split dwarf2_fetch_cfa_info from dwarf2_compile_expr_to_ax

This removes dwarf2_compile_expr_to_ax, replacing it with a utility
function that fetches the CFA data and adding the code to actually
compile to an agent expression directly into
dwarf2_compile_expr_to_ax.  This refactoring lets a later patch reuse
the new dwarf2_fetch_cfa_info.

gdb/ChangeLog
2014-12-12  Tom Tromey  <tromey@redhat.com>

	* dwarf2loc.c (dwarf2_compile_expr_to_ax) <DW_OP_call_frame_cfa>:
	Update.
	* dwarf2-frame.c (dwarf2_fetch_cfa_info): New function, based on
	dwarf2_compile_cfa_to_ax.
	(dwarf2_compile_cfa_to_ax): Remove.
	* dwarf2-frame.h (dwarf2_fetch_cfa_info): Declare.
	(dwarf2_compile_cfa_to_ax): Remove.

1 files changed, 21 insertions, 10 deletions

diff --git a/gdb/dwarf2-frame.h b/gdb/dwarf2-frame.h
index 0470cac..5ccf0c8 100644
--- a/gdb/dwarf2-frame.h
+++ b/gdb/dwarf2-frame.h
@@ -120,15 +120,26 @@ extern const struct frame_base *
 
 CORE_ADDR dwarf2_frame_cfa (struct frame_info *this_frame);
 
-/* Update the agent expression EXPR with code to compute the CFA for a
-   frame at PC.  GDBARCH is the architecture of the function at PC.
-   This function may call dwarf2_compile_expr_to_ax; DATA is passed
-   through to that function if needed.  */
-
-extern void dwarf2_compile_cfa_to_ax (struct agent_expr *expr,
-				      struct axs_value *loc,
-				      struct gdbarch *gdbarch,
-				      CORE_ADDR pc,
-				      struct dwarf2_per_cu_data *data);
+/* Find the CFA information for PC.
+
+   Return 1 if a register is used for the CFA, or 0 if another
+   expression is used.  Throw an exception on error.
+
+   GDBARCH is the architecture to use.
+   DATA is the per-CU data.
+
+   REGNUM_OUT is an out parameter that is set to the register number.
+   OFFSET_OUT is the offset to use from this register.
+   These are only filled in when 1 is returned.
+
+   TEXT_OFFSET_OUT, CFA_START_OUT, and CFA_END_OUT describe the CFA
+   in other cases.  These are only used when 0 is returned.  */
+
+extern int dwarf2_fetch_cfa_info (struct gdbarch *gdbarch, CORE_ADDR pc,
+				  struct dwarf2_per_cu_data *data,
+				  int *regnum_out, LONGEST *offset_out,
+				  CORE_ADDR *text_offset_out,
+				  const gdb_byte **cfa_start_out,
+				  const gdb_byte **cfa_end_out);
 
 #endif /* dwarf2-frame.h */