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fix corner cases in if_return
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fixes mishoo#5583
fixes mishoo#5584
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@alexlamsl
alexlamsl committed Jul 30, 2022
1 parent 08c386f commit c1ef904
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Showing 2 changed files with 212 additions and 12 deletions.
45 changes: 33 additions & 12 deletions lib/compress.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -3547,7 +3547,6 @@ Compressor.prototype.compress = function(node) {
if (stat instanceof AST_If && stat.body instanceof AST_Return) {
var value = stat.body.value;
var in_bool = stat.body.in_bool || next instanceof AST_Return && next.in_bool;
//---
// if (foo()) return x; return y; ---> return foo() ? x : y;
if (!stat.alternative && next instanceof AST_Return) {
changed = true;
Expand All @@ -3558,16 +3557,33 @@ Compressor.prototype.compress = function(node) {
statements.splice(j, 1);
continue;
}
//---
// if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
if (!stat.alternative && !next && in_lambda && (in_bool || value && multiple_if_returns)) {
changed = true;
stat = stat.clone();
stat.alternative = make_node(AST_Return, stat, { value: null });
statements.splice(i, 1, stat.transform(compressor));
continue;
if (!stat.alternative && !next && in_lambda) {
// if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
if (in_bool || value && multiple_if_returns) {
changed = true;
stat = stat.clone();
stat.alternative = make_node(AST_Return, stat, { value: null });
statements.splice(i, 1, stat.transform(compressor));
continue;
}
// if (foo()) return bar() ? x : void 0; ---> return foo() && bar() ? x : void 0;
// if (foo()) return bar() ? void 0 : x; ---> return foo() || bar() ? void 0 : x;
var or;
if (value instanceof AST_Conditional
&& ((or = is_undefined(value.consequent, compressor))
|| is_undefined(value.alternative, compressor))) {
changed = true;
var ret = stat.body.clone();
ret.value = value.clone();
ret.value.condition = make_node(AST_Binary, stat, {
operator: or ? "||" : "&&",
left: stat.condition,
right: value.condition,
});
statements.splice(i, 1, ret.transform(compressor));
continue;
}
}
//---
// if (a) return b; if (c) return d; e; ---> return a ? b : c ? d : void e;
//
// if sequences is not enabled, this can lead to an endless loop (issue #866).
Expand Down Expand Up @@ -3647,14 +3663,19 @@ Compressor.prototype.compress = function(node) {
if (!(ab instanceof AST_Return)) return false;
var value = ab.value;
if (value && !is_undefined(value.tail_node())) return false;
if (self instanceof AST_SwitchBranch) merge_jump = 4;
if (!(self instanceof AST_SwitchBranch)) return true;
if (jump instanceof AST_Break) {
merge_jump = 4;
} else if (jump instanceof AST_Exit && !jump.value) {
merge_jump = true;
}
return true;
}
if (!(ab instanceof AST_LoopControl)) return false;
if (jump && self instanceof AST_SwitchBranch) merge_jump = true;
var lct = compressor.loopcontrol_target(ab);
if (ab instanceof AST_Continue) return match_target(loop_body(lct));
if (lct instanceof AST_IterationStatement) return false;
if (jump) merge_jump = jump.equals(ab);
return match_target(lct);
}

Expand Down
179 changes: 179 additions & 0 deletions test/compress/if_return.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -218,6 +218,79 @@ if_return_8: {
}
}

if_return_cond_void_1: {
options = {
if_return: true,
}
input: {
function f(a) {
if (a)
return console.log("foo") ? console.log("bar") : void 0;
}
f();
f(42);
}
expect: {
function f(a) {
return a && console.log("foo") ? console.log("bar") : void 0;
}
f();
f(42);
}
expect_stdout: "foo"
}

if_return_cond_void_2: {
options = {
if_return: true,
}
input: {
function f(a) {
if (a)
return console.log("foo") ? void 0 : console.log("bar");
}
f();
f(42);
}
expect: {
function f(a) {
return a || console.log("foo") ? void 0 : console.log("bar");
}
f();
f(42);
}
expect_stdout: [
"foo",
"bar",
]
}

if_return_cond_void_3: {
options = {
if_return: true,
}
input: {
function f(a) {
if (a)
return console.log("foo") ? void console.log("bar") : void console.log("baz");
}
f();
f(42);
}
expect: {
function f(a) {
if (a)
return console.log("foo") ? void console.log("bar") : void console.log("baz");
}
f();
f(42);
}
expect_stdout: [
"foo",
"baz",
]
}

issue_1089: {
options = {
booleans: true,
Expand Down Expand Up @@ -1588,3 +1661,109 @@ switch_return_4: {
"bar",
]
}

switch_return_5: {
options = {
dead_code: true,
if_return: true,
}
input: {
function f(a) {
switch (console.log("foo")) {
case console.log("bar"):
if (a)
return;
return;
break;
case null:
FAIL;
}
}
f();
f(42);
}
expect: {
function f(a) {
switch (console.log("foo")) {
case console.log("bar"):
if (a);
return;
case null:
FAIL;
}
}
f();
f(42);
}
expect_stdout: [
"foo",
"bar",
"foo",
"bar",
]
}

issue_5583: {
options = {
conditionals: true,
if_return: true,
side_effects: true,
}
input: {
do {
switch (console) {
default:
if (!console.log("foo"))
continue;
break;
case console.log("bar"):
FAIL;
}
} while (console.log("baz"));
}
expect: {
do {
switch (console) {
default:
console.log("foo");
break;
case console.log("bar"):
FAIL;
}
} while (console.log("baz"));
}
expect_stdout: [
"bar",
"foo",
"baz",
]
}

issue_5584: {
options = {
conditionals: true,
if_return: true,
}
input: {
function f(a) {
switch (a) {
case 42:
if (!console.log("PASS"))
return;
return FAIL;
}
}
f(42);
}
expect: {
function f(a) {
switch (a) {
case 42:
if (console.log("PASS"))
return FAIL;
}
}
f(42);
}
expect_stdout: "PASS"
}

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