RISC-V: Add 'Zicntr' and 'Zihpm' support with compatibility measures

This commit adds support for 'Zicntr' and 'Zihpm' extensions (version 2.0).

However, because GNU Binutils handled those as a part of 'I' and there was
a time when a ratified specification did split counters from the 'I'
extension without separate extension names, we need to take care of
possible compatibility issues.

So, if a 'Zicntr' pseudoinstruction is used without that extension,
it generates not an error but a warning.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_implicit_subsets): Add implications related
	to counter extensions.
	(riscv_supported_std_z_ext): Add 'Zicntr' and 'Zihpm' extensions.
	Define default versions of 'Zicsr' and 'Zifencei' on the draft ISA
	because they might be used on the 'E' extension handling.
	(riscv_is_subset_of_i_2p0): New function.
	(riscv_parse_add_subset): If a subset of the 'I' extension version
	2.0 is being added, check the version of 'I' and allow its version
	unknown when the 'I' extension version is less than 2.1.
	(riscv_multi_subset_supports, riscv_multi_subset_supports_ext):
	Add support for the 'Zicntr' extension with compatibility measure.

gas/ChangeLog:

	* config/tc-riscv.c (enum riscv_csr_class): Add new CSR classes
	corresponding 'Zicntr' and 'Zihpm' extensions.
	(riscv_csr_address): Add handling for new CSR classes.
	(riscv_ip): Raise a warning if a 'Zicntr' pseudoinstruction is
	used without that extension.
	* testsuite/gas/riscv/csr-insns-pseudo.s: Rename section names
	to indicate that the extension 'Zicntr' is needed.
	* testsuite/gas/riscv/csr-insns-pseudo.d: Add "zicntr" to arch.
	* testsuite/gas/riscv/csr-insns-pseudo-noalias.d: Likewise.
	* testsuite/gas/riscv/csr-insns-pseudo-zfinx.d: Likewise.
	* testsuite/gas/riscv/csr-insns-read-only.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p9p1.d: Specify versions.
	* testsuite/gas/riscv/csr-version-1p10.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p11.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p12.d: Likewise.
	* testsuite/gas/riscv/csr-version-1p9p1.l: Add warnings regarding
	'Zicntr' and 'Zihpm' extension recategorization.
	* testsuite/gas/riscv/csr-version-1p10.l: Likewise.
	* testsuite/gas/riscv/csr-version-1p11.l: Likewise.
	* testsuite/gas/riscv/csr-version-1p12.l: Likewise.
	* testsuite/gas/riscv/march-imply-i2p0-01.d: 'I' version 2.0
	effectively imples 'Zicsr' and 'Zifencei' but should not be
	reflected to the expanded architectural string.
	* testsuite/gas/riscv/march-ok-reorder.d: Use 'I' version 2.1 and
	use other extensions to test proper ordering.
	* testsuite/gas/riscv/csr-insns-pseudo-nozicntr.d: New test to
	see warnings are generated when the 'Zicntr' extension is not
	specified.
	* testsuite/gas/riscv/csr-insns-pseudo-nozicntr.l: Likewise.

include/ChangeLog:

	* opcode/riscv-opc.h: Recategorize user counter CSRs.
	* opcode/riscv.h (enum riscv_insn_class): Add INSN_CLASS_ZICNTR
	for 'Zicntr' pseudoinstructions.

opcodes/ChangeLog:

	* riscv-opc.c (riscv_opcodes): Recategorize counter
	pseudoinstructions to the 'Zicntr' extension.

bfd/elfxx-riscv.c

@@ -1097,6 +1097,8 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
   {"e", "i",		check_implicit_always},
   {"i", "zicsr",	check_implicit_for_i},
   {"i", "zifencei",	check_implicit_for_i},
+  {"i", "zicntr",	check_implicit_for_i},
+  {"i", "zihpm",	check_implicit_for_i},
   {"g", "i",		check_implicit_always},
   {"g", "m",		check_implicit_always},
   {"g", "a",		check_implicit_always},
@@ -1148,6 +1150,8 @@ static struct riscv_implicit_subset riscv_implicit_subsets[] =
   {"zhinx", "zhinxmin",	check_implicit_always},
   {"zhinxmin", "zfinx",	check_implicit_always},
   {"zfinx", "zicsr",	check_implicit_always},
+  {"zicntr", "zicsr",	check_implicit_always},
+  {"zihpm", "zicsr",	check_implicit_always},
   {"zk", "zkn",		check_implicit_always},
   {"zk", "zkr",		check_implicit_always},
   {"zk", "zkt",		check_implicit_always},
@@ -1251,13 +1255,17 @@ static struct riscv_supported_ext riscv_supported_std_z_ext[] =
   {"zicbom",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zicbop",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zicboz",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
+  {"zicntr",		ISA_SPEC_CLASS_DRAFT,		2, 0,  0 },
   {"zicond",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zicsr",		ISA_SPEC_CLASS_20191213,	2, 0,  0 },
   {"zicsr",		ISA_SPEC_CLASS_20190608,	2, 0,  0 },
+  {"zicsr",		ISA_SPEC_CLASS_DRAFT,		2, 0,  0 },
   {"zifencei",		ISA_SPEC_CLASS_20191213,	2, 0,  0 },
   {"zifencei",		ISA_SPEC_CLASS_20190608,	2, 0,  0 },
+  {"zifencei",		ISA_SPEC_CLASS_DRAFT,		2, 0,  0 },
   {"zihintntl",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zihintpause",	ISA_SPEC_CLASS_DRAFT,		2, 0,  0 },
+  {"zihpm",		ISA_SPEC_CLASS_DRAFT,		2, 0,  0 },
   {"zmmul",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zawrs",		ISA_SPEC_CLASS_DRAFT,		1, 0,  0 },
   {"zfa",		ISA_SPEC_CLASS_DRAFT,		0, 1,  0 },
@@ -1649,6 +1657,18 @@ riscv_get_default_ext_version (enum riscv_spec_class *default_isa_spec,
     }
 }
 
+/* Check if the subset is one of the extensions split from
+   the 'I' extension version 2.0.  */
+
+static bool
+riscv_is_subset_of_i_2p0 (const char *subset)
+{
+  return (strcmp (subset, "zicsr") == 0
+	  || strcmp (subset, "zifencei") == 0
+	  || strcmp (subset, "zicntr") == 0
+	  || strcmp (subset, "zihpm") == 0);
+}
+
 /* Find the default versions for the extension before adding them to
    the subset list, if their versions are RISCV_UNKNOWN_VERSION.
    Afterwards, report errors if we can not find their default versions.  */
@@ -1662,9 +1682,26 @@ riscv_parse_add_subset (riscv_parse_subset_t *rps,
 {
   int major_version = major;
   int minor_version = minor;
+  bool handle_subset_of_i_2p0 = false;
+
+  /* If a subset of the 'I' extension version 2.0 is being added,
+     check the version of 'I' and allow its version unknown when the
+     'I' extension version is less than 2.1.
+     Draft 'E' is arbitrarily handled since it's a draft but the default
+     handling is the same as 'I' >= 2.1 because non-draft 'E' extension
+     does not have 'I' version 2.0 subsets.  */
+  if (riscv_is_subset_of_i_2p0 (subset))
+    {
+      riscv_subset_t *ext_i;
+      if (riscv_lookup_subset (rps->subset_list, "i", &ext_i)
+	  && (ext_i->major_version < 2
+	      || (ext_i->major_version == 2 && ext_i->minor_version < 1)))
+	handle_subset_of_i_2p0 = true;
+    }
 
-  if (major_version == RISCV_UNKNOWN_VERSION
-       || minor_version == RISCV_UNKNOWN_VERSION)
+  if (!handle_subset_of_i_2p0
+      && (major_version == RISCV_UNKNOWN_VERSION
+	  || minor_version == RISCV_UNKNOWN_VERSION))
     riscv_get_default_ext_version (rps->isa_spec, subset,
 				   &major_version, &minor_version);
 
@@ -1677,9 +1714,9 @@ riscv_parse_add_subset (riscv_parse_subset_t *rps,
 	rps->error_handler
 	  (_("x ISA extension `%s' must be set with the versions"),
 	   subset);
-      /* Allow old ISA spec can recognize zicsr and zifencei.  */
-      else if (strcmp (subset, "zicsr") != 0
-	       && strcmp (subset, "zifencei") != 0)
+      /* Allow old ISA spec (version 2.2) can recognize extensions
+	 effectively split from the base 'I' extension version 2.0.  */
+      else if (!riscv_is_subset_of_i_2p0 (subset))
 	rps->error_handler
 	  (_("cannot find default versions of the ISA extension `%s'"),
 	   subset);
@@ -2389,6 +2426,9 @@ riscv_multi_subset_supports (riscv_parse_subset_t *rps,
       return riscv_subset_supports (rps, "zicbop");
     case INSN_CLASS_ZICBOZ:
       return riscv_subset_supports (rps, "zicboz");
+    case INSN_CLASS_ZICNTR:
+      /* Instead of 'Zicntr', query for 'I' for compatibility.  */
+      return riscv_subset_supports (rps, "i");
     case INSN_CLASS_ZICOND:
       return riscv_subset_supports (rps, "zicond");
     case INSN_CLASS_ZICSR:
@@ -2592,6 +2632,8 @@ riscv_multi_subset_supports_ext (riscv_parse_subset_t *rps,
       return "zicbop";
     case INSN_CLASS_ZICBOZ:
       return "zicboz";
+    case INSN_CLASS_ZICNTR:
+      return "zicntr";
     case INSN_CLASS_ZICOND:
       return "zicond";
     case INSN_CLASS_ZICSR:

gas/config/tc-riscv.c

@@ -66,6 +66,10 @@ enum riscv_csr_class
 
   CSR_CLASS_I,
   CSR_CLASS_I_32,	/* rv32 only */
+  CSR_CLASS_ZICNTR,	/* basic hardware perf counter */
+  CSR_CLASS_ZICNTR_32,	/* basic hardware perf counter, rv32 only */
+  CSR_CLASS_ZIHPM,	/* additional hardware perf counter */
+  CSR_CLASS_ZIHPM_32,	/* additional hardware perf counter, rv32 only */
   CSR_CLASS_F,		/* f-ext only */
   CSR_CLASS_ZKR,	/* zkr only */
   CSR_CLASS_V,		/* rvv only */
@@ -1033,6 +1037,18 @@ riscv_csr_address (const char *csr_name,
       need_check_version = true;
       extension = "i";
       break;
+    case CSR_CLASS_ZICNTR_32:
+      is_rv32_only = true;
+      /* Fall through.  */
+    case CSR_CLASS_ZICNTR:
+      extension = "zicntr";
+      break;
+    case CSR_CLASS_ZIHPM_32:
+      is_rv32_only = true;
+      /* Fall through.  */
+    case CSR_CLASS_ZIHPM:
+      extension = "zihpm";
+      break;
     case CSR_CLASS_H_32:
       is_rv32_only = true;
       /* Fall through.  */
@@ -2611,6 +2627,15 @@ riscv_ip (char *str, struct riscv_cl_insn *ip, expressionS *imm_expr,
 		      insn_with_csr = false;
 		    }
 
+		  /* Check if we are using a 'Zicntr' pseudoinstruction
+		     without the 'Zicntr' extension.  */
+		  if (insn->insn_class == INSN_CLASS_ZICNTR
+		      && !riscv_subset_supports (&riscv_rps_as, "zicntr"))
+		    {
+		      as_warn (_("`%s' needs `zicntr' extension"),
+			       insn->name);
+		    }
+
 		  /* The (segmant) load and store with EEW 64 cannot be used
 		     when zve32x is enabled.  */
 		  if (ip->insn_mo->pinfo & INSN_V_EEW64

gas/testsuite/gas/riscv/csr-insns-pseudo-noalias.d

@@ -1,5 +1,5 @@
 #source: csr-insns-pseudo.s
-#as: -march=rv32if
+#as: -march=rv32if_zicntr
 #objdump: -dr -Mno-aliases
 
 .*:[ 	]+file format .*

gas/testsuite/gas/riscv/csr-insns-pseudo-nozicntr.d

@@ -0,0 +1,37 @@
+#source: csr-insns-pseudo.s
+#as: -march=rv32i2p1_f2p2
+#warning_output: csr-insns-pseudo-nozicntr.l
+#objdump: -dr
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <pseudo_csr_insn>:
+[ 	]+[0-9a-f]+:[ 	]+000022f3[ 	]+csrr[ 	]+t0,ustatus
+[ 	]+[0-9a-f]+:[ 	]+00029073[ 	]+csrw[ 	]+ustatus,t0
+[ 	]+[0-9a-f]+:[ 	]+0002a073[ 	]+csrs[ 	]+ustatus,t0
+[ 	]+[0-9a-f]+:[ 	]+0002b073[ 	]+csrc[ 	]+ustatus,t0
+[ 	]+[0-9a-f]+:[ 	]+000fd073[ 	]+csrwi[ 	]+ustatus,31
+[ 	]+[0-9a-f]+:[ 	]+000fe073[ 	]+csrsi[ 	]+ustatus,31
+[ 	]+[0-9a-f]+:[ 	]+000ff073[ 	]+csrci[ 	]+ustatus,31
+[ 	]+[0-9a-f]+:[ 	]+c00022f3[ 	]+rdcycle[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+c01022f3[ 	]+rdtime[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+c02022f3[ 	]+rdinstret[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+c80022f3[ 	]+rdcycleh[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+c81022f3[ 	]+rdtimeh[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+c82022f3[ 	]+rdinstreth[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+003022f3[ 	]+frcsr[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+003392f3[ 	]+fscsr[ 	]+t0,t2
+[ 	]+[0-9a-f]+:[ 	]+00339073[ 	]+fscsr[ 	]+t2
+[ 	]+[0-9a-f]+:[ 	]+002022f3[ 	]+frrm[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+002312f3[ 	]+fsrm[ 	]+t0,t1
+[ 	]+[0-9a-f]+:[ 	]+00231073[ 	]+fsrm[ 	]+t1
+[ 	]+[0-9a-f]+:[ 	]+002fd2f3[ 	]+fsrmi[ 	]+t0,31
+[ 	]+[0-9a-f]+:[ 	]+002fd073[ 	]+fsrmi[ 	]+zero,31
+[ 	]+[0-9a-f]+:[ 	]+001022f3[ 	]+frflags[ 	]+t0
+[ 	]+[0-9a-f]+:[ 	]+001312f3[ 	]+fsflags[ 	]+t0,t1
+[ 	]+[0-9a-f]+:[ 	]+00131073[ 	]+fsflags[ 	]+t1
+[ 	]+[0-9a-f]+:[ 	]+001fd2f3[ 	]+fsflagsi[ 	]+t0,31
+[ 	]+[0-9a-f]+:[ 	]+001fd073[ 	]+fsflagsi[ 	]+zero,31

gas/testsuite/gas/riscv/csr-insns-pseudo-nozicntr.l

@@ -0,0 +1,7 @@
+.*Assembler messages:
+.*Warning: `rdcycle' needs `zicntr' extension
+.*Warning: `rdtime' needs `zicntr' extension
+.*Warning: `rdinstret' needs `zicntr' extension
+.*Warning: `rdcycleh' needs `zicntr' extension
+.*Warning: `rdtimeh' needs `zicntr' extension
+.*Warning: `rdinstreth' needs `zicntr' extension

gas/testsuite/gas/riscv/csr-insns-pseudo-zfinx.d

@@ -1,5 +1,5 @@
 #source: csr-insns-pseudo.s
-#as: -march=rv32i_zfinx
+#as: -march=rv32i_zicntr_zfinx
 #objdump: -dr
 
 .*:[ 	]+file format .*

gas/testsuite/gas/riscv/csr-insns-pseudo.d

@@ -1,5 +1,5 @@
 #source: csr-insns-pseudo.s
-#as: -march=rv32if
+#as: -march=rv32if_zicntr
 #objdump: -dr
 
 .*:[ 	]+file format .*

gas/testsuite/gas/riscv/csr-insns-pseudo.s

@@ -8,11 +8,12 @@ pseudo_csr_insn:
 	csrsi 0x0, 31
 	csrci 0x0, 31
 
+	# Zicntr
 	rdcycle t0
 	rdtime t0
 	rdinstret t0
 
-	# rv32i-ext
+	# Zicntr (RV32)
 	rdcycleh t0
 	rdtimeh t0
 	rdinstreth t0

gas/testsuite/gas/riscv/csr-insns-read-only.d

@@ -1,3 +1,3 @@
-#as: -march=rv32if -mcsr-check -mpriv-spec=1.11
+#as: -march=rv32if_zicntr -mcsr-check -mpriv-spec=1.11
 #source: csr-insns-read-only.s
 #warning_output: csr-insns-read-only.l

gas/testsuite/gas/riscv/csr-version-1p10.d

@@ -1,4 +1,4 @@
-#as: -march=rv64i_zicsr -mcsr-check -mpriv-spec=1.10
+#as: -march=rv64i2p1_zicsr2p0 -mcsr-check -mpriv-spec=1.10
 #source: csr.s
 #warning_output: csr-version-1p10.l
 #objdump: -dr -Mpriv-spec=1.10