Re: [RFA] Runtime Dwarf2 CFI engine cleanup

Michal Ludvig
2003-02-10T12:30:36Z

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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