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enhance reduce_vars #5616

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merged 1 commit into from
Aug 17, 2022
Merged

enhance reduce_vars #5616

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68 changes: 42 additions & 26 deletions lib/compress.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1053,9 +1053,6 @@ Compressor.prototype.compress = function(node) {
if (!fixed || sym.in_arg || !safe_to_assign(tw, d)) {
walk();
d.fixed = false;
} else if (modified) {
walk();
d.fixed = 0;
} else {
push_ref(d, sym);
mark(tw, d);
Expand All @@ -1064,7 +1061,8 @@ Compressor.prototype.compress = function(node) {
d.single_use = false;
}
tw.loop_ids[d.id] = tw.in_loop;
sym.fixed = d.fixed = fixed;
d.fixed = modified ? 0 : fixed;
sym.fixed = fixed;
sym.fixed.assigns = [ node ];
mark_escaped(tw, d, sym.scope, node, right, 0, 1);
}
Expand Down Expand Up @@ -1355,8 +1353,10 @@ Compressor.prototype.compress = function(node) {
this.definition().fixed = false;
});
def(AST_SymbolRef, function(tw, descend, compressor) {
var d = this.definition();
push_ref(d, this);
var ref = this;
var d = ref.definition();
var fixed = d.fixed || d.last_ref && d.last_ref.fixed;
push_ref(d, ref);
if (d.references.length == 1 && !d.fixed && d.orig[0] instanceof AST_SymbolDefun) {
tw.loop_ids[d.id] = tw.in_loop;
}
Expand All @@ -1371,14 +1371,27 @@ Compressor.prototype.compress = function(node) {
if (!safe) return;
safe.assign = true;
});
if (d.fixed === false || d.fixed === 0) {
if (d.single_use == "m" && d.fixed) {
d.fixed = 0;
d.single_use = false;
}
switch (d.fixed) {
case 0:
if (!safe_to_read(tw, d)) d.fixed = false;
case false:
var redef = d.redefined();
if (redef && cross_scope(d.scope, this.scope)) redef.single_use = false;
} else if (d.fixed === undefined || !safe_to_read(tw, d)) {
if (redef && cross_scope(d.scope, ref.scope)) redef.single_use = false;
break;
case undefined:
d.fixed = false;
} else if (d.fixed) {
if (this.in_arg && d.orig[0] instanceof AST_SymbolLambda) this.fixed = d.scope;
var value = this.fixed_value();
break;
default:
if (!safe_to_read(tw, d)) {
d.fixed = false;
break;
}
if (ref.in_arg && d.orig[0] instanceof AST_SymbolLambda) ref.fixed = d.scope;
var value = ref.fixed_value();
if (recursive) {
d.recursive_refs++;
} else if (value && ref_once(compressor, d)) {
Expand All @@ -1387,25 +1400,26 @@ Compressor.prototype.compress = function(node) {
&& !value.pinned()
&& (!d.in_loop || tw.parent() instanceof AST_Call)
|| !d.in_loop
&& d.scope === this.scope.resolve()
&& d.scope === ref.scope.resolve()
&& value.is_constant_expression();
} else {
d.single_use = false;
}
if (is_modified(compressor, tw, this, value, 0, is_immutable(value), recursive)) {
if (is_modified(compressor, tw, ref, value, 0, is_immutable(value), recursive)) {
if (d.single_use) {
d.single_use = "m";
} else {
d.fixed = 0;
}
}
if (d.fixed && tw.loop_ids[d.id] !== tw.in_loop) d.cross_loop = true;
mark_escaped(tw, d, this.scope, this, value, 0, 1);
mark_escaped(tw, d, ref.scope, ref, value, 0, 1);
break;
}
if (!this.fixed) this.fixed = d.fixed;
if (!ref.fixed) ref.fixed = d.fixed === 0 ? fixed : d.fixed;
var parent;
if (value instanceof AST_Lambda
&& !((parent = tw.parent()) instanceof AST_Call && parent.expression === this)) {
&& !((parent = tw.parent()) instanceof AST_Call && parent.expression === ref)) {
mark_fn_def(tw, d, value);
}
});
Expand Down Expand Up @@ -1578,16 +1592,18 @@ Compressor.prototype.compress = function(node) {
this.walk(tw);
});

AST_Symbol.DEFMETHOD("fixed_value", function() {
var fixed = this.definition().fixed;
AST_Symbol.DEFMETHOD("fixed_value", function(ref_only) {
var def = this.definition();
var fixed = def.fixed;
if (fixed) {
if (this.fixed) fixed = this.fixed;
return (fixed instanceof AST_Node ? fixed : fixed()).tail_node();
}
fixed = fixed === 0 && this.fixed;
if (!fixed) return fixed;
var value = (fixed instanceof AST_Node ? fixed : fixed()).tail_node();
return value.is_constant() && value;
if (ref_only && def.escaped.depth != 1 && is_object(value, true)) return value;
if (value.is_constant()) return value;
});

AST_SymbolRef.DEFMETHOD("is_immutable", function() {
Expand Down Expand Up @@ -4509,7 +4525,7 @@ Compressor.prototype.compress = function(node) {
if (is_arguments(def) && !def.scope.rest && all(def.scope.argnames, function(argname) {
return argname instanceof AST_SymbolFunarg;
})) return def.scope.uses_arguments > 2;
var fixed = this.fixed_value();
var fixed = this.fixed_value(true);
if (!fixed) return true;
this._dot_throw = return_true;
if (fixed._dot_throw(compressor)) {
Expand Down Expand Up @@ -11453,14 +11469,14 @@ Compressor.prototype.compress = function(node) {

var indexFns = makePredicate("indexOf lastIndexOf");
var commutativeOperators = makePredicate("== === != !== * & | ^");
function is_object(node) {
if (node instanceof AST_Assign) return node.operator == "=" && is_object(node.right);
if (node instanceof AST_Sequence) return is_object(node.tail_node());
if (node instanceof AST_SymbolRef) return is_object(node.fixed_value());
function is_object(node, plain) {
if (node instanceof AST_Assign) return !plain && node.operator == "=" && is_object(node.right);
if (node instanceof AST_New) return !plain;
if (node instanceof AST_Sequence) return is_object(node.tail_node(), plain);
if (node instanceof AST_SymbolRef) return !plain && is_object(node.fixed_value());
return node instanceof AST_Array
|| node instanceof AST_Class
|| node instanceof AST_Lambda
|| node instanceof AST_New
|| node instanceof AST_Object;
}

Expand Down
2 changes: 0 additions & 2 deletions test/compress/dead-code.js
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Original file line number Diff line number Diff line change
Expand Up @@ -1485,8 +1485,6 @@ self_assignments_5: {
}
expect: {
var i = 0, l = [ "FAIL", "PASS" ];
l[0];
l[0];
l[0] = l[1];
console.log(l[0], 2);
}
Expand Down
195 changes: 195 additions & 0 deletions test/compress/issue-5614.js
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Original file line number Diff line number Diff line change
@@ -0,0 +1,195 @@
record_update: {
options = {
loops: true,
passes: 3,
pure_getters: "strict",
reduce_vars: true,
side_effects: true,
toplevel: true,
unused: true,
}
input: {
var value = { a: 42, b: "PASS" };
var unused = _Utils_update(value, { b: "FAIL" });
function _Utils_update(oldRecord, updatedFields) {
var newRecord = {};
for (var key in oldRecord)
newRecord[key] = oldRecord[key];
for (var key in updatedFields)
newRecord[key] = updatedFields[key];
return newRecord;
}
}
expect: {}
}

currying: {
options = {
inline: true,
passes: 2,
pure_getters: "strict",
reduce_funcs: true,
reduce_vars: true,
sequences: true,
side_effects: true,
toplevel: true,
unused: true,
}
input: {
function F(arity, fun, wrapper) {
wrapper.a = arity;
wrapper.f = fun;
return wrapper;
}
function F2(fun) {
return F(2, fun, function(a) {
return function(b) {
return fun(a, b);
};
});
}
function _Utils_eq(x, y) {
var pair, stack = [], isEqual = _Utils_eqHelp(x, y, 0, stack);
while (isEqual && (pair = stack.pop()))
isEqual = _Utils_eqHelp(pair.a, pair.b, 0, stack);
return isEqual;
}
var _Utils_equal = F2(_Utils_eq);
}
expect: {}
}

conditional_property_write: {
options = {
pure_getters: "strict",
reduce_vars: true,
unused: true,
}
input: {
function f(a) {
var o = {};
if (a)
o.p = console.log("foo");
else
o.q = console.log("bar");
o.r = console.log("baz");
}
f(42);
f(null);
}
expect: {
function f(a) {
if (a)
console.log("foo");
else
console.log("bar");
console.log("baz");
}
f(42);
f(null);
}
expect_stdout: [
"foo",
"baz",
"bar",
"baz",
]
}

reassign_1: {
options = {
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var a = "PASS", b = "FAIL";
(b = a).toString();
console.log(b);
}
expect: {
var b = "FAIL";
(b = "PASS").toString();
console.log(b);
}
expect_stdout: "PASS"
}

reassign_2: {
options = {
evaluate: true,
reduce_vars: true,
toplevel: true,
}
input: {
var a = "PASS";
if (false) {
a = null + 0;
a();
}
console.log(a);
}
expect: {
var a = "PASS";
if (false) {
a = 0;
a();
}
console.log(a);
}
expect_stdout: "PASS"
}

reassign_3: {
options = {
evaluate: true,
reduce_vars: true,
toplevel: true,
}
input: {
var a = 0;
(a = a || "PASS").toString();
console.log(a);
}
expect: {
var a = 0;
(a = (0, "PASS")).toString();
console.log(a);
}
expect_stdout: "PASS"
}

retain_instance_write: {
options = {
pure_getters: true,
reduce_vars: true,
unused: true,
}
input: {
function f(a) {
return a;
}
function g() {
var o = {};
var b = new f(o);
if (console)
b.p = "PASS";
return o;
}
console.log(g().p);
}
expect: {
function f(a) {
return a;
}
function g() {
var o = {};
var b = new f(o);
if (console)
b.p = "PASS";
return o;
}
console.log(g().p);
}
expect_stdout: "PASS"
}