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[PATCH] Handle empty DWARF CFI return address column
- From: Mark Kettenis <kettenis at chello dot nl>
- To: gdb-patches at sources dot redhat dot com
- Date: Mon, 2 Feb 2004 23:03:45 +0100 (CET)
- Subject: [PATCH] Handle empty DWARF CFI return address column
Thanks to Ulrich Weigand for pointing this out.
Ulrich, I'm convinced this is the right approach. FS->retaddr_column
pointing outside the table is essentially the same as the the column
being "unspecified". And copying a "same value" rule makes no sense
of course.
Tested on i386-unknown-freebsd4.7 and x86_64-unknown-freebsd5.2.
Committed,
Mark
Index: ChangeLog
from Mark Kettenis <kettenis@gnu.org>
* dwarf2-frame.c (dwarf2_frame_cache): Deal with a return address
column that's "empty" or "same value" when eliminating REG_RA
rules.
Index: dwarf2-frame.c
===================================================================
RCS file: /cvs/src/src/gdb/dwarf2-frame.c,v
retrieving revision 1.26
diff -u -p -r1.26 dwarf2-frame.c
--- dwarf2-frame.c 18 Jan 2004 21:22:50 -0000 1.26
+++ dwarf2-frame.c 2 Feb 2004 21:53:36 -0000
@@ -661,14 +661,19 @@ dwarf2_frame_cache (struct frame_info *n
{
if (cache->reg[regnum].how == REG_RA)
{
- if (fs->retaddr_column < fs->regs.num_regs)
+ /* It seems rather bizarre to specify an "empty" column as
+ the return adress column. However, this is exactly
+ what GCC does on some targets. It turns out that GCC
+ assumes that the return address can be found in the
+ register corresponding to the return address column.
+ Incidentally, that's how should treat a return address
+ column specifying "same value" too. */
+ if (fs->retaddr_column < fs->regs.num_regs
+ && fs->regs.reg[fs->retaddr_column].how != REG_UNSPECIFIED
+ && fs->regs.reg[fs->retaddr_column].how != REG_SAME_VALUE)
cache->reg[regnum] = fs->regs.reg[fs->retaddr_column];
else
{
- /* It turns out that GCC assumes that if the return
- address column is "empty" the return address can be
- found in the register corresponding to the return
- address column. */
cache->reg[regnum].loc.reg = fs->retaddr_column;
cache->reg[regnum].how = REG_SAVED_REG;
}