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[AArch64] Add feature flags and command line for ARMv8.2 FP16 support.


ARMv8.2 adds optional support for 16-bit operations to the FP and
Adv.SIMD instructions. This patch adds a feature macro for this support
with a new command line option "+fp16" to enable/disable it.

Although the command line option is added as an architecture extension,
it only affects instructions available with when +fp or +simd is
enabled. If +fp16 is specified then it will also enable +fp.

There are currently no FP16 instructions implemented in binutils, this
patch is to enable subsequent work on supporting the extension.

Tested aarch64-none-linux-gnu with cross-compiled check-binutils and
check-gas. Checked the HTML documentaion in Firefox.

Ok for trunk?

2015-11-24  Matthew Wahab  <>

	* config/tc-aarch64.c (aarch64_features): Add "fp16".
	* doc/c-aarch64.texi (Architecture Extensions): Add "fp16".

2015-11-24  Matthew Wahab  <>

	* aarch64.h (AARCH64_FEATURE_F16): New.
	(AARCH64_ARCH_V8_2): Add AARCH64_FEATURE_F16 to ARMv8.2

>From 6dfbe0f6039db718cef85c95e710977ee6d397af Mon Sep 17 00:00:00 2001
From: Matthew Wahab <>
Date: Tue, 15 Sep 2015 17:25:04 +0100
Subject: [PATCH] [AArch64] Add feature flags and command line for ARMv8.2 FP16

 gas/config/tc-aarch64.c  | 2 ++
 gas/doc/c-aarch64.texi   | 3 +++
 include/opcode/aarch64.h | 2 ++
 3 files changed, 7 insertions(+)

diff --git a/gas/config/tc-aarch64.c b/gas/config/tc-aarch64.c
index 0fd6443..d306710 100644
--- a/gas/config/tc-aarch64.c
+++ b/gas/config/tc-aarch64.c
@@ -7738,6 +7738,8 @@ static const struct aarch64_option_cpu_value_table aarch64_features[] = {
   {"lor",		AARCH64_FEATURE (AARCH64_FEATURE_LOR, 0)},
 					 | AARCH64_FEATURE_RDMA, 0)},
+					 | AARCH64_FEATURE_FP, 0)},
diff --git a/gas/doc/c-aarch64.texi b/gas/doc/c-aarch64.texi
index bfd41c3..2717af2 100644
--- a/gas/doc/c-aarch64.texi
+++ b/gas/doc/c-aarch64.texi
@@ -142,6 +142,9 @@ automatically cause those extensions to be disabled.
  @tab Enable Limited Ordering Regions extensions.
 @item @code{rdma} @tab ARMv8-A @tab ARMv8-A or later
  @tab Enable ARMv8.1 Advanced SIMD extensions.  This implies @code{simd}.
+@item @code{fp16} @tab ARMv8.2-A @tab ARMv8.2-A or later
+ @tab Enable ARMv8.2 16-bit floating-point support.  This implies
+ @code{fp}.
 @end multitable
 @node AArch64 Syntax
diff --git a/include/opcode/aarch64.h b/include/opcode/aarch64.h
index 996ed85..f1658bc 100644
--- a/include/opcode/aarch64.h
+++ b/include/opcode/aarch64.h
@@ -48,6 +48,7 @@ typedef uint32_t aarch64_insn;
 #define AARCH64_FEATURE_LOR	0x00400000	/* LOR instructions.  */
 #define AARCH64_FEATURE_RDMA	0x00800000	/* v8.1 SIMD instructions.  */
 #define AARCH64_FEATURE_V8_1	0x01000000	/* v8.1 features.  */
+#define AARCH64_FEATURE_F16	0x01000000	/* v8.2 FP16 instructions.  */
 /* Architectures are the sum of the base and extensions.  */
@@ -63,6 +64,7 @@ typedef uint32_t aarch64_insn;
 						 AARCH64_FEATURE_V8_2	\
+						 | AARCH64_FEATURE_F16	\
 						 | AARCH64_FEATURE_FP	\
 						 | AARCH64_FEATURE_SIMD \
 						 | AARCH64_FEATURE_LSE	\

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