enhance unused (#3794)

test/compress/asm.js

@@ -91,8 +91,7 @@ asm_mixed: {
         function no_asm_GeometricMean(stdlib, foreign, buffer) {
             function logSum(start, end) {
                 start |= 0, end |= 0;
-                var sum = 0, p = 0, q = 0;
-                for (p = start << 3, q = end << 3; (0 | p) < (0 | q); p = p + 8 | 0) sum += +log(values[p >> 3]);
+                for (var sum = 0, p = 0, q = 0, p = start << 3, q = end << 3; (0 | p) < (0 | q); p = p + 8 | 0) sum += +log(values[p >> 3]);
                 return +sum;
             }
             function geometricMean(start, end) {

test/compress/collapse_vars.js

@@ -2570,8 +2570,7 @@ chained_3: {
     }
     expect: {
         console.log(function(a, b) {
-            var c = 1;
-            c = b;
+            var c = 1, c = b;
             b++;
             return c;
         }(0, 2));

test/compress/drop-unused.js

@@ -2444,3 +2444,23 @@ issue_3746: {
     }
     expect_stdout: "PASS"
 }
+
+drop_duplicated_side_effects: {
+    options = {
+        toplevel: true,
+        unused: true,
+    }
+    input: {
+        var a = 0;
+        for (var i = 1; i--;)
+            var a = 0, b = ++a;
+        console.log(a);
+    }
+    expect: {
+        var a = 0;
+        for (var i = 1; i--;)
+            a = 0, ++a;
+        console.log(a);
+    }
+    expect_stdout: "1"
+}

test/compress/keep_fargs.js

@@ -1226,8 +1226,7 @@ chained_3: {
     }
     expect: {
         console.log(function(b) {
-            var c = 1;
-            c = b;
+            var c = 1, c = b;
             b++;
             return c;
         }(2));

test/compress/reduce_vars.js

@@ -5434,8 +5434,7 @@ lvalues_def_1: {
     }
     expect: {
         var b = 1;
-        var a = b++;
-        b = NaN;
+        var a = b++, b = NaN;
         console.log(a, b);
     }
     expect_stdout: "1 NaN"
@@ -5454,8 +5453,7 @@ lvalues_def_2: {
     }
     expect: {
         var b = 1;
-        var a = b += 1;
-        b = NaN;
+        var a = b += 1, b = NaN;
         console.log(a, b);
     }
     expect_stdout: "2 NaN"
@@ -6867,9 +6865,9 @@ issue_3666: {
         } finally {
             for (;!a;)
                 a++;
-            var b = a = "PASS";
+            a = "PASS";
         }
-        console.log(a, b);
+        console.log(a, "PASS");
     }
     expect_stdout: "PASS PASS"
 }