RE: [PATCH 2/2 ver2] PowerPC: fix for gdb.reverse/finish-precsave.exp and gdb.reverse/finish-reverse.exp

Carl Love via Gdb-patches
2023-03-21T03:17:33Z

Tom, Luis, GDB maintainers:

The recent commit to fix the reverse-finish command on PowerPC
introduced some regression test failures on X86 and Arm. The following
patch fixes the failures.

The fix has been tested on Power10 and X86.

Please let me know if this patch is acceptable. Thanks.

Carl

----------------------------------------
PowerPC: regression fix for reverse-finish command.

The recent commit:

commit 2a8339b71f37f2d02f5b2194929c9d702ef27223
Author: Carl Love <cel@us.ibm.com>
Date: Thu Mar 9 16:10:18 2023 -0500

PowerPC: fix for gdb.reverse/finish-precsave.exp and gdb.reverse/finish-rev\
erse.exp

PPC64 multiple entry points, a normal entry point and an alternate entry
point. The alternate entry point is to setup the Table of Contents (TOC)
register before continuing at the normal entry point. When the TOC is
already valid, the normal entry point is used, this is typically the case.
The alternate entry point is typically referred to as the global entry
point (GEP) in IBM. The normal entry point is typically referred to as
the local entry point (LEP).
.....

Is causing regression failures on on PowerPC platforms. The regression
failures are in tests:

gdb.reverse/finish-precsave.exp
gdb.btrace/tailcall.exp
gdb.mi/mi-reverse.exp
gdb.btrace/step.exp
gdb.reverse/until-precsave.exp
gdb.reverse/finish-reverse.exp
gdb.btrace/tailcall-only.exp

The issue is in gdb/infcmd.c, function finish_command. The value of the
two new variables ALT_ENTRY_POINT and ENTRY_POINT are being initializezed
to SAL.PC. However, SAL has just been declared. The value of SAL.PC is
zero at this point. The intialization of ALT_ENTRY_POINT and ENTRY_POINT
needs to be after the initialization of SAL.

This patch moves the initialization of ALT_ENTRY_POINT and ENTRY_POINT
variables to fix the regression failures.

The patch has been tested on Power10 and on X86.
---
gdb/infcmd.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index f46461512fe..e2032d18564 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -1710,8 +1710,8 @@ finish_backward (struct finish_command_fsm *sm)
struct thread_info *tp = inferior_thread ();
CORE_ADDR pc;
CORE_ADDR func_addr;
- CORE_ADDR alt_entry_point = sal.pc;
- CORE_ADDR entry_point = alt_entry_point;
+ CORE_ADDR alt_entry_point;
+ CORE_ADDR entry_point;
frame_info_ptr frame = get_selected_frame (nullptr);
struct gdbarch *gdbarch = get_frame_arch (frame);

@@ -1721,6 +1721,8 @@ finish_backward (struct finish_command_fsm *sm)
error (_("Cannot find bounds of current function"));

sal = find_pc_line (func_addr, 0);
+ alt_entry_point = sal.pc;
+ entry_point = alt_entry_point;

if (gdbarch_skip_entrypoint_p (gdbarch))
/* Some architectures, like PowerPC use local and global entry points.
--
2.37.2