[PATCH v2 1/3] RISC-V: Add stub support for existing extensions (privileged)

[Tsukasa OI via Gcc-patches]

From: Tsukasa OI <research_tra...@irq.a4lg.com>

After commit c283c4774d1c ("RISC-V: Throw compilation error for unknown
extensions") changed how do we handle unknown extensions, we have no
guarantee that we can share the same architectural string with Binutils
(specifically, the assembler).

To avoid compilation errors on shared Assembler-C/C++ projects, GCC should
support almost all extensions that Binutils support, even if the GCC does
not touch a thing.

As a start, this commit adds stub supported *privileged* extensions to
riscv_ext_version_table and its implications to riscv_implied_info
(all information is copied from Binutils' bfd/elfxx-riscv.c).

gcc/ChangeLog:

        * common/config/riscv/riscv-common.cc
        (riscv_implied_info): Add implications from privileged extensions.
        (riscv_ext_version_table): Add stub support for all privileged
        extensions supported by Binutils.

gcc/testsuite/ChangeLog:

        * gcc.target/riscv/predef-29.c: New test for a stub privileged
        extension 'Smstateen' with some implications.
---
 gcc/common/config/riscv/riscv-common.cc    | 18 +++++++++++
 gcc/testsuite/gcc.target/riscv/predef-29.c | 35 ++++++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-29.c

diff --git a/gcc/common/config/riscv/riscv-common.cc 
b/gcc/common/config/riscv/riscv-common.cc
index 21f83f26371f..91b0316acfea 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -130,6 +130,14 @@ static const riscv_implied_info_t riscv_implied_info[] =
   {"zhinx", "zhinxmin"},
   {"zhinxmin", "zfinx"},
 
+  {"smaia", "ssaia"},
+  {"smstateen", "ssstateen"},
+  {"smepmp", "zicsr"},
+  {"ssaia", "zicsr"},
+  {"sscofpmf", "zicsr"},
+  {"ssstateen", "zicsr"},
+  {"sstc", "zicsr"},
+
   {NULL, NULL}
 };
 
@@ -264,8 +272,18 @@ static const struct riscv_ext_version 
riscv_ext_version_table[] =
 
   {"zmmul", ISA_SPEC_CLASS_NONE, 1, 0},
 
+  {"smaia",     ISA_SPEC_CLASS_NONE, 1, 0},
+  {"smepmp",    ISA_SPEC_CLASS_NONE, 1, 0},
+  {"smstateen", ISA_SPEC_CLASS_NONE, 1, 0},
+
+  {"ssaia",     ISA_SPEC_CLASS_NONE, 1, 0},
+  {"sscofpmf",  ISA_SPEC_CLASS_NONE, 1, 0},
+  {"ssstateen", ISA_SPEC_CLASS_NONE, 1, 0},
+  {"sstc",      ISA_SPEC_CLASS_NONE, 1, 0},
+
   {"svinval", ISA_SPEC_CLASS_NONE, 1, 0},
   {"svnapot", ISA_SPEC_CLASS_NONE, 1, 0},
+  {"svpbmt",  ISA_SPEC_CLASS_NONE, 1, 0},
 
   {"xtheadba", ISA_SPEC_CLASS_NONE, 1, 0},
   {"xtheadbb", ISA_SPEC_CLASS_NONE, 1, 0},
diff --git a/gcc/testsuite/gcc.target/riscv/predef-29.c 
b/gcc/testsuite/gcc.target/riscv/predef-29.c
new file mode 100644
index 000000000000..61c6429be558
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/predef-29.c
@@ -0,0 +1,35 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64i_smstateen -mabi=lp64 -mcmodel=medlow 
-misa-spec=20191213" } */
+
+int main () {
+
+#ifndef __riscv_arch_test
+#error "__riscv_arch_test"
+#endif
+
+#if __riscv_xlen != 64
+#error "__riscv_xlen"
+#endif
+
+#if !defined(__riscv_i) || (__riscv_i != (2 * 1000 * 1000 + 1 * 1000))
+#error "__riscv_i"
+#endif
+
+#if defined(__riscv_e)
+#error "__riscv_e"
+#endif
+
+#if !defined(__riscv_zicsr)
+#error "__riscv_zicsr"
+#endif
+
+#if !defined(__riscv_smstateen)
+#error "__riscv_smstateen"
+#endif
+
+#if !defined(__riscv_ssstateen)
+#error "__riscv_ssstateen"
+#endif
+
+  return 0;
+}
-- 
2.41.0