aarch64: Add command-line support for Armv8.7-a

This patch adds support for -march=armv8.7-a in GCC.
It adds the +ls64 extension that's included in this architecture revision.
Currently this is just the command-line option and +ls64 allows the relevant instructions
to be used in inline assembly. The ACLE defines some intrinsics for them but those can be
added separately later (together with the appropriate __ARM_FEATURE_* predefine).

2021-09-28  Kyrylo Tkachov  <kyrylo.tkachov@arm.com>

	* config/aarch64/aarch64.h (AARCH64_FL_LS64): Define
	(AARCH64_FL_V8_7): Likewise.
	(AARCH64_FL_FOR_ARCH8_7): Likewise.
	* config/aarch64/aarch64-arches.def (armv8.7-a): Define.
	* config/aarch64/aarch64-option-extensions.def (ls64): Define.
	* doc/invoke.texi: Document the above.

4 files changed, 17 insertions, 0 deletions

diff --git a/gcc/config/aarch64/aarch64-arches.def b/gcc/config/aarch64/aarch64-arches.def
index b749727..91410e3 100644
--- a/gcc/config/aarch64/aarch64-arches.def
+++ b/gcc/config/aarch64/aarch64-arches.def
@@ -37,6 +37,7 @@ AARCH64_ARCH("armv8.3-a",     generic,	     8_3A,	8,  AARCH64_FL_FOR_ARCH8_3)
 AARCH64_ARCH("armv8.4-a",     generic,	     8_4A,	8,  AARCH64_FL_FOR_ARCH8_4)
 AARCH64_ARCH("armv8.5-a",     generic,	     8_5A,	8,  AARCH64_FL_FOR_ARCH8_5)
 AARCH64_ARCH("armv8.6-a",     generic,	     8_6A,	8,  AARCH64_FL_FOR_ARCH8_6)
+AARCH64_ARCH("armv8.7-a",     generic,       8_7A,      8,  AARCH64_FL_FOR_ARCH8_7)
 AARCH64_ARCH("armv8-r",       generic,	     8R  ,	8,  AARCH64_FL_FOR_ARCH8_R)
 
 #undef AARCH64_ARCH
diff --git a/gcc/config/aarch64/aarch64-option-extensions.def b/gcc/config/aarch64/aarch64-option-extensions.def
index 579328c..b61f1df 100644
--- a/gcc/config/aarch64/aarch64-option-extensions.def
+++ b/gcc/config/aarch64/aarch64-option-extensions.def
@@ -232,4 +232,7 @@ AARCH64_OPT_EXTENSION("flagm", AARCH64_FL_FLAGM, 0, 0, false, "flagm")
 /* Enabling/Disabling "pauth" only changes "pauth".  */
 AARCH64_OPT_EXTENSION("pauth", AARCH64_FL_PAUTH, 0, 0, false, "paca pacg")
 
+/* Enabling/Disabling "ls64" only changes "ls64".  */
+AARCH64_OPT_EXTENSION("ls64", AARCH64_FL_LS64, 0, 0, false, "")
+
 #undef AARCH64_OPT_EXTENSION
diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h
index a5ba6c2..0c172c7 100644
--- a/gcc/config/aarch64/aarch64.h
+++ b/gcc/config/aarch64/aarch64.h
@@ -231,6 +231,12 @@ extern unsigned aarch64_architecture_version;
 /* Pointer Authentication (PAUTH) extension.  */
 #define AARCH64_FL_PAUTH      (1ULL << 40)
 
+/* 64-byte atomic load/store extensions.  */
+#define AARCH64_FL_LS64      (1ULL << 41)
+
+/* Armv8.7-a architecture extensions.  */
+#define AARCH64_FL_V8_7       (1ULL << 42)
+
 /* Has FP and SIMD.  */
 #define AARCH64_FL_FPSIMD     (AARCH64_FL_FP | AARCH64_FL_SIMD)
 
@@ -255,6 +261,9 @@ extern unsigned aarch64_architecture_version;
 #define AARCH64_FL_FOR_ARCH8_6			\
   (AARCH64_FL_FOR_ARCH8_5 | AARCH64_FL_V8_6 | AARCH64_FL_FPSIMD \
    | AARCH64_FL_I8MM | AARCH64_FL_BF16)
+#define AARCH64_FL_FOR_ARCH8_7			\
+  (AARCH64_FL_FOR_ARCH8_6 | AARCH64_FL_V8_7 | AARCH64_FL_LS64)
+
 #define AARCH64_FL_FOR_ARCH8_R     \
   (AARCH64_FL_FOR_ARCH8_4 | AARCH64_FL_V8_R)
 
diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 6d9a107..5b01616 100644
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -18570,6 +18570,7 @@ and the features that they enable by default:
 @item @samp{armv8.4-a} @tab Armv8.4-A @tab @samp{armv8.3-a}, @samp{+flagm}, @samp{+fp16fml}, @samp{+dotprod}
 @item @samp{armv8.5-a} @tab Armv8.5-A @tab @samp{armv8.4-a}, @samp{+sb}, @samp{+ssbs}, @samp{+predres}
 @item @samp{armv8.6-a} @tab Armv8.6-A @tab @samp{armv8.5-a}, @samp{+bf16}, @samp{+i8mm}
+@item @samp{armv8.7-a} @tab Armv8.7-a @tab @samp{armv8.6-a}, @samp{+ls64}
 @item @samp{armv8-r} @tab Armv8-R @tab @samp{armv8-r}
 @end multitable
 
@@ -18856,6 +18857,9 @@ Enable brain half-precision floating-point instructions.  This also enables
 Advanced SIMD and floating-point instructions.  This option is enabled by
 default for @option{-march=armv8.6-a}.  Use of this option with architectures
 prior to Armv8.2-A is not supported.
+@item ls64
+Enable the 64-byte atomic load and store instructions for accelerators.
+This option is enabled by default for @option{-march=armv8.7-a}.
 @item flagm
 Enable the Flag Manipulation instructions Extension.
 @item pauth