[src/trunk]: src/sys/arch/sh3/include Fix inline asm for tas.b. "=m" is not ...

[uwe <uwe%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/3f7f449f8c75
branches:  trunk
changeset: 748096:3f7f449f8c75
user:      uwe <uwe%NetBSD.org@localhost>
date:      Tue Oct 13 12:55:53 2009 +0000

description:
Fix inline asm for tas.b.  "=m" is not restrictive enough and gcc may
decide to use addressing modes that tas.b does not support.  'V' is
advertised to be "non-offsettable" subset of 'm' but there's a bug in
gcc that prevents "=V" from working.

When in doubt use brute force, so pass lock pointer as "r" input and
declare "memory" as clobbered.

Landisk kernel diff is 5 instructions (register choice for lock
address in __cpu_simple_lock_try).

sys/dev/raidframe/rf_copyback.c - where old __asm triggered incorrect code
- successfully compiles (as part of sys/rump/dev/lib/libraidframe).

diffstat:

 sys/arch/sh3/include/lock.h |  20 ++++++++++----------
 1 files changed, 10 insertions(+), 10 deletions(-)

diffs (42 lines):

diff -r f8f9df8dc4c5 -r 3f7f449f8c75 sys/arch/sh3/include/lock.h
--- a/sys/arch/sh3/include/lock.h       Tue Oct 13 12:38:14 2009 +0000
+++ b/sys/arch/sh3/include/lock.h       Tue Oct 13 12:55:53 2009 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: lock.h,v 1.15 2008/04/28 20:23:35 martin Exp $ */
+/*     $NetBSD: lock.h,v 1.16 2009/10/13 12:55:53 uwe Exp $    */
 
 /*-
  * Copyright (c) 2002 The NetBSD Foundation, Inc.
@@ -81,11 +81,11 @@
 {
 
         __asm volatile(
-               "1:     tas.b   %0      \n"
+               "1:     tas.b   @%0     \n"
                "       bf      1b      \n"
-               : "=m" (*alp)
-               : /* no inputs */
-               : "cc");
+               : /* no outputs */
+               : "r" (alp)
+               : "cc", "memory");
 }
 
 static __inline int
@@ -94,11 +94,11 @@
        int __rv;
 
        __asm volatile(
-               "       tas.b   %0      \n"
-               "       movt    %1      \n"
-               : "=m" (*alp), "=r" (__rv)
-               : /* no inputs */
-               : "cc");
+               "       tas.b   @%1     \n"
+               "       movt    %0      \n"
+               : "=r" (__rv)
+               : "r" (alp)
+               : "cc", "memory");
 
        return (__rv);
 }