Re: [PATCH] RISC-V: Add Zawrs ISA extension support

[Palmer Dabbelt]

On Thu, 27 Oct 2022 11:23:17 PDT (-0700), christoph.muell...@vrull.eu wrote:
On Thu, Oct 27, 2022 at 8:11 PM Christoph Muellner <
christoph.muell...@vrull.eu> wrote:
From: Christoph Muellner <cmuell...@gcc.gnu.org>

This patch adds support for the Zawrs ISA extension.
The patch depends on the corresponding Binutils patch
to be usable (see [1])

The specification can be found here:
https://github.com/riscv/riscv-zawrs/blob/main/zawrs.adoc

Note, that the Zawrs extension is not frozen or ratified yet.
Therefore this patch is an RFC and not intended to get merged.


Sorry, forgot to update this part:
The Zawrs extension is frozen but not ratified.
Let me know if I should send a v2 for this change of the commit msg.

IMO it's fine to just fix it up at commit time.  This LGTM, we just need 
the NEWS entry too.  I also don't see any build/test results.

Thanks!

Binuitls support has been merged recently:

https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=eb668e50036e979fb0a74821df4eee0307b44e66



[1] https://sourceware.org/pipermail/binutils/2022-April/120559.html

gcc/ChangeLog:

        * common/config/riscv/riscv-common.cc: Add zawrs extension.
        * config/riscv/riscv-opts.h (MASK_ZAWRS): New.
        (TARGET_ZAWRS): New.
        * config/riscv/riscv.opt: New.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/zawrs.c: New test.

Signed-off-by: Christoph Muellner <cmuell...@gcc.gnu.org>
---
 gcc/common/config/riscv/riscv-common.cc |  4 ++++
 gcc/config/riscv/riscv-opts.h           |  3 +++
 gcc/config/riscv/riscv.opt              |  3 +++
 gcc/testsuite/gcc.target/riscv/zawrs.c  | 13 +++++++++++++
 4 files changed, 23 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/zawrs.c

diff --git a/gcc/common/config/riscv/riscv-common.cc
b/gcc/common/config/riscv/riscv-common.cc
index d6404a01205..4b7f777c103 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -163,6 +163,8 @@ static const struct riscv_ext_version
riscv_ext_version_table[] =
   {"zifencei", ISA_SPEC_CLASS_20191213, 2, 0},
   {"zifencei", ISA_SPEC_CLASS_20190608, 2, 0},

+  {"zawrs", ISA_SPEC_CLASS_NONE, 1, 0},
+
   {"zba", ISA_SPEC_CLASS_NONE, 1, 0},
   {"zbb", ISA_SPEC_CLASS_NONE, 1, 0},
   {"zbc", ISA_SPEC_CLASS_NONE, 1, 0},
@@ -1180,6 +1182,8 @@ static const riscv_ext_flag_table_t
riscv_ext_flag_table[] =
   {"zicsr",    &gcc_options::x_riscv_zi_subext, MASK_ZICSR},
   {"zifencei", &gcc_options::x_riscv_zi_subext, MASK_ZIFENCEI},

+  {"zawrs", &gcc_options::x_riscv_za_subext, MASK_ZAWRS},
+
   {"zba",    &gcc_options::x_riscv_zb_subext, MASK_ZBA},
   {"zbb",    &gcc_options::x_riscv_zb_subext, MASK_ZBB},
   {"zbc",    &gcc_options::x_riscv_zb_subext, MASK_ZBC},
diff --git a/gcc/config/riscv/riscv-opts.h b/gcc/config/riscv/riscv-opts.h
index 1dfe8c89209..25fd85b09b1 100644
--- a/gcc/config/riscv/riscv-opts.h
+++ b/gcc/config/riscv/riscv-opts.h
@@ -73,6 +73,9 @@ enum stack_protector_guard {
 #define TARGET_ZICSR    ((riscv_zi_subext & MASK_ZICSR) != 0)
 #define TARGET_ZIFENCEI ((riscv_zi_subext & MASK_ZIFENCEI) != 0)

+#define MASK_ZAWRS   (1 << 0)
+#define TARGET_ZAWRS ((riscv_za_subext & MASK_ZAWRS) != 0)
+
 #define MASK_ZBA      (1 << 0)
 #define MASK_ZBB      (1 << 1)
 #define MASK_ZBC      (1 << 2)
diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 426ea95cd14..7c3ca48d1cc 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -203,6 +203,9 @@ long riscv_stack_protector_guard_offset = 0
 TargetVariable
 int riscv_zi_subext

+TargetVariable
+int riscv_za_subext
+
 TargetVariable
 int riscv_zb_subext

diff --git a/gcc/testsuite/gcc.target/riscv/zawrs.c
b/gcc/testsuite/gcc.target/riscv/zawrs.c
new file mode 100644
index 00000000000..0b7e2662343
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/zawrs.c
@@ -0,0 +1,13 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64gc_zawrs" { target { rv64 } } } */
+/* { dg-options "-march=rv32gc_zawrs" { target { rv32 } } } */
+
+#ifndef __riscv_zawrs
+#error Feature macro not defined
+#endif
+
+int
+foo (int a)
+{
+  return a;
+}
--
2.37.3