feat(asm): the operand forms and defines GOROOT writes

Assisted-by: GLM 5.3 Flash

parser/parser.go

@@ -489,6 +489,17 @@ func parseImmediate(g []token.Token) ast.Immediate {
 	} else if g[i].Kind == token.Plus {
 		i++
 	}
+	// A constant expression after the sign: $-(R - 8), $+(32-shift).  The
+	// toolchain folds the negated value in place (the cgo ABI macros write
+	// ADJSP $-(REGS_HOST_TO_ABI0_STACK - 8)), so the sign applies to the
+	// folded value exactly as it does to a bare literal.
+	if i < len(g) && (g[i].Kind == token.LParen || g[i].Kind == token.Tilde) {
+		if v, rest, ok := foldExpr(g[i:]); ok && len(rest) == 0 {
+			imm.Val = v
+			imm.HasVal = true
+			return imm
+		}
+	}
 	if i < len(g) && g[i].Kind == token.Number {
 		text := g[i].Text
 		if v, ok := tryInt(text); ok {