Re: PING: [RFA] Runtime Dwarf2 CFI engine cleanup

[Michal Ludvig <mludvig@suse.cz>]

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Michal Ludvig wrote:
> Daniel Jacobowitz wrote:
> 
>> In any case I am withdrawing my attempt to be helpful, since obviously
>> I'm being pushy again instead of helpful.  Michal can go back to
>> waiting for someone else's response since my "help" has obviously
>> injured the entire process.
> 
> Thank you very much, anyway! You at least attempted to solve this issue.
> Other "responsible" maintainers didn't bother to respond until you 
> approved my patch. Then Andrew felt he should step in, revert your 
> approval and say NO (why there doesn't come a *constructive* critique 
> along with your no, Andrew?). And Elena - apparently the only one who 
> could say yes - disappeared... Sigh.
> 
> I'm asking once again:
> - Can I *at* *least* commit the dwarf2cfi.c part? Without the infcmd.c 
> hook? I know it duplicates the solib cleaner logic, but is that a 
> showstopper?
> - Ad run_command() hook - would something like this be acceptable?
> 
> Index: config/i386/tm-x86-64linux.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/config/i386/tm-x86-64linux.h,v
> retrieving revision 1.1
> diff -u -p -r1.1 tm-x86-64linux.h
> --- config/i386/tm-x86-64linux.h        1 Jul 2002 22:09:52 -0000       1.1
> +++ config/i386/tm-x86-64linux.h        27 Feb 2003 08:02:50 -0000
> @@ -33,4 +33,6 @@
>  #define SVR4_SHARED_LIBS
>  #include "solib.h"              /* Support for shared libraries. */
> 
> +#define DWARF2CFI_USED
> +
>  #endif /* #ifndef TM_X86_64LINUX_H */
> Index: infcmd.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/infcmd.c,v
> retrieving revision 1.54.6.2
> diff -u -p -r1.54.6.2 infcmd.c
> --- infcmd.c    25 Sep 2002 20:43:21 -0000      1.54.6.2
> +++ infcmd.c    27 Feb 2003 08:02:50 -0000
> @@ -390,6 +390,10 @@ Start it from the beginning? "))
> 
>    clear_breakpoint_hit_counts ();
> 
> +#if defined(DWARF2CFI_USED)
> +  cleanup_cfi ();
> +#endif
> +
>    /* Purge old solib objfiles. */
>    objfile_purge_solibs ();
> 
> Every target that will use the CFI engine will just add one define to 
> their tm.h. No need to link dwarf2cfi.o to all targets.

I've extended this approach a little bit. Now it's enough to define 
USED_DWARF2CFI=1 in config/arch/target.mh file and everything will be 
configured automatically, ie. dwarf2cfi.o will be added to the list of 
files to compile and -DUSED_DWARF2CFI=1 will be added to CFLAGS.
So only those targets that explicitly say "Yes, I want CFI engine" will 
have it and the run_command cleanup hook will go in for them as well.

Is this a way to go?

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

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2003-02-27  Michal Ludvig  <mludvig@suse.cz>

	* config/i386/x86-64linux.mt (TDEPFILES): Remove dwarf2cfi.o
	(USED_DWARF2CFI): New define.
	* Makefile.in: Handle USED_DWARF2CFI define.
	* infcmd.c (run_command): Add cleanup_cfi() if USED_DWARF2CFI
	is defined.
	* dwarf2cfi.c (struct cie_unit): New fields keep, refs.
	(cleanup_cfi): New function.

Index: config/i386/x86-64linux.mt
===================================================================
RCS file: /cvs/src/src/gdb/config/i386/x86-64linux.mt,v
retrieving revision 1.5
diff -u -p -r1.5 x86-64linux.mt
--- config/i386/x86-64linux.mt	1 Jul 2002 22:09:52 -0000	1.5
+++ config/i386/x86-64linux.mt	27 Feb 2003 10:01:03 -0000
@@ -1,7 +1,9 @@
 # Target: AMD x86-64 running GNU/Linux
-TDEPFILES= x86-64-tdep.o x86-64-linux-tdep.o dwarf2cfi.o \
+TDEPFILES= x86-64-tdep.o x86-64-linux-tdep.o \
 	solib.o solib-svr4.o solib-legacy.o
 
 GDB_MULTI_ARCH=GDB_MULTI_ARCH_TM
 
 TM_FILE=tm-x86-64linux.h
+
+USED_DWARF2CFI=1
Index: Makefile.in
===================================================================
RCS file: /cvs/src/src/gdb/Makefile.in,v
retrieving revision 1.257.2.5
diff -u -p -r1.257.2.5 Makefile.in
--- Makefile.in	25 Nov 2002 22:05:38 -0000	1.257.2.5
+++ Makefile.in	27 Feb 2003 10:01:03 -0000
@@ -414,6 +414,12 @@ ANNOTATE_OBS = annotate.o
 @target_makefile_frag@
 # End of host and target-dependent makefile fragments
 
+# Make a list of linked files depending on target's defines.
+ifeq ($(USED_DWARF2CFI), 1)
+	TDEPFILES+=dwarf2cfi.o
+	CFLAGS+=-DUSED_DWARF2CFI
+endif
+
 # Possibly ignore the simulator.  If the simulator is being ignored, 
 # these expand into SIM= and SIM_OBJ=, overriding the entries from 
 # target_makefile_frag
Index: infcmd.c
===================================================================
RCS file: /cvs/src/src/gdb/infcmd.c,v
retrieving revision 1.54.6.2
diff -u -p -r1.54.6.2 infcmd.c
--- infcmd.c	25 Sep 2002 20:43:21 -0000	1.54.6.2
+++ infcmd.c	27 Feb 2003 10:01:03 -0000
@@ -390,6 +390,10 @@ Start it from the beginning? "))
 
   clear_breakpoint_hit_counts ();
 
+#if defined(USED_DWARF2CFI)
+  cleanup_cfi ();
+#endif
+
   /* Purge old solib objfiles. */
   objfile_purge_solibs ();
 
Index: dwarf2cfi.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2cfi.c,v
retrieving revision 1.16.6.1
diff -u -p -r1.16.6.1 dwarf2cfi.c
--- dwarf2cfi.c	3 Feb 2003 14:40:09 -0000	1.16.6.1
+++ dwarf2cfi.c	27 Feb 2003 10:01:04 -0000
@@ -54,6 +54,12 @@ struct cie_unit
 
   /* Next in chain.  */
   struct cie_unit *next;
+
+  /* Keep or destroy this CIE on new run? */
+  int keep;
+
+  /* How many FDEs refer to this CIE? */
+  int refs;
 };
 
 /* Frame Description Entry.  */
@@ -319,6 +260,90 @@ frame_state_alloc (void)
   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
 unwind_tmp_obstack_init (void)
 {