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fix corner case in if_return (#5598)
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fixes #5597
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@alexlamsl
alexlamsl authored Aug 3, 2022
1 parent 8076d66 commit 884842c
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Showing 2 changed files with 41 additions and 11 deletions.
26 changes: 15 additions & 11 deletions lib/compress.js
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Original file line number Diff line number Diff line change
Expand Up @@ -3452,16 +3452,15 @@ Compressor.prototype.compress = function(node) {
var parent = compressor.parent();
var self = compressor.self();
var declare_only, jump, merge_jump;
var in_tail = in_lambda && self instanceof AST_Block && self.body === statements;
var in_iife = in_tail && parent && parent.TYPE == "Call" && parent.expression === self;
var chain_if_returns = in_tail && compressor.option("conditionals") && compressor.option("sequences");
var in_iife = in_lambda && parent && parent.TYPE == "Call" && parent.expression === self;
var chain_if_returns = in_lambda && compressor.option("conditionals") && compressor.option("sequences");
var multiple_if_returns = has_multiple_if_returns(statements);
for (var i = statements.length; --i >= 0;) {
var stat = statements[i];
var j = next_index(i);
var next = statements[j];

if (in_tail && declare_only && !next && stat instanceof AST_Return
if (in_lambda && declare_only && !next && stat instanceof AST_Return
&& !(self instanceof AST_SwitchBranch)
&& !(in_try && in_try.bfinally && in_async_generator(in_lambda))) {
var body = stat.value;
Expand All @@ -3486,6 +3485,7 @@ Compressor.prototype.compress = function(node) {

if (stat instanceof AST_If) {
var ab = aborts(stat.body);
// if (foo()) { bar(); return; } else baz(); moo(); ---> if (foo()) bar(); else { baz(); moo(); }
if (can_merge_flow(ab)) {
if (ab.label) remove(ab.label.thedef.references, ab);
changed = true;
Expand All @@ -3500,7 +3500,7 @@ Compressor.prototype.compress = function(node) {
statements[i] = stat.transform(compressor);
continue;
}

// if (foo()) { bar(); return x; } return y; ---> if (!foo()) return y; bar(); return x;
if (ab && !stat.alternative && next instanceof AST_Jump) {
var cond = stat.condition;
var preference = i + 1 == j && stat.body instanceof AST_BlockStatement;
Expand All @@ -3514,12 +3514,17 @@ Compressor.prototype.compress = function(node) {
body: extract_functions(true, null, j + 1),
});
statements.splice(i, 1, stat, body);
statements[i] = stat.transform(compressor);
// proceed further only if `TreeWalker.stack` is in a consistent state
// https://github.com/mishoo/UglifyJS/issues/5595
// https://github.com/mishoo/UglifyJS/issues/5597
if (!in_lambda || self instanceof AST_Block && self.body === statements) {
statements[i] = stat.transform(compressor);
}
continue;
}
}

var alt = aborts(stat.alternative);
// if (foo()) bar(); else { baz(); return; } moo(); ---> if (foo()) { bar(); moo(); } else baz();
if (can_merge_flow(alt)) {
if (alt.label) remove(alt.label.thedef.references, alt);
changed = true;
Expand All @@ -3534,7 +3539,6 @@ Compressor.prototype.compress = function(node) {
statements[i] = stat.transform(compressor);
continue;
}

if (compressor.option("typeofs")) {
if (ab && !alt) {
var stats = make_node(AST_BlockStatement, self, { body: statements.slice(i + 1) });
Expand Down Expand Up @@ -3564,7 +3568,7 @@ Compressor.prototype.compress = function(node) {
// if (foo()) return x; [ return ; ] ---> return foo() ? x : undefined;
// 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;
if (in_tail && declare_only && !next && !stat.alternative && (in_bool
if (in_lambda && declare_only && !next && !stat.alternative && (in_bool
|| value && multiple_if_returns
|| value instanceof AST_Conditional && (is_undefined(value.consequent, compressor)
|| is_undefined(value.alternative, compressor)))) {
Expand Down Expand Up @@ -3645,7 +3649,7 @@ Compressor.prototype.compress = function(node) {
function can_drop_abort(ab) {
if (ab instanceof AST_Exit) {
if (merge_jump = match_return(ab)) return true;
if (!in_tail) return false;
if (!in_lambda) return false;
if (!(ab instanceof AST_Return)) return false;
var value = ab.value;
if (value && !is_undefined(value.tail_node())) return false;
Expand All @@ -3658,7 +3662,7 @@ Compressor.prototype.compress = function(node) {
if (!(ab instanceof AST_LoopControl)) return false;
if (jump && self instanceof AST_SwitchBranch) {
if (jump instanceof AST_Exit) {
if (!in_tail) return false;
if (!in_lambda) return false;
if (jump.value) return false;
} else if (compressor.loopcontrol_target(jump) !== parent) {
return false;
Expand Down
26 changes: 26 additions & 0 deletions test/compress/if_return.js
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2279,3 +2279,29 @@ issue_5595: {
}
expect_stdout: "PASS"
}

issue_5597: {
options = {
conditionals: true,
if_return: true,
unused: true,
}
input: {
function f(a) {
if (a) L: {
return;
var b;
} else
return "FAIL";
}
console.log(f(42) || "PASS");
}
expect: {
function f(a) {
if (!a)
return "FAIL";
}
console.log(f(42) || "PASS");
}
expect_stdout: "PASS"
}

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