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improve collapsible value detection (#1638)

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- #1634 bars variables with cross-scope references in between to collapse
- but if assigned value is side-effect-free, no states can be modified, so it is safe to move
This commit is contained in:
Alex Lam S.L
2017-03-24 02:55:32 +08:00
committed by GitHub
parent 6b2f34769a
commit e918748d88
3 changed files with 73 additions and 3 deletions
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4
lib/compress.js
View File

@@ -592,9 +592,10 @@ merge(Compressor.prototype, {
// Restrict var replacement to constants if side effects encountered.
if (side_effects_encountered |= lvalues_encountered) continue;
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 |= var_decl.value.has_side_effects(compressor);
side_effects_encountered |= value_has_side_effects;
continue;
}
@@ -620,6 +621,7 @@ merge(Compressor.prototype, {
|| (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 == "||")

68
test/compress/collapse_vars.js
View File

@@ -1522,3 +1522,71 @@ issue_1631_3: {
}
expect_stdout: "6"
}
var_side_effects_1: {
options = {
collapse_vars: true,
}
input: {
var print = console.log.bind(console);
function foo(x) {
var twice = x * 2;
print('Foo:', twice);
}
foo(10);
}
expect: {
var print = console.log.bind(console);
function foo(x) {
print('Foo:', 2 * x);
}
foo(10);
}
expect_stdout: true
}
var_side_effects_2: {
options = {
collapse_vars: true,
}
input: {
var print = console.log.bind(console);
function foo(x) {
var twice = x.y * 2;
print('Foo:', twice);
}
foo({ y: 10 });
}
expect: {
var print = console.log.bind(console);
function foo(x) {
var twice = 2 * x.y;
print('Foo:', twice);
}
foo({ y: 10 });
}
expect_stdout: true
}
var_side_effects_3: {
options = {
collapse_vars: true,
pure_getters: true,
}
input: {
var print = console.log.bind(console);
function foo(x) {
var twice = x.y * 2;
print('Foo:', twice);
}
foo({ y: 10 });
}
expect: {
var print = console.log.bind(console);
function foo(x) {
print('Foo:', 2 * x.y);
}
foo({ y: 10 });
}
expect_stdout: true
}

4
test/mocha/glob.js
View File

@@ -5,7 +5,7 @@ var path = require("path");
describe("minify() with input file globs", function() {
it("minify() with one input file glob string.", function() {
var result = Uglify.minify("test/input/issue-1242/foo.*");
assert.strictEqual(result.code, 'function foo(o){var n=2*o;print("Foo:",n)}var print=console.log.bind(console);');
assert.strictEqual(result.code, 'function foo(o){print("Foo:",2*o)}var print=console.log.bind(console);');
});
it("minify() with an array of one input file glob.", function() {
var result = Uglify.minify([
@@ -20,7 +20,7 @@ describe("minify() with input file globs", function() {
], {
compress: { toplevel: true }
});
assert.strictEqual(result.code, 'var print=console.log.bind(console),a=function(n){return 3*n}(3),b=function(n){return n/2}(12);print("qux",a,b),function(n){var o=2*n;print("Foo:",o)}(11);');
assert.strictEqual(result.code, 'var print=console.log.bind(console),a=function(n){return 3*n}(3),b=function(n){return n/2}(12);print("qux",a,b),function(n){print("Foo:",2*n)}(11);');
});
it("should throw with non-matching glob string", function() {
var glob = "test/input/issue-1242/blah.*";