[pypy-commit] pypy default: int_lshift(0, x) -> 0

[alex_gaynor]

Author: Alex Gaynor <alex.gaynor at gmail.com>
Branch: 
Changeset: r67131:b6009ce47b65
Date: 2013-09-28 16:32 -0700
http://bitbucket.org/pypy/pypy/changeset/b6009ce47b65/

Log:	int_lshift(0, x) -> 0 int_rshift(0, x) -> 0

diff --git a/rpython/jit/metainterp/optimizeopt/rewrite.py b/rpython/jit/metainterp/optimizeopt/rewrite.py
--- a/rpython/jit/metainterp/optimizeopt/rewrite.py
+++ b/rpython/jit/metainterp/optimizeopt/rewrite.py
@@ -171,6 +171,8 @@
 
         if v2.is_constant() and v2.box.getint() == 0:
             self.make_equal_to(op.result, v1)
+        elif v1.is_constant() and v1.box.getint() == 0:
+            self.make_constant_int(op.result, 0)
         else:
             self.emit_operation(op)
 
@@ -180,6 +182,8 @@
 
         if v2.is_constant() and v2.box.getint() == 0:
             self.make_equal_to(op.result, v1)
+        elif v1.is_constant() and v1.box.getint() == 0:
+            self.make_constant_int(op.result, 0)
         else:
             self.emit_operation(op)
 
diff --git a/rpython/jit/metainterp/optimizeopt/test/test_optimizebasic.py b/rpython/jit/metainterp/optimizeopt/test/test_optimizebasic.py
--- a/rpython/jit/metainterp/optimizeopt/test/test_optimizebasic.py
+++ b/rpython/jit/metainterp/optimizeopt/test/test_optimizebasic.py
@@ -3749,6 +3749,19 @@
         """
         self.optimize_loop(ops, expected)
 
+    def test_shift_zero(self):
+        ops = """
+        [i0]
+        i1 = int_lshift(0, i0)
+        i2 = int_rshift(0, i0)
+        jump(i1, i2)
+        """
+        expected = """
+        [i0]
+        jump(0, 0)
+        """
+        self.optimize_loop(ops, expected)
+
     def test_bound_and(self):
         ops = """
         [i0]