cmd/internal/obj/s390x: add MVCLE instruction

MVCLE (Move Long Extended) instruction is used to move large data storage-to-storage.
This change will add MVCLE into the Go asm for s390x architecture.
Upcoming PR of runtime/memmove_s390x.s will use this instruction for performance improvement.

Change-Id: I3bbb6668c736a36849917887398c74cebb1c3a99
Reviewed-on: https://go-review.googlesource.com/c/go/+/677455
Reviewed-by: Srinivas Pokala <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Auto-Submit: Michael Knyszek <[email protected]>
Reviewed-by: Keith Randall <[email protected]>
Reviewed-by: Michael Munday <[email protected]>
Reviewed-by: Vishwanatha HD <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>

Author: kmvijay

src/cmd/asm/internal/asm/testdata/s390x.s

@@ -263,10 +263,15 @@ TEXT main·foo(SB),DUPOK|NOSPLIT,$16-0 // TEXT main.foo(SB), DUPOK|NOSPLIT, $16-
 	NC	$8, (R15), n-8(SP)       // d407f010f000
 	OC	$8, (R15), n-8(SP)       // d607f010f000
 	MVC	$8, (R15), n-8(SP)       // d207f010f000
+	MVC	$256, 8192(R1), 8192(R2) // b90400a2c2a800002000b90400b1c2b800002000d2ffa000b000
 	MVCIN	$8, (R15), n-8(SP)       // e807f010f000
 	CLC	$8, (R15), n-8(SP)       // d507f000f010
 	XC	$256, -8(R15), -8(R15)   // b90400afc2a8fffffff8d7ffa000a000
-	MVC	$256, 8192(R1), 8192(R2) // b90400a2c2a800002000b90400b1c2b800002000d2ffa000b000
+	MVCLE   0, R4, R6                // a8640000
+	MVCLE   4095, R4, R6             // a8640fff
+	MVCLE   $4095, R4, R6            // a8640fff
+	MVCLE   (R3), R4, R6             // a8643000
+	MVCLE   10(R3), R4, R6           // a864300a
 
 	CMP	R1, R2                 // b9200012
 	CMP	R3, $32767             // a73f7fff

src/cmd/internal/obj/s390x/a.out.go

@@ -444,6 +444,7 @@ const (
 	// storage-and-storage
 	AMVC
 	AMVCIN
+	AMVCLE
 	ACLC
 	AXC
 	AOC

src/cmd/internal/obj/s390x/anames.go

@@ -449,6 +449,10 @@ var optab = []Optab{
 
 	// VRR-f
 	{i: 122, as: AVLVGP, a1: C_REG, a2: C_REG, a6: C_VREG},
+
+	// MVC storage and storage
+	{i: 127, as: AMVCLE, a1: C_LOREG, a2: C_REG, a6: C_REG},
+	{i: 127, as: AMVCLE, a1: C_SCON, a2: C_REG, a6: C_REG},
 }
 
 var oprange [ALAST & obj.AMask][]Optab
@@ -4453,6 +4457,24 @@ func (c *ctxtz) asmout(p *obj.Prog, asm *[]byte) {
 			}
 		}
 		zRRF(opcode, uint32(p.Reg), 0, uint32(p.From.Reg), uint32(p.To.Reg), asm)
+
+	case 127:
+		// NOTE: Mapping MVCLE operands is as follows:
+		// Instruction Format: MVCLE R1,R3,D2(B2)
+		// R1 - prog.To (for Destination)
+		// R3 - prog.Reg (for Source)
+		// B2 - prog.From (for Padding Byte)
+		d2 := c.regoff(&p.From)
+		if p.To.Reg&1 != 0 {
+			c.ctxt.Diag("output argument must be even register in %v", p)
+		}
+		if p.Reg&1 != 0 {
+			c.ctxt.Diag("input argument must be an even register in %v", p)
+		}
+		if (p.From.Reg == p.To.Reg) || (p.From.Reg == p.Reg) {
+			c.ctxt.Diag("padding byte register cannot be same as input or output register %v", p)
+		}
+		zRS(op_MVCLE, uint32(p.To.Reg), uint32(p.Reg), uint32(p.From.Reg), uint32(d2), asm)
 	}
 }