+Fri Oct 23 11:19:06 1998 Martin v. Löwis <loewis@informatik.hu-berlin.de>
+
+ * frame.c: Somewhat explain `FDE'.
+ Suggested by Brendan Kehoe
+
Fri Oct 23 00:56:11 1998 Jason Merrill <jason@yorick.cygnus.com>
* expr.c (pending_chain): Move up.
typedef int saddr __attribute__ ((mode (pointer)));
typedef unsigned char ubyte;
+/* Terminology:
+ CIE - Common Information Element
+ FDE - Frame Descriptor Element
+
+ There is one per function, and it describes where the function code
+ is located, and what the register lifetimes and stack layout are
+ within the function.
+
+ The data structures are defined in the DWARF specfication, although
+ not in a very readable way (see LITERATURE).
+
+ Every time an exception is thrown, the code needs to locate the FDE
+ for the current function, and starts to look for exception regions
+ from that FDE. This works in a two-level search:
+ a) in a linear search, find the shared image (i.e. DLL) containing
+ the PC
+ b) using the FDE table for that shared object, locate the FDE using
+ binary search (which requires the sorting). */
+
/* The first few fields of a CIE. The CIE_id field is 0 for a CIE,
to distinguish it from a valid FDE. FDEs are aligned to an addressing
unit boundary, but the fields within are unaligned. */