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Re: [RFA] Runtime Dwarf2 CFI engine cleanup


Elena Zannoni wrote:
Michal Ludvig writes:
> Hi all,
> the attached is a fix for the problem described here:
> http://sources.redhat.com/ml/gdb/2002-12/msg00246.html
> > I've created a new function cleanup_cfi() in dwarf2cfi.c that deletes > all CIEs and FDEs of objfiles removed later by objfile_purge_solibs().
> So far it works fine but I don't know how should I correctly call it.


I have tried your function, and it does fixes some weird errors which occur
on rerun.
I just tried by using the hack of defining GDB_TARGET_IS_X86_64, which
is definitely a bad thing.

I think that the best way is to define a gdbarch method, just like it
was done for gdbarch_dwarf2_build_frame_info.
How about adding dwarf2cfi.o to all targets? When there is for example mipsread.o compiled into gdb on x86-64 (why? because there is no option to say what features a given target needs.) than dwarf2cfi.o could go there as well...
I hope more and more targets will use it in the near future.

The attached is a version that adds dwarf2cfi.o for all targets. If it's unacceptable this way I'll provide gdbarch-ed version instead. But I think that gdbarch_*() functions are good for the case when on different targets a different functions are called to do a given task (eg. read register). But in this case you must call cleanup_cfi() in all targets that use CFI. No option. Calling it shouldn't depend on setting gdbarch value. Instead it should depend on linking dwarf2cfi.o into the gdb.

In the patch below, you cannot use printf's. Use printf_filtered. But
maybe, better yet, using a warning here would be more appropriate.
It isn't a warning, just an informational message. Now it's printed only when info_verbose is set.

Watch out for the non-GNU indentation and spacing.
Reindented.

OK to commit?

Michal Ludvig
--
* SuSE CR, s.r.o     * mludvig@suse.cz
* (+420) 296.545.373 * http://www.suse.cz
2003-02-10  Michal Ludvig  <mludvig@suse.cz>

	* dwarf2cfi.c (struct cie_unit): New items 'keep' and 'refs'.
	(cleanup_cfi): New function.
	* infcmd.c (run_command): Call cleanup_cfi().
	* Makefile.in: Link dwarf2cfi.[co] to all targets.
	* config/i386/x86-64linux.mt: Remove dwarf2cfi.o from
	TDEPFILES.

Index: dwarf2cfi.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
retrieving revision 1.31
diff -u -p -r1.31 dwarf2cfi.c
--- dwarf2cfi.c	10 Feb 2003 11:50:20 -0000	1.31
+++ dwarf2cfi.c	10 Feb 2003 12:10:21 -0000
@@ -64,6 +64,12 @@ struct cie_unit
 
   struct objfile *objfile;
 
+  /* Keep or destroy this CIE on new run? */
+  int keep;
+
+  /* How many FDEs refer to this CIE? */
+  int refs;
+
   /* Next in chain.  */
   struct cie_unit *next;
 };
@@ -289,6 +295,90 @@ frame_state_alloc (void)
     (struct frame_state_reg *) obstack_alloc (&unwind_tmp_obstack, regs_size);
   memset (fs->regs.reg, 0, regs_size);
   return fs;
+}
+
+void
+cleanup_cfi (void *name)
+{
+  struct objfile *ofp;
+  struct cie_unit *cie, *cie_prev;
+  int fde_index = 0, fde_free = 0;
+
+  cie = cie_chunks;
+  while (cie)
+    {
+      cie->refs = 0;
+      cie->keep = 0;
+      cie = cie->next;
+    }
+
+  /* Mark all unwanted CIEs. */
+  ALL_OBJFILES (ofp)
+  {
+    if (!(ofp->flags & OBJF_USERLOADED) && (ofp->flags & OBJF_SHARED))
+      {
+	if (info_verbose)
+	  printf_filtered ("\tRemoving %s...\n", ofp->name);
+      }
+    else
+      {
+	if (info_verbose)
+	  printf_filtered ("\tKeeping %s...\n", ofp->name);
+
+	cie = cie_chunks;
+	while (cie)
+	  {
+	    if (cie->objfile == ofp)
+	      cie->keep = 1;
+	    cie = cie->next;
+	  }
+      }
+  }
+
+  /* Remove all FDEs pointing to unwanted CIEs. */
+  for (fde_index = 0, fde_free = 0;
+       fde_index < fde_chunks.elems; fde_index++, fde_free++)
+    {
+      if (!fde_chunks.array[fde_index]->cie_ptr->keep)
+	{
+	  fde_free--;
+	  continue;
+	}
+      else if (fde_free < fde_index)
+	fde_chunks.array[fde_free] = fde_chunks.array[fde_index];
+      fde_chunks.array[fde_free]->cie_ptr->refs++;
+    }
+  fde_chunks.elems = fde_free;
+
+  /* Remove all unwanted CIEs. */
+  cie = cie_chunks;
+  cie_prev = NULL;
+  while (cie)
+    {
+      struct cie_unit *cie_tmp;
+
+      if (!cie->keep || !cie->refs)
+	{
+	  cie_tmp = cie;
+	  if (cie_prev == NULL)
+	    {
+	      cie_chunks = cie->next;
+	      cie = cie_chunks;
+	    }
+	  else
+	    {
+	      cie_prev->next = cie->next;
+	      cie = cie->next;
+	    }
+	  /* cie_prev must remain unchanged. */
+	  xfree (cie_tmp);
+	}
+      else
+	{
+	  cie_prev = cie;
+	  cie = cie->next;
+	}
+    }
 }
 
 static void
Index: infcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/infcmd.c,v
retrieving revision 1.72
diff -u -p -r1.72 infcmd.c
--- infcmd.c	1 Feb 2003 17:28:40 -0000	1.72
+++ infcmd.c	10 Feb 2003 12:10:21 -0000
@@ -401,6 +401,8 @@ Start it from the beginning? "))
 
   clear_breakpoint_hit_counts ();
 
+  cleanup_cfi ();
+
   /* Purge old solib objfiles. */
   objfile_purge_solibs ();
 
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.328
diff -u -p -r1.328 Makefile.in
--- Makefile.in	7 Feb 2003 05:33:44 -0000	1.328
+++ Makefile.in	10 Feb 2003 12:10:21 -0000
@@ -514,7 +514,7 @@ SFILES = ada-exp.y ada-lang.c ada-typepr
 	charset.c cli-out.c coffread.c complaints.c completer.c corefile.c \
 	cp-abi.c cp-support.c cp-valprint.c \
 	dbxread.c demangle.c disasm.c doublest.c \
-	dummy-frame.c dwarfread.c dwarf2read.c \
+	dummy-frame.c dwarfread.c dwarf2read.c dwarf2cfi.c \
 	elfread.c environ.c eval.c event-loop.c event-top.c expprint.c \
 	f-exp.y f-lang.c f-typeprint.c f-valprint.c findvar.c frame.c \
 	frame-unwind.c \
@@ -835,7 +835,7 @@ COMMON_OBS = version.o blockframe.o brea
 	gdb-events.o \
 	exec.o bcache.o objfiles.o minsyms.o maint.o demangle.o \
 	dbxread.o coffread.o elfread.o \
-	dwarfread.o dwarf2read.o mipsread.o stabsread.o corefile.o \
+	dwarfread.o dwarf2read.o dwarf2cfi.o mipsread.o stabsread.o corefile.o \
 	c-lang.o f-lang.o \
 	ui-out.o cli-out.o \
 	varobj.o wrapper.o \
Index: config/i386/x86-64linux.mt
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/x86-64linux.mt,v
retrieving revision 1.6
diff -u -p -r1.6 x86-64linux.mt
--- config/i386/x86-64linux.mt	21 Dec 2002 21:09:58 -0000	1.6
+++ config/i386/x86-64linux.mt	10 Feb 2003 12:10:21 -0000
@@ -1,6 +1,6 @@
 # Target: AMD x86-64 running GNU/Linux
-TDEPFILES= x86-64-tdep.o x86-64-linux-tdep.o dwarf2cfi.o \
-	i386-tdep.o i387-tdep.o \
+TDEPFILES= x86-64-tdep.o x86-64-linux-tdep.o \
+	i386-tdep.o i386-linux-tdep.o i387-tdep.o \
 	solib.o solib-svr4.o solib-legacy.o
 
 GDB_MULTI_ARCH=GDB_MULTI_ARCH_TM

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