Introduce find_function_entry_range_from_pc and use it in infrun.c
An earlier version of this patch used the returned block in conjunction with BLOCK_ENTRY_PC to set stop_func_start in fill_in_stop_func() in infrun.c. While I think this was the correct thing to do, changes to find_inferior_partial_function could potentially end up with stop_func_end < stop_func_start, which is definitely wrong. For this case, we want to set both stop_func_start and stop_func_end to the start and end of the range containing the function's entry pc. I think that this functionality will be useful in many other places too - it probably ought to be used in all of the various prologue analyzers in GDB. The change to infrun.c was simple: the call to find_pc_partial_function was replaced with a call to find_function_entry_range_from_pc. The difference between these two functions is that find_pc_partial_entry_function will (potentially) return the start and end address corresponding to the range in which PC is found, but find_function_entry_range_from_pc will (again, potentially) return the start and end address of the range containing the entry pc. find_pc_partial_function has the property that *ADDRESS <= PC < *ENDADDR. This condition does not necessarily hold for the outputs of find_function_entry_range_from_pc. It should be noted that for functions which contain only a single range, the outputs of find_pc_partial_function and find_function_entry_range_from_pc are identical. I think it might happen that find_function_entry_range_from_pc will come to be used in place of many of the calls to find_pc_partial_function within GDB. Care must be taken in making this change, however, since some of this code depends on the *ADDRESS <= PC < *ENDADDR property. Finally, a note regarding the name: I had initially chosen a different name with a find_pc_partial_ prefix, but Simon suggested the current name citing the goal of eventually making naming consistent using the form find_X_from_Y. In this case X is "function_entry_range" and Y is "pc". Both the name and rationale made sense to me, so that's how it came to be. gdb/ChangeLog: * infrun.c (fill_in_stop_func): Use find_function_entry_range_from_pc in place of find_pc_partial_function. * blockframe.c (find_function_entry_range_from_pc): New function. * symtab.h (find_function_entry_range_from_pc): Declare and document.
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