[Patch AArch64] Add __ARM_FEATURE_ATOMICS

This keeps coming up repeatedly and the ACLE has finally added
__ARM_FEATURE_ATOMICS for the LSE feature in GCC. This is now part of
the latest ACLE release
(https://developer.arm.com/docs/101028/latest/5-feature-test-macros)

I know it's late for GCC-9 but this is a simple macro which need not
wait  for another year.

Ok for trunk and to backport to all release branches ?

Tested with a simple build and a smoke test.

PR target/86538
* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins): Define
__ARM_FEATURE_ATOMICS

From-SVN: r270686

2 files changed, 7 insertions, 0 deletions

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index cb69c4d..471a96f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2019-04-30  Ramana Radhakrishnan  <ramana.radhakrishnan@arm.com>
+
+	PR target/86538
+	* config/aarch64/aarch64-c.c (aarch64_update_cpp_builtins):
+	Define __ARM_FEATURE_ATOMICS
+
 2019-04-30  Martin Liska  <mliska@suse.cz>
 
 	* gimple-fold.c (gimple_fold_builtin_memory_op): Change endp
diff --git a/gcc/config/aarch64/aarch64-c.c b/gcc/config/aarch64/aarch64-c.c
index fcb1e80..6d5acb0 100644
--- a/gcc/config/aarch64/aarch64-c.c
+++ b/gcc/config/aarch64/aarch64-c.c
@@ -147,6 +147,7 @@ aarch64_update_cpp_builtins (cpp_reader *pfile)
       builtin_define_with_int_value ("__ARM_FEATURE_SVE_BITS", bits);
     }
 
+  aarch64_def_or_undef (TARGET_LSE, "__ARM_FEATURE_ATOMICS", pfile);
   aarch64_def_or_undef (TARGET_AES, "__ARM_FEATURE_AES", pfile);
   aarch64_def_or_undef (TARGET_SHA2, "__ARM_FEATURE_SHA2", pfile);
   aarch64_def_or_undef (TARGET_SHA3, "__ARM_FEATURE_SHA3", pfile);