+#define bci_STKCHECK 26
+#define bci_JMP 27
+#define bci_CCALL 28
+#define bci_SWIZZLE 29
+
+/* If a BCO definitely requires less than this many words of stack,
+ don't include an explicit STKCHECK insn in it. The interpreter
+ will check for this many words of stack before running each BCO,
+ rendering an explicit check unnecessary in the majority of
+ cases. */
+#define INTERP_STACK_CHECK_THRESH 50