[PATCH 2/2] RISC-V: Handle implied extension for -march parser.

[Kito Cheng]

  - Implied rule are introduced into latest RISC-V isa spec.

  - Only implemented D implied F-extension. Zicsr and Zifence are not
    implement yet, so the rule not included in this patch.

gcc/ChangeLog

        * common/config/riscv/riscv-common.c (riscv_implied_info_t): New.
        (riscv_implied_info): New.
        (riscv_subset_list): Add handle_implied_ext.
        (riscv_subset_list::handle_implied_ext): New.
        (riscv_subset_list::parse_std_ext): Call handle_implied_ext.

gcc/testsuite/ChangeLog

        * gcc.target/riscv/arch-6.c: New.
        * gcc.target/riscv/attribute-11.c: New.
---
 gcc/common/config/riscv/riscv-common.c        | 39 +++++++++++++++++++
 gcc/testsuite/gcc.target/riscv/arch-6.c       |  5 +++
 gcc/testsuite/gcc.target/riscv/attribute-11.c |  6 +++
 3 files changed, 50 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/arch-6.c
 create mode 100644 gcc/testsuite/gcc.target/riscv/attribute-11.c

diff --git a/gcc/common/config/riscv/riscv-common.c 
b/gcc/common/config/riscv/riscv-common.c
index a2e8d7003cc..24100cfae74 100644
--- a/gcc/common/config/riscv/riscv-common.c
+++ b/gcc/common/config/riscv/riscv-common.c
@@ -44,6 +44,20 @@ struct riscv_subset_t
   struct riscv_subset_t *next;
 };
 
+/* Type for implied ISA info.  */
+struct riscv_implied_info_t
+{
+  const char *ext;
+  const char *implied_ext;
+};
+
+/* Implied ISA info, must end with NULL sentinel.  */
+riscv_implied_info_t riscv_implied_info[] =
+{
+  {"d", "f"},
+  {NULL, NULL}
+};
+
 /* Subset list.  */
 class riscv_subset_list
 {
@@ -73,6 +87,8 @@ private:
   const char *parse_multiletter_ext (const char *, const char *,
                                     const char *);
 
+  void handle_implied_ext (const char *, int, int);
+
 public:
   ~riscv_subset_list ();
 
@@ -394,11 +410,34 @@ riscv_subset_list::parse_std_ext (const char *p)
 
       subset[0] = std_ext;
 
+      handle_implied_ext (subset, major_version, minor_version);
+
       add (subset, major_version, minor_version);
     }
   return p;
 }
 
+
+/* Check any implied extensions for EXT with version
+   MAJOR_VERSION.MINOR_VERSION.  */
+void
+riscv_subset_list::handle_implied_ext (const char *ext,
+                                      int major_version,
+                                      int minor_version)
+{
+  riscv_implied_info_t *implied_info;
+  for (implied_info = &riscv_implied_info[0];
+       implied_info->ext;
+       ++implied_info)
+    {
+      if (strcmp (ext, implied_info->ext) != 0)
+       continue;
+
+      /* TODO: Implied extension might use differet version.  */
+      add (implied_info->implied_ext, major_version, minor_version);
+    }
+}
+
 /* Parsing function for multi-letter extensions.
 
    Return Value:
diff --git a/gcc/testsuite/gcc.target/riscv/arch-6.c 
b/gcc/testsuite/gcc.target/riscv/arch-6.c
new file mode 100644
index 00000000000..b36dccbf46b
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/arch-6.c
@@ -0,0 +1,5 @@
+/* { dg-do compile } */
+/* { dg-options "-O -march=rv32id -mabi=ilp32" } */
+int foo()
+{
+}
diff --git a/gcc/testsuite/gcc.target/riscv/attribute-11.c 
b/gcc/testsuite/gcc.target/riscv/attribute-11.c
new file mode 100644
index 00000000000..a8649508b2f
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/attribute-11.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-O -mriscv-attribute -march=rv32id -mabi=ilp32" } */
+int foo()
+{
+}
+/* { dg-final { scan-assembler ".attribute arch, \"rv32i2p0_f2p0_d2p0\"" } } */
-- 
2.25.2