cmd/internal/obj/arm64: support MSR DIT

Set the right instruction bits in asmout in order to allow using MSR with DIT and an immediate value. This allows us to avoid using an intermediary register when we want to set DIT (unsetting DIT already worked with the zero register). Ref: https://developer.arm.com/documentation/ddi0602/2024-06/Base-Instructions/MSR--immediate---Move-immediate-value-to-special-register-?lang=en Change-Id: Id049a0b4e0feb534cea992553228f9b5e12ddcea Reviewed-on: https://go-review.googlesource.com/c/go/+/597595 LUCI-TryBot-Result: Go LUCI <[email protected]> Reviewed-by: Cherry Mui <[email protected]>
nqv · Jul 24, 2024 · b5c2b1e · b5c2b1e
1 parent c0eac35
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diff --git a/src/cmd/asm/internal/asm/testdata/arm64.s b/src/cmd/asm/internal/asm/testdata/arm64.s
@@ -1777,6 +1777,7 @@ next:
 	MSR	R17, ZCR_EL1                       // 111218d5
 	SYS	$32768, R1                         // 018008d5
 	SYS	$32768                             // 1f8008d5
+	MSR	$1, DIT                            // 5f4103d5
 
 // TLBI instruction
 	TLBI	VMALLE1IS                          // 1f8308d5

diff --git a/src/cmd/internal/obj/arm64/asm7.go b/src/cmd/internal/obj/arm64/asm7.go
@@ -4229,6 +4229,9 @@ func (c *ctxt7) asmout(p *obj.Prog, o *Optab, out []uint32) {
 		// PSTATEfield can be special registers and special operands.
 		if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_SPSel {
 			v = 0<<16 | 4<<12 | 5<<5
+		} else if p.To.Type == obj.TYPE_REG && p.To.Reg == REG_DIT {
+			// op1 = 011 (3) op2 = 010 (2)
+			v = 3<<16 | 2<<5
 		} else if p.To.Type == obj.TYPE_SPECIAL {
 			opd := SpecialOperand(p.To.Offset)
 			for _, pf := range pstatefield {