[patch/rfa/hppa] Use frame pointer for unwinding

[Randolph Chung <randolph@tausq.org>]

One more patch --

Currently we don't use the frame pointer to unwind the stack, we rely
only on unwinding records. However, this doesn't work for functions that
call alloca() because the unwinding record does not account for the
variable-sized stack frame. In this case, the ABI requires that the
compiler always maintain a frame pointer.

Fixes these two FAILs from the testsuite, no new regressions.
+PASS: gdb.base/funcargs.exp: backtrace from call_after_alloca_subr
+PASS: gdb.base/selftest.exp: backtrace through signal handler

ok to apply?
randolph


2004-05-15  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	16 May 2004 01:42:56 -0000
@@ -1761,15 +1798,26 @@ 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)
+    if (get_frame_type (next_frame) == NORMAL_FRAME
+        && u->Save_SP 
+	&& (fp = frame_unwind_register_unsigned (next_frame, HPPA_FP_REGNUM)))
+      {
+	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))
           {

-- 
Randolph Chung
Debian GNU/Linux Developer, hppa/ia64 ports
http://www.tausq.org/