RISC-V: Add T-Head SYNC vendor extension

T-Head has a range of vendor-specific instructions.
Therefore it makes sense to group them into smaller chunks
in form of vendor extensions.

This patch adds the XTheadSync extension, a collection of
T-Head-specific multi-processor synchronization instructions.
The 'th' prefix and the "XTheadSync" extension are documented in a PR
for the RISC-V toolchain conventions ([1]).

[1] https://github.com/riscv-non-isa/riscv-toolchain-conventions/pull/19

Co-developed-by: Lifang Xia <lifang_xia@linux.alibaba.com>
Signed-off-by: Christoph Müllner <christoph.muellner@vrull.eu>

6 files changed, 40 insertions, 0 deletions

diff --git a/gas/doc/c-riscv.texi b/gas/doc/c-riscv.texi
index 10e9429..c55dd0b 100644
--- a/gas/doc/c-riscv.texi
+++ b/gas/doc/c-riscv.texi
@@ -709,4 +709,9 @@ The XTheadCmo extension provides instructions for cache management.
 
 It is documented in @url{https://github.com/T-head-Semi/thead-extension-spec/releases/download/2.0.0/xthead-2022-09-05-2.0.0.pdf}.
 
+@item XTheadSync
+The XTheadSync extension provides instructions for multi-processor synchronization.
+
+It is documented in @url{https://github.com/T-head-Semi/thead-extension-spec/releases/download/2.0.0/xthead-2022-09-05-2.0.0.pdf}.
+
 @end table
diff --git a/gas/testsuite/gas/riscv/x-thead-sync-fail.d b/gas/testsuite/gas/riscv/x-thead-sync-fail.d
new file mode 100644
index 0000000..1d3fdbd
--- /dev/null
+++ b/gas/testsuite/gas/riscv/x-thead-sync-fail.d
@@ -0,0 +1,3 @@
+#as: -march=rv64i_xtheadsync
+#source: x-thead-sync-fail.s
+#error_output: x-thead-sync-fail.l
diff --git a/gas/testsuite/gas/riscv/x-thead-sync-fail.l b/gas/testsuite/gas/riscv/x-thead-sync-fail.l
new file mode 100644
index 0000000..5242000
--- /dev/null
+++ b/gas/testsuite/gas/riscv/x-thead-sync-fail.l
@@ -0,0 +1,6 @@
+.*: Assembler messages:
+.*: Error: illegal operands `th.sfence.vmas'
+.*: Error: illegal operands `th.sync a0'
+.*: Error: illegal operands `th.sync.i a0'
+.*: Error: illegal operands `th.sync.is a0'
+.*: Error: illegal operands `th.sync.s a0'
diff --git a/gas/testsuite/gas/riscv/x-thead-sync-fail.s b/gas/testsuite/gas/riscv/x-thead-sync-fail.s
new file mode 100644
index 0000000..722a6da
--- /dev/null
+++ b/gas/testsuite/gas/riscv/x-thead-sync-fail.s
@@ -0,0 +1,6 @@
+target:
+	th.sfence.vmas
+	th.sync		a0
+	th.sync.i	a0
+	th.sync.is	a0
+	th.sync.s	a0
diff --git a/gas/testsuite/gas/riscv/x-thead-sync.d b/gas/testsuite/gas/riscv/x-thead-sync.d
new file mode 100644
index 0000000..3c5e9ea
--- /dev/null
+++ b/gas/testsuite/gas/riscv/x-thead-sync.d
@@ -0,0 +1,14 @@
+#as: -march=rv64i_xtheadsync
+#source: x-thead-sync.s
+#objdump: -dr
+
+.*:[ 	]+file format .*
+
+Disassembly of section .text:
+
+0+000 <target>:
+[ 	]+[0-9a-f]+:[ 	]+04b5000b[ 	]+th.sfence.vmas[ 	]+a0,a1
+[ 	]+[0-9a-f]+:[ 	]+0180000b[ 	]+th.sync
+[ 	]+[0-9a-f]+:[ 	]+01a0000b[ 	]+th.sync.i
+[ 	]+[0-9a-f]+:[ 	]+01b0000b[ 	]+th.sync.is
+[ 	]+[0-9a-f]+:[ 	]+0190000b[ 	]+th.sync.s
diff --git a/gas/testsuite/gas/riscv/x-thead-sync.s b/gas/testsuite/gas/riscv/x-thead-sync.s
new file mode 100644
index 0000000..85b4856
--- /dev/null
+++ b/gas/testsuite/gas/riscv/x-thead-sync.s
@@ -0,0 +1,6 @@
+target:
+	th.sfence.vmas	a0, a1
+	th.sync
+	th.sync.i
+	th.sync.is
+	th.sync.s