit 0f4f01b66cb2aa4356309c70a7d6a95618603630
Author: Alex Lam S.L <alexlamsl at gmail.com>
Date: Tue Apr 18 21:45:34 2017 +0800
clean up `collapse_vars` (#1826)
- remove overlap in functionality of singular, consecutive reference of constant value
- remove workarounds for previous bugs in `lib/scope.js`
- distribute recursive `collapse_single_use_vars()` calls to their respective `OPT(AST_Node)`
- enable collapsing of variables within a single `AST_Definitions`
---
lib/compress.js | 245 ++++++++++++++++++++---------------------
test/compress/collapse_vars.js | 104 +++++++++++------
2 files changed, 189 insertions(+), 160 deletions(-)
diff --git a/lib/compress.js b/lib/compress.js
index 596b03f..a364157 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -642,151 +642,134 @@ merge(Compressor.prototype, {
// and if it has exactly one reference then attempt to replace its reference
// in the statement with the var value and then erase the var definition.
- var self = compressor.self();
- var var_defs_removed = false;
+ var scope = compressor.find_parent(AST_Scope);
var toplevel = compressor.option("toplevel");
for (var stat_index = statements.length; --stat_index >= 0;) {
var stat = statements[stat_index];
- if (stat instanceof AST_Definitions) continue;
-
- // Process child blocks of statement if present.
- [stat, stat.body, stat.alternative, stat.bcatch, stat.bfinally].forEach(function(node) {
- node && node.body && collapse_single_use_vars(node.body, compressor);
- });
- // The variable definition must precede a statement.
- if (stat_index <= 0) break;
- var prev_stat_index = stat_index - 1;
- var prev_stat = statements[prev_stat_index];
- if (!(prev_stat instanceof AST_Definitions)) continue;
- var var_defs = prev_stat.definitions;
- if (var_defs == null) continue;
-
- var var_names_seen = {};
+ var var_names_seen = Object.create(null);
var side_effects_encountered = false;
var lvalues_encountered = false;
- var lvalues = {};
+ var lvalues = Object.create(null);
+ var prev_stat_index, var_defs, var_defs_index;
// Scan variable definitions from right to left.
- for (var var_defs_index = var_defs.length; --var_defs_index >= 0;) {
-
- // Obtain var declaration and var name with basic sanity check.
- var var_decl = var_defs[var_defs_index];
- if (var_decl.value == null) break;
- var var_name = var_decl.name.name;
- if (!var_name || !var_name.length) break;
-
- // Bail if we've seen a var definition of same name before.
- if (var_name in var_names_seen) break;
- var_names_seen[var_name] = true;
-
- // Only interested in cases with just one reference to the variable.
- var def = self.find_variable && self.find_variable(var_name);
- if (!def || !def.references || def.references.length !== 1
- || var_name == "arguments" || (!toplevel && def.global)) {
- side_effects_encountered = true;
- continue;
+ if (stat instanceof AST_Definitions) {
+ prev_stat_index = stat_index;
+ var_defs = stat.definitions;
+ for (var_defs_index = var_defs.length - 1; --var_defs_index >= 0;) {
+ if (collapse(var_defs[var_defs_index + 1])) break;
}
- var ref = def.references[0];
-
- // Don't replace ref if eval() or with statement in scope.
- if (ref.scope.uses_eval || ref.scope.uses_with) break;
-
- // Constant single use vars can be replaced in any scope.
- if (var_decl.value.is_constant()) {
- var ctt = new TreeTransformer(function(node) {
- var parent = ctt.parent();
- if (parent instanceof AST_IterationStatement
- && (parent.condition === node || parent.init === node)) {
- return node;
- }
- if (node === ref)
- return replace_var(node, parent, true);
- });
- stat.transform(ctt);
- continue;
+ } else if (stat_index > 0) {
+ // The variable definition must precede a statement.
+ prev_stat_index = stat_index - 1;
+ var prev_stat = statements[prev_stat_index];
+ if (!(prev_stat instanceof AST_Definitions)) continue;
+ var_defs = prev_stat.definitions;
+ for (var_defs_index = var_defs.length; --var_defs_index >= 0;) {
+ if (collapse(stat)) break;
}
+ }
+ }
- // Restrict var replacement to constants if side effects encountered.
- if (side_effects_encountered |= lvalues_encountered) continue;
+ return statements;
- var value_has_side_effects = var_decl.value.has_side_effects(compressor);
- // Non-constant single use vars can only be replaced in same scope.
- if (ref.scope !== self) {
- side_effects_encountered |= value_has_side_effects;
- continue;
- }
+ function collapse(stat) {
+ var var_decl = var_defs[var_defs_index];
+ // `drop_unused()` shuffles variables without values to the top,
+ // so we can terminate upon first sighting as an optimization.
+ if (var_decl.value == null) return true;
+ var var_name = var_decl.name.name;
+
+ // Bail if we've seen a var definition of same name before.
+ if (var_name in var_names_seen) return true;
+ var_names_seen[var_name] = true;
+
+ // Only interested in non-constant values.
+ if (var_decl.value.is_constant()) return;
+
+ // Only interested in cases with just one reference to the variable.
+ var def = var_decl.name.definition();
+ if (def.references.length !== 1
+ || var_name == "arguments" || (!toplevel && def.global)) {
+ side_effects_encountered = true;
+ return;
+ }
+ var ref = def.references[0];
+
+ // Don't replace ref if eval() or with statement in scope.
+ if (ref.scope.uses_eval || ref.scope.uses_with) return true;
+
+ // Restrict var replacement to constants if side effects encountered.
+ if (side_effects_encountered |= lvalues_encountered) return;
- // Detect lvalues in var value.
- var tw = new TreeWalker(function(node){
- if (node instanceof AST_SymbolRef && is_lvalue(node, tw.parent())) {
- lvalues[node.name] = lvalues_encountered = true;
+ var value_has_side_effects = var_decl.value.has_side_effects(compressor);
+ // Non-constant single use vars can only be replaced in same scope.
+ if (ref.scope !== scope) {
+ side_effects_encountered |= value_has_side_effects;
+ return;
+ }
+
+ // Detect lvalues in var value.
+ var tw = new TreeWalker(function(node){
+ if (node instanceof AST_SymbolRef && is_lvalue(node, tw.parent())) {
+ lvalues[node.name] = lvalues_encountered = true;
+ }
+ });
+ var_decl.value.walk(tw);
+
+ // Replace the non-constant single use var in statement if side effect free.
+ var unwind = false;
+ var tt = new TreeTransformer(
+ function preorder(node) {
+ if (unwind || node instanceof AST_Scope && node !== scope) return node;
+ var parent = tt.parent();
+ if (node instanceof AST_Try
+ || node instanceof AST_With
+ || node instanceof AST_Case
+ || node instanceof AST_IterationStatement
+ || (parent instanceof AST_If && node !== parent.condition)
+ || (parent instanceof AST_Conditional && node !== parent.condition)
+ || (node instanceof AST_SymbolRef
+ && value_has_side_effects
+ && !are_references_in_scope(node.definition(), scope))
+ || (parent instanceof AST_Binary
+ && (parent.operator == "&&" || parent.operator == "||")
+ && node === parent.right)
+ || (parent instanceof AST_Switch && node !== parent.expression)) {
+ return side_effects_encountered = unwind = true, node;
}
- });
- var_decl.value.walk(tw);
-
- // Replace the non-constant single use var in statement if side effect free.
- var unwind = false;
- var tt = new TreeTransformer(
- function preorder(node) {
- if (unwind) return node;
- var parent = tt.parent();
- if (node instanceof AST_Lambda
- || node instanceof AST_Try
- || node instanceof AST_With
- || node instanceof AST_Case
- || node instanceof AST_IterationStatement
- || (parent instanceof AST_If && node !== parent.condition)
- || (parent instanceof AST_Conditional && node !== parent.condition)
- || (node instanceof AST_SymbolRef
- && value_has_side_effects
- && !are_references_in_scope(node.definition(), self))
- || (parent instanceof AST_Binary
- && (parent.operator == "&&" || parent.operator == "||")
- && node === parent.right)
- || (parent instanceof AST_Switch && node !== parent.expression)) {
- return side_effects_encountered = unwind = true, node;
- }
- function are_references_in_scope(def, scope) {
- if (def.orig.length === 1
- && def.orig[0] instanceof AST_SymbolDefun) return true;
- if (def.scope !== scope) return false;
- var refs = def.references;
- for (var i = 0, len = refs.length; i < len; i++) {
- if (refs[i].scope !== scope) return false;
- }
- return true;
- }
- },
- function postorder(node) {
- if (unwind) return node;
- if (node === ref)
- return unwind = true, replace_var(node, tt.parent(), false);
- if (side_effects_encountered |= node.has_side_effects(compressor))
- return unwind = true, node;
- if (lvalues_encountered && node instanceof AST_SymbolRef && node.name in lvalues) {
- side_effects_encountered = true;
- return unwind = true, node;
+ function are_references_in_scope(def, scope) {
+ if (def.orig.length === 1
+ && def.orig[0] instanceof AST_SymbolDefun) return true;
+ if (def.scope !== scope) return false;
+ var refs = def.references;
+ for (var i = 0, len = refs.length; i < len; i++) {
+ if (refs[i].scope !== scope) return false;
}
+ return true;
}
- );
- stat.transform(tt);
- }
- }
-
- // Remove extraneous empty statments in block after removing var definitions.
- // Leave at least one statement in `statements`.
- if (var_defs_removed) for (var i = statements.length; --i >= 0;) {
- if (statements.length > 1 && statements[i] instanceof AST_EmptyStatement)
- statements.splice(i, 1);
+ },
+ function postorder(node) {
+ if (unwind) return node;
+ if (node === ref)
+ return unwind = true, replace_var(var_decl, node, tt.parent(), false);
+ if (side_effects_encountered |= node.has_side_effects(compressor))
+ return unwind = true, node;
+ if (lvalues_encountered && node instanceof AST_SymbolRef && node.name in lvalues) {
+ side_effects_encountered = true;
+ return unwind = true, node;
+ }
+ }
+ );
+ stat.transform(tt);
}
- return statements;
-
function is_lvalue(node, parent) {
return node instanceof AST_SymbolRef && is_lhs(node, parent);
}
- function replace_var(node, parent, is_constant) {
+
+ function replace_var(var_decl, node, parent, is_constant) {
if (is_lvalue(node, parent)) return node;
// Remove var definition and return its value to the TreeTransformer to replace.
@@ -795,14 +778,19 @@ merge(Compressor.prototype, {
var_defs.splice(var_defs_index, 1);
if (var_defs.length === 0) {
- statements[prev_stat_index] = make_node(AST_EmptyStatement, self);
- var_defs_removed = true;
+ statements.splice(prev_stat_index, 1);
+ stat_index--;
}
// Further optimize statement after substitution.
stat.reset_opt_flags(compressor);
- compressor.info("Collapsing " + (is_constant ? "constant" : "variable") +
- " " + var_name + " [{file}:{line},{col}]", node.start);
+ compressor.info("Collapsing {type} {name} [{file}:{line},{col}]", {
+ type: is_constant ? "constant" : "variable",
+ name: var_decl.name.name,
+ file: node.start.file,
+ line: node.start.line,
+ col: node.start.col
+ });
CHANGED = true;
return value;
}
@@ -1746,6 +1734,7 @@ merge(Compressor.prototype, {
def(AST_SymbolRef, function(compressor){
return this.undeclared();
});
+ def(AST_SymbolDeclaration, return_false);
def(AST_Object, function(compressor){
return any(this.properties, compressor);
});
diff --git a/test/compress/collapse_vars.js b/test/compress/collapse_vars.js
index c01572d..0f82b74 100644
--- a/test/compress/collapse_vars.js
+++ b/test/compress/collapse_vars.js
@@ -2,7 +2,7 @@ collapse_vars_side_effects_1: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -151,7 +151,7 @@ collapse_vars_issue_721: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
define(["require", "exports", 'handlebars'], function (require, exports, hb) {
@@ -217,7 +217,7 @@ collapse_vars_properties: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(obj) {
@@ -244,7 +244,7 @@ collapse_vars_if: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -294,7 +294,7 @@ collapse_vars_while: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:false, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(y) {
@@ -393,9 +393,9 @@ collapse_vars_do_while: {
}
function f3(y) {
function fn(n) { console.log(n); }
- var a = 2;
+ var a = 2, x = 7;
do {
- fn(a = 7);
+ fn(a = x);
break;
} while (y);
}
@@ -468,8 +468,9 @@ collapse_vars_do_while_drop_assign: {
}
function f3(y) {
function fn(n) { console.log(n); }
+ var x = 7;
do {
- fn(7);
+ fn(x);
break;
} while (y);
}
@@ -670,7 +671,7 @@ collapse_vars_lvalues: {
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var w = e1(), v = e2(), c = v = --x; return (w = x) - c; }
function f6(x) { var w = e1(), v = e2(); return (v = --x) - (w = x); }
- function f7(x) { var w = e1(), v = e2(), c = v - x; return (w = x) - c; }
+ function f7(x) { var w = e1(), c = e2() - x; return (w = x) - c; }
function f8(x) { var w = e1(), v = e2(); return (w = x) - (v - x); }
function f9(x) { var w = e1(); return e2() - x - (w = x); }
}
@@ -702,7 +703,7 @@ collapse_vars_lvalues_drop_assign: {
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var v = (e1(), e2()), c = v = --x; return x - c; }
function f6(x) { e1(), e2(); return --x - x; }
- function f7(x) { var v = (e1(), e2()), c = v - x; return x - c; }
+ function f7(x) { var c = (e1(), e2() - x); return x - c; }
function f8(x) { var v = (e1(), e2()); return x - (v - x); }
function f9(x) { e1(); return e2() - x - x; }
}
@@ -712,7 +713,7 @@ collapse_vars_misc1: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f0(o, a, h) {
@@ -789,7 +790,7 @@ collapse_vars_repeated: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -812,19 +813,17 @@ collapse_vars_repeated: {
}
expect: {
function f1() {
- return -3
+ return -3;
}
function f2(x) {
- return x
+ return x;
}
(function(x){
- var a = "GOOD" + x, e = "BAD", e = a;
- console.log(e + "!");
- })("!"),
+ console.log("GOOD!!");
+ })(),
(function(x){
- var a = "GOOD" + x, e = "BAD" + x, e = a;
- console.log(e + "!");
- })("!");
+ console.log("GOOD!!");
+ })();
}
expect_stdout: true
}
@@ -833,7 +832,7 @@ collapse_vars_closures: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function constant_vars_can_be_replaced_in_any_scope() {
@@ -923,7 +922,7 @@ collapse_vars_try: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1() {
@@ -1121,7 +1120,7 @@ collapse_vars_constants: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
- keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
+ keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true, reduce_vars:true
}
input: {
function f1(x) {
@@ -1159,7 +1158,7 @@ collapse_vars_arguments: {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true,
- toplevel:true
+ toplevel:true, reduce_vars:true
}
input: {
var outer = function() {
@@ -1286,6 +1285,7 @@ collapse_vars_regexp: {
join_vars: true,
cascade: true,
side_effects: true,
+ reduce_vars: true,
}
input: {
function f1() {
@@ -1319,8 +1319,8 @@ collapse_vars_regexp: {
};
}
(function(){
- var result, s = "acdabcdeabbb", rx = /ab*/g;
- while (result = rx.exec(s))
+ var result, rx = /ab*/g;
+ while (result = rx.exec("acdabcdeabbb"))
console.log(result[0]);
})();
}
@@ -1344,7 +1344,10 @@ issue_1537: {
issue_1562: {
options = {
collapse_vars: true,
+ evaluate: true,
+ reduce_vars: true,
toplevel: true,
+ unused: true,
}
input: {
var v = 1, B = 2;
@@ -1363,14 +1366,11 @@ issue_1562: {
var v = 1;
for (v in objs) f(2);
- var x = 3;
- while(x + 2) bar(10);
+ while(5) bar(10);
- var y = 4;
- do bar(20); while(y + 2);
+ do bar(20); while(6);
- var z = 5;
- for (; f(z + 2) ;) bar(30);
+ for (; f(7) ;) bar(30);
}
}
@@ -1614,3 +1614,43 @@ reduce_vars_assign: {
}
expect_stdout: "0"
}
+
+iife_1: {
+ options = {
+ collapse_vars: true,
+ reduce_vars: true,
+ toplevel: true,
+ unused: true,
+ }
+ input: {
+ var log = function(x) {
+ console.log(x);
+ }, foo = bar();
+ log(foo);
+ }
+ expect: {
+ (function(x) {
+ console.log(x);
+ })(bar());
+ }
+}
+
+iife_2: {
+ options = {
+ collapse_vars: true,
+ reduce_vars: false,
+ toplevel: true,
+ unused: false,
+ }
+ input: {
+ var foo = bar();
+ !function(x) {
+ console.log(x);
+ }(foo);
+ }
+ expect: {
+ !function(x) {
+ console.log(x);
+ }(bar());
+ }
+}
--
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