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enhance collapse_vars (#3896)

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This commit is contained in:
Alex Lam S.L
2020-05-14 00:52:42 +01:00
committed by GitHub
parent fe2f1965d6
commit 938368ba21
2 changed files with 39 additions and 6 deletions
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10
lib/compress.js
View File

@@ -1350,7 +1350,7 @@ merge(Compressor.prototype, {
var lhs = get_lhs(candidate); var lhs = get_lhs(candidate);
var side_effects = lhs && lhs.has_side_effects(compressor); var side_effects = lhs && lhs.has_side_effects(compressor);
var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs, compressor); var scan_lhs = lhs && !side_effects && !is_lhs_read_only(lhs, compressor);
var scan_rhs = foldable(get_rhs(candidate)); var scan_rhs = foldable(candidate);
if (!scan_lhs && !scan_rhs) continue; if (!scan_lhs && !scan_rhs) continue;
var modify_toplevel = false; var modify_toplevel = false;
// Locate symbols which may execute code outside of scanning range // Locate symbols which may execute code outside of scanning range
@@ -1841,10 +1841,6 @@ merge(Compressor.prototype, {
} }
} }
function get_rhs(expr) {
return candidate instanceof AST_Assign && candidate.operator == "=" && candidate.right;
}
function invariant(expr) { function invariant(expr) {
if (expr instanceof AST_Array) return false; if (expr instanceof AST_Array) return false;
if (expr instanceof AST_Binary && lazy_op[expr.operator]) { if (expr instanceof AST_Binary && lazy_op[expr.operator]) {
@@ -1859,7 +1855,9 @@ merge(Compressor.prototype, {
} }
function foldable(expr) { function foldable(expr) {
if (!expr) return false; while (expr instanceof AST_Assign && expr.operator == "=") {
expr = expr.right;
}
if (expr instanceof AST_SymbolRef) { if (expr instanceof AST_SymbolRef) {
var value = expr.evaluate(compressor); var value = expr.evaluate(compressor);
if (value === expr) return rhs_exact_match; if (value === expr) return rhs_exact_match;

35
test/compress/collapse_vars.js
View File

@@ -8015,3 +8015,38 @@ issue_3891: {
} }
expect_stdout: "function" expect_stdout: "function"
} }
issue_3894: {
options = {
collapse_vars: true,
inline: true,
reduce_vars: true,
unused: true,
}
input: {
function log(msg) {
console.log(msg ? "FAIL" : "PASS");
}
var a, c;
(function(b) {
a = c = 0,
log(b);
})(-0);
log(a);
log(c);
}
expect: {
function log(msg) {
console.log(msg ? "FAIL" : "PASS");
}
var a, c;
void log(-(a = c = 0));
log(a);
log(c);
}
expect_stdout: [
"PASS",
"PASS",
"PASS",
]
}