* Re: dwarf2 and frame bases
[not found] ` <20041111171232.GA10326@nevyn.them.org>
@ 2004-11-11 21:18 ` Randolph Chung
2004-11-11 23:33 ` Daniel Jacobowitz
0 siblings, 1 reply; 2+ messages in thread
From: Randolph Chung @ 2004-11-11 21:18 UTC (permalink / raw)
To: gdb; +Cc: gdb-patches
> Suppose we're in frame A, called from frame B. We're at the first
> instruction. If we ask the sentinel frame to unwind the value of r3,
> we'll get its real register value - regardless of where we are in the
> sequence. If we ask frame A to unwind r3, we want to get frame B's r3.
> Where frame A is in its prologue has no effect on what frame B's r3 was
> at the time of calling A.
ok ok, how about this fix? all the recurse.exp tests pass now.
thanks,
randolph
2004-11-11 Randolph Chung <tausq@debian.org>
* hppa-tdep.c (hppa_frame_cache): Properly handle the frame pointer
register so that it can be unwound from anywhere in the prologue.
Index: hppa-tdep.c
===================================================================
RCS file: /cvs/src/src/gdb/hppa-tdep.c,v
retrieving revision 1.177
diff -u -p -r1.177 hppa-tdep.c
--- hppa-tdep.c 10 Nov 2004 16:26:55 -0000 1.177
+++ hppa-tdep.c 11 Nov 2004 21:02:42 -0000
@@ -1562,6 +1573,7 @@ hppa_frame_cache (struct frame_info *nex
long frame_size;
struct unwind_table_entry *u;
CORE_ADDR prologue_end;
+ int fp_in_r1 = 0;
int i;
if (hppa_debug)
@@ -1694,6 +1712,10 @@ hppa_frame_cache (struct frame_info *nex
looking_for_sp = 0;
cache->saved_regs[HPPA_FP_REGNUM].addr = 0;
}
+ else if (inst == 0x08030241) /* copy %r3, %r1 */
+ {
+ fp_in_r1 = 1;
+ }
/* Account for general and floating-point register saves. */
reg = inst_saves_gr (inst);
@@ -1802,9 +1824,6 @@ hppa_frame_cache (struct frame_info *nex
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 may be zero if it is not available in an inner frame because
- it has been modified by not yet saved.
-
TODO: For the HP compiler, maybe we should use the alloca_frame flag
instead of Save_SP. */
@@ -1867,13 +1886,26 @@ hppa_frame_cache (struct frame_info *nex
}
}
- /* If the frame pointer was not saved in this frame, but we should be saving
- it, set it to an invalid value so that another frame will not pick up the
- wrong frame pointer. This can happen if we start unwinding after the
- frame pointer has been modified, but before we've saved it to the
- stack. */
- if (u->Save_SP && !trad_frame_addr_p (cache->saved_regs, HPPA_FP_REGNUM))
- trad_frame_set_value (cache->saved_regs, HPPA_FP_REGNUM, 0);
+ /* If Save_SP is set, then we expect the frame pointer to be saved in the
+ frame. However, there is a one-insn window where we haven't saved it
+ yet, but we've already clobbered it. Detect this case and fix it up.
+
+ The prologue sequence for frame-pointer functions is:
+ 0: stw %rp, -20(%sp)
+ 4: copy %r3, %r1
+ 8: copy %sp, %r3
+ c: stw,ma %r1, XX(%sp)
+
+ So if we are at offset c, the r3 value that we want is not yet saved
+ on the stack, but it's been overwritten. The prologue analyzer will
+ set fp_in_r1 when it sees the copy insn so we know to get the value
+ from r1 instead. */
+ if (u->Save_SP && !trad_frame_addr_p (cache->saved_regs, HPPA_FP_REGNUM)
+ && fp_in_r1)
+ {
+ ULONGEST r1 = frame_unwind_register_unsigned (next_frame, 1);
+ trad_frame_set_value (cache->saved_regs, HPPA_FP_REGNUM, r1);
+ }
{
/* Convert all the offsets into addresses. */
^ permalink raw reply [flat|nested] 2+ messages in thread