+ Relative pointers
+
+ Several pointer fields in info tables are expressed as offsets
+ relative to the info pointer, so that we can generate
+ position-independent code.
+
+ There is a complication on the x86_64 platform, where pointeres are
+ 64 bits, but the tools don't support 64-bit relative relocations.
+ However, the default memory model (small) ensures that all symbols
+ have values in the lower 2Gb of the address space, so offsets all
+ fit in 32 bits. Hence we can use 32-bit offset fields.
+ ------------------------------------------------------------------------- */
+
+#if x86_64_TARGET_ARCH
+#define OFFSET_FIELD(n) StgHalfInt n; StgHalfWord __pad_##n;
+#else
+#define OFFSET_FIELD(n) StgInt n;
+#endif
+
+/* ----------------------------------------------------------------------------