This is the mail archive of the
gdb-patches@sources.redhat.com
mailing list for the GDB project.
Re: [patch/rfa/hppa] Use frame pointer for unwinding
> What seems to be happening is that the signal handler is triggered
> before the frame pointer is stored in func1:
so, here's my 3rd try ;-)
2004-05-16 Randolph Chung <tausq@debian.org>
* hppa-tdep.c (hppa_frame_cache): If a frame pointer is available, use
it for unwinding the stack.
Index: hppa-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/hppa-tdep.c,v
retrieving revision 1.156
diff -u -p -r1.156 hppa-tdep.c
--- hppa-tdep.c 8 May 2004 03:59:34 -0000 1.156
+++ hppa-tdep.c 17 May 2004 02:29:53 -0000
@@ -1761,15 +1798,42 @@ hppa_frame_cache (struct frame_info *nex
the current function (and is thus equivalent to the "saved"
stack pointer. */
CORE_ADDR this_sp = frame_unwind_register_unsigned (next_frame, HPPA_SP_REGNUM);
+ CORE_ADDR fp;
if (hppa_debug)
fprintf_unfiltered (gdb_stdlog, " (this_sp=0x%s, pc=0x%s, "
"prologue_end=0x%s) ",
paddr_nz (this_sp),
paddr_nz (frame_pc_unwind (next_frame)),
paddr_nz (prologue_end));
- if (frame_pc_unwind (next_frame) >= prologue_end)
+ /* Check to see if a frame pointer is available, and use it for
+ frame unwinding if it is.
+
+ There are some situations where we need to rely on the frame
+ pointer to do stack unwinding. For example, if a function calls
+ alloca (), the stack pointer can get adjusted inside the body of
+ the function. In this case, the ABI requires that the compiler
+ maintain a frame pointer for the function.
+
+ The unwind record has a flag (alloca_frame) that indicates that
+ a function has a variable frame; unfortunately, gcc/binutils
+ does not set this flag. Instead, whenever a frame pointer is used
+ and saved on the stack, the Save_SP flag is set. We use this to
+ decide whether to use the frame pointer for unwinding. */
+
+ fp = frame_unwind_register_unsigned (next_frame, HPPA_FP_REGNUM);
+
+ if (frame_pc_unwind (next_frame) >= prologue_end
+ && u->Save_SP && fp != 0)
+ {
+ cache->base = fp;
+
+ if (hppa_debug)
+ fprintf_unfiltered (gdb_stdlog, " (base=0x%s) [frame pointer] }",
+ paddr_nz (cache->base));
+ }
+ else if (frame_pc_unwind (next_frame) >= prologue_end)
{
if (u->Save_SP && trad_frame_addr_p (cache->saved_regs, HPPA_SP_REGNUM))
{