RISC-V: Initial RV64E and LP64E support

Along with RV32E, RV64E is ratified.  Though ILP32E and LP64E ABIs are
still draft, it's worth supporting it.

This commit should not be merged until two proposals below are
going to proceed.

LP64E proposal (including suggested changes):
<riscv-non-isa/riscv-elf-psabi-doc#299>

New "__riscv_64e" proposal by the author of this commit:
<riscv-non-isa/riscv-c-api-doc#52>

gcc/ChangeLog:

	* common/config/riscv/riscv-common.cc
	(riscv_subset_list::parse_std_ext): Allow RV64E.
	* config.gcc: Parse base ISA RV64E and ABI LP64E.
	* config/riscv/arch-canonicalize: Parse base ISA 'rv64e'.
	* config/riscv/riscv-c.cc (riscv_cpu_cpp_builtins):
	Build different macro per RV32E/RV64E.
	Add handling for ABI_LP64E.
	* config/riscv/riscv-d.cc (riscv_d_handle_target_float_abi):
	Add handling for ABI_LP64E.
	* config/riscv/riscv-opts.h (enum riscv_abi_type): Add ABI_LP64E.
	* config/riscv/riscv.cc (riscv_option_override): Enhance error
	handling to support RV64E and LP64E.
	(riscv_conditional_register_usage): Change "RV32E" in a comment
	to "RV32E/RV64E".
	* config/riscv/riscv.h
	(UNITS_PER_FP_ARG): Add handling for ABI_LP64E.
	(STACK_BOUNDARY): Ditto.
	(ABI_STACK_BOUNDARY): Ditto.
	(MAX_ARGS_IN_REGISTERS): Ditto.
	(ABI_SPEC): Add support for "lp64e".
	* config/riscv/riscv.opt: Parse -mabi=lp64e as ABI_LP64E.
	* doc/invoke.texi: Add documentation of the LP64E ABI.

gcc/testsuite/ChangeLog:

	* gcc.target/riscv/predef-1.c: Test for __riscv_64e.
	* gcc.target/riscv/predef-2.c: Ditto.
	* gcc.target/riscv/predef-3.c: Ditto.
	* gcc.target/riscv/predef-4.c: Ditto.
	* gcc.target/riscv/predef-5.c: Ditto.
	* gcc.target/riscv/predef-6.c: Ditto.
	* gcc.target/riscv/predef-7.c: Ditto.
	* gcc.target/riscv/predef-8.c: Ditto.
	* gcc.target/riscv/predef-9.c: New test for RV32E and LP64E,
	based on predef-7.c.

Author: a4lg

gcc/common/config/riscv/riscv-common.cc

@@ -818,7 +818,7 @@ riscv_subset_list::parse_std_ext (const char *p)
 
       add ("e", major_version, minor_version, explicit_version_p, false);
 
-      if (m_xlen > 32)
+      if (m_xlen > 64)
 	{
 	  error_at (m_loc, "%<-march=%s%>: rv%de is not a valid base ISA",
 		    m_arch, m_xlen);

gcc/config.gcc

@@ -4608,7 +4608,7 @@ case "${target}" in
 
 		# Infer arch from --with-arch, --target, and --with-abi.
 		case "${with_arch}" in
-		rv32e* | rv32i* | rv32g* | rv64i* | rv64g*)
+		rv32e* | rv32i* | rv32g* | rv64e* | rv64i* | rv64g*)
 			# OK.
 			;;
 		"")
@@ -4617,11 +4617,12 @@ case "${target}" in
 			ilp32e) with_arch="rv32e" ;;
 			ilp32 | ilp32f | ilp32d) with_arch="rv32gc" ;;
 			lp64 | lp64f | lp64d) with_arch="rv64gc" ;;
+			lp64e) with_arch="rv64e" ;;
 			*) with_arch="rv${xlen}gc" ;;
 			esac
 			;;
 		*)
-			echo "--with-arch=${with_arch} is not supported.  The argument must begin with rv32e, rv32i, rv32g, rv64i, or rv64g." 1>&2
+			echo "--with-arch=${with_arch} is not supported.  The argument must begin with rv32e, rv32i, rv32g, rv64e, rv64i, or rv64g." 1>&2
 			exit 1
 			;;
 		esac
@@ -4635,14 +4636,15 @@ case "${target}" in
 		# pick a default based on the ISA, preferring soft-float
 		# unless the D extension is present.
 		case "${with_abi}" in
-		ilp32 | ilp32e | ilp32f | ilp32d | lp64 | lp64f | lp64d)
+		ilp32 | ilp32e | ilp32f | ilp32d | lp64 | lp64e | lp64f | lp64d)
 			;;
 		"")
 			case "${with_arch}" in
 			rv32*d* | rv32g*) with_abi=ilp32d ;;
 			rv32e*) with_abi=ilp32e ;;
 			rv32*) with_abi=ilp32 ;;
 			rv64*d* | rv64g*) with_abi=lp64d ;;
+			rv64e*) with_abi=lp64e ;;
 			rv64*) with_abi=lp64 ;;
 			esac
 			;;
@@ -4658,7 +4660,7 @@ case "${target}" in
 		ilp32,rv32* | ilp32e,rv32e* \
 		| ilp32f,rv32*f* | ilp32f,rv32g* \
 		| ilp32d,rv32*d* | ilp32d,rv32g* \
-		| lp64,rv64* \
+		| lp64,rv64* | lp64e,rv64e* \
 		| lp64f,rv64*f* | lp64f,rv64g* \
 		| lp64d,rv64*d* | lp64d,rv64g*)
 			;;

gcc/config/riscv/arch-canonicalize

@@ -76,7 +76,7 @@ def arch_canonicalize(arch, isa_spec):
   new_arch = ""
   extra_long_ext = []
   std_exts = []
-  if arch[:5] in ['rv32e', 'rv32i', 'rv32g', 'rv64i', 'rv64g']:
+  if arch[:5] in ['rv32e', 'rv32i', 'rv32g', 'rv64e', 'rv64i', 'rv64g']:
     new_arch = arch[:5].replace("g", "i")
     if arch[:5] in ['rv32g', 'rv64g']:
       std_exts = ['m', 'a', 'f', 'd']

gcc/config/riscv/riscv-c.cc

@@ -51,7 +51,7 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
     builtin_define ("__riscv_compressed");
 
   if (TARGET_RVE)
-    builtin_define ("__riscv_32e");
+    builtin_define (TARGET_64BIT ? "__riscv_64e" : "__riscv_32e");
 
   if (TARGET_ATOMIC)
     builtin_define ("__riscv_atomic");
@@ -76,6 +76,7 @@ riscv_cpu_cpp_builtins (cpp_reader *pfile)
   switch (riscv_abi)
     {
     case ABI_ILP32E:
+    case ABI_LP64E:
       builtin_define ("__riscv_abi_rve");
       gcc_fallthrough ();
 

gcc/config/riscv/riscv-d.cc

@@ -52,6 +52,7 @@ riscv_d_handle_target_float_abi (void)
     {
     case ABI_ILP32E:
     case ABI_ILP32:
+    case ABI_LP64E:
     case ABI_LP64:
       abi = "soft";
       break;

gcc/config/riscv/riscv-opts.h

@@ -27,6 +27,7 @@ enum riscv_abi_type {
   ABI_ILP32F,
   ABI_ILP32D,
   ABI_LP64,
+  ABI_LP64E,
   ABI_LP64F,
   ABI_LP64D
 };

gcc/config/riscv/riscv.cc

@@ -6460,13 +6460,18 @@ riscv_option_override (void)
     error ("requested ABI requires %<-march%> to subsume the %qc extension",
 	   UNITS_PER_FP_ARG > 8 ? 'Q' : (UNITS_PER_FP_ARG > 4 ? 'D' : 'F'));
 
-  if (TARGET_RVE && riscv_abi != ABI_ILP32E)
-    error ("rv32e requires ilp32e ABI");
+  /* RVE requires specific ABI.  */
+  if (TARGET_RVE)
+    if (!TARGET_64BIT && riscv_abi != ABI_ILP32E)
+      error ("rv32e requires ilp32e ABI");
+    else if (TARGET_64BIT && riscv_abi != ABI_LP64E)
+      error ("rv64e requires lp64e ABI");
 
-  // Zfinx require abi ilp32,ilp32e or lp64.
-  if (TARGET_ZFINX && riscv_abi != ABI_ILP32
-      && riscv_abi != ABI_LP64 && riscv_abi != ABI_ILP32E)
-    error ("z*inx requires ABI ilp32, ilp32e or lp64");
+  /* Zfinx require abi ilp32, ilp32e, lp64 or lp64e.  */
+  if (TARGET_ZFINX
+      && riscv_abi != ABI_ILP32 && riscv_abi != ABI_LP64
+      && riscv_abi != ABI_ILP32E && riscv_abi != ABI_LP64E)
+    error ("z*inx requires ABI ilp32, ilp32e, lp64 or lp64e");
 
   /* We do not yet support ILP32 on RV64.  */
   if (BITS_PER_WORD != POINTER_SIZE)
@@ -6553,7 +6558,7 @@ riscv_option_override (void)
 static void
 riscv_conditional_register_usage (void)
 {
-  /* We have only x0~x15 on RV32E.  */
+  /* We have only x0~x15 on RV32E/RV64E.  */
   if (TARGET_RVE)
     {
       for (int r = 16; r <= 31; r++)

gcc/config/riscv/riscv.h

@@ -164,7 +164,7 @@ ASM_MISA_SPEC
 /* The largest type that can be passed in floating-point registers.  */
 #define UNITS_PER_FP_ARG						\
   ((riscv_abi == ABI_ILP32 || riscv_abi == ABI_ILP32E			\
-    || riscv_abi == ABI_LP64)						\
+    || riscv_abi == ABI_LP64 || riscv_abi == ABI_LP64E)			\
    ? 0 									\
    : ((riscv_abi == ABI_ILP32F || riscv_abi == ABI_LP64F) ? 4 : 8))
 
@@ -187,10 +187,15 @@ ASM_MISA_SPEC
 
 /* The smallest supported stack boundary the calling convention supports.  */
 #define STACK_BOUNDARY \
-  (riscv_abi == ABI_ILP32E ? BITS_PER_WORD : 2 * BITS_PER_WORD)
+  (riscv_abi == ABI_ILP32E || riscv_abi == ABI_LP64E \
+   ? BITS_PER_WORD \
+   : 2 * BITS_PER_WORD)
 
 /* The ABI stack alignment.  */
-#define ABI_STACK_BOUNDARY (riscv_abi == ABI_ILP32E ? BITS_PER_WORD : 128)
+#define ABI_STACK_BOUNDARY \
+  (riscv_abi == ABI_ILP32E || riscv_abi == ABI_LP64E \
+   ? BITS_PER_WORD \
+   : 128)
 
 /* There is no point aligning anything to a rounder boundary than this.  */
 #define BIGGEST_ALIGNMENT 128
@@ -634,7 +639,10 @@ enum reg_class
 #define GP_RETURN GP_ARG_FIRST
 #define FP_RETURN (UNITS_PER_FP_ARG == 0 ? GP_RETURN : FP_ARG_FIRST)
 
-#define MAX_ARGS_IN_REGISTERS (riscv_abi == ABI_ILP32E ? 6 : 8)
+#define MAX_ARGS_IN_REGISTERS \
+  (riscv_abi == ABI_ILP32E || riscv_abi == ABI_LP64E \
+   ? 6 \
+   : 8)
 
 /* Symbolic macros for the first/last argument registers.  */
 
@@ -1044,6 +1052,7 @@ extern poly_int64 riscv_v_adjust_bytesize (enum machine_mode, int);
   "%{mabi=ilp32f:ilp32f}" \
   "%{mabi=ilp32d:ilp32d}" \
   "%{mabi=lp64:lp64}" \
+  "%{mabi=lp64e:lp64e}" \
   "%{mabi=lp64f:lp64f}" \
   "%{mabi=lp64d:lp64d}" \
 

gcc/config/riscv/riscv.opt

@@ -64,6 +64,9 @@ Enum(abi_type) String(ilp32d) Value(ABI_ILP32D)
 EnumValue
 Enum(abi_type) String(lp64) Value(ABI_LP64)
 
+EnumValue
+Enum(abi_type) String(lp64e) Value(ABI_LP64E)
+
 EnumValue
 Enum(abi_type) String(lp64f) Value(ABI_LP64F)
 

gcc/doc/invoke.texi

@@ -28936,9 +28936,10 @@ conventions are: @samp{ilp32}, @samp{ilp32f}, @samp{ilp32d}, @samp{lp64},
 @samp{lp64f}, and @samp{lp64d}.  Some calling conventions are impossible to
 implement on some ISAs: for example, @samp{-march=rv32if -mabi=ilp32d} is
 invalid because the ABI requires 64-bit values be passed in F registers, but F
-registers are only 32 bits wide.  There is also the @samp{ilp32e} ABI that can
-only be used with the @samp{rv32e} architecture.  This ABI is not well
-specified at present, and is subject to change.
+registers are only 32 bits wide.  There are also the @samp{ilp32e} ABI that can
+only be used with the @samp{rv32e} architecture and @samp{lp64e} ABI that can
+only be used with the @samp{rv64e}.  Those ABI are not well specified at
+present, and is subject to change.
 
 @opindex mfdiv
 @item -mfdiv