RISC-V: Support Zacas extension.

https://github.com/riscvarchive/riscv-zacas/releases/tag/v1.0

The Zacas extension introduce compare-and-swap instructions to operate
on 32-bit, 64-bit and 128-bit (RV64 only) data values.

It introduces three new instructions:
  - amocas.w (32-bit CAS)
  - amocas.d (64-bit CAS)
  - amocas.q (128-bit CAS, RV64 only)

Like other AMOs in the A extension, Zacas instructions have '.aq',
'.rl' and '.aqrl' variations.

bfd/ChangeLog:

	* elfxx-riscv.c (riscv_implicit_subsets): 'A' implied by 'Zacas'.
	(riscv_supported_std_z_ext): Add 'Zacas' extension.
	(riscv_multi_subset_supports, riscv_multi_subset_supports_ext):
	Handle INSN_CLASS_ZACAS case.

gas/ChangeLog:

	* NEWS: Updated.
	* testsuite/gas/riscv/march-help.l: Updated.
	* testsuite/gas/riscv/zacas-32.d: New test (RV32).
        * testsuite/gas/riscv/zacas-fail-32.d: Likewise.
	* testsuite/gas/riscv/zacas-64.d: New test (RV64).
        * testsuite/gas/riscv/zacas-fail-64.d: Likewise.
	* testsuite/gas/riscv/zacas.s: New test source.
	* testsuite/gas/riscv/zacas-fail.s: Likewise.
	* testsuite/gas/riscv/zacas-fail-32.l: New file.
	* testsuite/gas/riscv/zacas-fail-64.l: Likewise.

include/ChangeLog:

	* include/opcode/riscv.h (INSN_CLASS_ZACAS): New definition.
	* include/opcode/riscv-opc.h (MATCH_AMOCAS_W, MASK_AMOCAS_W)
	(MATCH_AMOCAS_D, MASK_AMOCAS_D, MATCH_AMOCAS_Q, MASK_AMOCAS_Q):
	Likewise.
	(amocas_w, amocas_d, amocas_q): Declare instructions.

opcodes/ChangeLog:

	* riscv-opc.c (match_rs2_rd_even): New function.
	(amocas_w, amocas_d, amocas_q, amocas_w.aq)
	(amocas_d.aq, amocas_q.aq, amocas_w.rl, amocas_d.rl, amocas_q.rl)
	(amocas_w.aqrl, amocas_d.aqrl, amocas_q.aqrl): Add instructions.

1 files changed, 26 insertions, 0 deletions

diff --git a/opcodes/riscv-opc.c b/opcodes/riscv-opc.c
index ff08bd5..e101c3d 100644
--- a/opcodes/riscv-opc.c
+++ b/opcodes/riscv-opc.c
@@ -198,6 +198,14 @@ match_rs1_eq_rs2 (const struct riscv_opcode *op, insn_t insn)
 }
 
 static int
+match_rs2_rd_even (const struct riscv_opcode *op, insn_t insn)
+{
+  int rs2 = (insn & MASK_RS2) >> OP_SH_RS2;
+  int rd = (insn & MASK_RD) >> OP_SH_RD;
+  return ((rs2 & 1) == 0) && ((rd & 1) == 0) && match_opcode (op, insn);
+}
+
+static int
 match_rd_nonzero (const struct riscv_opcode *op, insn_t insn)
 {
   return (op->pinfo == INSN_MACRO || match_opcode (op, insn))
@@ -748,6 +756,24 @@ const struct riscv_opcode riscv_opcodes[] =
 {"amomin.h.aqrl",   0, INSN_CLASS_ZABHA, "d,t,0(s)", MATCH_AMOMIN_H|MASK_AQRL, MASK_AMOMIN_H|MASK_AQRL, match_opcode, INSN_DREF|INSN_2_BYTE },
 {"amominu.h.aqrl",  0, INSN_CLASS_ZABHA, "d,t,0(s)", MATCH_AMOMINU_H|MASK_AQRL, MASK_AMOMINU_H|MASK_AQRL, match_opcode, INSN_DREF|INSN_2_BYTE },
 
+/* Zacas instruction subset.  */
+{"amocas.w",         0, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_W, MASK_AMOCAS_W|MASK_AQRL, match_opcode, INSN_DREF|INSN_4_BYTE },
+{"amocas.d",        32, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D, MASK_AMOCAS_D|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_8_BYTE },
+{"amocas.d",        64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D, MASK_AMOCAS_D|MASK_AQRL, match_opcode, INSN_DREF|INSN_8_BYTE },
+{"amocas.q",        64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_Q, MASK_AMOCAS_Q|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_16_BYTE },
+{"amocas.w.aq",      0, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_W|MASK_AQ, MASK_AMOCAS_W|MASK_AQRL, match_opcode, INSN_DREF|INSN_4_BYTE },
+{"amocas.d.aq",     32, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_AQ, MASK_AMOCAS_D|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_8_BYTE },
+{"amocas.d.aq",     64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_AQ, MASK_AMOCAS_D|MASK_AQRL, match_opcode, INSN_DREF|INSN_8_BYTE },
+{"amocas.q.aq",     64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_Q|MASK_AQ, MASK_AMOCAS_Q|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_16_BYTE },
+{"amocas.w.rl",      0, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_W|MASK_RL, MASK_AMOCAS_W|MASK_AQRL, match_opcode, INSN_DREF|INSN_4_BYTE },
+{"amocas.d.rl",     32, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_RL, MASK_AMOCAS_D|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_8_BYTE },
+{"amocas.d.rl",     64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_RL, MASK_AMOCAS_D|MASK_AQRL, match_opcode, INSN_DREF|INSN_8_BYTE },
+{"amocas.q.rl",     64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_Q|MASK_RL, MASK_AMOCAS_Q|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_16_BYTE },
+{"amocas.w.aqrl",    0, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_W|MASK_AQRL, MASK_AMOCAS_W|MASK_AQRL, match_opcode, INSN_DREF|INSN_4_BYTE },
+{"amocas.d.aqrl",   32, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_AQRL, MASK_AMOCAS_D|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_8_BYTE },
+{"amocas.d.aqrl",   64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_D|MASK_AQRL, MASK_AMOCAS_D|MASK_AQRL, match_opcode, INSN_DREF|INSN_8_BYTE },
+{"amocas.q.aqrl",   64, INSN_CLASS_ZACAS, "d,t,0(s)", MATCH_AMOCAS_Q|MASK_AQRL, MASK_AMOCAS_Q|MASK_AQRL, match_rs2_rd_even, INSN_DREF|INSN_16_BYTE },
+
 /* Multiply/Divide instruction subset.  */
 {"mul",        0, INSN_CLASS_ZCB_AND_ZMMUL, "Cs,Cw,Ct",  MATCH_C_MUL, MASK_C_MUL, match_opcode, INSN_ALIAS },
 {"mul",        0, INSN_CLASS_ZMMUL, "d,s,t",     MATCH_MUL, MASK_MUL, match_opcode, 0 },