[pypy-commit] pypy default: Don't emit write barriers for constants in the JIT - they all can't move. Be a bit future-proof by calling can_move, which is going to always be true, until we merge pinning

[fijal]

Author: Maciej Fijalkowski <fijall at gmail.com>
Branch: 
Changeset: r73534:8707febbf25b
Date: 2014-09-14 15:54 -0600
http://bitbucket.org/pypy/pypy/changeset/8707febbf25b/

Log:	Don't emit write barriers for constants in the JIT - they all can't
	move. Be a bit future-proof by calling can_move, which is going to
	always be true, until we merge pinning

diff --git a/rpython/jit/backend/llsupport/rewrite.py b/rpython/jit/backend/llsupport/rewrite.py
--- a/rpython/jit/backend/llsupport/rewrite.py
+++ b/rpython/jit/backend/llsupport/rewrite.py
@@ -1,3 +1,4 @@
+from rpython.rlib import rgc
 from rpython.rlib.rarithmetic import ovfcheck
 from rpython.rtyper.lltypesystem import llmemory
 from rpython.jit.metainterp import history
@@ -390,8 +391,8 @@
         val = op.getarg(0)
         if val not in self.write_barrier_applied:
             v = op.getarg(1)
-            if isinstance(v, BoxPtr) or (isinstance(v, ConstPtr) and
-                                         bool(v.value)): # store a non-NULL
+            if (isinstance(v, BoxPtr) or (isinstance(v, ConstPtr) and
+                               rgc.needs_write_barrier(v.value))):
                 self.gen_write_barrier(val)
                 #op = op.copy_and_change(rop.SETFIELD_RAW)
         self.newops.append(op)
@@ -400,8 +401,8 @@
         val = op.getarg(0)
         if val not in self.write_barrier_applied:
             v = op.getarg(2)
-            if isinstance(v, BoxPtr) or (isinstance(v, ConstPtr) and
-                                         bool(v.value)): # store a non-NULL
+            if (isinstance(v, BoxPtr) or (isinstance(v, ConstPtr) and
+                                         rgc.needs_write_barrier(v.value))):
                 self.gen_write_barrier_array(val, op.getarg(1))
                 #op = op.copy_and_change(rop.SET{ARRAYITEM,INTERIORFIELD}_RAW)
         self.newops.append(op)
diff --git a/rpython/rlib/rgc.py b/rpython/rlib/rgc.py
--- a/rpython/rlib/rgc.py
+++ b/rpython/rlib/rgc.py
@@ -86,6 +86,14 @@
         collect(i)
         i += 1
 
+def needs_write_barrier(obj):
+    """ We need to emit write barrier if the right hand of assignment
+    is in nursery, used by the JIT for handling set*_gc(Const)
+    """
+    if not obj:
+        return False
+    return can_move(obj)
+
 def _heap_stats():
     raise NotImplementedError # can't be run directly