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enhance dead_code & if_return (#5520)

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This commit is contained in:
Alex Lam S.L
2022-06-26 05:32:25 +01:00
committed by GitHub
parent 9f57920566
commit 8b464331ba
2 changed files with 89 additions and 8 deletions
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43
lib/compress.js
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@@ -1951,13 +1951,26 @@ Compressor.prototype.compress = function(node) {
return statements;
function last_of(compressor, predicate) {
var block = compressor.self(), stat, level = 0;
var block = compressor.self(), level = 0;
do {
do {
if (block instanceof AST_Catch || block instanceof AST_Finally) {
block = compressor.parent(level++);
} else if (block instanceof AST_LabeledStatement) {
block = block.body;
}
var stat = null;
while (true) {
if (predicate(block)) return true;
block = compressor.parent(level++);
} while (block instanceof AST_If && (stat = block));
} while ((block instanceof AST_BlockStatement || block instanceof AST_Scope)
if (!(block instanceof AST_If)) break;
stat = block;
}
} while (stat
&& (block instanceof AST_BlockStatement
|| block instanceof AST_Catch
|| block instanceof AST_Finally
|| block instanceof AST_Scope
|| block instanceof AST_Try)
&& is_last_statement(block.body, stat));
}
@@ -3677,6 +3690,11 @@ Compressor.prototype.compress = function(node) {
function eliminate_dead_code(statements, compressor) {
var has_quit;
var self = compressor.self();
if (self instanceof AST_Catch || self instanceof AST_Finally) {
self = compressor.parent();
} else if (self instanceof AST_LabeledStatement) {
self = self.body;
}
for (var i = 0, n = 0, len = statements.length; i < len; i++) {
var stat = statements[i];
if (stat instanceof AST_LoopControl) {
@@ -5965,10 +5983,19 @@ Compressor.prototype.compress = function(node) {
});
OPT(AST_LabeledStatement, function(self, compressor) {
if (compressor.option("dead_code")
&& self.body instanceof AST_Break
&& compressor.loopcontrol_target(self.body) === self.body) {
return make_node(AST_EmptyStatement, self);
if (self.body instanceof AST_If || self.body instanceof AST_Break) {
var body = tighten_body([ self.body ], compressor);
switch (body.length) {
case 0:
self.body = make_node(AST_EmptyStatement, self);
break;
case 1:
self.body = body[0];
break;
default:
self.body = make_node(AST_BlockStatement, self, { body: body });
break;
}
}
return compressor.option("unused") && self.label.references.length == 0 ? self.body : self;
});