(__arch_compare_and_exchange_bool_32_acq): Fix case where oldval is negative. (__arch...

diff --git a/sysdeps/powerpc/powerpc64/bits/atomic.h b/sysdeps/powerpc/powerpc64/bits/atomic.h
index 16bb994..1a20e3f 100644 (file)
--- a/sysdeps/powerpc/powerpc64/bits/atomic.h
+++ b/sysdeps/powerpc/powerpc64/bits/atomic.h
@@ -18,44 +18,40 @@
    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
    02111-1307 USA.  */
 
-/*
- * The 32-bit exchange_bool is different on powerpc64 because the subf
- * does signed 64-bit arthmatic while the lwarx is 32-bit unsigned
- * (a load word and zero (high 32) form) load.
- * In powerpc64 register values are 64-bit by default,  including oldval.
- * Net we need to extend sign word the result of lwarx to 64-bit so the
- * 64-bit subtract from gives the expected result and sets the condition
- * correctly.
- */
+/* The 32-bit exchange_bool is different on powerpc64 because the subf
+   does signed 64-bit arthmatic while the lwarx is 32-bit unsigned
+   (a load word and zero (high 32) form) load.
+   In powerpc64 register values are 64-bit by default,  including oldval.
+   The value in old val unknown sign extension, lwarx loads the 32-bit
+   value as unsigned.  So we explicitly clear the high 32 bits in oldval.  */
 # define __arch_compare_and_exchange_bool_32_acq(mem, newval, oldval) \
 ({                                                                           \
-  unsigned int __tmp;                                                        \
-  __asm __volatile (                                                         \
-                   "1: lwarx   %0,0,%1\n"                                    \
-                   "   extsw   %0,%0\n"                                      \
-                   "   subf.   %0,%2,%0\n"                                   \
+  unsigned int __tmp, __tmp2;                                                \
+  __asm __volatile ("   clrldi  %1,%1,32\n"                                  \
+                   "1: lwarx   %0,0,%2\n"                                    \
+                   "   subf.   %0,%1,%0\n"                                   \
                    "   bne     2f\n"                                         \
-                   "   stwcx.  %3,0,%1\n"                                    \
+                   "   stwcx.  %4,0,%2\n"                                    \
                    "   bne-    1b\n"                                         \
                    "2: " __ARCH_ACQ_INSTR                                    \
-                   : "=&r" (__tmp)                                           \
-                   : "b" (mem), "r" (oldval), "r" (newval)                   \
+                   : "=&r" (__tmp), "=r" (__tmp2)                            \
+                   : "b" (mem), "1" (oldval), "r" (newval)                   \
                    : "cr0", "memory");                                       \
   __tmp != 0;                                                                \
 })
 
 # define __arch_compare_and_exchange_bool_32_rel(mem, newval, oldval) \
 ({                                                                           \
-  unsigned int __tmp;                                                        \
+  unsigned int __tmp, __tmp2;                                                \
   __asm __volatile (__ARCH_REL_INSTR "\n"                                    \
-                   "1: lwarx   %0,0,%1\n"                                    \
-                   "   extsw   %0,%0\n"                                      \
-                   "   subf.   %0,%2,%0\n"                                   \
+                   "   clrldi  %1,%1,32\n"                                   \
+                   "1: lwarx   %0,0,%2\n"                                    \
+                   "   subf.   %0,%1,%0\n"                                   \
                    "   bne     2f\n"                                         \
-                   "   stwcx.  %3,0,%1\n"                                    \
+                   "   stwcx.  %4,0,%2\n"                                    \
                    "   bne-    1b\n"                                         \
                    "2: "                                                     \
-                   : "=&r" (__tmp)                                           \
+                   : "=&r" (__tmp), "=r" (__tmp2)                            \
                    : "b" (mem), "r" (oldval), "r" (newval)                   \
                    : "cr0", "memory");                                       \
   __tmp != 0;                                                                \