From: Andi Kleen <a...@linux.intel.com>
For a large LTO test case The previous pointer hash change brought
the collision rate for the WPA gimple type hash table from 90% to
70. This patch uses the well known murmur3 to improve it further
to 64%.
gcc/:
2013-04-18 Andi Kleen <a...@linux.intel.com>
* Makefile.in (tree.o): Add murmurhash3.h dependency.
* tree.c (tree_map_base_hash): Use murmurhash3.
---
gcc/Makefile.in | 2 +-
gcc/tree.c | 4 +++-
2 files changed, 4 insertions(+), 2 deletions(-)
diff --git a/gcc/Makefile.in b/gcc/Makefile.in
index 109f865..28815a2 100644
--- a/gcc/Makefile.in
+++ b/gcc/Makefile.in
@@ -2216,7 +2216,7 @@ tree.o: tree.c $(CONFIG_H) $(SYSTEM_H) coretypes.h
$(TM_H) $(TREE_H) \
$(BASIC_BLOCK_H) $(TREE_FLOW_H) $(OBSTACK_H) pointer-set.h \
$(TREE_PASS_H) $(LANGHOOKS_DEF_H) $(DIAGNOSTIC_H) $(CGRAPH_H) \
$(EXCEPT_H) debug.h intl.h tree-diagnostic.h $(TREE_PRETTY_PRINT_H) \
- $(COMMON_TARGET_H)
+ $(COMMON_TARGET_H) murmurhash.h
tree-dump.o: tree-dump.c $(CONFIG_H) $(SYSTEM_H) $(TM_H) $(TREE_H) \
langhooks.h $(TREE_DUMP_H) tree-iterator.h $(TREE_PRETTY_PRINT_H)
tree-inline.o : tree-inline.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
diff --git a/gcc/tree.c b/gcc/tree.c
index d8f2424..2fb732f 100644
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -59,6 +59,7 @@ along with GCC; see the file COPYING3. If not see
#include "except.h"
#include "debug.h"
#include "intl.h"
+#include "murmurhash3.h"
/* Tree code classes. */
@@ -5935,7 +5936,8 @@ tree_map_base_eq (const void *va, const void *vb)
unsigned int
tree_map_base_hash (const void *item)
{
- return htab_hash_pointer (((const struct tree_map_base *)item)->from);
+ return murmurhash3_32 (&((const struct tree_map_base *)item)->from,
+ sizeof (void *), 0);
}
/* Return true if this tree map structure is marked for garbage collection
--
1.8.1.4
