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fix replacement logic in collapse_vars (#2475)

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This commit is contained in:
Alex Lam S.L
2017-11-13 07:37:42 +08:00
committed by GitHub
parent 2ac5086831
commit 49fbe9c5ac
2 changed files with 174 additions and 102 deletions
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110
lib/compress.js
View File

@@ -839,30 +839,7 @@ merge(Compressor.prototype, {
var args;
var candidates = [];
var stat_index = statements.length;
while (--stat_index >= 0) {
// Treat parameters as collapsible in IIFE, i.e.
// function(a, b){ ... }(x());
// would be translated into equivalent assignments:
// var a = x(), b = undefined;
if (stat_index == 0 && compressor.option("unused")) extract_args();
// Find collapsible assignments
extract_candidates(statements[stat_index]);
while (candidates.length > 0) {
var candidate = candidates.pop();
var lhs = get_lhs(candidate);
if (!lhs || is_lhs_read_only(lhs) || lhs.has_side_effects(compressor)) continue;
// Locate symbols which may execute code outside of scanning range
var lvalues = get_lvalues(candidate);
if (lhs instanceof AST_SymbolRef) lvalues[lhs.name] = false;
var replace_all = candidate.multiple;
if (!replace_all && lhs instanceof AST_SymbolRef) {
var def = lhs.definition();
replace_all = def.references.length - def.replaced == 1;
}
var side_effects = value_has_side_effects(candidate);
var hit = candidate.name instanceof AST_SymbolFunarg;
var abort = false, replaced = 0, can_replace = !args || !hit;
var tt = new TreeTransformer(function(node, descend) {
var scanner = new TreeTransformer(function(node, descend) {
if (abort) return node;
// Skip nodes before `candidate` as quickly as possible
if (!hit) {
@@ -873,7 +850,7 @@ merge(Compressor.prototype, {
return;
}
// Stop immediately if these node types are encountered
var parent = tt.parent();
var parent = scanner.parent();
if (node instanceof AST_Assign && node.operator != "=" && lhs.equivalent_to(node.left)
|| node instanceof AST_Call && lhs instanceof AST_PropAccess && lhs.equivalent_to(node.expression)
|| node instanceof AST_Debugger
@@ -888,8 +865,11 @@ merge(Compressor.prototype, {
// Replace variable with assignment when found
if (can_replace
&& !(node instanceof AST_SymbolDeclaration)
&& !is_lhs(node, parent)
&& lhs.equivalent_to(node)) {
if (is_lhs(node, parent)) {
if (candidate.multiple) replaced++;
return node;
}
CHANGED = abort = true;
replaced++;
compressor.info("Collapsing {name} [{file}:{line},{col}]", {
@@ -937,32 +917,16 @@ merge(Compressor.prototype, {
|| parent instanceof AST_Case
|| parent instanceof AST_Conditional
|| parent instanceof AST_If)) {
if (!(node instanceof AST_Scope)) descend(node, tt);
if (!(node instanceof AST_Scope)) descend(node, scanner);
abort = true;
return node;
}
// Skip (non-executed) functions and (leading) default case in switch statements
if (node instanceof AST_Default || node instanceof AST_Scope) return node;
});
if (!can_replace) {
for (var j = compressor.self().argnames.lastIndexOf(candidate.name) + 1; !abort && j < args.length; j++) {
args[j].transform(tt);
}
can_replace = true;
}
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(tt);
}
if (candidate.multiple) {
var def = candidate.name.definition();
if (abort && def.references.length > replaced) replaced = false;
else {
abort = false;
hit = candidate.name instanceof AST_SymbolFunarg;
var value_def = candidate.value.definition();
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(new TreeTransformer(function(node) {
var multi_replacer = new TreeTransformer(function(node) {
if (abort) return node;
// Skip nodes before `candidate` as quickly as possible
if (!hit) {
if (node === candidate) {
hit = true;
@@ -970,13 +934,59 @@ merge(Compressor.prototype, {
}
return;
}
if (node instanceof AST_SymbolRef && node.name == def.name) {
// Replace variable when found
if (node instanceof AST_SymbolRef
&& node.name == def.name) {
if (!--replaced) abort = true;
if (is_lhs(node, multi_replacer.parent())) return node;
def.replaced++;
value_def.replaced--;
if (!--replaced) abort = true;
return candidate.value;
}
}));
// Skip (non-executed) functions and (leading) default case in switch statements
if (node instanceof AST_Default || node instanceof AST_Scope) return node;
});
while (--stat_index >= 0) {
// Treat parameters as collapsible in IIFE, i.e.
// function(a, b){ ... }(x());
// would be translated into equivalent assignments:
// var a = x(), b = undefined;
if (stat_index == 0 && compressor.option("unused")) extract_args();
// Find collapsible assignments
extract_candidates(statements[stat_index]);
while (candidates.length > 0) {
var candidate = candidates.pop();
var lhs = get_lhs(candidate);
if (!lhs || is_lhs_read_only(lhs) || lhs.has_side_effects(compressor)) continue;
// Locate symbols which may execute code outside of scanning range
var lvalues = get_lvalues(candidate);
if (lhs instanceof AST_SymbolRef) lvalues[lhs.name] = false;
var replace_all = candidate.multiple;
if (!replace_all && lhs instanceof AST_SymbolRef) {
var def = lhs.definition();
replace_all = def.references.length - def.replaced == 1;
}
var side_effects = value_has_side_effects(candidate);
var hit = candidate.name instanceof AST_SymbolFunarg;
var abort = false, replaced = 0, can_replace = !args || !hit;
if (!can_replace) {
for (var j = compressor.self().argnames.lastIndexOf(candidate.name) + 1; !abort && j < args.length; j++) {
args[j].transform(scanner);
}
can_replace = true;
}
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(scanner);
}
if (candidate.multiple) {
var def = candidate.name.definition();
if (abort && def.references.length - def.replaced > replaced) replaced = false;
else {
abort = false;
hit = candidate.name instanceof AST_SymbolFunarg;
var value_def = candidate.value.definition();
for (var i = stat_index; !abort && i < statements.length; i++) {
statements[i].transform(multi_replacer);
}
}
}
@@ -2549,12 +2559,14 @@ merge(Compressor.prototype, {
var def = tail.pop();
compressor.warn("Converting duplicated definition of variable {name} to assignment [{file}:{line},{col}]", template(def.name));
remove(var_defs, def);
drop_decl(def.name.definition());
side_effects.unshift(make_node(AST_Assign, def, {
operator: "=",
left: make_node(AST_SymbolRef, def.name, def.name),
right: def.value
}));
def = def.name.definition();
drop_decl(def);
def.replaced--;
}
}
if (head.length > 0 || tail.length > 0) {

60
test/compress/collapse_vars.js
View File

@@ -3518,3 +3518,63 @@ issue_2436_12: {
}
}
}
issue_2436_13: {
options = {
collapse_vars: true,
reduce_vars: true,
unused: true,
}
input: {
var a = "PASS";
(function() {
function f(b) {
(function g(b) {
var b = b && (b.null = "FAIL");
})(a);
}
f();
})();
console.log(a);
}
expect: {
var a = "PASS";
(function() {
(function(b) {
(function(b) {
a && (a.null = "FAIL");
})();
})();
})();
console.log(a);
}
expect_stdout: "PASS"
}
issue_2436_14: {
options = {
collapse_vars: true,
reduce_vars: true,
unused: true,
}
input: {
var a = "PASS";
var b = {};
(function() {
var c = a;
c && function(c, d) {
console.log(c, d);
}(b, c);
})();
}
expect: {
var a = "PASS";
var b = {};
(function() {
a && function(c, d) {
console.log(c, d);
}(b, a);
})();
}
expect_stdout: true
}