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enhance merge_vars (#4105)

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This commit is contained in:
Alex Lam S.L
2020-09-15 15:59:10 +01:00
committed by GitHub
parent 335456cf77
commit a62b086184
2 changed files with 85 additions and 17 deletions
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65
lib/compress.js
View File

@@ -4309,7 +4309,7 @@ merge(Compressor.prototype, {
AST_Scope.DEFMETHOD("merge_variables", function(compressor) {
if (!compressor.option("merge_vars")) return;
var self = this, segment = self;
var self = this, segment;
var first = [], last = [], index = 0;
var references = Object.create(null);
var prev = Object.create(null);
@@ -4334,8 +4334,9 @@ merge(Compressor.prototype, {
if (node instanceof AST_Conditional) {
node.condition.walk(tw);
var save = segment;
segment = node;
segment = node.consequent;
node.consequent.walk(tw);
segment = node.alternative;
node.alternative.walk(tw);
segment = save;
return true;
@@ -4364,7 +4365,10 @@ merge(Compressor.prototype, {
var save = segment;
segment = node;
node.body.walk(tw);
if (node.alternative) node.alternative.walk(tw);
if (node.alternative) {
segment = node.alternative;
node.alternative.walk(tw);
}
segment = save;
return true;
}
@@ -4388,10 +4392,21 @@ merge(Compressor.prototype, {
}
if (node instanceof AST_Switch) {
node.expression.walk(tw);
var save = segment;
segment = node;
var save = segment, first = true;
node.body.forEach(function(branch) {
branch.walk(tw);
if (branch instanceof AST_Default) return;
if (first) {
first = false;
} else {
segment = branch.expression;
}
branch.expression.walk(tw);
});
node.body.forEach(function(branch) {
segment = branch;
branch.body.forEach(function(stat) {
stat.walk(tw);
});
});
segment = save;
return true;
@@ -4410,7 +4425,10 @@ merge(Compressor.prototype, {
node.body.forEach(function(branch) {
branch.walk(tw);
});
if (node.bcatch) node.bcatch.walk(tw);
if (node.bcatch) {
segment = node.bcatch;
node.bcatch.walk(tw);
}
segment = save;
if (node.bfinally) node.bfinally.walk(tw);
return true;
@@ -4437,11 +4455,16 @@ merge(Compressor.prototype, {
if (!(def.id in prev)) continue;
if (!references[def.id]) continue;
while (def.id in merged) def = merged[def.id];
var skipped = [];
do {
var tail = last.pop();
if (!tail) continue;
if (tail.index > head.index) continue;
if (!references[tail.definition.id]) continue;
if (references[def.id].segment !== references[tail.definition.id].segment) {
skipped.unshift(tail);
continue;
}
var orig = [], refs = [];
references[tail.definition.id].forEach(function(sym) {
push(sym);
@@ -4456,6 +4479,7 @@ merge(Compressor.prototype, {
merged[tail.definition.id] = def;
break;
} while (last.length);
if (skipped.length) last = last.concat(skipped);
}
function read(def) {
@@ -4468,21 +4492,28 @@ merge(Compressor.prototype, {
function mark(sym, write_only) {
var def = sym.definition();
if (segment !== self) references[def.id] = false;
if (def.id in references) {
if (!references[def.id]) return;
references[def.id].push(sym);
var refs = references[def.id];
if (!refs) return;
if (refs.segment !== segment) return references[def.id] = false;
refs.push(sym);
if (def.id in prev) last[prev[def.id]] = null;
read(def);
} else if (compressor.exposed(def) || self.variables.get(def.name) !== def) {
} else if (self.variables.get(def.name) !== def || compressor.exposed(def)) {
references[def.id] = false;
} else {
references[def.id] = [ sym ];
if (!write_only) return read(def);
first.push({
index: index++,
definition: def,
});
var refs = [ sym ];
references[def.id] = refs;
if (write_only) {
refs.segment = segment;
first.push({
index: index++,
definition: def,
});
} else {
refs.segment = self;
read(def);
}
}
}

37
test/compress/merge_vars.js
View File

@@ -76,6 +76,43 @@ merge_toplevel: {
]
}
segment: {
options = {
merge_vars: true,
toplevel: true,
}
input: {
var a = "foo";
console.log(a);
for (var c, i = 0; i < 1; i++) {
var b = "bar";
console.log(b);
c = "baz";
console.log(c);
}
var d = "moo";
console.log(d);
}
expect: {
var d = "foo";
console.log(d);
for (var c, i = 0; i < 1; i++) {
var c = "bar";
console.log(c);
c = "baz";
console.log(c);
}
var d = "moo";
console.log(d);
}
expect_stdout: [
"foo",
"bar",
"baz",
"moo",
]
}
init_scope_vars: {
options = {
merge_vars: true,