On Wed, Nov 05, 2014 at 11:31:28AM +0100, Dominik Vogt wrote:
> On Tue, Nov 04, 2014 at 02:39:34PM -0800, Ian Taylor wrote:
> > Note that libgo/runtime/runtime.c now refers to S390_HAVE_STCKF. It's
> > not obvious to me that that is defined anywhere. Perhaps it is in a
> > later patch in this series--I haven't looked.
The attached patch fixes this (by using stckf unconditionally).
Ciao
Dominik ^_^ ^_^
--
Dominik Vogt
IBM Germany
ChangeLog
2014-11-05 Dominik Vogt <v...@linux.vnet.ibm.com>
* libgo/runtime/runtime.c (runtime_cputicks): s390: use stckf
unconditionally
>From 9b787b6190b5dd12e5be42e4c65a6907ca99bb59 Mon Sep 17 00:00:00 2001
From: Dominik Vogt <v...@linux.vnet.ibm.com>
Date: Wed, 5 Nov 2014 13:38:23 +0100
Subject: [PATCH 1/2] libgo: Use stckf unconditionally on s390[x].
---
libgo/runtime/runtime.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/libgo/runtime/runtime.c b/libgo/runtime/runtime.c
index abc1aff..496e77b 100644
--- a/libgo/runtime/runtime.c
+++ b/libgo/runtime/runtime.c
@@ -195,12 +195,12 @@ runtime_cputicks(void)
asm("rdtsc" : "=a" (low), "=d" (high));
return (int64)(((uint64)high << 32) | (uint64)low);
#elif defined (__s390__) || defined (__s390x__)
- uint64 clock;
-#ifdef S390_HAVE_STCKF
- asm("stckf\t%0" : "=Q" (clock) : : );
-#else
- clock = 0;
-#endif
+ uint64 clock = 0;
+ /* stckf may not write the return variable in case of a clock error, so make
+ it read-write to prevent that the initialisation is optimised out.
+ Note: Targets below z9-109 will crash when executing store clock fast, i.e.
+ we don't support Go for machines older than that. */
+ asm volatile(".insn s,0xb27c0000,%0" /* stckf */ : "+Q" (clock) : : "cc" );
return (int64)clock;
#else
// FIXME: implement for other processors.
--
1.8.4.2
