RE: [PATCH v4 2/4] gdb/symtab: add lookup for trampoline functions

["Ijaz, Abdul B" <abdul.b.ijaz@intel.com>]

Hi Tom,

Thanks for the feedback.

Tom> This can be done using 'adjust' rather than 'relocate' in the first patch, and by using the unrelocated_addr type rather than CORE_ADDR for storage.

Will be updated accordingly in V5 patch series.

Thanks & Best Regards
Abdul Basit

-----Original Message-----
From: Tom Tromey <tom@tromey.com> 
Sent: Wednesday, August 2, 2023 10:18 PM
To: Abdul Basit Ijaz via Gdb-patches <gdb-patches@sourceware.org>
Cc: Ijaz, Abdul B <abdul.b.ijaz@intel.com>; JiniSusan.George@amd.com; tom@tromey.com; eliz@gnu.org; blarsen@redhat.com; Nils-Christian Kempke <nils-christian.kempke@intel.com>
Subject: Re: [PATCH v4 2/4] gdb/symtab: add lookup for trampoline functions

>>>>> "Abdul" == Abdul Basit Ijaz via Gdb-patches <gdb-patches@sourceware.org> writes:

Abdul> From: Nils-Christian Kempke <nils-christian.kempke@intel.com> In 
Abdul> order to query information about the DW_AT_trampoline tag for 
Abdul> subroutines and inlined subroutines, two function were added to symtab.

Thanks for the patch.

Abdul> +CORE_ADDR
Abdul> +find_function_trampoline_target (CORE_ADDR pc) {
...
Abdul> +      else if (trampoline->target_kind () == TRAMPOLINE_TARGET_PHYSADDR)
Abdul> +	{
Abdul> +	  /* If the function symbol containing this trampoline target has
Abdul> +	     been relocated we assume the target_address also needs relocation.
Abdul> +	     If it has not been relocated the offset should be zero.  */
Abdul> +	  target_address
Abdul> +	    = (trampoline->target_physaddr ()
Abdul> +	       + sym->objfile ()->section_offsets[sym->section_index 
Abdul> +()]);

First, I'm all in favor of storing unrelocated addresses in data structures and then relocating them at point of use.

However, in this case, I think the stored address is already relocated.
From the previous patch:

+	  unrelocated_addr target_addr_reloc = attr->as_address ();
+	  CORE_ADDR target_addr
+	    = cu->per_objfile->relocate (target_addr_reloc);
+	  target_addr = gdbarch_adjust_dwarf2_addr (objfile->arch (),
+						    target_addr);
+	  TYPE_TRAMPOLINE_TARGET (ftype)->set_target_physaddr (target_addr);

... this brings up another issue, though -- if a relocated address is stored, then it must be relocated by objfile_relocate.

So perhaps storing the unrelocated address here really would be better.
This can be done using 'adjust' rather than 'relocate' in the first patch, and by using the unrelocated_addr type rather than CORE_ADDR for storage.

Tom
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