#define GET_SRC_REG(x) (((x) >> 21) & 0x1f)
CORE_ADDR
-skip_prologue (pc, fdata)
- CORE_ADDR pc;
- struct rs6000_framedata *fdata;
+skip_prologue (CORE_ADDR pc, struct rs6000_framedata *fdata)
{
CORE_ADDR orig_pc = pc;
+ CORE_ADDR last_prologue_pc;
char buf[4];
unsigned long op;
long offset = 0;
- int lr_reg = 0;
- int cr_reg = 0;
+ int lr_reg = -1;
+ int cr_reg = -1;
int reg;
int framep = 0;
int minimal_toc_loaded = 0;
- static struct rs6000_framedata zero_frame;
+ int prev_insn_was_prologue_insn = 1;
- *fdata = zero_frame;
+ memset (fdata, 0, sizeof (struct rs6000_framedata));
fdata->saved_gpr = -1;
fdata->saved_fpr = -1;
fdata->alloca_reg = -1;
fdata->frameless = 1;
fdata->nosavedpc = 1;
- if (target_read_memory (pc, buf, 4))
- return pc; /* Can't access it -- assume no prologue. */
-
- /* Assume that subsequent fetches can fail with low probability. */
pc -= 4;
for (;;)
{
pc += 4;
- op = read_memory_integer (pc, 4);
+
+ /* Sometimes it isn't clear if an instruction is a prologue
+ instruction or not. When we encounter one of these ambiguous
+ cases, we'll set prev_insn_was_prologue_insn to 0 (false).
+ Otherwise, we'll assume that it really is a prologue instruction. */
+ if (prev_insn_was_prologue_insn)
+ last_prologue_pc = pc;
+ prev_insn_was_prologue_insn = 1;
+
+ if (target_read_memory (pc, buf, 4))
+ break;
+ op = extract_signed_integer (buf, 4);
if ((op & 0xfc1fffff) == 0x7c0802a6)
{ /* mflr Rx */
}
continue;
+ }
+ else if ((op & 0xffff0000) == 0x60000000)
+ {
+ /* nop */
+ /* Allow nops in the prologue, but do not consider them to
+ be part of the prologue unless followed by other prologue
+ instructions. */
+ prev_insn_was_prologue_insn = 0;
+ continue;
+
}
else if ((op & 0xffff0000) == 0x3c000000)
{ /* addis 0,0,NUM, used
continue;
}
- else if ((op & 0xffff0000) == lr_reg)
+ else if (lr_reg != -1 && (op & 0xffff0000) == lr_reg)
{ /* st Rx,NUM(r1)
where Rx == lr */
fdata->lr_offset = SIGNED_SHORT (op) + offset;
continue;
}
- else if ((op & 0xffff0000) == cr_reg)
+ else if (cr_reg != -1 && (op & 0xffff0000) == cr_reg)
{ /* st Rx,NUM(r1)
where Rx == cr */
fdata->cr_offset = SIGNED_SHORT (op) + offset;
#endif /* 0 */
fdata->offset = -fdata->offset;
- return pc;
+ return last_prologue_pc;
}