[PATCH 2/3] RISC-V: Support zicsr and zifencei extension for -march.

[Kito Cheng]

 - CSR related instructions and fence instructions has to be splitted from
   baseline ISA, zicsr and zifencei are corresponding sub-extension.

gcc/ChangeLog:

        * common/config/riscv/riscv-common.c (riscv_implied_info):
        d and f implied zicsr.
        (riscv_ext_flag_table): Handle zicsr and zifencei.
        * config/riscv/riscv-opts.h (MASK_ZICSR): New.
        (MASK_ZIFENCEI): Ditto.
        (TARGET_ZICSR): Ditto.
        (TARGET_ZIFENCEI): Ditto.
        * config/riscv/riscv.c (riscv_memmodel_needs_release_fence):
        Check fence is available by TARGET_ZIFENCEI.
        * config/riscv/riscv.opt (riscv_zi_subext): New.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/arch-8.c: New.
        * gcc.target/riscv/attribute-14.c: Ditto.
---
 gcc/common/config/riscv/riscv-common.c        | 6 ++++++
 gcc/config/riscv/riscv-opts.h                 | 6 ++++++
 gcc/config/riscv/riscv.c                      | 3 +++
 gcc/config/riscv/riscv.md                     | 7 ++++---
 gcc/config/riscv/riscv.opt                    | 3 +++
 gcc/testsuite/gcc.target/riscv/arch-8.c       | 5 +++++
 gcc/testsuite/gcc.target/riscv/attribute-14.c | 6 ++++++
 7 files changed, 33 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.target/riscv/arch-8.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/attribute-14.c

diff --git a/gcc/common/config/riscv/riscv-common.c 
b/gcc/common/config/riscv/riscv-common.c
index f5f7be3cfff..ca88ca1dacd 100644
--- a/gcc/common/config/riscv/riscv-common.c
+++ b/gcc/common/config/riscv/riscv-common.c
@@ -57,6 +57,8 @@ struct riscv_implied_info_t
 static const riscv_implied_info_t riscv_implied_info[] =
 {
   {"d", "f"},
+  {"f", "zicsr"},
+  {"d", "zicsr"},
   {NULL, NULL}
 };
 
@@ -812,6 +814,10 @@ static const riscv_ext_flag_table_t riscv_ext_flag_table[] 
=
   {"f", &gcc_options::x_target_flags, MASK_HARD_FLOAT},
   {"d", &gcc_options::x_target_flags, MASK_DOUBLE_FLOAT},
   {"c", &gcc_options::x_target_flags, MASK_RVC},
+
+  {"zicsr",    &gcc_options::x_riscv_zi_subext, MASK_ZICSR},
+  {"zifencei", &gcc_options::x_riscv_zi_subext, MASK_ZIFENCEI},
+
   {NULL, NULL, 0}
 };
 
diff --git a/gcc/config/riscv/riscv-opts.h b/gcc/config/riscv/riscv-opts.h
index 2a3f9d9eef5..de8ac0e038d 100644
--- a/gcc/config/riscv/riscv-opts.h
+++ b/gcc/config/riscv/riscv-opts.h
@@ -57,4 +57,10 @@ enum stack_protector_guard {
   SSP_GLOBAL                   /* global canary */
 };
 
+#define MASK_ZICSR    (1 << 0)
+#define MASK_ZIFENCEI (1 << 1)
+
+#define TARGET_ZICSR    ((riscv_zi_subext & MASK_ZICSR) != 0)
+#define TARGET_ZIFENCEI ((riscv_zi_subext & MASK_ZIFENCEI) != 0)
+
 #endif /* ! GCC_RISCV_OPTS_H */
diff --git a/gcc/config/riscv/riscv.c b/gcc/config/riscv/riscv.c
index 738556539f6..2aaa8e96451 100644
--- a/gcc/config/riscv/riscv.c
+++ b/gcc/config/riscv/riscv.c
@@ -3337,6 +3337,9 @@ riscv_memmodel_needs_amo_acquire (enum memmodel model)
 static bool
 riscv_memmodel_needs_release_fence (enum memmodel model)
 {
+  if (!TARGET_ZIFENCEI)
+    return false;
+
   switch (model)
     {
       case MEMMODEL_ACQ_REL:
diff --git a/gcc/config/riscv/riscv.md b/gcc/config/riscv/riscv.md
index f15bad3b29e..756b35fb8c0 100644
--- a/gcc/config/riscv/riscv.md
+++ b/gcc/config/riscv/riscv.md
@@ -1543,19 +1543,20 @@
                     LCT_NORMAL, VOIDmode, operands[0], Pmode,
                     operands[1], Pmode, const0_rtx, Pmode);
 #else
-  emit_insn (gen_fence_i ());
+  if (TARGET_ZIFENCEI)
+    emit_insn (gen_fence_i ());
 #endif
   DONE;
 })
 
 (define_insn "fence"
   [(unspec_volatile [(const_int 0)] UNSPECV_FENCE)]
-  ""
+  "TARGET_ZIFENCEI"
   "%|fence%-")
 
 (define_insn "fence_i"
   [(unspec_volatile [(const_int 0)] UNSPECV_FENCE_I)]
-  ""
+  "TARGET_ZIFENCEI"
   "fence.i")
 
 ;;
diff --git a/gcc/config/riscv/riscv.opt b/gcc/config/riscv/riscv.opt
index 808b4a04405..ca2fc7c8021 100644
--- a/gcc/config/riscv/riscv.opt
+++ b/gcc/config/riscv/riscv.opt
@@ -183,3 +183,6 @@ Use the given offset for addressing the stack-protector 
guard.
 
 TargetVariable
 long riscv_stack_protector_guard_offset = 0
+
+TargetVariable
+int riscv_zi_subext
diff --git a/gcc/testsuite/gcc.target/riscv/arch-8.c 
b/gcc/testsuite/gcc.target/riscv/arch-8.c
new file mode 100644
index 00000000000..d7760fc576f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/arch-8.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-O -march=rv32id_zicsr_zifence -mabi=ilp32" } */
+int foo()
+{
+}
diff --git a/gcc/testsuite/gcc.target/riscv/attribute-14.c 
b/gcc/testsuite/gcc.target/riscv/attribute-14.c
new file mode 100644
index 00000000000..48456277152
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/attribute-14.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O -mriscv-attribute -march=rv32if -mabi=ilp32" } */
+int foo()
+{
+}
+/* { dg-final { scan-assembler ".attribute arch, \"rv32i2p0_f2p0_zicsr2p0\"" } 
} */
-- 
2.29.2