[gcc/devel/omp/gcc-11] [PATCH] GCN: Implement __atomic_compare_exchange_{1, 2} in libgcc [PR102215]

[Andrew Jenner <andrewjenner@gcc.gnu.org>]

https://gcc.gnu.org/g:dfe61b1ec5f5c7953bebb11b0dfb7b32e2c39b02

commit dfe61b1ec5f5c7953bebb11b0dfb7b32e2c39b02
Author: Andrew Jenner <andrew@codesourcery.com>
Date:   Mon May 30 10:12:15 2022 +0000

    [PATCH] GCN: Implement __atomic_compare_exchange_{1,2} in libgcc [PR102215]
    
    libgcc/ChangeLog:
    
            PR target/102215
            * config/gcn/atomic.c (__sync_val_compare_and_swap_##SIZE): Move
            a line up to non-arg-dependent value first.
            (__ATOMIC_COMPARE_EXCHANGE): Define + call to generate
            __atomic_compare_exchange_{1,2}.

Diff:
---
 libgcc/ChangeLog.omp       |  7 +++++++
 libgcc/config/gcn/atomic.c | 29 ++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/libgcc/ChangeLog.omp b/libgcc/ChangeLog.omp
new file mode 100644
index 00000000000..4d5600e71a1
--- /dev/null
+++ b/libgcc/ChangeLog.omp
@@ -0,0 +1,7 @@
+2022-03-09  Tobias Burnus  <tobias@codesourcery.com>
+
+	PR target/102215
+	* config/gcn/atomic.c (__sync_val_compare_and_swap_##SIZE): Move
+	a line up to non-arg-dependent value first.
+	(__ATOMIC_COMPARE_EXCHANGE): Define + call to generate
+	__atomic_compare_exchange_{1,2}.
diff --git a/libgcc/config/gcn/atomic.c b/libgcc/config/gcn/atomic.c
index 1f6ee9e0dfd..c0ea6612cdc 100644
--- a/libgcc/config/gcn/atomic.c
+++ b/libgcc/config/gcn/atomic.c
@@ -28,9 +28,9 @@
 TYPE									     \
 __sync_val_compare_and_swap_##SIZE (TYPE *ptr, TYPE oldval, TYPE newval)     \
 {									     \
+  unsigned int valmask = (1 << (SIZE * 8)) - 1;				     \
   unsigned int *wordptr = (unsigned int *)((__UINTPTR_TYPE__ ) ptr & ~3UL);  \
   int shift = ((__UINTPTR_TYPE__ ) ptr & 3UL) * 8;			     \
-  unsigned int valmask = (1 << (SIZE * 8)) - 1;				     \
   unsigned int wordmask = ~(valmask << shift);				     \
   unsigned int oldword = *wordptr;					     \
   for (;;)								     \
@@ -57,3 +57,30 @@ __sync_bool_compare_and_swap_##SIZE (TYPE *ptr, TYPE oldval, TYPE newval)    \
 __SYNC_SUBWORD_COMPARE_AND_SWAP (unsigned char, 1)
 __SYNC_SUBWORD_COMPARE_AND_SWAP (unsigned short, 2)
 
+
+#define __ATOMIC_COMPARE_EXCHANGE(TYPE,SIZE)				      \
+bool									      \
+__atomic_compare_exchange_##SIZE (TYPE *ptr, TYPE *expected,		      \
+				  TYPE desired, bool weak,		      \
+				  int success_memorder, int failure_memorder) \
+{									      \
+  unsigned int valmask = (1 << (SIZE * 8)) - 1;				      \
+									      \
+  unsigned int *wordptr = (unsigned int *)((__UINTPTR_TYPE__ ) ptr & ~3UL);   \
+  int ptrshift = ((__UINTPTR_TYPE__ ) ptr & 3UL) * 8;			      \
+  unsigned int wordmask = ~(valmask << ptrshift);			      \
+									      \
+  unsigned int ptrword = *wordptr;					      \
+  unsigned int exptword = ptrword & wordmask;				      \
+  unsigned int newword = ptrword & wordmask;				      \
+  exptword |= ((unsigned int) *expected) << ptrshift;			      \
+  newword |= ((unsigned int) desired) << ptrshift;			      \
+  if (__atomic_compare_exchange_4 (wordptr, &exptword, newword, weak,	      \
+				   success_memorder, failure_memorder))	      \
+    return true;							      \
+  *expected = (TYPE) ((exptword >> ptrshift) & valmask);		      \
+  return false;								      \
+}
+
+__ATOMIC_COMPARE_EXCHANGE (unsigned char, 1)
+__ATOMIC_COMPARE_EXCHANGE (unsigned short, 2)