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* rs6000-tdep.c (bl_to_blrl_insn_p): New function.

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(skip_prologue): Allow bl->blrl used by PIC code.
This commit is contained in:
Daniel Jacobowitz 2007-02-08 14:22:53 +00:00
parent c1b6e682ab
commit 3c77c82a9b
2 changed files with 37 additions and 0 deletions
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7
gdb/ChangeLog
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@ -1,3 +1,10 @@
2007-02-08 Joel Brobecker <brobecker@gnat.com>
Jan Kratochvil <jan.kratochvil@redhat.com>
Daniel Jacobowitz <dan@codesourcery.com>
* rs6000-tdep.c (bl_to_blrl_insn_p): New function.
(skip_prologue): Allow bl->blrl used by PIC code.
2007-02-08 Mark Kettenis <kettenis@gnu.org>
Daniel Jacobowitz <dan@codesourcery.com>

30
gdb/rs6000-tdep.c
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@ -902,6 +902,30 @@ store_param_on_stack_p (unsigned long op, int framep, int *r0_contains_arg)
return 0;
}
/* Assuming that INSN is a "bl" instruction located at PC, return
nonzero if the destination of the branch is a "blrl" instruction.
This sequence is sometimes found in certain function prologues.
It allows the function to load the LR register with a value that
they can use to access PIC data using PC-relative offsets. */
static int
bl_to_blrl_insn_p (CORE_ADDR pc, int insn)
{
const int opcode = 18;
const CORE_ADDR dest = branch_dest (opcode, insn, pc, -1);
int dest_insn;
if (dest == -1)
return 0; /* Should never happen, but just return zero to be safe. */
dest_insn = read_memory_integer (dest, 4);
if ((dest_insn & 0xfc00ffff) == 0x4c000021) /* blrl */
return 1;
return 0;
}
static CORE_ADDR
skip_prologue (CORE_ADDR pc, CORE_ADDR lim_pc, struct rs6000_framedata *fdata)
{
@ -1133,6 +1157,12 @@ skip_prologue (CORE_ADDR pc, CORE_ADDR lim_pc, struct rs6000_framedata *fdata)
to save fprs??? */
fdata->frameless = 0;
/* If the return address has already been saved, we can skip
calls to blrl (for PIC). */
if (lr_reg != -1 && bl_to_blrl_insn_p (pc, op))
continue;
/* Don't skip over the subroutine call if it is not within
the first three instructions of the prologue and either
we have no line table information or the line info tells