gdb: Add guess_tracepoint_registers hook to gdbarch.

When we're looking at a tracefile trace frame where registers are not
available, and the tracepoint has only one location, we supply
the location's address as the PC register.  However, this only works
if PC is not a pseudo register, and individual architectures may want
to guess more registers.  Add a gdbarch hook that will handle that.

gdb/ChangeLog:

	* arch-utils.c (default_guess_tracepoint_registers): New function.
	* arch-utils.h (default_guess_tracepoint_registers): New prototype.
	* gdbarch.c: Regenerate.
	* gdbarch.h: Regenerate.
	* gdbarch.sh: Add guess_tracepoint_registers hook.
	* tracefile.c (tracefile_fetch_registers): Use the new gdbarch hook.

1 files changed, 23 insertions, 0 deletions

diff --git a/gdb/arch-utils.c b/gdb/arch-utils.c
index fe64627..c3d7802 100644
--- a/gdb/arch-utils.c
+++ b/gdb/arch-utils.c
@@ -897,6 +897,29 @@ default_addressable_memory_unit_size (struct gdbarch *gdbarch)
   return 1;
 }
 
+void
+default_guess_tracepoint_registers (struct gdbarch *gdbarch,
+				    struct regcache *regcache,
+				    CORE_ADDR addr)
+{
+  int pc_regno = gdbarch_pc_regnum (gdbarch);
+  gdb_byte *regs;
+
+  /* This guessing code below only works if the PC register isn't
+     a pseudo-register.  The value of a pseudo-register isn't stored
+     in the (non-readonly) regcache -- instead it's recomputed
+     (probably from some other cached raw register) whenever the
+     register is read.  In this case, a custom method implementation
+     should be used by the architecture.  */
+  if (pc_regno < 0 || pc_regno >= gdbarch_num_regs (gdbarch))
+    return;
+
+  regs = (gdb_byte *) alloca (register_size (gdbarch, pc_regno));
+  store_unsigned_integer (regs, register_size (gdbarch, pc_regno),
+			  gdbarch_byte_order (gdbarch), addr);
+  regcache_raw_supply (regcache, pc_regno, regs);
+}
+
 /* -Wmissing-prototypes */
 extern initialize_file_ftype _initialize_gdbarch_utils;