/* Target-dependent code for GDB, the GNU debugger.
- Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996,
- 1997, 2000, 2001
+ Copyright 1986, 1987, 1989, 1991, 1992, 1993, 1994, 1995, 1996, 1997,
+ 1998, 1999, 2000, 2001
Free Software Foundation, Inc.
This file is part of GDB.
#include "symfile.h"
#include "objfiles.h"
#include "arch-utils.h"
+#include "regcache.h"
#include "bfd/libbfd.h" /* for bfd_default_set_arch_mach */
#include "coff/internal.h" /* for libcoff.h */
/* AIX does not support PT_STEP. Simulate it. */
void
-rs6000_software_single_step (unsigned int signal, int insert_breakpoints_p)
+rs6000_software_single_step (enum target_signal signal,
+ int insert_breakpoints_p)
{
#define INSNLEN(OPCODE) 4
static CORE_ADDR rs6000_struct_return_address;
-/* Indirect function calls use a piece of trampoline code to do context
- switching, i.e. to set the new TOC table. Skip such code if we are on
- its first instruction (as when we have single-stepped to here).
- Also skip shared library trampoline code (which is different from
+/* Return whether handle_inferior_event() should proceed through code
+ starting at PC in function NAME when stepping.
+
+ The AIX -bbigtoc linker option generates functions @FIX0, @FIX1, etc. to
+ handle memory references that are too distant to fit in instructions
+ generated by the compiler. For example, if 'foo' in the following
+ instruction:
+
+ lwz r9,foo(r2)
+
+ is greater than 32767, the linker might replace the lwz with a branch to
+ somewhere in @FIX1 that does the load in 2 instructions and then branches
+ back to where execution should continue.
+
+ GDB should silently step over @FIX code, just like AIX dbx does.
+ Unfortunately, the linker uses the "b" instruction for the branches,
+ meaning that the link register doesn't get set. Therefore, GDB's usual
+ step_over_function() mechanism won't work.
+
+ Instead, use the IN_SOLIB_RETURN_TRAMPOLINE and SKIP_TRAMPOLINE_CODE hooks
+ in handle_inferior_event() to skip past @FIX code. */
+
+int
+rs6000_in_solib_return_trampoline (CORE_ADDR pc, char *name)
+{
+ return name && !strncmp (name, "@FIX", 4);
+}
+
+/* Skip code that the user doesn't want to see when stepping:
+
+ 1. Indirect function calls use a piece of trampoline code to do context
+ switching, i.e. to set the new TOC table. Skip such code if we are on
+ its first instruction (as when we have single-stepped to here).
+
+ 2. Skip shared library trampoline code (which is different from
indirect function call trampolines).
+
+ 3. Skip bigtoc fixup code.
+
Result is desired PC to step until, or NULL if we are not in
- trampoline code. */
+ code that should be skipped. */
CORE_ADDR
rs6000_skip_trampoline_code (CORE_ADDR pc)
{
register unsigned int ii, op;
+ int rel;
CORE_ADDR solib_target_pc;
+ struct minimal_symbol *msymbol;
static unsigned trampoline_code[] =
{
0
};
+ /* Check for bigtoc fixup code. */
+ msymbol = lookup_minimal_symbol_by_pc (pc);
+ if (msymbol && rs6000_in_solib_return_trampoline (pc, SYMBOL_NAME (msymbol)))
+ {
+ /* Double-check that the third instruction from PC is relative "b". */
+ op = read_memory_integer (pc + 8, 4);
+ if ((op & 0xfc000003) == 0x48000000)
+ {
+ /* Extract bits 6-29 as a signed 24-bit relative word address and
+ add it to the containing PC. */
+ rel = ((int)(op << 6) >> 6);
+ return pc + 8 + rel;
+ }
+ }
+
/* If pc is in a shared library trampoline, return its target. */
solib_target_pc = find_solib_trampoline_target (pc);
if (solib_target_pc)
if (!from_xcoff_exec)
{
- arch = info.bfd_architecture;
+ arch = info.bfd_arch_info->arch;
mach = info.bfd_arch_info->mach;
}
else