[pypy-commit] pypy int-tag-untag-as-operations: check that operations on untagged integers get their overflow checks removed

[cfbolz]

Author: Carl Friedrich Bolz <cfbolz at gmx.de>
Branch: int-tag-untag-as-operations
Changeset: r48367:c7b823622f57
Date: 2011-10-24 08:35 +0200
http://bitbucket.org/pypy/pypy/changeset/c7b823622f57/

Log:	check that operations on untagged integers get their overflow checks
	removed

diff --git a/pypy/jit/metainterp/optimizeopt/intbounds.py b/pypy/jit/metainterp/optimizeopt/intbounds.py
--- a/pypy/jit/metainterp/optimizeopt/intbounds.py
+++ b/pypy/jit/metainterp/optimizeopt/intbounds.py
@@ -1,3 +1,4 @@
+import sys
 from pypy.jit.metainterp.optimizeopt.optimizer import Optimization, CONST_1, CONST_0, \
                                                   MODE_ARRAY, MODE_STR, MODE_UNICODE
 from pypy.jit.metainterp.history import ConstInt
@@ -286,14 +287,25 @@
 
     def optimize_INT_TAG(self, op):
         self.emit_operation(op) # XXX for now
-        self.emit_operation(self.nextop)
+        v1 = self.getvalue(op.getarg(0))
+        r = self.getvalue(op.result)
+        resbound = v1.intbound.mul(2).add(1)
+        r.intbound.intersect(resbound)
+        no_guard = False
         if self.nextop.getopnum() == rop.GUARD_NO_OVERFLOW:
+            maxbounds = IntBound((-sys.maxint-1) >> 1, sys.maxint >> 1)
+            v1.intbound.intersect(maxbounds)
             self.pure(rop.INT_UNTAG, [op.result], op.getarg(0))
+            no_guard = resbound.has_lower and resbound.has_upper
+        if not no_guard:
+            self.emit_operation(self.nextop)
 
     def optimize_INT_UNTAG(self, op):
+        v1 = self.getvalue(op.getarg(0))
+        self.pure(rop.INT_TAG, [op.result], op.getarg(0))
+        r = self.getvalue(op.result)
+        r.intbound.intersect(v1.intbound.rshift_bound(IntBound(1, 1)))
         self.emit_operation(op)
-        self.pure(rop.INT_TAG, [op.result], op.getarg(0))
-
 
     def optimize_ARRAYLEN_GC(self, op):
         self.emit_operation(op)
diff --git a/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py b/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
--- a/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
+++ b/pypy/jit/metainterp/optimizeopt/test/test_optimizeopt.py
@@ -5108,6 +5108,32 @@
         """
         self.optimize_loop(ops, expected)
 
+    def test_int_tag_remove_overflow_checking(self):
+        ops = """
+        [i0]
+        i2 = int_tag(i0)
+        guard_no_overflow() []
+        i3 = int_untag(i2)
+        i4 = int_add_ovf(i3, 1)
+        guard_no_overflow() []
+        jump(i4)
+        """
+        expected = """
+        [i0]
+        i2 = int_tag(i0)
+        guard_no_overflow() []
+        i3 = int_add(i0, 1)
+        jump(i3)
+        """
+        preamble = """
+        [i0]
+        i2 = int_tag(i0)
+        guard_no_overflow() []
+        i3 = int_add(i0, 1)
+        jump(i3)
+        """
+        self.optimize_loop(ops, expected, preamble)
+
 
     def test_mul_ovf(self):
         ops = """