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drop unused: toplevel, assign-only

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- assign statement does not count towards variable usage by default
- only works with assignments on the same scope level as declaration
- can be disabled with `unused` set to "keep_assign"
- `toplevel` to drop unused top-level variables and/or functions
- `top_retain` to whitelist top-level exceptions

closes #1450
This commit is contained in:
alexlamsl
2017-02-18 19:03:53 +08:00
parent d11dca3cf9
commit 148047fbbf
4 changed files with 565 additions and 10 deletions
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114
test/compress/collapse_vars.js
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@@ -338,8 +338,9 @@ collapse_vars_while: {
collapse_vars_do_while: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:false, loops:false, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
comparisons:true, evaluate:true, booleans:false, loops:false, unused:"keep_assign",
hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true, cascade:true,
side_effects:true
}
input: {
function f1(y) {
@@ -409,6 +410,79 @@ collapse_vars_do_while: {
}
}
collapse_vars_do_while_drop_assign: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:false, loops:false, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
}
input: {
function f1(y) {
// The constant do-while condition `c` will be replaced.
var c = 9;
do { } while (c === 77);
}
function f2(y) {
// The non-constant do-while condition `c` will not be replaced.
var c = 5 - y;
do { } while (c);
}
function f3(y) {
// The constant `x` will be replaced in the do loop body.
function fn(n) { console.log(n); }
var a = 2, x = 7;
do {
fn(a = x);
break;
} while (y);
}
function f4(y) {
// The non-constant `a` will not be replaced in the do loop body.
var a = y / 4;
do {
return a;
} while (y);
}
function f5(y) {
function p(x) { console.log(x); }
do {
// The non-constant `a` will be replaced in p(a)
// because it is declared in same block.
var a = y - 3;
p(a);
} while (--y);
}
}
expect: {
function f1(y) {
do ; while (false);
}
function f2(y) {
var c = 5 - y;
do ; while (c);
}
function f3(y) {
function fn(n) { console.log(n); }
do {
fn(7);
break;
} while (y);
}
function f4(y) {
var a = y / 4;
do
return a;
while (y);
}
function f5(y) {
function p(x) { console.log(x); }
do {
p(y - 3);
} while (--y);
}
}
}
collapse_vars_seq: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
@@ -567,8 +641,9 @@ collapse_vars_assignment: {
collapse_vars_lvalues: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
comparisons:true, evaluate:true, booleans:true, loops:true, unused:"keep_assign",
hoist_funs:true, keep_fargs:true, if_return:true, join_vars:true, cascade:true,
side_effects:true
}
input: {
function f0(x) { var i = ++x; return x += i; }
@@ -593,7 +668,38 @@ collapse_vars_lvalues: {
function f7(x) { var w = e1(), v = e2(), c = v - x; return (w = x) - c; }
function f8(x) { var w = e1(), v = e2(); return (w = x) - (v - x); }
function f9(x) { var w = e1(); return e2() - x - (w = x); }
}
}
collapse_vars_lvalues_drop_assign: {
options = {
collapse_vars:true, sequences:true, properties:true, dead_code:true, conditionals:true,
comparisons:true, evaluate:true, booleans:true, loops:true, unused:true, hoist_funs:true,
keep_fargs:true, if_return:true, join_vars:true, cascade:true, side_effects:true
}
input: {
function f0(x) { var i = ++x; return x += i; }
function f1(x) { var a = (x -= 3); return x += a; }
function f2(x) { var z = x, a = ++z; return z += a; }
function f3(x) { var a = (x -= 3), b = x + a; return b; }
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var w = e1(), v = e2(), c = v = --x, b = w = x; return b - c; }
function f6(x) { var w = e1(), v = e2(), c = v = --x, b = w = x; return c - b; }
function f7(x) { var w = e1(), v = e2(), c = v - x, b = w = x; return b - c; }
function f8(x) { var w = e1(), v = e2(), b = w = x, c = v - x; return b - c; }
function f9(x) { var w = e1(), v = e2(), b = w = x, c = v - x; return c - b; }
}
expect: {
function f0(x) { var i = ++x; return x += i; }
function f1(x) { var a = (x -= 3); return x += a; }
function f2(x) { var z = x, a = ++z; return z += a; }
function f3(x) { var a = (x -= 3); return x + a; }
function f4(x) { var a = (x -= 3); return x + a; }
function f5(x) { var v = (e1(), e2()), c = v = --x; return x - c; }
function f6(x) { e1(), e2(); return --x - x; }
function f7(x) { var v = (e1(), e2()), c = v - x; return x - c; }
function f8(x) { var v = (e1(), e2()); return x - (v - x); }
function f9(x) { e1(); return e2() - x - x; }
}
}