[pypy-commit] pypy default: repeated float_neg have a known reesult.

[alex_gaynor]

Author: Alex Gaynor <alex.gaynor at gmail.com>
Branch: 
Changeset: r44996:299fbd1d3f00
Date: 2011-06-18 18:57 -0700
http://bitbucket.org/pypy/pypy/changeset/299fbd1d3f00/

Log:	repeated float_neg have a known reesult.

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
@@ -205,6 +205,11 @@
                     return
         self.emit_operation(op)
 
+    def optimize_FLOAT_NEG(self, op):
+        v1 = op.getarg(0)
+        self.emit_operation(op)
+        self.pure(rop.FLOAT_NEG, [op.result], v1)
+
     def optimize_CALL_PURE(self, op):
         arg_consts = []
         for i in range(op.numargs()):
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
@@ -2182,6 +2182,25 @@
         """
         self.optimize_loop(ops, expected)
 
+    def test_fold_repeated_float_neg(self):
+        ops = """
+        [f0]
+        f1 = float_neg(f0)
+        f2 = float_neg(f1)
+        f3 = float_neg(f2)
+        f4 = float_neg(f3)
+        escape(f4)
+        jump(f4)
+        """
+        expected = """
+        [f0]
+        # The backend removes this dead op.
+        f1 = float_neg(f0)
+        escape(f0)
+        jump(f0)
+        """
+        self.optimize_loop(ops, expected)
+
     # ----------
 
     def make_fail_descr(self):