[Help-smalltalk] [PATCH] embedded: Allow to disable the prefetching.

[Holger Hans Peter Freyther]

Disabling the prefetching is a win on arm9 (arm926ejs, e.g. TI
Davinci DM644x). This was benchmarked using the simple Bench.st
benchmark.

2013-04-28  Holger Hans Peter Freyther  <address@hidden>

        * libgst/gstpriv.h: Allow to disable the DO_PREFETCH.
---
 libgst/ChangeLog   |    4 ++++
 libgst/gstpriv.h   |    7 +++++--
 libgst/md-config.h |    1 +
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/libgst/ChangeLog b/libgst/ChangeLog
index 4a51cee..3812850 100644
--- a/libgst/ChangeLog
+++ b/libgst/ChangeLog
@@ -1,5 +1,9 @@
 2013-04-28  Holger Hans Peter Freyther  <address@hidden>
 
+       * libgst/gstpriv.h: Allow to disable the DO_PREFETCH.
+
+2013-04-28  Holger Hans Peter Freyther  <address@hidden>
+
        * libgst/cint.c: Bind link, fsync, sync for additional C level access.
 
 2013-04-25  Holger Hans Peter Freyther  <address@hidden>
diff --git a/libgst/gstpriv.h b/libgst/gstpriv.h
index 7127438..7ffe37b 100644
--- a/libgst/gstpriv.h
+++ b/libgst/gstpriv.h
@@ -115,6 +115,7 @@
 #endif
 
 #include "gst.h"
+#include "md-config.h"
 
 /* Convenience macros to test the versions of GCC.  Note - they won't
    work for GCC1, since the _MINOR macros were not defined then, but
@@ -175,7 +176,9 @@
 #define PREF_T2 8
 #define PREF_NTA 12
 
-#if GNUC_PREREQ (3, 1)
+/* the prefetch is a loss on on a ARM9 (TI Davinci), hack it out */
+#if !defined(DISABLE_PREFETCH) && GNUC_PREREQ (3, 1)
+#warning "ENABLE PREFETCH"
 #define DO_PREFETCH(x, distance, k) \
   __builtin_prefetch (((char *) (x)) \
                      + (((k) & PREF_BACKWARDS ? -(distance) : (distance)) \
@@ -183,6 +186,7 @@
                      (k) & PREF_WRITE, \
                      3 - (k) / (PREF_NTA / 3))
 #else
+#warning "DISABLE PREFETCH"
 #define DO_PREFETCH(x, distance, kind) ((void)(x))
 #endif
 
@@ -556,7 +560,6 @@ extern OOP _gst_nil_oop
 #include "socketx.h"
 #include "strspell.h"
 #include "alloc.h"
-#include "md-config.h"
 #include "avltrees.h"
 #include "rbtrees.h"
 
diff --git a/libgst/md-config.h b/libgst/md-config.h
index 862fdfd..b8ba5bf 100644
--- a/libgst/md-config.h
+++ b/libgst/md-config.h
@@ -74,6 +74,7 @@
 # define __DECL_REG3 __asm("r6")
 # define BRANCH_REGISTER(name) register void *name __asm("r7")
 # define L1_CACHE_SHIFT 4
+# define DISABLE_PREFETCH
 #endif
 
 #if !defined(__DECL_REG1) && defined(__alpha__)
-- 
1.7.10.4