loong64: add the mapping of platform instruction JIRL to plan9 instru…

…ction RET

Change-Id: Ifec777b10bc9a5a8e5e9b4fd6bd2077205ad4151
Reviewed-on: https://go-review.googlesource.com/c/arch/+/609495
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
Reviewed-by: abner chenc <chenguoqi@loongson.cn>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Qiqi Huang <huangqiqi@loongson.cn>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>

loong64/loong64asm/inst.go

@@ -40,7 +40,9 @@ func (i Inst) String() string {
 		}
 
 	case JIRL:
-		if i.Args[0].(Reg) == R0 && i.Args[2].(OffsetSimm).Imm == 0 {
+		if i.Args[0].(Reg) == R0 && i.Args[1].(Reg) == R1 && i.Args[2].(OffsetSimm).Imm == 0 {
+			return "ret"
+		} else if i.Args[0].(Reg) == R0 && i.Args[2].(OffsetSimm).Imm == 0 {
 			return "jr " + args[1]
 		}
 

loong64/loong64asm/plan9x.go

@@ -96,8 +96,13 @@ func GoSyntax(inst Inst, pc uint64, symname func(uint64) (string, uint64)) strin
 		rd := inst.Args[0].(Reg)
 		rj := inst.Args[1].(Reg)
 		regno := uint16(rj) & 31
-		if rd == R0 {
+		off := inst.Args[2].(OffsetSimm).Imm
+		if rd == R0 && rj == R1 && off == 0 {
+			return fmt.Sprintf("RET")
+		} else if rd == R0 && off == 0 {
 			return fmt.Sprintf("JMP (R%d)", regno)
+		} else if rd == R0 {
+			return fmt.Sprintf("JMP %d(R%d)", off, regno)
 		}
 		return fmt.Sprintf("CALL (R%d)", regno)
 

loong64/loong64asm/testdata/gnucases.txt

@@ -253,6 +253,8 @@ ac154806|	iocsrwr.h $t0, $t1
 ac194806|	iocsrwr.w $t0, $t1
 ac1d4806|	iocsrwr.d $t0, $t1
 82b54906|	invtlb 0x2, $t0, $t1
+2000004c|	ret
+2008004c|	jirl $zero, $ra, 8
 ac11004c|	jirl $t0, $t1, 16
 ac410028|	ld.b $t0, $t1, 16
 ac41002a|	ld.bu $t0, $t1, 16

loong64/loong64asm/testdata/plan9cases.txt

@@ -119,6 +119,8 @@ a0110058|	BEQ R13, 4(PC)
 47d5ff6f|	BGEU R10, R7, -11(PC)
 802c006c|	BGEU R4, 11(PC)
 04d8ff67|	BLEZ R4, -10(PC)
+2000004c|	RET
+2008004c|	JMP 8(R1)
 00040058|	JMP 1(PC)
 8000004c|	JMP (R4)
 00340050|	JMP 13(PC)