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fix corner cases in reduce_vars (#5717)
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fixes #5716
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@alexlamsl
alexlamsl committed Oct 19, 2022
1 parent 8319bad commit 19c471c
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Showing 2 changed files with 178 additions and 41 deletions.
84 changes: 43 additions & 41 deletions lib/compress.js
View file
Expand Up @@ -501,6 +501,23 @@ Compressor.prototype.compress = function(node) {
if (parent instanceof AST_VarDef) return parent.value === node;
}

function make_ref(ref, fixed) {
var node = make_node(AST_SymbolRef, ref);
node.fixed = fixed || make_node(AST_Undefined, ref);
return node;
}

function replace_ref(resolve, fixed) {
return function(node) {
var ref = resolve(node);
var node = make_ref(ref, fixed);
var def = ref.definition();
def.references.push(node);
def.replaced++;
return node;
};
}

var RE_POSITIVE_INTEGER = /^(0|[1-9][0-9]*)$/;
(function(def) {
def(AST_Node, noop);
Expand Down Expand Up @@ -705,22 +722,6 @@ Compressor.prototype.compress = function(node) {
});
}

function make_ref(ref, fixed) {
var node = make_node(AST_SymbolRef, ref);
node.fixed = fixed || make_node(AST_Undefined, ref);
return node;
}

function replace_ref(ref, fixed) {
return function() {
var node = make_ref(ref, fixed);
var def = ref.definition();
def.references.push(node);
def.replaced++;
return node;
};
}

function ref_once(compressor, def) {
return compressor.option("unused")
&& !def.scope.pinned()
Expand Down Expand Up @@ -1021,7 +1022,9 @@ Compressor.prototype.compress = function(node) {
};
left.fixed.assigns = !fixed || !fixed.assigns ? [ ld.orig[0] ] : fixed.assigns.slice();
left.fixed.assigns.push(node);
left.fixed.to_binary = replace_ref(left, fixed);
left.fixed.to_binary = replace_ref(function(node) {
return node.left;
}, fixed);
} else {
left.walk(tw);
ld.fixed = false;
Expand Down Expand Up @@ -1529,7 +1532,9 @@ Compressor.prototype.compress = function(node) {
});
};
exp.fixed.assigns = fixed && fixed.assigns;
exp.fixed.to_prefix = replace_ref(exp, d.fixed);
exp.fixed.to_prefix = replace_ref(function(node) {
return node.expression;
}, d.fixed);
}
} else {
exp.walk(tw);
Expand Down Expand Up @@ -2156,7 +2161,7 @@ Compressor.prototype.compress = function(node) {
abort = true;
folded = make_node(AST_Binary, candidate, {
operator: compound,
left: lhs.fixed && lhs.definition().fixed ? lhs.fixed.to_binary() : lhs,
left: lhs.fixed && lhs.definition().fixed ? lhs.fixed.to_binary(candidate) : lhs,
right: rvalue,
});
}
Expand Down Expand Up @@ -2220,7 +2225,7 @@ Compressor.prototype.compress = function(node) {
}
if (candidate instanceof AST_UnaryPostfix) return make_node(AST_UnaryPrefix, candidate, {
operator: candidate.operator,
expression: lhs.fixed && lhs.definition().fixed ? lhs.fixed.to_prefix() : lhs,
expression: lhs.fixed && lhs.definition().fixed ? lhs.fixed.to_prefix(candidate) : lhs,
});
if (candidate instanceof AST_UnaryPrefix) {
clear_write_only(candidate);
Expand Down Expand Up @@ -12780,34 +12785,19 @@ Compressor.prototype.compress = function(node) {
}
if (compressor.option("assignments")) {
if (self.operator == "=" && self.left instanceof AST_SymbolRef && self.right instanceof AST_Binary) {
var ref;
// x = expr1 OP expr2
if ((ref = self.right.left) instanceof AST_SymbolRef
&& ref.name == self.left.name
if (self.right.left instanceof AST_SymbolRef
&& self.right.left.name == self.left.name
&& ASSIGN_OPS[self.right.operator]) {
// x = x - 2 ---> x -= 2
if (self.left.fixed) self.left.fixed.to_binary = function() {
return ref;
};
return make_node(AST_Assign, self, {
operator: self.right.operator + "=",
left: self.left,
right: self.right.right,
});
return make_compound(self.right.right);
}
if ((ref = self.right.right) instanceof AST_SymbolRef
&& ref.name == self.left.name
if (self.right.right instanceof AST_SymbolRef
&& self.right.right.name == self.left.name
&& ASSIGN_OPS_COMMUTATIVE[self.right.operator]
&& !self.right.left.has_side_effects(compressor)) {
// x = 2 & x ---> x &= 2
if (self.left.fixed) self.left.fixed.to_binary = function() {
return ref;
};
return make_node(AST_Assign, self, {
operator: self.right.operator + "=",
left: self.left,
right: self.right.left,
});
return make_compound(self.right.left);
}
}
if ((self.operator == "-=" || self.operator == "+="
Expand Down Expand Up @@ -12870,6 +12860,18 @@ Compressor.prototype.compress = function(node) {
return find_try(compressor, level, node, scope, may_throw, sync);
}

function make_compound(rhs) {
var fixed = self.left.fixed;
if (fixed) fixed.to_binary = replace_ref(function(node) {
return node.left;
}, fixed);
return make_node(AST_Assign, self, {
operator: self.right.operator + "=",
left: self.left,
right: rhs,
});
}

function strip_assignment(def) {
if (def) def.fixed = false;
return (self.operator != "=" ? make_node(AST_Binary, self, {
Expand Down
135 changes: 135 additions & 0 deletions test/compress/reduce_vars.js
View file
Expand Up @@ -7927,3 +7927,138 @@ issue_5623: {
}
expect_stdout: "1"
}

issue_5716_1: {
options = {
collapse_vars: true,
inline: true,
merge_vars: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var a;
function f() {
var b = [ c, c ], c = function() {
return b++ + (a = b);
}();
}
f();
console.log(a);
}
expect: {
c = [ c, c ],
void (c = ++c);
var c;
console.log(c);
}
expect_stdout: "NaN"
}

issue_5716_2: {
options = {
collapse_vars: true,
inline: true,
merge_vars: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var a;
function f() {
var b = [ c, c ], c = function() {
return (b += 4) + (a = b += 2);
}();
}
f();
console.log(a);
}
expect: {
void (c = c = (c = [ c, c ]) + 4 + 2);
var c;
console.log(c);
}
expect_stdout: ",42"
}

issue_5716_3: {
options = {
assignments: true,
collapse_vars: true,
inline: true,
merge_vars: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var a;
function f() {
var b = [ c, c ], c = function() {
return (b = b + 4) + (a = b += 2);
}();
}
f();
console.log(a);
}
expect: {
void (c = c = (c = [ c, c ]) + 4 + 2);
var c;
console.log(c);
}
expect_stdout: ",42"
}

issue_5716_4: {
options = {
assignments: true,
collapse_vars: true,
inline: true,
merge_vars: true,
reduce_vars: true,
toplevel: true,
unused: true,
}
input: {
var a;
function f() {
var b = [ c, c ], c = function() {
return (b = true | b) + (a = b *= 42);
}();
}
f();
console.log(a);
}
expect: {
void (c = c = ((c = [ c, c ]) | true) * 42);
var c;
console.log(c);
}
expect_stdout: "42"
}

issue_5716_5: {
options = {
assignments: true,
reduce_vars: true,
}
input: {
console.log(function() {
return 0 || (a = 42 | a);
var a = function() {
return a;
};
}());
}
expect: {
console.log(function() {
return 0 || (a |= 42);
var a = function() {
return a;
};
}());
}
expect_stdout: "42"
}

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