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optimize try-catch-finally (#1731)

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- eliminate empty blocks
- flatten out if try-block does not throw
This commit is contained in:
Alex Lam S.L
2017-03-30 12:16:58 +08:00
committed by GitHub
parent 0f910ee25c
commit 7bea38a05d
5 changed files with 81 additions and 12 deletions
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9
lib/compress.js
View File

@@ -2606,6 +2606,15 @@ merge(Compressor.prototype, {
OPT(AST_Try, function(self, compressor){
self.body = tighten_body(self.body, compressor);
if (self.bcatch && self.bfinally && all(self.bfinally.body, is_empty)) self.bfinally = null;
if (all(self.body, is_empty)) {
var body = [];
if (self.bcatch) extract_declarations_from_unreachable_code(compressor, self.bcatch, body);
if (self.bfinally) body = body.concat(self.bfinally.body);
return body.length > 0 ? make_node(AST_BlockStatement, self, {
body: body
}).optimize(compressor) : make_node(AST_EmptyStatement, self);
}
return self;
});

42
test/compress/dead-code.js
View File

@@ -214,3 +214,45 @@ dead_code_const_annotation_complex_scope: {
}
expect_stdout: true
}
try_catch_finally: {
options = {
conditionals: true,
dead_code: true,
evaluate: true,
}
input: {
var a = 1;
!function() {
try {
if (false) throw x;
} catch (a) {
var a = 2;
console.log("FAIL");
} finally {
a = 3;
console.log("PASS");
}
}();
try {
console.log(a);
} finally {
}
}
expect: {
var a = 1;
!function() {
var a;
a = 3;
console.log("PASS");
}();
try {
console.log(a);
} finally {
}
}
expect_stdout: [
"PASS",
"1",
]
}

32
test/compress/drop-unused.js
View File

@@ -853,7 +853,9 @@ issue_1715_1: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a;
}
}
@@ -864,7 +866,9 @@ issue_1715_1: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a;
}
}
@@ -882,7 +886,9 @@ issue_1715_2: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a = 2;
}
}
@@ -893,7 +899,9 @@ issue_1715_2: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a;
}
}
@@ -911,7 +919,9 @@ issue_1715_3: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
console;
} catch (a) {
var a = 2 + x();
}
}
@@ -922,7 +932,9 @@ issue_1715_3: {
var a = 1;
function f() {
a++;
try {} catch (a) {
try {
console;
} catch (a) {
var a = x();
}
}
@@ -940,7 +952,9 @@ issue_1715_4: {
var a = 1;
!function a() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a;
}
}();
@@ -950,7 +964,9 @@ issue_1715_4: {
var a = 1;
!function() {
a++;
try {} catch (a) {
try {
x();
} catch (a) {
var a;
}
}();

2
test/compress/issue-1673.js
View File

@@ -70,6 +70,7 @@ side_effects_finally: {
function f() {
function g() {
try {
x();
} catch (e) {
} finally {
console.log("PASS");
@@ -83,6 +84,7 @@ side_effects_finally: {
function f() {
(function() {
try {
x();
} catch (e) {
} finally {
console.log("PASS");

8
test/compress/screw-ie8.js
View File

@@ -204,13 +204,13 @@ issue_1586_1: {
input: {
function f() {
try {
x();
} catch (err) {
console.log(err.message);
}
}
}
expect_exact: "function f(){try{}catch(c){console.log(c.message)}}"
expect_stdout: true
expect_exact: "function f(){try{x()}catch(c){console.log(c.message)}}"
}
issue_1586_2: {
@@ -223,11 +223,11 @@ issue_1586_2: {
input: {
function f() {
try {
x();
} catch (err) {
console.log(err.message);
}
}
}
expect_exact: "function f(){try{}catch(c){console.log(c.message)}}"
expect_stdout: true
expect_exact: "function f(){try{x()}catch(c){console.log(c.message)}}"
}