cmd/internal/obj/loong64: Add preld{,x} instructions support

Go asm syntax:
	PRELD	16(R4), $8
	PRELDX	(R4)(R5), $8

Equivalent platform assembler syntax:
	preld	$8, $r4, 16
	preldx	$8, $r4, $r5

Change-Id: Ie81d22ebaf4153388a7e9d8fa0f618a0ae7a1c9f
Reviewed-on: https://go-review.googlesource.com/c/go/+/671875
Reviewed-by: sophie zhao <zhaoxiaolin@loongson.cn>
Reviewed-by: Meidan Li <limeidan@loongson.cn>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

Author: abner-chenc

src/cmd/asm/internal/arch/loong64.go

@@ -46,6 +46,14 @@ func IsLoong64RDTIME(op obj.As) bool {
 	return false
 }
 
+func IsLoong64PRELD(op obj.As) bool {
+	switch op {
+	case loong64.APRELD, loong64.APRELDX:
+		return true
+	}
+	return false
+}
+
 func IsLoong64AMO(op obj.As) bool {
 	return loong64.IsAtomicInst(op)
 }

src/cmd/asm/internal/asm/asm.go

@@ -654,6 +654,12 @@ func (p *Parser) asmInstruction(op obj.As, cond string, a []obj.Addr) {
 				prog.RegTo2 = a[1].Reg
 				break
 			}
+
+			if arch.IsLoong64PRELD(op) {
+				prog.From = a[0]
+				prog.AddRestSource(a[1])
+				break
+			}
 		}
 		prog.From = a[0]
 		prog.To = a[1]

src/cmd/asm/internal/asm/testdata/loong64enc1.s

@@ -1010,3 +1010,11 @@ lable2:
 	VFCLASSD	V1, V2		// 22d89c72
 	XVFCLASSF	X1, X2		// 22d49c76
 	XVFCLASSD	X1, X2		// 22d89c76
+
+	// PRELD{,X} instructions
+	PRELD	(R4), $0		// 8000c02a
+	PRELD	-1(R4), $8		// 88fcff2a
+	PRELD	8(R4),  $31		// 9f20c02a
+	PRELDX	(R4)(R5), $0		// 80142c38
+	PRELDX	(R4)(R6), $8		// 88182c38
+	PRELDX	(R4)(R7), $31		// 9f1c2c38

src/cmd/internal/obj/loong64/a.out.go

@@ -663,6 +663,10 @@ const (
 	ABSTRPICKW
 	ABSTRPICKV
 
+	// 2.2.5.4. Prefetch Instructions
+	APRELD
+	APRELDX
+
 	// 2.2.9. CRC Check Instructions
 	ACRCWBW
 	ACRCWHW

src/cmd/internal/obj/loong64/anames.go

@@ -412,6 +412,9 @@ var optab = []Optab{
 
 	{AVMOVQ, C_ELEM, C_NONE, C_NONE, C_ARNG, C_NONE, 45, 4, 0, 0},
 
+	{APRELD, C_SOREG, C_NONE, C_U5CON, C_NONE, C_NONE, 46, 4, 0, 0},
+	{APRELDX, C_ROFF, C_NONE, C_U5CON, C_NONE, C_NONE, 47, 4, 0, 0},
+
 	{obj.APCALIGN, C_U12CON, C_NONE, C_NONE, C_NONE, C_NONE, 0, 0, 0, 0},
 	{obj.APCDATA, C_32CON, C_NONE, C_NONE, C_32CON, C_NONE, 0, 0, 0, 0},
 	{obj.APCDATA, C_DCON, C_NONE, C_NONE, C_DCON, C_NONE, 0, 0, 0, 0},
@@ -1486,6 +1489,8 @@ func buildop(ctxt *obj.Link) {
 			ANEGW,
 			ANEGV,
 			AWORD,
+			APRELD,
+			APRELDX,
 			obj.ANOP,
 			obj.ATEXT,
 			obj.AFUNCDATA,
@@ -1907,6 +1912,10 @@ func OP_16IRR(op uint32, i uint32, r2 uint32, r3 uint32) uint32 {
 	return op | (i&0xFFFF)<<10 | (r2&0x1F)<<5 | (r3&0x1F)<<0
 }
 
+func OP_12IR_5I(op uint32, i1 uint32, r2 uint32, i2 uint32) uint32 {
+	return op | (i1&0xFFF)<<10 | (r2&0x1F)<<5 | (i2&0x1F)<<0
+}
+
 func OP_12IRR(op uint32, i uint32, r2 uint32, r3 uint32) uint32 {
 	return op | (i&0xFFF)<<10 | (r2&0x1F)<<5 | (r3&0x1F)<<0
 }
@@ -2444,6 +2453,17 @@ func (c *ctxt0) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		c.checkindex(p, index, m)
 		o1 = v | (index << 10) | (vj << 5) | vd
 
+	case 46:
+		// preld  offset(Rbase), hint
+		offs := c.regoff(&p.From)
+		hint := p.GetFrom3().Offset
+		o1 = OP_12IR_5I(c.opiir(p.As), uint32(offs), uint32(p.From.Reg), uint32(hint))
+
+	case 47:
+		// preldx (Rbase)(Roff), hint
+		hint := p.GetFrom3().Offset
+		o1 = OP_5IRR(c.opirr(p.As), uint32(p.From.Index), uint32(p.From.Reg), uint32(hint))
+
 	case 49:
 		if p.As == ANOOP {
 			// andi r0, r0, 0
@@ -3836,7 +3856,8 @@ func (c *ctxt0) opirr(a obj.As) uint32 {
 		return 0x12<<26 | 0x1<<8
 	case ABFPF:
 		return 0x12<<26 | 0x0<<8
-
+	case APRELDX:
+		return 0x07058 << 15 // preldx
 	case AMOVB,
 		AMOVBU:
 		return 0x0a4 << 22
@@ -4063,6 +4084,15 @@ func (c *ctxt0) opirir(a obj.As) uint32 {
 	return 0
 }
 
+func (c *ctxt0) opiir(a obj.As) uint32 {
+	switch a {
+	case APRELD:
+		return 0x0AB << 22 // preld
+	}
+
+	return 0
+}
+
 func (c *ctxt0) specialFpMovInst(a obj.As, fclass int, tclass int) uint32 {
 	switch a {
 	case AMOVV: