[PATCH v2 2/3] RISC-V: Add stub support for existing extensions (vendor)

[Tsukasa OI <research_trasio@irq.a4lg.com>]

From: Tsukasa OI <research_trasio@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.

This commit adds stub supported vendor extensions to
riscv_ext_version_table (no riscv_implied_info entries to add; all
information is copied from Binutils' bfd/elfxx-riscv.c).

gcc/ChangeLog:

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

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/predef-30.c: New test for a stub
	vendor extension 'XVentanaCondOps'.
---
 gcc/common/config/riscv/riscv-common.cc    |  2 ++
 gcc/testsuite/gcc.target/riscv/predef-30.c | 27 ++++++++++++++++++++++
 2 files changed, 29 insertions(+)
 create mode 100644 gcc/testsuite/gcc.target/riscv/predef-30.c

diff --git a/gcc/common/config/riscv/riscv-common.cc b/gcc/common/config/riscv/riscv-common.cc
index 91b0316acfea..0c351105e015 100644
--- a/gcc/common/config/riscv/riscv-common.cc
+++ b/gcc/common/config/riscv/riscv-common.cc
@@ -298,6 +298,8 @@ static const struct riscv_ext_version riscv_ext_version_table[] =
   {"xtheadmempair", ISA_SPEC_CLASS_NONE, 1, 0},
   {"xtheadsync", ISA_SPEC_CLASS_NONE, 1, 0},
 
+  {"xventanacondops", ISA_SPEC_CLASS_NONE, 1, 0},
+
   /* Terminate the list.  */
   {NULL, ISA_SPEC_CLASS_NONE, 0, 0}
 };
diff --git a/gcc/testsuite/gcc.target/riscv/predef-30.c b/gcc/testsuite/gcc.target/riscv/predef-30.c
new file mode 100644
index 000000000000..9784b9ce5033
--- /dev/null
+++ b/gcc/testsuite/gcc.target/riscv/predef-30.c
@@ -0,0 +1,27 @@
+/* { dg-do compile } */
+/* { dg-options "-march=rv64i_xventanacondops -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_xventanacondops)
+#error "__riscv_xventanacondops"
+#endif
+
+  return 0;
+}
-- 
2.41.0