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enhance dead_code (#3575)

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This commit is contained in:
Alex Lam S.L
2019-11-08 13:45:28 +08:00
committed by GitHub
parent 87e67ec299
commit 10648c9af6
2 changed files with 60 additions and 17 deletions
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39
lib/compress.js
View File

@@ -6543,23 +6543,28 @@ merge(Compressor.prototype, {
} }
} }
} else if (self.left instanceof AST_SymbolRef) { } else if (self.left instanceof AST_SymbolRef) {
if (self.left.is_immutable()) return strip_assignment();
var def = self.left.definition(); var def = self.left.definition();
if (def.scope === compressor.find_parent(AST_Lambda)) { var local = def.scope.resolve() === compressor.find_parent(AST_Lambda);
if (self.left.is_immutable()) return strip_assignment(); var level = 0, node, parent = self;
var level = 0, node, parent = self; do {
do { node = parent;
node = parent; parent = compressor.parent(level++);
parent = compressor.parent(level++); if (parent instanceof AST_Assign) {
if (parent instanceof AST_Exit) { if (!(parent.left instanceof AST_SymbolRef)) continue;
if (in_try(level, parent)) break; if (parent.left.definition() !== def) continue;
if (is_reachable(def.scope, [ def ])) break; def.fixed = false;
def.fixed = false; return strip_assignment();
return strip_assignment(); } else if (parent instanceof AST_Exit) {
} if (!local) break;
} while (parent instanceof AST_Binary && parent.right === node if (in_try(level, parent)) break;
|| parent instanceof AST_Sequence && parent.tail_node() === node if (is_reachable(def.scope, [ def ])) break;
|| parent instanceof AST_UnaryPrefix); def.fixed = false;
} return strip_assignment();
}
} while (parent instanceof AST_Binary && parent.right === node
|| parent instanceof AST_Sequence && parent.tail_node() === node
|| parent instanceof AST_UnaryPrefix);
} }
} }
self = self.lift_sequences(compressor); self = self.lift_sequences(compressor);
@@ -6599,7 +6604,7 @@ merge(Compressor.prototype, {
self.right = make_node(AST_Null, right); self.right = make_node(AST_Null, right);
var may_throw = node.may_throw(compressor); var may_throw = node.may_throw(compressor);
self.right = right; self.right = right;
var scope = self.left.definition().scope; var scope = self.left.definition().scope.resolve();
var parent; var parent;
while ((parent = compressor.parent(level++)) !== scope) { while ((parent = compressor.parent(level++)) !== scope) {
if (parent instanceof AST_Try) { if (parent instanceof AST_Try) {

38
test/compress/dead-code.js
View File

@@ -1064,3 +1064,41 @@ issue_3552: {
} }
expect_stdout: "PASS" expect_stdout: "PASS"
} }
unreachable_assign: {
options = {
dead_code: true,
}
input: {
console.log(A = "P" + (A = "A" + (B = "S" + (A = B = "S"))), A, B);
}
expect: {
console.log(A = "P" + "A" + (B = "S" + "S"), A, B);
}
expect_stdout: "PASS PASS SS"
}
catch_return_assign: {
options = {
dead_code: true,
}
input: {
console.log(function() {
try {
throw "FAIL";
} catch (e) {
return e = "PASS";
}
}());
}
expect: {
console.log(function() {
try {
throw "FAIL";
} catch (e) {
return "PASS";
}
}());
}
expect_stdout: "PASS"
}