cmd/internal/obj/arm64: fix assemble hlt/hvc/smc/brk/clrex bug

When instruction has only one argument, Go parser saves the
argument value into prog.From without any special handling.
But assembler gets the argument value from prog.To.

The fix adds special handling for CLREX and puts other instructions
arguments value into prog.From.

Uncomment hlt/hvc/smc/brk/dcps1/dcps2/dcps3/clrex test cases.

Fixes #20765

Change-Id: I1fc0d2faafb19b537cab5a665bd4af56c3a2c925
Reviewed-on: https://go-review.googlesource.com/78275
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

src/cmd/asm/internal/asm/testdata/arm64enc.s

@@ -57,7 +57,7 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$-8
    CALL -1(PC)                                // ffffff97
    CALL (R15)                                 // e0013fd6
    JMP  (R29)                                 // a0031fd6
-   // BRK $35943                              // e08c31d4
+   BRK $35943                                 // e08c31d4
    CBNZW R2, -1(PC)                           // e2ffff35
    CBNZ R7, -1(PC)                            // e7ffffb5
    CBZW R15, -1(PC)                           // efffff34
@@ -81,8 +81,8 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$-8
    CINVW EQ, R2, R17                          // 5110825a
    CINV VS, R12, R7                           // 87718cda
    CINV VS, R30, R30                          // de739eda
-   // CLREX $4                                // 5f3403d5
-   // CLREX $0                                // 5f3003d5
+   CLREX $4                                   // 5f3403d5
+   CLREX $0                                   // 5f3003d5
    CLSW R15, R6                               // e615c05a
    CLS R15, ZR                                // ff15c0da
    CLZW R1, R14                               // 2e10c05a
@@ -128,9 +128,9 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$-8
    CSNEGW HS, R16, R29, R10                   // 0a269d5a
    CSNEG NE, R21, R18, R11                    // ab1692da
    //TODO DC
-   // DCPS1 $11378                            // 418ea5d4
-   // DCPS2 $10699                            // 6239a5d4
-   // DCPS3 $24415                            // e3ebabd4
+   DCPS1 $11378                               // 418ea5d4
+   DCPS2 $10699                               // 6239a5d4
+   DCPS3 $24415                               // e3ebabd4
    DMB $1                                     // bf3103d5
    DMB $0                                     // bf3003d5
    DRPS                                       // e003bfd6
@@ -145,8 +145,8 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$-8
    EXTR $35, R22, R12, R8                     // 888dd693
    SEVL                                       // bf2003d5
    HINT $6                                    // df2003d5
-   // HLT $65509                              // a0fc5fd4
-   // HVC $61428                              // 82fe1dd4
+   HLT $65509                                 // a0fc5fd4
+   HVC $61428                                 // 82fe1dd4
    ISB $1                                     // df3103d5
    ISB $15                                    // df3f03d5
    LDARW (R12), R29                           // 9dfddf88
@@ -304,7 +304,7 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$-8
    SMNEGL R26, R3, R15                        // 6ffc3a9b
    SMULH R17, R21, R21                        // b57e519b
    SMULL R0, R5, R0                           // a07c209b
-   // SMC $37977                              // 238b12d4
+   SMC $37977                                 // 238b12d4
    STLRW R16, (R22)                           // d0fe9f88
    STLR R3, (R24)                             // 03ff9fc8
    //TODO STLRB R11, (R22)                    // cbfe9f08

src/cmd/internal/obj/arm64/asm7.go

@@ -271,7 +271,7 @@ var optab = []Optab{
 	{ALSL, C_VCON, C_NONE, C_REG, 8, 4, 0, 0, 0},
 	{ALSL, C_REG, C_NONE, C_REG, 9, 4, 0, 0, 0},
 	{ALSL, C_REG, C_REG, C_REG, 9, 4, 0, 0, 0},
-	{ASVC, C_NONE, C_NONE, C_VCON, 10, 4, 0, 0, 0},
+	{ASVC, C_VCON, C_NONE, C_NONE, 10, 4, 0, 0, 0},
 	{ASVC, C_NONE, C_NONE, C_NONE, 10, 4, 0, 0, 0},
 	{ADWORD, C_NONE, C_NONE, C_VCON, 11, 8, 0, 0, 0},
 	{ADWORD, C_NONE, C_NONE, C_LEXT, 11, 8, 0, 0, 0},
@@ -1914,8 +1914,8 @@ func buildop(ctxt *obj.Link) {
 			break
 
 		case ASVC:
-			oprangeset(AHLT, t)
 			oprangeset(AHVC, t)
+			oprangeset(AHLT, t)
 			oprangeset(ASMC, t)
 			oprangeset(ABRK, t)
 			oprangeset(ADCPS1, t)
@@ -2301,8 +2301,8 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 	case 10: /* brk/hvc/.../svc [$con] */
 		o1 = c.opimm(p, p.As)
 
-		if p.To.Type != obj.TYPE_NONE {
-			o1 |= uint32((p.To.Offset & 0xffff) << 5)
+		if p.From.Type != obj.TYPE_NONE {
+			o1 |= uint32((p.From.Offset & 0xffff) << 5)
 		}
 
 	case 11: /* dword */

src/cmd/internal/obj/arm64/obj7.go

@@ -813,7 +813,7 @@ var unaryDst = map[obj.As]bool{
 	ADWORD: true,
 	ABL:    true,
 	AB:     true,
-	ASVC:   true,
+	ACLREX: true,
 }
 
 var Linkarm64 = obj.LinkArch{