Re: entryval tail call frames $sp adjustment vs. gdbarches [Re: New ARI warning Thu Oct 13 01:55:36 UTC 2011]

[Jan Kratochvil <jan dot kratochvil at redhat dot com>]

On Wed, 19 Oct 2011 17:51:45 +0200, Ulrich Weigand wrote:
> It's just that some of those assumptions seem really unnecessary to me.
> For example, the assumption that there is a fixed "PC" register:
> 
>       prev_gdbarch = frame_unwind_arch (this_frame);
>       pc_regnum = gdbarch_pc_regnum (prev_gdbarch);
>       if (pc_regnum == -1)
>         break;
> 
>       /* Simulate frame_unwind_pc without setting this_frame->prev_pc.p.  */
>       prev_pc = frame_unwind_register_unsigned (this_frame, pc_regnum);
> 
> Why don't you just do something like:
> 
>       prev_gdbarch = frame_unwind_arch (this_frame);
> 
>       /* Simulate frame_unwind_pc without setting this_frame->prev_pc.p.  */
>       prev_pc = gdbarch_unwind_pc (prev_gdbarch, this_frame);

I agree with this simplification, used it.


> Yes, dwarf2_frame_cfa would be preferable here.

Also I agree.  Checked in both changes.

No regressions on {x86_64,x86_64-m32,i686}-fedora16pre-linux-gnu.


Thanks,
Jan


http://sourceware.org/ml/gdb-cvs/2011-10/msg00156.html

--- src/gdb/ChangeLog	2011/10/20 23:12:59	1.13448
+++ src/gdb/ChangeLog	2011/10/20 23:57:23	1.13449
@@ -1,3 +1,12 @@
+2011-10-20  Jan Kratochvil  <jan.kratochvil@redhat.com>
+	    Ulrich Weigand  <uweigand@de.ibm.com>
+
+	* dwarf2-frame-tailcall.c: Include dwarf2-frame.h.
+	(dwarf2_tailcall_prev_register_first): Use dwarf2_frame_cfa.
+	(dwarf2_tailcall_sniffer_first): Remove variable pc_regnum.  Replace
+	gdbarch_pc_regnum and frame_unwind_register_unsigned by
+	gdbarch_unwind_pc.
+
 2011-10-20  Cary Coutant  <ccoutant@google.com>
 
 	* dwarf2read.c (dw2_get_file_names): Move adjustment for type
--- src/gdb/dwarf2-frame-tailcall.c	2011/10/09 20:21:48	1.1
+++ src/gdb/dwarf2-frame-tailcall.c	2011/10/20 23:57:23	1.2
@@ -29,6 +29,7 @@
 #include "gdbtypes.h"
 #include "regcache.h"
 #include "value.h"
+#include "dwarf2-frame.h"
 
 /* Contains struct tailcall_cache indexed by next_bottom_frame.  */
 static htab_t cache_htab;
@@ -280,7 +281,7 @@
       if (next_levels == cache->chain_levels - 1)
 	addr = cache->prev_sp;
       else
-	addr = get_frame_base (this_frame) - cache->entry_cfa_sp_offset;
+	addr = dwarf2_frame_cfa (this_frame) - cache->entry_cfa_sp_offset;
     }
   else
     return NULL;
@@ -380,15 +381,12 @@
   /* Catch any unwinding errors.  */
   TRY_CATCH (except, RETURN_MASK_ERROR)
     {
-      int pc_regnum, sp_regnum;
+      int sp_regnum;
 
       prev_gdbarch = frame_unwind_arch (this_frame);
-      pc_regnum = gdbarch_pc_regnum (prev_gdbarch);
-      if (pc_regnum == -1)
-	break;
 
       /* Simulate frame_unwind_pc without setting this_frame->prev_pc.p.  */
-      prev_pc = frame_unwind_register_unsigned (this_frame, pc_regnum);
+      prev_pc = gdbarch_unwind_pc (prev_gdbarch, this_frame);
 
       /* call_site_find_chain can throw an exception.  */
       chain = call_site_find_chain (prev_gdbarch, prev_pc, this_pc);