RISC-V: Implement new style of architecture extension test macros.

- This patch introduce new set of architecture extension test macros
  which is accept on riscv-c-api-doc recently.
  - https://github.com/riscv/riscv-c-api-doc/blob/master/riscv-c-api.md#architecture-extension-test-macro

- We will also mark deprecated for legacy architecture extension test macros
  in GCC 11, but still support that for 1 or 2 release cycles.

gcc/ChangeLog:

	* common/config/riscv/riscv-common.c (riscv_current_subset_list): New.
	* config/riscv/riscv-c.c (riscv-subset.h): New.
	(INCLUDE_STRING): Define.
	(riscv_cpu_cpp_builtins): Add new style architecture extension
	test macros.
	* config/riscv/riscv-subset.h (riscv_subset_list::begin): New.
	(riscv_subset_list::end): New.
	(riscv_current_subset_list): New.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/predef-10.c: New.
	* gcc.target/riscv/predef-11.c: New.
	* gcc.target/riscv/predef-12.c: New.
	* gcc.target/riscv/predef-13.c: New.

gcc/common/config/riscv/riscv-common.c

@@ -112,6 +112,11 @@ static const char *riscv_supported_std_ext (void);
 
 static riscv_subset_list *current_subset_list = NULL;
 
+const riscv_subset_list *riscv_current_subset_list ()
+{
+  return current_subset_list;
+}
+
 riscv_subset_t::riscv_subset_t ()
   : name (), major_version (0), minor_version (0), next (NULL),
     explicit_version_p (false), implied_p (false)

gcc/config/riscv/riscv-c.c

@@ -20,12 +20,14 @@ along with GCC; see the file COPYING3.  If not see
 
 #define IN_TARGET_CODE 1
 
+#define INCLUDE_STRING
 #include "config.h"
 #include "system.h"
 #include "coretypes.h"
 #include "tm.h"
 #include "c-family/c-common.h"
 #include "cpplib.h"
+#include "riscv-subset.h"
 
 #define builtin_define(TXT) cpp_define (pfile, TXT)
 
@@ -101,4 +103,34 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
       break;
 
     }
+
+  /* Define architecture extension test macros.  */
+  builtin_define_with_int_value ("__riscv_arch_test", 1);
+
+  const riscv_subset_list *subset_list = riscv_current_subset_list ();
+  size_t max_ext_len = 0;
+
+  /* Figure out the max length of extension name for reserving buffer.   */
+  for (const riscv_subset_t *subset = subset_list->begin ();
+       subset != subset_list->end ();
+       subset = subset->next)
+    max_ext_len = MAX (max_ext_len, subset->name.length ());
+
+  char *buf = (char *)alloca (max_ext_len + 10 /* For __riscv_ and '\0'.  */);
+
+  for (const riscv_subset_t *subset = subset_list->begin ();
+       subset != subset_list->end ();
+       subset = subset->next)
+    {
+      int version_value = (subset->major_version * 1000000)
+			   + (subset->minor_version * 1000);
+      /* Special rule for zicsr and zifencei, it's used for ISA spec 2.2 or
+	 earlier.  */
+      if ((subset->name == "zicsr" || subset->name == "zifencei")
+	  && version_value == 0)
+	version_value = 2000000;
+
+      sprintf (buf, "__riscv_%s", subset->name.c_str ());
+      builtin_define_with_int_value (buf, version_value);
+    }
 }

gcc/config/riscv/riscv-subset.h

@@ -85,6 +85,11 @@ public:
   unsigned xlen () const {return m_xlen;};
 
   static riscv_subset_list *parse (const char *, location_t);
+
+  const riscv_subset_t *begin () const {return m_head;};
+  const riscv_subset_t *end () const {return NULL;};
 };
 
+extern const riscv_subset_list *riscv_current_subset_list (void);
+
 #endif /* ! GCC_RISCV_SUBSET_H */

gcc/testsuite/gcc.target/riscv/predef-10.c

@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=rv32i2p0 -mabi=ilp32 -mcmodel=medlow -misa-spec=2.2" } */
+
+int main () {
+
+#ifndef __riscv_arch_test
+#error "__riscv_arch_test"
+#endif
+
+#if __riscv_xlen != 32
+#error "__riscv_xlen"
+#endif
+
+#if !defined(__riscv_i) || (__riscv_i != (2 * 1000 * 1000))
+#error "__riscv_i"
+#endif
+
+#if defined(__riscv_c)
+#error "__riscv_c"
+#endif
+
+#if defined(__riscv_e)
+#error "__riscv_e"
+#endif
+
+#if defined(__riscv_a)
+#error "__riscv_a"
+#endif
+
+#if defined(__riscv_m)
+#error "__riscv_m"
+#endif
+
+#if defined(__riscv_f)
+#error "__riscv_f"
+#endif
+
+#if defined(__riscv_d)
+#error "__riscv_d"
+#endif
+
+  return 0;
+}

gcc/testsuite/gcc.target/riscv/predef-11.c

@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=rv64gc -mabi=lp64 -mcmodel=medlow -misa-spec=2.2" } */
+
+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))
+#error "__riscv_i"
+#endif
+
+#if !defined(__riscv_c) || (__riscv_c != (2 * 1000 * 1000))
+#error "__riscv_c"
+#endif
+
+#if defined(__riscv_e)
+#error "__riscv_e"
+#endif
+
+#if !defined(__riscv_a) || (__riscv_a != (2 * 1000 * 1000))
+#error "__riscv_a"
+#endif
+
+#if !defined(__riscv_m) || (__riscv_m != (2 * 1000 * 1000))
+#error "__riscv_m"
+#endif
+
+#if !defined(__riscv_f) || (__riscv_f != (2 * 1000 * 1000))
+#error "__riscv_f"
+#endif
+
+#if !defined(__riscv_d) || (__riscv_d != (2 * 1000 * 1000))
+#error "__riscv_d"
+#endif
+
+  return 0;
+}

gcc/testsuite/gcc.target/riscv/predef-12.c

@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=rv64gc -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_c) || (__riscv_c != (2 * 1000 * 1000))
+#error "__riscv_c"
+#endif
+
+#if defined(__riscv_e)
+#error "__riscv_e"
+#endif
+
+#if !defined(__riscv_a) || (__riscv_a != (2 * 1000 * 1000 + 1 * 1000))
+#error "__riscv_a"
+#endif
+
+#if !defined(__riscv_m) || (__riscv_m != (2 * 1000 * 1000))
+#error "__riscv_m"
+#endif
+
+#if !defined(__riscv_f) || (__riscv_f != (2 * 1000 * 1000 + 2 * 1000))
+#error "__riscv_f"
+#endif
+
+#if !defined(__riscv_d) || (__riscv_d != (2 * 1000 * 1000 + 2 * 1000))
+#error "__riscv_d"
+#endif
+
+  return 0;
+}

gcc/testsuite/gcc.target/riscv/predef-13.c

@@ -0,0 +1,43 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -march=rv32e -mabi=ilp32e -mcmodel=medlow -misa-spec=2.2" } */
+
+int main () {
+
+#ifndef __riscv_arch_test
+#error "__riscv_arch_test"
+#endif
+
+#if __riscv_xlen != 32
+#error "__riscv_xlen"
+#endif
+
+#if defined(__riscv_i)
+#error "__riscv_i"
+#endif
+
+#if defined(__riscv_c)
+#error "__riscv_c"
+#endif
+
+#if !defined(__riscv_e) || (__riscv_e != (1 * 1000 * 1000 + 9 * 1000))
+#error "__riscv_e"
+#endif
+
+#if defined(__riscv_a)
+#error "__riscv_a"
+#endif
+
+#if defined(__riscv_m)
+#error "__riscv_m"
+#endif
+
+#if defined(__riscv_f)
+#error "__riscv_f"
+#endif
+
+#if defined(__riscv_d)
+#error "__riscv_d"
+#endif
+
+  return 0;
+}