RISC-V: Convert the ADD/ADDI to the compressed MV/LI if RS1 is zero.

2020-02-19  Nelson Chu  <nelson.chu@sifive.com>
	gas/
	* testsuite/gas/riscv/c-add-addi.d: New testcase.
	* testsuite/gas/riscv/c-add-addi.s: Likewise.
	opcodes/
	* riscv-opc.c (riscv_opcodes): Convert add/addi to the compressed
	c.mv/c.li if rs1 is zero.

Change-Id: Id939b5e6db80d267a832545f3ffef7b9ba881f7d

gas/ChangeLog

@@ -1,3 +1,8 @@
+2020-02-19  Nelson Chu  <nelson.chu@sifive.com>
+
+	* testsuite/gas/riscv/c-add-addi.d: New testcase.
+	* testsuite/gas/riscv/c-add-addi.s: Likewise.
+
 2020-02-19  Sergey Belyashov  <sergey.belyashov@gmail.com>
 
 	PR 25576

gas/testsuite/gas/riscv/c-add-addi.d

@@ -0,0 +1,11 @@
+#as:
+#objdump: -dr
+
+.*:[ 	]+file format .*
+
+
+Disassembly of section .text:
+
+0+000 <.text>:
+[ 	]+0:[ 	]+4605[ 	]+li[ 	]+a2,1
+[ 	]+2:[ 	]+852e[ 	]+mv[ 	]+a0,a1

gas/testsuite/gas/riscv/c-add-addi.s

@@ -0,0 +1,3 @@
+.option rvc
+addi a2, zero, 1
+add a0, zero, a1

opcodes/ChangeLog

@@ -1,3 +1,8 @@
+2020-02-19  Nelson Chu  <nelson.chu@sifive.com>
+
+	* riscv-opc.c (riscv_opcodes): Convert add/addi to the compressed
+	c.mv/c.li if rs1 is zero.
+
 2020-02-17  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* i386-gen.c (cpu_flag_init): Replace CpuABM with

opcodes/riscv-opc.c

@@ -269,12 +269,14 @@ const struct riscv_opcode riscv_opcodes[] =
 {"addi",        0, INSN_CLASS_C,   "d,CU,Cj",  MATCH_C_ADDI, MASK_C_ADDI, match_rd_nonzero, INSN_ALIAS },
 {"addi",        0, INSN_CLASS_C,   "d,CU,z",    MATCH_C_NOP, MASK_C_ADDI | MASK_RVC_IMM, match_c_nop, INSN_ALIAS },
 {"addi",        0, INSN_CLASS_C,   "Cc,Cc,CL", MATCH_C_ADDI16SP, MASK_C_ADDI16SP, match_c_addi16sp, INSN_ALIAS },
+{"addi",        0, INSN_CLASS_C,   "d,Cz,Co",  MATCH_C_LI, MASK_C_LI, match_rd_nonzero, INSN_ALIAS },
 {"addi",        0, INSN_CLASS_I,   "d,s,j",  MATCH_ADDI, MASK_ADDI, match_opcode, 0 },
 {"add",         0, INSN_CLASS_C,   "d,CU,CV",  MATCH_C_ADD, MASK_C_ADD, match_c_add, INSN_ALIAS },
 {"add",         0, INSN_CLASS_C,   "d,CV,CU",  MATCH_C_ADD, MASK_C_ADD, match_c_add, INSN_ALIAS },
 {"add",         0, INSN_CLASS_C,   "d,CU,Co",  MATCH_C_ADDI, MASK_C_ADDI, match_rd_nonzero, INSN_ALIAS },
 {"add",         0, INSN_CLASS_C,   "Ct,Cc,CK", MATCH_C_ADDI4SPN, MASK_C_ADDI4SPN, match_c_addi4spn, INSN_ALIAS },
 {"add",         0, INSN_CLASS_C,   "Cc,Cc,CL", MATCH_C_ADDI16SP, MASK_C_ADDI16SP, match_c_addi16sp, INSN_ALIAS },
+{"add",         0, INSN_CLASS_C,   "d,Cz,CV",  MATCH_C_MV, MASK_C_MV, match_c_add, INSN_ALIAS },
 {"add",         0, INSN_CLASS_I,   "d,s,t",  MATCH_ADD, MASK_ADD, match_opcode, 0 },
 /* This is used for TLS, where the fourth arg is %tprel_add, to get a reloc
    applied to an add instruction, for relaxation to use.  */