Re: [RFA] Runtime Dwarf2 CFI engine cleanup

[Michal Ludvig <mludvig@suse.cz>]

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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

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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