feat(asm): the segment-absolute and crash-store forms GOROOT writes

Assisted-by: GLM 5.3 Flash

parser/parser.go

@@ -684,6 +684,26 @@ func parseAddress(g []token.Token) ast.Address {
 	if i > 0 && i < len(g) {
 		addr.Shift = joinRaw(g[i:])
 	}
+	// A lone (possibly signed) number is an absolute address: MOVL $0xf1,
+	// 0xf1 stores through the bare displacement with no base at all.  In
+	// operand position a number without $ is an address, never a value.
+	if addr.Sym == nil && addr.Base == "" && addr.Index == "" && !addr.HasOff {
+		neg := false
+		j := 0
+		if j < len(g) && (g[j].Kind == token.Minus || g[j].Kind == token.Plus) {
+			neg = g[j].Kind == token.Minus
+			j++
+		}
+		if j == len(g)-1 && g[j].Kind == token.Number {
+			v := parseInt(g[j].Text)
+			if neg {
+				v = -v
+			}
+			addr.Offset = v
+			addr.HasOff = true
+			return addr
+		}
+	}
 	return addr
 }