[pypy-commit] pypy default: minimark: Tweaks to reduce by one the number of checks in the common

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r54194:01a73d86d3c7
Date: 2012-04-04 19:23 +0200
http://bitbucket.org/pypy/pypy/changeset/01a73d86d3c7/

Log:	minimark: Tweaks to reduce by one the number of checks in the common
	case.

diff --git a/pypy/rpython/memory/gc/minimark.py b/pypy/rpython/memory/gc/minimark.py
--- a/pypy/rpython/memory/gc/minimark.py
+++ b/pypy/rpython/memory/gc/minimark.py
@@ -1426,23 +1426,25 @@
                 self._visit_young_rawmalloced_object(obj)
             return
         #
-        # If 'obj' was already forwarded, change it to its forwarding address.
-        if self.is_forwarded(obj):
+        size_gc_header = self.gcheaderbuilder.size_gc_header
+        if self.header(obj).tid & GCFLAG_HAS_SHADOW == 0:
+            #
+            # Common case: 'obj' was not already forwarded (otherwise
+            # tid == -42, containing all flags), and it doesn't have the
+            # HAS_SHADOW flag either.  We must move it out of the nursery,
+            # into a new nonmovable location.
+            totalsize = size_gc_header + self.get_size(obj)
+            newhdr = self._malloc_out_of_nursery(totalsize)
+            #
+        elif self.is_forwarded(obj):
+            #
+            # 'obj' was already forwarded.  Change the original reference
+            # to point to its forwarding address, and we're done.
             root.address[0] = self.get_forwarding_address(obj)
             return
-        #
-        # First visit to 'obj': we must move it out of the nursery.
-        size_gc_header = self.gcheaderbuilder.size_gc_header
-        size = self.get_size(obj)
-        totalsize = size_gc_header + size
-        #
-        if self.header(obj).tid & GCFLAG_HAS_SHADOW == 0:
-            #
-            # Common case: allocate a new nonmovable location for it.
-            newhdr = self._malloc_out_of_nursery(totalsize)
             #
         else:
-            # The object has already a shadow.
+            # First visit to an object that has already a shadow.
             newobj = self.nursery_objects_shadows.get(obj)
             ll_assert(newobj != NULL, "GCFLAG_HAS_SHADOW but no shadow found")
             newhdr = newobj - size_gc_header
@@ -1450,6 +1452,8 @@
             # Remove the flag GCFLAG_HAS_SHADOW, so that it doesn't get
             # copied to the shadow itself.
             self.header(obj).tid &= ~GCFLAG_HAS_SHADOW
+            #
+            totalsize = size_gc_header + self.get_size(obj)
         #
         # Copy it.  Note that references to other objects in the
         # nursery are kept unchanged in this step.