Re: testandset on powerpc

[Franz Sirl <Franz dot Sirl-kernel at lauterbach dot com>]

On Fri, 21 Jul 2000, Andreas Jaeger wrote:
> >>>>> Andreas Jaeger writes:
> >>>>>
> >>>>> Franz Sirl writes:
>
> Franz> I have done a patch which defines IMPLEMENT_TAS_AS_CAS in
> powerpc/pt-machine.h and Franz> define testandset(p) to
> !__compare_and_swap(p,0,1) in spinlock.h then. I haven't sent it AJ> That
> sounds fine.  Please send the patch for review.
>
> Hi Franz,
>
> what happened to your fix?  Is it working?  In that case please send
> it soon to get ppc working again.

I finally found the main problem, Greg's bounded pointer work rendered 
sysdeps/powerpc/strchr.S unusable without bounded pointers. The build 
finishes now and make check passes nearly all tests. Since all the thread 
tests pass, I believe my threads patch is correct. For the rest of the 
failing tests I hopefully can take a look over the weekend.

Greg, my patch for strchr.S is probably not correct for the bounded pointer 
case, so please have a look again.

Franz.

? obj
? sysdeps/powerpc/murx
Index: linuxthreads/spinlock.h
===================================================================
RCS file: /cvs/glibc/libc/linuxthreads/spinlock.h,v
retrieving revision 1.15
diff -u -p -r1.15 spinlock.h
--- linuxthreads/spinlock.h	2000/07/19 06:24:02	1.15
+++ linuxthreads/spinlock.h	2000/07/22 00:17:02
@@ -48,6 +48,10 @@ static inline int compare_and_swap(long 
 
 #elif defined(HAS_COMPARE_AND_SWAP)
 
+#ifdef IMPLEMENT_TAS_WITH_CAS
+#define testandset(p) !__compare_and_swap(p, 0, 1)
+#endif
+
 #ifdef HAS_COMPARE_AND_SWAP_WITH_RELEASE_SEMANTICS
 
 static inline int
Index: linuxthreads/sysdeps/powerpc/pt-machine.h
===================================================================
RCS file: /cvs/glibc/libc/linuxthreads/sysdeps/powerpc/pt-machine.h,v
retrieving revision 1.6
diff -u -p -r1.6 pt-machine.h
--- linuxthreads/sysdeps/powerpc/pt-machine.h	2000/04/11 17:34:36	1.6
+++ linuxthreads/sysdeps/powerpc/pt-machine.h	2000/07/22 00:17:02
@@ -28,7 +28,7 @@
 /* For multiprocessor systems, we want to ensure all memory accesses
    are completed before we reset a lock.  On other systems, we still
    need to make sure that the compiler has flushed everything to memory.  */
-#define MEMORY_BARRIER() __asm__ ("sync" : : : "memory")
+#define MEMORY_BARRIER() __asm__ __volatile__ ("sync" : : : "memory")
 
 /* Get some notion of the current stack.  Need not be exactly the top
    of the stack, just something somewhere in the current frame.  */
@@ -36,9 +36,11 @@
 register char * stack_pointer __asm__ ("r1");
 
 /* Compare-and-swap for semaphores. */
-/* note that test-and-set(x) is the same as compare-and-swap(x, 0, 1) */
+/* note that test-and-set(x) is the same as !compare-and-swap(x, 0, 1) */
 
 #define HAS_COMPARE_AND_SWAP
+#define IMPLEMENT_TAS_WITH_CAS
+
 #if BROKEN_PPC_ASM_CR0
 static
 #else
@@ -50,7 +52,7 @@ __compare_and_swap (long int *p, long in
   int ret;
 
   MEMORY_BARRIER ();
-  __asm__ (
+  __asm__ __volatile__ (
 	   "0:    lwarx %0,0,%1 ;"
 	   "      xor. %0,%3,%0;"
 	   "      bne 1f;"
Index: sysdeps/powerpc/strchr.S
===================================================================
RCS file: /cvs/glibc/libc/sysdeps/powerpc/strchr.S,v
retrieving revision 1.4
diff -u -p -r1.4 strchr.S
--- sysdeps/powerpc/strchr.S	2000/07/04 00:24:42	1.4
+++ sysdeps/powerpc/strchr.S	2000/07/22 00:17:14
@@ -34,7 +34,7 @@ ENTRY (BP_SYM (strchr))
 # define rCHR	r5	/* byte we're looking for, spread over the whole word */
 # define rWORD	r8	/* the current word */
 #else
-# define rSTR	r3	/* current word pointer */
+# define rSTR	r8	/* current word pointer */
 # define rCHR	r4	/* byte we're looking for, spread over the whole word */
 # define rWORD	r5	/* the current word */
 #endif
@@ -52,10 +52,10 @@ ENTRY (BP_SYM (strchr))
 	rlwimi	rCHR, rCHR, 8, 16, 23
 	li	rMASK, -1
 	rlwimi	rCHR, rCHR, 16, 0, 15
-	rlwinm	rIGN, rSTR, 3, 27, 28
+	rlwinm	rIGN, rRTN, 3, 27, 28
 	lis	rFEFE, -0x101
 	lis	r7F7F, 0x7f7f
-	clrrwi	rSTR, rSTR, 2
+	clrrwi	rSTR, rRTN, 2
 	addi	rFEFE, rFEFE, -0x101
 	addi	r7F7F, r7F7F, 0x7f7f
 /* Test the first (partial?) word.  */
@@ -90,7 +90,7 @@ L(loopentry):
    happened, though.  */
 L(missed):
 	and.	rTMP1, rTMP1, rTMP2
-	li	rSTR, 0
+	li	rRTN, 0
 	STORE_RETURN_VALUE (rSTR)
 	beqlr
 /* It did happen. Decide which one was first...
@@ -108,7 +108,7 @@ L(missed):
 	bgtlr
 	cntlzw	rCLZB, rTMP2
 	srwi	rCLZB, rCLZB, 3
-	add	rSTR, rSTR, rCLZB
+	add	rRTN, rSTR, rCLZB
 	CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
 	STORE_RETURN_VALUE (rSTR)
 	blr
@@ -121,7 +121,7 @@ L(foundit):
 	cntlzw	rCLZB, rTMP2
 	subi	rSTR, rSTR, 4
 	srwi	rCLZB, rCLZB, 3
-	add	rSTR, rSTR, rCLZB
+	add	rRTN, rSTR, rCLZB
 	CHECK_BOUNDS_HIGH_RTN (rSTR, rTMP2, twlge)
 	STORE_RETURN_VALUE (rSTR)
 	blr