/* Analyze the function prologue from START_PC to LIMIT_PC. Builds
- the associated FRAME_CACHE if not null. */
+ the associated FRAME_CACHE if not null.
+ Return the address of the first instruction past the prologue. */
-static void
+static CORE_ADDR
mips16_scan_prologue (CORE_ADDR start_pc, CORE_ADDR limit_pc, CORE_ADDR sp,
struct frame_info *next_frame,
struct mips_frame_cache *this_cache)
unsigned entry_inst = 0; /* the entry instruction */
int reg, offset;
+ int extend_bytes = 0;
+ int prev_extend_bytes;
+ CORE_ADDR end_prologue_addr = 0;
+
for (cur_pc = start_pc; cur_pc < limit_pc; cur_pc += MIPS16_INSTLEN)
{
/* Save the previous instruction. If it's an EXTEND, we'll extract
/* Fetch and decode the instruction. */
inst = (unsigned short) mips_fetch_instruction (cur_pc);
+
+ /* Normally we ignore extend instructions. However, if it is
+ not followed by a valid prologue instruction, then this
+ instruction is not part of the prologue either. We must
+ remember in this case to adjust the end_prologue_addr back
+ over the extend. */
+ if ((inst & 0xf800) == 0xf000) /* extend */
+ {
+ extend_bytes = MIPS16_INSTLEN;
+ continue;
+ }
+
+ prev_extend_bytes = extend_bytes;
+ extend_bytes = 0;
+
if ((inst & 0xff00) == 0x6300 /* addiu sp */
|| (inst & 0xff00) == 0xfb00) /* daddiu sp */
{
entry_inst = inst; /* save for later processing */
else if ((inst & 0xf800) == 0x1800) /* jal(x) */
cur_pc += MIPS16_INSTLEN; /* 32-bit instruction */
+ else if ((inst & 0xff1c) == 0x6704) /* move reg,$a0-$a3 */
+ {
+ /* This instruction is part of the prologue, but we don't
+ need to do anything special to handle it. */
+ }
+ else
+ {
+ /* This instruction is not an instruction typically found
+ in a prologue, so we must have reached the end of the
+ prologue. */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = cur_pc - prev_extend_bytes;
+ }
}
/* The entry instruction is typically the first instruction in a function,
this_cache->saved_regs[NUM_REGS + mips_regnum (current_gdbarch)->pc]
= this_cache->saved_regs[NUM_REGS + RA_REGNUM];
}
+
+ /* If we didn't reach the end of the prologue when scanning the function
+ instructions, then set end_prologue_addr to the address of the
+ instruction immediately after the last one we scanned. */
+ if (end_prologue_addr == 0)
+ end_prologue_addr = cur_pc;
+
+ return end_prologue_addr;
}
/* Mark all the registers as unset in the saved_regs array
extract_unsigned_integer (buf, MIPS_INSTLEN));
}
-/* Skip the PC past function prologue instructions (16-bit version).
- This is a helper function for mips_skip_prologue. */
-
-static CORE_ADDR
-mips16_skip_prologue (CORE_ADDR pc, CORE_ADDR end_pc)
-{
- int extend_bytes = 0;
- int prev_extend_bytes;
-
- /* Table of instructions likely to be found in a function prologue. */
- static struct
- {
- unsigned short inst;
- unsigned short mask;
- }
- table[] =
- {
- {
- 0x6300, 0xff00}
- , /* addiu $sp,offset */
- {
- 0xfb00, 0xff00}
- , /* daddiu $sp,offset */
- {
- 0xd000, 0xf800}
- , /* sw reg,n($sp) */
- {
- 0xf900, 0xff00}
- , /* sd reg,n($sp) */
- {
- 0x6200, 0xff00}
- , /* sw $ra,n($sp) */
- {
- 0xfa00, 0xff00}
- , /* sd $ra,n($sp) */
- {
- 0x673d, 0xffff}
- , /* move $s1,sp */
- {
- 0xd980, 0xff80}
- , /* sw $a0-$a3,n($s1) */
- {
- 0x6704, 0xff1c}
- , /* move reg,$a0-$a3 */
- {
- 0xe809, 0xf81f}
- , /* entry pseudo-op */
- {
- 0x0100, 0xff00}
- , /* addiu $s1,$sp,n */
- {
- 0, 0} /* end of table marker */
- };
-
- /* Skip the typical prologue instructions. These are the stack adjustment
- instruction and the instructions that save registers on the stack
- or in the gcc frame. */
- for (; pc < end_pc; pc += MIPS16_INSTLEN)
- {
- unsigned short inst;
- int i;
-
- inst = mips_fetch_instruction (pc);
-
- /* Normally we ignore an extend instruction. However, if it is
- not followed by a valid prologue instruction, we must adjust
- the pc back over the extend so that it won't be considered
- part of the prologue. */
- if ((inst & 0xf800) == 0xf000) /* extend */
- {
- extend_bytes = MIPS16_INSTLEN;
- continue;
- }
- prev_extend_bytes = extend_bytes;
- extend_bytes = 0;
-
- /* Check for other valid prologue instructions besides extend. */
- for (i = 0; table[i].mask != 0; i++)
- if ((inst & table[i].mask) == table[i].inst) /* found, get out */
- break;
- if (table[i].mask != 0) /* it was in table? */
- continue; /* ignore it */
- else
- /* non-prologue */
- {
- /* Return the current pc, adjusted backwards by 2 if
- the previous instruction was an extend. */
- return pc - prev_extend_bytes;
- }
- }
- return pc;
-}
-
/* To skip prologues, I use this predicate. Returns either PC itself
if the code at PC does not look like a function prologue; otherwise
returns an address that (if we're lucky) follows the prologue. If
limit_pc = pc + 100; /* Magic. */
if (pc_is_mips16 (pc))
- return mips16_skip_prologue (pc, limit_pc);
+ return mips16_scan_prologue (pc, limit_pc, 0, NULL, NULL);
else
return mips32_scan_prologue (pc, limit_pc, 0, NULL, NULL);
}
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