cmd/internal/obj/arm64: add CASx/CASPx instructions

This patch adds support for CASx and CASPx atomic instructions.

  go syntax                 gnu syntax
CASD Rs, (Rn|RSP), Rt => cas Xs, Xt, (Xn|SP)
CASALW Rs, (Rn|RSP), Rt => casal Ws, Wt, (Xn|SP)
CASPD (Rs, Rs+1), (Rn|RSP), (Rt, Rt+1) => casp Xs, Xs+1, Xt, Xt+1, (Xn|SP)
CASPW (Rs, Rs+1), (Rn|RSP), (Rt, Rt+1) => casp Ws, Ws+1, Wt, Wt+1, (Xn|SP)

This patch changes the type of prog.RestArgs from "[]Addr" to
"[]struct{Addr, Pos}", Pos is a enum, indicating the position of
the operand.

This patch also adds test cases.

Change-Id: Ib971cfda7890b7aa895d17bab22dea326c7fcaa4
Reviewed-on: https://go-review.googlesource.com/c/go/+/233277
Trust: fannie zhang <Fannie.Zhang@arm.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

1 files changed, 12 insertions, 1 deletions

diff --git a/src/cmd/asm/internal/arch/arm64.go b/src/cmd/asm/internal/arch/arm64.go
index e643889aef..e557630ca6 100644
--- a/src/cmd/asm/internal/arch/arm64.go
+++ b/src/cmd/asm/internal/arch/arm64.go
@@ -75,7 +75,7 @@ func IsARM64STLXR(op obj.As) bool {
 		arm64.ASTXP, arm64.ASTXPW, arm64.ASTLXP, arm64.ASTLXPW:
 		return true
 	}
-	// atomic instructions
+	// LDADDx/SWPx/CASx atomic instructions
 	if arm64.IsAtomicInstruction(op) {
 		return true
 	}
@@ -93,6 +93,17 @@ func IsARM64TBL(op obj.As) bool {
 	return false
 }
 
+// IsARM64CASP reports whether the op (as defined by an arm64.A*
+// constant) is one of the CASP-like instructions, and its 2nd
+// destination is a register pair that require special handling.
+func IsARM64CASP(op obj.As) bool {
+	switch op {
+	case arm64.ACASPD, arm64.ACASPW:
+		return true
+	}
+	return false
+}
+
 // ARM64Suffix handles the special suffix for the ARM64.
 // It returns a boolean to indicate success; failure means
 // cond was unrecognized.