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fix corner cases in collapse_vars, unused & varify (#4292)

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fixes #4290
This commit is contained in:
Alex Lam S.L
2020-11-18 00:22:54 +00:00
committed by GitHub
parent caa92aea5d
commit 0bedd031da
4 changed files with 141 additions and 34 deletions
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73
lib/compress.js
View File

@@ -368,7 +368,7 @@ merge(Compressor.prototype, {
} while (sym = sym.parent_scope);
}
function can_drop_symbol(tw, ref, keep_lambda) {
function can_drop_symbol(ref, keep_lambda) {
var orig = ref.definition().orig;
if (ref.in_arg && (orig[0] instanceof AST_SymbolFunarg || orig[1] instanceof AST_SymbolFunarg)) return false;
return all(orig, function(sym) {
@@ -678,7 +678,7 @@ merge(Compressor.prototype, {
var d = sym.definition();
d.assignments++;
if (!is_modified(compressor, tw, node, node.right, 0)
&& can_drop_symbol(tw, sym) && safe_to_assign(tw, d)) {
&& can_drop_symbol(sym) && safe_to_assign(tw, d)) {
push_ref(d, sym);
mark(tw, d);
tw.loop_ids[d.id] = tw.in_loop;
@@ -1706,9 +1706,11 @@ merge(Compressor.prototype, {
if (node instanceof AST_DWLoop) return true;
if (node instanceof AST_LoopControl) return true;
if (node instanceof AST_SymbolRef) {
if (node.is_declared(compressor) ? node.fixed_value() || all(node.definition().orig, function(sym) {
return !(sym instanceof AST_SymbolConst || sym instanceof AST_SymbolLet);
}) : parent instanceof AST_Assign && parent.operator == "=" && parent.left === node) return false;
if (node.is_declared(compressor)) {
if (node.fixed_value() || can_drop_symbol(node)) return false;
} else if (parent instanceof AST_Assign && parent.operator == "=" && parent.left === node) {
return false;
}
if (!replace_all) return true;
scan_rhs = false;
return false;
@@ -1779,14 +1781,12 @@ merge(Compressor.prototype, {
}
if (side_effects && may_modify(node)) return true;
var def = node.definition();
return (in_try || def.scope.resolve() !== scope) && !all(def.orig, function(sym) {
return !(sym instanceof AST_SymbolConst || sym instanceof AST_SymbolLet);
});
return (in_try || def.scope.resolve() !== scope) && !can_drop_symbol(node);
}
if (node instanceof AST_This) return symbol_in_lvalues(node, parent);
if (node instanceof AST_VarDef) {
if ((in_try || !lhs_local) && node.name instanceof AST_Destructured) return true;
return node.value && node.name.match_symbol(function(node) {
return (node.value || parent instanceof AST_Let) && node.name.match_symbol(function(node) {
return node instanceof AST_SymbolDeclaration
&& (lvalues.has(node.name) || side_effects && may_modify(node));
});
@@ -4304,7 +4304,7 @@ merge(Compressor.prototype, {
});
def(AST_SymbolDeclaration, return_false);
def(AST_SymbolRef, function(compressor) {
return !this.is_declared(compressor) || !can_drop_symbol(compressor, this);
return !this.is_declared(compressor) || !can_drop_symbol(this);
});
def(AST_This, return_false);
def(AST_Try, function(compressor) {
@@ -4974,7 +4974,7 @@ merge(Compressor.prototype, {
var self = this;
var drop_funcs = !(self instanceof AST_Toplevel) || compressor.toplevel.funcs;
var drop_vars = !(self instanceof AST_Toplevel) || compressor.toplevel.vars;
var assign_as_unused = /keep_assign/.test(compressor.option("unused")) ? return_false : function(tw, node, props) {
var assign_as_unused = /keep_assign/.test(compressor.option("unused")) ? return_false : function(node, props) {
var sym, nested = false;
if (node instanceof AST_Assign) {
if (node.write_only || node.operator == "=") sym = node.left;
@@ -4990,7 +4990,7 @@ merge(Compressor.prototype, {
}
if (!(sym instanceof AST_SymbolRef)) return;
if (compressor.exposed(sym.definition())) return;
if (!can_drop_symbol(tw, sym, nested)) return;
if (!can_drop_symbol(sym, nested)) return;
return sym;
};
var assign_in_use = Object.create(null);
@@ -5046,8 +5046,9 @@ merge(Compressor.prototype, {
var redef = def.redefined();
if (redef) var_defs_by_id.add(redef.id, defn);
}
if ((!drop_vars || (node instanceof AST_Const ? def.redefined() : def.const_redefs))
&& !(def.id in in_use_ids)) {
if (!(def.id in in_use_ids) && (!drop_vars
|| (node instanceof AST_Const ? def.redefined() : def.const_redefs)
|| !(node instanceof AST_Var || is_safe_lexical(def)))) {
in_use_ids[def.id] = true;
in_use.push(def);
}
@@ -5128,7 +5129,7 @@ merge(Compressor.prototype, {
var tt = new TreeTransformer(function(node, descend, in_list) {
var parent = tt.parent();
if (drop_vars) {
var props = [], sym = assign_as_unused(tt, node, props);
var props = [], sym = assign_as_unused(node, props);
if (sym) {
var def = sym.definition();
var in_use = def.id in in_use_ids;
@@ -5245,6 +5246,7 @@ merge(Compressor.prototype, {
// into the next one, or next statement.
var side_effects = [];
var duplicated = 0;
var is_var = node instanceof AST_Var;
node.definitions.forEach(function(def) {
if (def.value) def.value = def.value.transform(tt);
if (def.name instanceof AST_Destructured) {
@@ -5313,7 +5315,11 @@ merge(Compressor.prototype, {
return node;
}
if (node instanceof AST_SymbolDeclaration) {
return !drop_vars || node.definition().id in in_use_ids || is_catch(node) ? node : null;
if (!drop_vars) return node;
if (node.definition().id in in_use_ids) return node;
if (is_catch(node)) return node;
if (is_var && !can_drop_symbol(node)) return node;
return null;
}
});
var name = def.name.transform(trimmer);
@@ -5326,7 +5332,8 @@ merge(Compressor.prototype, {
return;
}
var sym = def.name.definition();
if (!drop_vars || sym.id in in_use_ids) {
var drop_sym = !is_var || can_drop_symbol(def.name);
if (!drop_sym || !drop_vars || sym.id in in_use_ids) {
if (def.value && indexOf_assign(sym, def) < 0) {
var write_only = def.value.write_only;
var value = def.value.drop_side_effect_free(compressor);
@@ -5343,7 +5350,7 @@ merge(Compressor.prototype, {
}
var old_def, var_defs = var_defs_by_id.get(sym.id);
if (!def.value && !(node instanceof AST_Let)) {
if (var_defs.length > 1) {
if (drop_sym && var_defs.length > 1) {
AST_Node.info("Dropping declaration of variable {name} [{file}:{line},{col}]", template(def.name));
remove(var_defs, def);
sym.eliminated++;
@@ -5376,7 +5383,7 @@ merge(Compressor.prototype, {
});
body.push(defun);
} else {
if (var_defs.length > 1 && sym.orig.indexOf(def.name) > sym.eliminated) {
if (drop_sym && var_defs.length > 1 && sym.orig.indexOf(def.name) > sym.eliminated) {
remove(var_defs, def);
duplicated++;
}
@@ -5661,7 +5668,7 @@ merge(Compressor.prototype, {
var def = node.expression.definition();
if (def.scope === self) assignments.add(def.id, node);
}
var node_def, props = [], sym = assign_as_unused(tw, node, props);
var node_def, props = [], sym = assign_as_unused(node, props);
if (sym && self.variables.get(sym.name) === (node_def = sym.definition())) {
props.forEach(function(prop) {
prop.walk(tw);
@@ -6079,9 +6086,7 @@ merge(Compressor.prototype, {
&& all(def.references, function(ref) {
return ref.fixed_value() === right;
})
&& all(def.orig, function(sym) {
return !(sym instanceof AST_SymbolConst || sym instanceof AST_SymbolLet);
});
&& can_drop_symbol(sym);
}
});
@@ -6299,7 +6304,7 @@ merge(Compressor.prototype, {
return make_sequence(this, [ expression, property ]);
});
def(AST_SymbolRef, function(compressor) {
return this.is_declared(compressor) && can_drop_symbol(compressor, this) ? null : this;
return this.is_declared(compressor) && can_drop_symbol(this) ? null : this;
});
def(AST_This, return_null);
def(AST_Unary, function(compressor, first_in_statement) {
@@ -6308,9 +6313,7 @@ merge(Compressor.prototype, {
this.write_only = !exp.has_side_effects(compressor);
return this;
}
if (this.operator == "typeof" && exp instanceof AST_SymbolRef && can_drop_symbol(compressor, exp)) {
return null;
}
if (this.operator == "typeof" && exp instanceof AST_SymbolRef && can_drop_symbol(exp)) return null;
var node = exp.drop_side_effect_free(compressor, first_in_statement);
if (first_in_statement && node && is_iife_call(node)) {
if (node === exp && this.operator == "!") return this;
@@ -7080,6 +7083,10 @@ merge(Compressor.prototype, {
return make_sequence(this, assignments);
});
function is_safe_lexical(def) {
return def.orig.length < (def.orig[0] instanceof AST_SymbolLambda ? 3 : 2);
}
function may_overlap(compressor, def) {
if (compressor.exposed(def)) return true;
var scope = def.scope.resolve();
@@ -7109,7 +7116,8 @@ merge(Compressor.prototype, {
return compressor.option("varify") && all(self.definitions, function(defn) {
return !defn.name.match_symbol(function(node) {
if (node instanceof AST_SymbolDeclaration) {
return !node.fixed_value() || may_overlap(compressor, node.definition());
var def = node.definition();
return !node.fixed_value() || !is_safe_lexical(def) || may_overlap(compressor, def);
}
}, true);
}) ? to_var(self) : self;
@@ -8015,12 +8023,9 @@ merge(Compressor.prototype, {
// typeof always returns a non-empty string, thus it's
// always true in booleans
AST_Node.warn("Boolean expression always true [{file}:{line},{col}]", self.start);
return (exp instanceof AST_SymbolRef && all(exp.definition().orig, function(sym) {
return !(sym instanceof AST_SymbolConst || sym instanceof AST_SymbolLet);
}) ? make_node(AST_True, self) : make_sequence(self, [
exp,
make_node(AST_True, self)
])).optimize(compressor);
var exprs = [ make_node(AST_True, self) ];
if (!(exp instanceof AST_SymbolRef && can_drop_symbol(exp))) exprs.unshift(exp);
return make_sequence(self, exprs).optimize(compressor);
}
}
if (op == "-" && exp instanceof AST_Infinity) exp = exp.transform(compressor);

15
test/compress/const.js
View File

@@ -1225,3 +1225,18 @@ issue_4274_2: {
}
expect_stdout: true
}
issue_4290_1: {
options = {
unused: true,
}
input: {
const a = 0;
var a;
}
expect: {
const a = 0;
var a;
}
expect_stdout: true
}

50
test/compress/let.js
View File

@@ -1064,3 +1064,53 @@ issue_4276_2: {
expect_stdout: "PASS"
node_version: ">=4"
}
issue_4290_1: {
options = {
unused: true,
}
input: {
"use strict";
let a;
var a;
}
expect: {
"use strict";
let a;
var a;
}
expect_stdout: true
node_version: ">=4"
}
issue_4290_2: {
options = {
collapse_vars: true,
}
input: {
"use strict";
try {
console.log(function(a) {
a = c;
let c;
return a;
}());
} catch (e) {
console.log("PASS");
}
}
expect: {
"use strict";
try {
console.log(function(a) {
a = c;
let c;
return a;
}());
} catch (e) {
console.log("PASS");
}
}
expect_stdout: "PASS"
node_version: ">=4"
}

37
test/compress/varify.js
View File

@@ -353,3 +353,40 @@ forin_let_2: {
]
node_version: ">=6"
}
issue_4290_1_const: {
options = {
reduce_vars: true,
toplevel: true,
varify: true,
}
input: {
const a = 0;
var a;
}
expect: {
const a = 0;
var a;
}
expect_stdout: true
}
issue_4290_1_let: {
options = {
reduce_vars: true,
toplevel: true,
varify: true,
}
input: {
"use strict";
let a = 0;
var a;
}
expect: {
"use strict";
let a = 0;
var a;
}
expect_stdout: true
node_version: ">=4"
}