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better fix for #512 & #2010 (#2019)

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- remove duplicated functionalities
- fix similar issue with `else`
This commit is contained in:
Alex Lam S.L
2017-05-29 10:51:41 +08:00
committed by GitHub
parent e62b879b48
commit 1aa38051fb
3 changed files with 86 additions and 60 deletions
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120
lib/compress.js
View File

@@ -924,6 +924,45 @@ merge(Compressor.prototype, {
// step. nevertheless, it's good to check.
continue loop;
case stat instanceof AST_If:
var ab = aborts(stat.body);
if (can_merge_flow(ab)) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
var funs = extract_functions_from_statement_array(ret);
var body = as_statement_array_with_return(stat.body, ab);
stat = stat.clone();
stat.condition = stat.condition.negate(compressor);
stat.body = make_node(AST_BlockStatement, stat, {
body: as_statement_array(stat.alternative).concat(ret)
});
stat.alternative = make_node(AST_BlockStatement, stat, {
body: body
});
ret = [ stat.transform(compressor) ].concat(funs);
continue loop;
}
var ab = aborts(stat.alternative);
if (can_merge_flow(ab)) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
var funs = extract_functions_from_statement_array(ret);
stat = stat.clone();
stat.body = make_node(AST_BlockStatement, stat.body, {
body: as_statement_array(stat.body).concat(ret)
});
var body = as_statement_array_with_return(stat.alternative, ab);
stat.alternative = make_node(AST_BlockStatement, stat.alternative, {
body: body
});
ret = [ stat.transform(compressor) ].concat(funs);
continue loop;
}
if (stat.body instanceof AST_Return) {
var value = stat.body.value;
//---
@@ -960,23 +999,6 @@ merge(Compressor.prototype, {
continue loop;
}
//---
// if (foo()) return [ void bar() ]; [ else x...; ] y... ==> if (!foo()) { x...; y... } else bar();
if (in_lambda && (!value || value instanceof AST_UnaryPrefix && value.operator == "void")) {
CHANGED = true;
stat = stat.clone();
stat.condition = stat.condition.negate(compressor);
var funs = extract_functions_from_statement_array(ret);
var body = as_statement_array(stat.alternative).concat(ret);
stat.body = make_node(AST_BlockStatement, stat, {
body: body
});
stat.alternative = value ? make_node(AST_SimpleStatement, value, {
body: value.expression
}) : null;
ret = [ stat.transform(compressor) ].concat(funs);
continue loop;
}
//---
// 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).
@@ -995,48 +1017,6 @@ merge(Compressor.prototype, {
}
}
var ab = aborts(stat.body);
var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null;
if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda)
|| (ab instanceof AST_Continue && self === loop_body(lct))
|| (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
var body = as_statement_array(stat.body).slice(0, -1);
stat = stat.clone();
stat.condition = stat.condition.negate(compressor);
stat.body = make_node(AST_BlockStatement, stat, {
body: as_statement_array(stat.alternative).concat(ret)
});
stat.alternative = make_node(AST_BlockStatement, stat, {
body: body
});
ret = [ stat.transform(compressor) ];
continue loop;
}
var ab = aborts(stat.alternative);
var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null;
if (ab && ((ab instanceof AST_Return && !ab.value && in_lambda)
|| (ab instanceof AST_Continue && self === loop_body(lct))
|| (ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct))) {
if (ab.label) {
remove(ab.label.thedef.references, ab);
}
CHANGED = true;
stat = stat.clone();
stat.body = make_node(AST_BlockStatement, stat.body, {
body: as_statement_array(stat.body).concat(ret)
});
stat.alternative = make_node(AST_BlockStatement, stat.alternative, {
body: as_statement_array(stat.alternative).slice(0, -1)
});
ret = [ stat.transform(compressor) ];
continue loop;
}
ret.unshift(stat);
break;
default:
@@ -1056,6 +1036,28 @@ merge(Compressor.prototype, {
}
return false;
}
function is_return_void(value) {
return !value || value instanceof AST_UnaryPrefix && value.operator == "void";
}
function can_merge_flow(ab) {
if (!ab) return false;
var lct = ab instanceof AST_LoopControl ? compressor.loopcontrol_target(ab) : null;
return ab instanceof AST_Return && in_lambda && is_return_void(ab.value)
|| ab instanceof AST_Continue && self === loop_body(lct)
|| ab instanceof AST_Break && lct instanceof AST_BlockStatement && self === lct;
}
function as_statement_array_with_return(node, ab) {
var body = as_statement_array(node).slice(0, -1);
if (ab.value) {
body.push(make_node(AST_SimpleStatement, ab.value, {
body: ab.value.expression
}));
}
return body;
}
};
function eliminate_dead_code(statements, compressor) {

2
test/compress/if_return.js
View File

@@ -307,6 +307,8 @@ issue_512: {
options = {
conditionals: true,
if_return: true,
sequences: true,
side_effects: true,
}
input: {
function a() {

24
test/compress/issue-1052.js
View File

@@ -136,7 +136,29 @@ defun_hoist_funs: {
function f() {}
function g() {}
function h() {}
!window;
if (window);
}
}
}
defun_else_if_return: {
options = {
hoist_funs: false,
if_return: true,
}
input: {
function e() {
function f() {}
if (window) function g() {}
else return;
function h() {}
}
}
expect: {
function e() {
function f() {}
if (window) function g() {}
function h() {}
}
}
}