added additional optimizations

Author: reedM2

src/optimizer.js

@@ -50,6 +50,51 @@ const optimizers = {
     return e;
   },
 
+  BitwiseExpr(e) {
+    e.left = optimize(e.left);
+    e.right = optimize(e.right);
+    if (e.left.kind === 'num' && e.right.kind === 'num') {
+      let result;
+      switch (e.op) {
+        case '&': result = e.left.value & e.right.value; break;
+        case '|': result = e.left.value | e.right.value; break;
+        case '^': result = e.left.value ^ e.right.value; break;
+      }
+      return core.num(result);
+    }
+    if (e.op === '&') {
+      if ((e.left.kind === 'num' && e.left.value === 0) || 
+          (e.right.kind === 'num' && e.right.value === 0)) {
+        return core.num(0);
+      }
+    }
+    if (e.op === '|') {
+      if (e.left.kind === 'num' && e.left.value === 0) return e.right;
+      if (e.right.kind === 'num' && e.right.value === 0) return e.left;
+    }
+    if (e.op === '^' && e.right.kind === 'num' && e.right.value === 0) {
+      return e.left;
+    }
+    return e;
+  },
+  
+  ShiftExpr(e) {
+    e.left = optimize(e.left);
+    e.right = optimize(e.right);
+    if (e.left.kind === 'num' && e.right.kind === 'num') {
+      let result;
+      switch (e.op) {
+        case '<<': result = e.left.value << e.right.value; break;
+        case '>>': result = e.left.value >> e.right.value; break;
+      }
+      return core.num(result);
+    }
+    if (e.right.kind === 'num' && e.right.value === 0) {
+      return e.left;
+    }
+    return e;
+  },
+
   AddExpr(e) {
     e.left = optimize(e.left);
     e.right = optimize(e.right);
@@ -114,7 +159,7 @@ const optimizers = {
   },
 
   TimeCall(t) {
-    t.funcCall = optimize(t.funcCall);
+    t.id = optimize(t.id);
     t.timeValue = optimize(t.timeValue);
     return t;
   },

test/optimizer.test.js

@@ -140,6 +140,81 @@ const tests = [
     core.factor(null, "~", id("x")),
     core.factor(null, "~", id("x")),
   ],
+  [
+    "folds bitwise AND with constants",
+    core.bitwiseExpr(num(5), "&", num(3)),
+    num(1),
+  ],
+  [
+    "folds bitwise OR with constants",
+    core.bitwiseExpr(num(2), "|", num(8)),
+    num(10),
+  ],
+  [
+    "folds bitwise XOR with constants",
+    core.bitwiseExpr(num(6), "^", num(3)),
+    num(5),
+  ],
+  [
+    "optimizes x & 0 to 0",
+    core.bitwiseExpr(id("x"), "&", num(0)),
+    num(0),
+  ],
+  [
+    "optimizes 0 & x to 0",
+    core.bitwiseExpr(num(0), "&", id("x")),
+    num(0),
+  ],
+  [
+    "optimizes x | 0 to x",
+    core.bitwiseExpr(id("x"), "|", num(0)),
+    id("x"),
+  ],
+  [
+    "optimizes 0 | x to x",
+    core.bitwiseExpr(num(0), "|", id("x")),
+    id("x"),
+  ],
+  [
+    "optimizes x ^ 0 to x",
+    core.bitwiseExpr(id("x"), "^", num(0)),
+    id("x"),
+  ],
+  [
+    "leaves bitwise expression with variables unoptimized",
+    core.bitwiseExpr(id("a"), "&", id("b")),
+    core.bitwiseExpr(id("a"), "&", id("b")),
+  ],
+  [
+    "folds left shift with constants",
+    core.shiftExpr(num(4), "<<", num(2)),
+    num(16),
+  ],
+  [
+    "folds right shift with constants",
+    core.shiftExpr(num(16), ">>", num(2)),
+    num(4),
+  ],
+  [
+    "optimizes x << 0 to x",
+    core.shiftExpr(id("x"), "<<", num(0)),
+    id("x"),
+  ],
+  [
+    "optimizes x >> 0 to x",
+    core.shiftExpr(id("x"), ">>", num(0)),
+    id("x"),
+  ],
+  [
+    "leaves shift expression with variables unoptimized",
+    core.shiftExpr(id("a"), "<<", id("b")),
+    core.shiftExpr(id("a"), "<<", id("b")),
+  ],
+  [
+    "optimizes shift with negative numbers (JS semantics)",
+    core.shiftExpr(num(-4), ">>", num(1)),
+    num(-2), // In JS, -4 >> 1 is -2
+  ],
   [
     "optimizes print statement expression",
     core.printStmt(add(num(2), "+", num(3))),