+\f
+
+/* Architecture-specific operations. */
+
+/* Per-architecture data key. */
+static struct gdbarch_data *dwarf2_frame_data;
+
+struct dwarf2_frame_ops
+{
+ /* Pre-initialize the register state REG for register REGNUM. */
+ void (*init_reg) (struct gdbarch *, int, struct dwarf2_frame_state_reg *);
+};
+
+/* Default architecture-specific register state initialization
+ function. */
+
+static void
+dwarf2_frame_default_init_reg (struct gdbarch *gdbarch, int regnum,
+ struct dwarf2_frame_state_reg *reg)
+{
+ /* If we have a register that acts as a program counter, mark it as
+ a destination for the return address. If we have a register that
+ serves as the stack pointer, arrange for it to be filled with the
+ call frame address (CFA). The other registers are marked as
+ unspecified.
+
+ We copy the return address to the program counter, since many
+ parts in GDB assume that it is possible to get the return address
+ by unwinding the program counter register. However, on ISA's
+ with a dedicated return address register, the CFI usually only
+ contains information to unwind that return address register.
+
+ The reason we're treating the stack pointer special here is
+ because in many cases GCC doesn't emit CFI for the stack pointer
+ and implicitly assumes that it is equal to the CFA. This makes
+ some sense since the DWARF specification (version 3, draft 8,
+ p. 102) says that:
+
+ "Typically, the CFA is defined to be the value of the stack
+ pointer at the call site in the previous frame (which may be
+ different from its value on entry to the current frame)."
+
+ However, this isn't true for all platforms supported by GCC
+ (e.g. IBM S/390 and zSeries). Those architectures should provide
+ their own architecture-specific initialization function. */
+
+ if (regnum == PC_REGNUM)
+ reg->how = DWARF2_FRAME_REG_RA;
+ else if (regnum == SP_REGNUM)
+ reg->how = DWARF2_FRAME_REG_CFA;
+}
+
+/* Return a default for the architecture-specific operations. */
+
+static void *
+dwarf2_frame_init (struct obstack *obstack)
+{
+ struct dwarf2_frame_ops *ops;
+
+ ops = OBSTACK_ZALLOC (obstack, struct dwarf2_frame_ops);
+ ops->init_reg = dwarf2_frame_default_init_reg;
+ return ops;
+}
+
+/* Set the architecture-specific register state initialization
+ function for GDBARCH to INIT_REG. */
+
+void
+dwarf2_frame_set_init_reg (struct gdbarch *gdbarch,
+ void (*init_reg) (struct gdbarch *, int,
+ struct dwarf2_frame_state_reg *))
+{
+ struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
+
+ ops->init_reg = init_reg;
+}
+
+/* Pre-initialize the register state REG for register REGNUM. */
+
+static void
+dwarf2_frame_init_reg (struct gdbarch *gdbarch, int regnum,
+ struct dwarf2_frame_state_reg *reg)
+{
+ struct dwarf2_frame_ops *ops = gdbarch_data (gdbarch, dwarf2_frame_data);
+
+ ops->init_reg (gdbarch, regnum, reg);
+}
+\f