+/* Now that SPARC has precise GENCGC, several places that used to be
+ * #ifdef PCC need adjustment. Clearly, "PPC or SPARC" is as unhelpful
+ * a test as its reverse, "x86 or x86-64". However, the feature
+ * commonly used to differentiate between those two worlds is
+ * C_STACK_IS_CONTROL_STACK, and clearly (or at least in my humble
+ * opinion), at some point we'd like to have precise GC on x86 while
+ * still sharing the C stack, so stack usage ought not imply GC
+ * conservativeness. So let's have a helper feature that makes the code
+ * a bit more future-proof, even if it is itself currently defined in
+ * the naive way: */
+#if defined(LISP_FEATURE_GENCGC) && !defined(LISP_FEATURE_C_STACK_IS_CONTROL_STACK)
+# define GENCGC_IS_PRECISE 1
+#endif
+