fix corner case in sign propagation (#3696)

- migrate de-facto functionality to `evaluate`

fixes #3695

1 files changed, 11 insertions, 8 deletions

diff --git a/lib/compress.js b/lib/compress.js
index f2dfb64c..9b054ca3 100644
--- a/lib/compress.js
+++ b/lib/compress.js
@@ -6062,6 +6062,8 @@ merge(Compressor.prototype, {
         return self;
     });
 
+    var SIGN_OPS = makePredicate("+ -");
+    var MULTIPLICATIVE_OPS = makePredicate("* / %");
     OPT(AST_UnaryPrefix, function(self, compressor) {
         var e = self.expression;
         if (compressor.option("evaluate")
@@ -6112,12 +6114,12 @@ merge(Compressor.prototype, {
                 ])).optimize(compressor);
             }
         }
-        if (self.operator == "-" && e instanceof AST_Infinity) {
-            e = e.transform(compressor);
-        }
-        if (e instanceof AST_Binary
-            && (self.operator == "+" || self.operator == "-")
-            && (e.operator == "*" || e.operator == "/" || e.operator == "%")) {
+        if (self.operator == "-" && e instanceof AST_Infinity) e = e.transform(compressor);
+        if (compressor.option("evaluate")
+            && e instanceof AST_Binary
+            && SIGN_OPS[self.operator]
+            && MULTIPLICATIVE_OPS[e.operator]
+            && (e.left.is_constant() || !e.right.has_side_effects(compressor))) {
             return make_node(AST_Binary, self, {
                 operator: e.operator,
                 left: make_node(AST_UnaryPrefix, e.left, {
@@ -6387,7 +6389,8 @@ merge(Compressor.prototype, {
             if (self.right instanceof AST_Binary
                 && self.operator == self.right.operator
                 && (self.left.is_string(compressor) && self.right.is_string(compressor)
-                    || self.right.left.is_string(compressor) && !self.right.right.has_side_effects(compressor))) {
+                    || self.right.left.is_string(compressor)
+                        && (self.left.is_constant() || !self.right.right.has_side_effects(compressor)))) {
                 swap_chain();
             }
         }
@@ -7084,7 +7087,7 @@ merge(Compressor.prototype, {
         return reachable;
     }
 
-    var ASSIGN_OPS = makePredicate("+ - / * % >> << >>> | ^ &");
+    var ASSIGN_OPS = makePredicate("+ - * / % >> << >>> | ^ &");
     var ASSIGN_OPS_COMMUTATIVE = makePredicate("* | ^ &");
     OPT(AST_Assign, function(self, compressor) {
         if (compressor.option("dead_code")) {