RISC-V/SiFive: Added SiFive custom cache control instructions.

According to the chapter 10 of the following U74-MC manual,
https://sifive.cdn.prismic.io/sifive/6d9a2510-2632-44f3-adb9-d0430f139372_sifive_coreip_U74MC_AXI4_rtl_v19_08p2p0_release_manual.pdf

and the implementations of freedom-metal,
https://github.com/sifive/freedom-metal/blob/v201908-branch/src/cache.c

* Encodings,
31-25   24-20 19-15 14-12  11-7  6-0
FUNCT7  RS2   RS1   FUNCT3 RD    OPCODE
1111110 00000 xxxxx 000    00000 1110011 CFLUSH.D.L1
1111110 00010 xxxxx 000    00000 1110011 CDISCARD.D.L1
1111110 00001 00000 000    00000 1110011 CFLUSH.I.L1

* Extension names,
xsfcflushdlone:   CFLUSH.D.L1.
xsfcdiscarddlone: CDISCARD.D.L1.
xsfcflushilone:   CFLUSH.I.L1.

* Vendor target triples,
For assembler, the target vendor is defined as TARGET_VENDOR in the
gas/config.h, but I don't see any related settings in bfd/config.h
and opcode/config.  Since we may have vendor relocations in the future,
and these relocation numbers may repeat, I add a new RISCV_TARGET_VENDOR
in the bfd/config.h for riscv.  The vendor name will be stored in the
bfd/cpu-riscv.c, so that all tools (gas, bfd, opcode, ...) can get
the vendor name from the configure setting.

If the --with-arch configure option, -march gas option and elf architecture
attributes are not set, then we will generate the default ISA string
according to the chosen target vendor.  For example, if you build the
binutils with the configure option, --target=riscv64-sifive-elf, then
the assembler will find the whole supported extension tables in the
bfd/elfxx-riscv.c, and generate the suitable ISA string.

bfd/
	* configure.ac (RISCV_TARGET_VENDOR): Defined to store target_vendor,
	only when the target is riscv*.
	* config.in: Regenerated.
	* configure: Regenerated.
	* cpu-riscv.c (riscv_vendor_name): Defined to RISCV_TARGET_VENDOR.
	* cpu-riscv.h (enum riscv_spec_class): Added VENDOR_SPEC_CLASS_SIFIVE.
	* elfxx-riscv. (EXT_SIFIVE): Defined to choose the default extensions
	for sifive.
	(riscv_supported_vendor_sifive_ext): Added extensions for sifive cache
	control instructions.
	(riscv_supported_std_ext, riscv_all_supported_ext): Updated.
	(riscv_get_default_ext_version): Updated.
	(riscv_set_default_arch): Updated.
gas/
	* config/tc-riscv.c (VENDOR_SIFIVE_EXT): Added.
	(riscv_extended_subset_supports): Handle INSN_CLASS_XSF*.
	(op_vendor_sifive_hash): Added to store sifive opcodes.
	(md_begin): Init the op_vendor_sifive_hash.
	(riscv_find_extended_opcode_hash): Find the opcodes from
	op_vendor_sifive_hash.
	* testsuite/gas/riscv/extended/sifive-insns.d: New testcase.
	* testsuite/gas/riscv/extended/sifive-insns.s: Likewise.
include/
	* opcode/riscv-opc-extended.h: Added opcodes for sifive cache
	instructions.
	* opcode/riscv.h (enum riscv_extended_insn_class): Added INSN_CLASS_XSF*.
opcodes/
	* riscv-opc.c (riscv_vendor_sifive_opcodes): Added.
	(riscv_extended_opcodes): Updated.

bfd/config.in

@@ -257,6 +257,9 @@
 /* Define to the version of this package. */
 #undef PACKAGE_VERSION
 
+/* RISCV target vendor. */
+#undef RISCV_TARGET_VENDOR
+
 /* The size of `int', as computed by sizeof. */
 #undef SIZEOF_INT
 

bfd/configure

@@ -13658,6 +13658,16 @@ test -n "${selarchs}" && tdefaults="${tdefaults} -DSELECT_ARCHITECTURES='${selar
 
 
 
+case "${target_cpu}" in
+  riscv*)
+
+cat >>confdefs.h <<_ACEOF
+#define RISCV_TARGET_VENDOR "${target_vendor}"
+_ACEOF
+
+    ;;
+esac
+
 # If we are configured native, pick a core file support file.
 COREFILE=
 COREFLAG=

bfd/configure.ac

@@ -822,6 +822,12 @@ AC_SUBST(bfd_default_target_size)
 AC_SUBST(tdefaults)
 AC_SUBST(havevecs)
 
+case "${target_cpu}" in
+  riscv*)
+    AC_DEFINE_UNQUOTED(RISCV_TARGET_VENDOR, "${target_vendor}", [RISCV target vendor.])
+    ;;
+esac
+
 # If we are configured native, pick a core file support file.
 COREFILE=
 COREFLAG=

bfd/cpu-riscv.c

@@ -25,6 +25,8 @@
 #include "libbfd.h"
 #include "cpu-riscv.h"
 
+const char *riscv_vendor_name = RISCV_TARGET_VENDOR;
+
 static const bfd_arch_info_type *
 riscv_compatible (const bfd_arch_info_type *a, const bfd_arch_info_type *b)
 {

bfd/cpu-riscv.h

@@ -18,6 +18,8 @@
    Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
    MA 02110-1301, USA.  */
 
+extern const char *riscv_vendor_name;
+
 enum riscv_spec_class
 {
   /* ISA spec.  */
@@ -36,6 +38,9 @@ enum riscv_spec_class
 
   /* Vendor spec for T_HEAD XuanTie.  */
   VENDOR_SPEC_CLASS_THEAD,
+
+  /* Vendor spec for SiFive.  */
+  VENDOR_SPEC_CLASS_SIFIVE,
 };
 
 struct riscv_spec

bfd/elfxx-riscv.c

@@ -1109,7 +1109,8 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
 /* For default_enable field, decide if the extension should
    be enbaled by default.  */
 
-#define EXT_DEFAULT   0x1
+#define EXT_DEFAULT	0x1
+#define EXT_SIFIVE	(0x1 << 2)
 
 /* List all extensions that binutils should know about.  */
 
@@ -1134,7 +1135,7 @@ static struct riscv_supported_ext riscv_supported_std_ext[] =
   {"i",		ISA_SPEC_CLASS_2P2,		2, 0, 0 },
   /* The g is a special case which we don't want to output it,
      but still need it when adding implicit extensions.  */
-  {"g",		ISA_SPEC_CLASS_NONE, RISCV_UNKNOWN_VERSION, RISCV_UNKNOWN_VERSION, EXT_DEFAULT },
+  {"g",		ISA_SPEC_CLASS_NONE, RISCV_UNKNOWN_VERSION, RISCV_UNKNOWN_VERSION, EXT_DEFAULT|EXT_SIFIVE },
   {"m",		ISA_SPEC_CLASS_20191213,	2, 0, 0 },
   {"m",		ISA_SPEC_CLASS_20190608,	2, 0, 0 },
   {"m",		ISA_SPEC_CLASS_2P2,		2, 0, 0 },
@@ -1223,6 +1224,14 @@ static struct riscv_supported_ext riscv_supported_vendor_thead_ext[] =
   {NULL, 0, 0, 0, 0}
 };
 
+static struct riscv_supported_ext riscv_supported_vendor_sifive_ext[] =
+{
+  {"xsfcdiscarddlone",	VENDOR_SPEC_CLASS_SIFIVE,	0, 1, EXT_SIFIVE},
+  {"xsfcflushdlone",	VENDOR_SPEC_CLASS_SIFIVE,	0, 1, EXT_SIFIVE},
+  {"xsfcflushilone",	VENDOR_SPEC_CLASS_SIFIVE,	0, 1, EXT_SIFIVE},
+  {NULL, 0, 0, 0, 0}
+};
+
 const struct riscv_supported_ext *riscv_all_supported_ext[] =
 {
   riscv_supported_std_ext,
@@ -1231,6 +1240,7 @@ const struct riscv_supported_ext *riscv_all_supported_ext[] =
   riscv_supported_std_h_ext,
   riscv_supported_std_zxm_ext,
   riscv_supported_vendor_thead_ext,
+  riscv_supported_vendor_sifive_ext,
   NULL
 };
 
@@ -1495,7 +1505,10 @@ riscv_get_default_ext_version (enum riscv_spec_class default_isa_spec,
     case RV_ISA_CLASS_S: table = riscv_supported_std_s_ext; break;
     case RV_ISA_CLASS_H: table = riscv_supported_std_h_ext; break;
     case RV_ISA_CLASS_X:
-      table = riscv_supported_vendor_thead_ext;
+      if (strncmp (name, "xsf", 3) == 0)
+	table = riscv_supported_vendor_sifive_ext;
+      else
+	table = riscv_supported_vendor_thead_ext;
       break;
     default:
       table = riscv_supported_std_ext;
@@ -1507,6 +1520,7 @@ riscv_get_default_ext_version (enum riscv_spec_class default_isa_spec,
       if (strcmp (table[i].name, name) == 0
 	  && (table[i].isa_spec_class == ISA_SPEC_CLASS_DRAFT
 	      || table[i].isa_spec_class == VENDOR_SPEC_CLASS_THEAD
+	      || table[i].isa_spec_class == VENDOR_SPEC_CLASS_SIFIVE
 	      || table[i].isa_spec_class == default_isa_spec))
 	{
 	  *major_version = table[i].major_version;
@@ -1917,8 +1931,14 @@ riscv_parse_check_conflicts (riscv_parse_subset_t *rps)
 static void
 riscv_set_default_arch (riscv_parse_subset_t *rps)
 {
-  unsigned long enable = EXT_DEFAULT;
+  unsigned long enable;
   int i, j;
+
+  if (strcmp (riscv_vendor_name, "sifive") == 0)
+    enable = EXT_SIFIVE;
+  else
+    enable = EXT_DEFAULT;
+
   for (i = 0; riscv_all_supported_ext[i] != NULL; i++)
     {
       const struct riscv_supported_ext *table = riscv_all_supported_ext[i];

gas/config/tc-riscv.c

@@ -40,6 +40,7 @@ enum
 {
   DRAFT_EXT = 0,
   VENDOR_THEAD_EXT,
+  VENDOR_SIFIVE_EXT,
   EXTENDED_EXT_NUM
 };
 
@@ -310,6 +311,13 @@ riscv_extended_subset_supports (int insn_class)
     case INSN_CLASS_THEADSE:
       return riscv_subset_supports ("xtheadse");
 
+    case INSN_CLASS_XSF_CDISCARDDLONE:
+      return riscv_subset_supports ("xsfcdiscarddlone");
+    case INSN_CLASS_XSF_CFLUSHDLONE:
+      return riscv_subset_supports ("xsfcflushdlone");
+    case INSN_CLASS_XSF_CFLUSHILONE:
+      return riscv_subset_supports ("xsfcflushilone");
+
     default:
       as_fatal ("internal: unknown INSN_CLASS (0x%x)", insn_class);
       return false;
@@ -461,6 +469,9 @@ static htab_t op_draft_hash = NULL;
 /* Handle of the T-HEAD OPCODE hash table.  */
 static htab_t op_vendor_thead_hash = NULL;
 
+/* Handle of the sifive OPCODE hash table.  */
+static htab_t op_vendor_sifive_hash = NULL;
+
 /* Handle of the type of .insn hash table.  */
 static htab_t insn_type_hash = NULL;
 
@@ -1481,7 +1492,10 @@ md_begin (void)
   hash_reg_names (RCLASS_VECR, riscv_vecr_names_numeric, NVECR);
   hash_reg_names (RCLASS_VECM, riscv_vecm_names_numeric, NVECM);
   op_draft_hash = init_opcode_hash (riscv_extended_opcodes[DRAFT_EXT], false);
-  op_vendor_thead_hash = init_opcode_hash (riscv_extended_opcodes[VENDOR_THEAD_EXT], false);
+  op_vendor_thead_hash =
+	init_opcode_hash (riscv_extended_opcodes[VENDOR_THEAD_EXT], false);
+  op_vendor_sifive_hash =
+	init_opcode_hash (riscv_extended_opcodes[VENDOR_SIFIVE_EXT], false);
 }
 
 static insn_t
@@ -1593,6 +1607,8 @@ riscv_find_extended_opcode_hash (char *str ATTRIBUTE_UNUSED)
 	case VENDOR_THEAD_EXT:
 	  insn = (struct riscv_opcode *) str_hash_find (op_vendor_thead_hash, str);
 	  break;
+	case VENDOR_SIFIVE_EXT:
+	  insn = (struct riscv_opcode *) str_hash_find (op_vendor_sifive_hash, str);
 	default:
 	  break;
 	}

gas/testsuite/gas/riscv/extended/sifive-insns.d

@@ -0,0 +1,12 @@
+#as: -march=rv32i_xsfcdiscarddlone_xsfcflushdlone_xsfcflushilone
+#objdump: -dr
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <target>:
+[ 	]+0:[ 	]+fc050073[ 	]+cflush.d.l1[ 	]+a0
+[ 	]+4:[ 	]+fc250073[ 	]+cdiscard.d.l1[ 	]+a0
+[ 	]+8:[ 	]+fc100073[ 	]+cflush.i.l1

gas/testsuite/gas/riscv/extended/sifive-insns.s

@@ -0,0 +1,4 @@
+target:
+	cflush.d.l1	x10
+	cdiscard.d.l1	x10
+	cflush.i.l1

include/opcode/riscv-opc-extended.h

@@ -2078,3 +2078,14 @@ DECLARE_CSR(shpmcounter29, CSR_SHPMCOUNTER29, CSR_CLASS_VENDOR_THEAD, PRIV_SPEC_
 DECLARE_CSR(shpmcounter30, CSR_SHPMCOUNTER30, CSR_CLASS_VENDOR_THEAD, PRIV_SPEC_CLASS_NONE, PRIV_SPEC_CLASS_NONE)
 DECLARE_CSR(shpmcounter31, CSR_SHPMCOUNTER31, CSR_CLASS_VENDOR_THEAD, PRIV_SPEC_CLASS_NONE, PRIV_SPEC_CLASS_NONE)
 #endif /* DECLARE_CSR */
+
+#ifndef __RISCV_OPC_SIFIVE_THEAD__
+#define __RISCV_OPC_SIFIVE_THEAD__
+/* SiFive cache control instructions.  */
+#define MATCH_CFLUSH_D_L1	0xfc000073
+#define MASK_CFLUSH_D_L1	0xfff07fff
+#define MATCH_CDISCARD_D_L1	0xfc200073
+#define MASK_CDISCARD_D_L1	0xfff07fff
+#define MATCH_CFLUSH_I_L1	0xfc100073
+#define MASK_CFLUSH_I_L1	0xffffffff
+#endif /* __RISCV_OPC_SIFIVE_THEAD__ */

include/opcode/riscv.h

@@ -529,6 +529,11 @@ enum riscv_extended_insn_class
   INSN_CLASS_THEADC_OR_THEADE_OR_THEADSE,
   INSN_CLASS_THEADE,
   INSN_CLASS_THEADSE,
+
+  /* SiFive.  */
+  INSN_CLASS_XSF_CDISCARDDLONE,
+  INSN_CLASS_XSF_CFLUSHDLONE,
+  INSN_CLASS_XSF_CFLUSHILONE,
 };
 
 /* This is a list of macro expanded instructions for extended

opcodes/riscv-opc.c

@@ -2302,10 +2302,24 @@ struct riscv_opcode riscv_vendor_thead_opcodes[] =
 
 };
 
+/* Vendor SiFive extensions.  */
+const struct riscv_opcode riscv_vendor_sifive_opcodes[] =
+{
+/* name, xlen, isa, operands, match, mask, match_func, pinfo.  */
+/* Half-precision floating-point instruction subset.  */
+{"cflush.d.l1",		0, INSN_CLASS_XSF_CFLUSHDLONE,   "s", MATCH_CFLUSH_D_L1, MASK_CFLUSH_D_L1, match_opcode, 0 },
+{"cdiscard.d.l1",	0, INSN_CLASS_XSF_CDISCARDDLONE, "s", MATCH_CDISCARD_D_L1, MASK_CDISCARD_D_L1, match_opcode, 0 },
+{"cflush.i.l1",		0, INSN_CLASS_XSF_CFLUSHILONE,   "",  MATCH_CFLUSH_I_L1, MASK_CFLUSH_I_L1, match_opcode, 0 },
+
+/* Terminate the list.  */
+{0, 0, INSN_CLASS_NONE, 0, 0, 0, 0, 0 },
+};
+
 /* The supported extended extensions.  */
 const struct riscv_opcode *riscv_extended_opcodes[] =
 {
   riscv_draft_opcodes,
   riscv_vendor_thead_opcodes,
+  riscv_vendor_sifive_opcodes,
   NULL
 };