[pypy-commit] pypy default: optimize int_floordiv(0, i) to always return 0.

[alex_gaynor]

Author: Alex Gaynor <alex.gay...@gmail.com>
Branch: 
Changeset: r48350:13caa6fd920e
Date: 2011-10-22 17:01 -0700
http://bitbucket.org/pypy/pypy/changeset/13caa6fd920e/

Log:    optimize int_floordiv(0, i) to always return 0.

diff --git a/pypy/jit/metainterp/optimizeopt/rewrite.py 
b/pypy/jit/metainterp/optimizeopt/rewrite.py
--- a/pypy/jit/metainterp/optimizeopt/rewrite.py
+++ b/pypy/jit/metainterp/optimizeopt/rewrite.py
@@ -448,6 +448,9 @@
         if v2.is_constant() and v2.box.getint() == 1:
             self.make_equal_to(op.result, v1)
             return
+        elif v1.is_constant() and v1.box.getint() == 0:
+            self.make_constant_int(op.result, 0)
+            return
         if v1.intbound.known_ge(IntBound(0, 0)) and v2.is_constant():
             val = v2.box.getint()
             if val & (val - 1) == 0 and val > 0: # val == 2**shift
diff --git a/pypy/jit/metainterp/optimizeopt/test/test_optimizebasic.py 
b/pypy/jit/metainterp/optimizeopt/test/test_optimizebasic.py
--- a/pypy/jit/metainterp/optimizeopt/test/test_optimizebasic.py
+++ b/pypy/jit/metainterp/optimizeopt/test/test_optimizebasic.py
@@ -2181,6 +2181,17 @@
         """
         self.optimize_loop(ops, expected)
 
+        ops = """
+        [i0]
+        i1 = int_floordiv(0, i0)
+        jump(i1)
+        """
+        expected = """
+        [i0]
+        jump(0)
+        """
+        self.optimize_loop(ops, expected)
+
     def test_fold_partially_constant_ops_ovf(self):
         ops = """
         [i0]
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