pv_t
pv_add (pv_t a, pv_t b)
{
constant_last (&a, &b);
/* We can add a constant to a register. */
if (a.kind == pvk_register
&& b.kind == pvk_constant)
return pv_register (a.reg, a.k + b.k);
/* We can add a constant to another constant. */
else if (a.kind == pvk_constant
&& b.kind == pvk_constant)
return pv_constant (a.k + b.k);
/* Anything else we don't know how to add. We don't have a
representation for, say, the sum of two registers, or a multiple
of a register's value (adding a register to itself). */
else
return pv_unknown ();
}
pv_t
pv_subtract (pv_t a, pv_t b)
{
/* This isn't quite the same as negating B and adding it to A, since
we don't have a representation for the negation of anything but a
constant. For example, we can't negate { pvk_register, R1, 10 },
but we do know that { pvk_register, R1, 10 } minus { pvk_register,
R1, 5 } is { pvk_constant, <ignored>, 5 }.
This means, for example, that we could subtract two stack
addresses; they're both relative to the original SP. Since the
frame pointer is set based on the SP, its value will be the
original SP plus some constant (probably zero), so we can use its
value just fine, too. */
constant_last (&a, &b);
/* We can subtract two constants. */
if (a.kind == pvk_constant
&& b.kind == pvk_constant)
return pv_constant (a.k - b.k);
/* We can subtract a constant from a register. */
else if (a.kind == pvk_register
&& b.kind == pvk_constant)
return pv_register (a.reg, a.k - b.k);
/* We can subtract a register from itself, yielding a constant. */
else if (a.kind == pvk_register
&& b.kind == pvk_register
&& a.reg == b.reg)
return pv_constant (a.k - b.k);
/* We don't know how to subtract anything else. */
else
return pv_unknown ();
}
/* Analyze a prologue starting at START_PC, going no further than
LIMIT_PC. Fill in RESULT as appropriate. */
static void
rx_analyze_prologue (CORE_ADDR start_pc,
CORE_ADDR limit_pc, struct rx_prologue *result)
{
CORE_ADDR pc, next_pc;
int rn;
pv_t reg[RX_NUM_REGS];
struct pv_area *stack;
struct cleanup *back_to;
CORE_ADDR after_last_frame_setup_insn = start_pc;
memset (result, 0, sizeof (*result));
for (rn = 0; rn < RX_NUM_REGS; rn++)
{
reg[rn] = pv_register (rn, 0);
result->reg_offset[rn] = 1;
}
stack = make_pv_area (RX_SP_REGNUM, gdbarch_addr_bit (target_gdbarch));
back_to = make_cleanup_free_pv_area (stack);
/* The call instruction has saved the return address on the stack. */
reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[RX_PC_REGNUM]);
pc = start_pc;
while (pc < limit_pc)
{
int bytes_read;
struct rx_get_opcode_byte_handle opcode_handle;
RX_Opcode_Decoded opc;
opcode_handle.pc = pc;
bytes_read = rx_decode_opcode (pc, &opc, rx_get_opcode_byte,
&opcode_handle);
next_pc = pc + bytes_read;
if (opc.id == RXO_pushm /* pushm r1, r2 */
&& opc.op[1].type == RX_Operand_Register
&& opc.op[2].type == RX_Operand_Register)
{
int r1, r2;
int r;
r1 = opc.op[1].reg;
r2 = opc.op[2].reg;
for (r = r2; r >= r1; r--)
{
reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[r]);
}
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == RXO_mov /* mov.l rdst, rsrc */
&& opc.op[0].type == RX_Operand_Register
&& opc.op[1].type == RX_Operand_Register
&& opc.size == RX_Long)
{
int rdst, rsrc;
rdst = opc.op[0].reg;
rsrc = opc.op[1].reg;
reg[rdst] = reg[rsrc];
if (rdst == RX_FP_REGNUM && rsrc == RX_SP_REGNUM)
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == RXO_mov /* mov.l rsrc, [-SP] */
&& opc.op[0].type == RX_Operand_Predec
&& opc.op[0].reg == RX_SP_REGNUM
&& opc.op[1].type == RX_Operand_Register
&& opc.size == RX_Long)
{
int rsrc;
rsrc = opc.op[1].reg;
reg[RX_SP_REGNUM] = pv_add_constant (reg[RX_SP_REGNUM], -4);
pv_area_store (stack, reg[RX_SP_REGNUM], 4, reg[rsrc]);
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == RXO_add /* add #const, rsrc, rdst */
&& opc.op[0].type == RX_Operand_Register
&& opc.op[1].type == RX_Operand_Immediate
&& opc.op[2].type == RX_Operand_Register)
{
int rdst = opc.op[0].reg;
int addend = opc.op[1].addend;
int rsrc = opc.op[2].reg;
reg[rdst] = pv_add_constant (reg[rsrc], addend);
/* Negative adjustments to the stack pointer or frame pointer
are (most likely) part of the prologue. */
if ((rdst == RX_SP_REGNUM || rdst == RX_FP_REGNUM) && addend < 0)
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == RXO_mov
&& opc.op[0].type == RX_Operand_Indirect
&& opc.op[1].type == RX_Operand_Register
&& opc.size == RX_Long
&& (opc.op[0].reg == RX_SP_REGNUM
|| opc.op[0].reg == RX_FP_REGNUM)
&& (RX_R1_REGNUM <= opc.op[1].reg
&& opc.op[1].reg <= RX_R4_REGNUM))
{
/* This moves an argument register to the stack. Don't
record it, but allow it to be a part of the prologue. */
}
else if (opc.id == RXO_branch
&& opc.op[0].type == RX_Operand_Immediate
&& next_pc < opc.op[0].addend)
{
/* When a loop appears as the first statement of a function
body, gcc 4.x will use a BRA instruction to branch to the
loop condition checking code. This BRA instruction is
marked as part of the prologue. We therefore set next_pc
to this branch target and also stop the prologue scan.
The instructions at and beyond the branch target should
no longer be associated with the prologue.
Note that we only consider forward branches here. We
presume that a forward branch is being used to skip over
a loop body.
A backwards branch is covered by the default case below.
If we were to encounter a backwards branch, that would
most likely mean that we've scanned through a loop body.
We definitely want to stop the prologue scan when this
happens and that is precisely what is done by the default
case below. */
after_last_frame_setup_insn = opc.op[0].addend;
break; /* Scan no further if we hit this case. */
}
else
{
/* Terminate the prologue scan. */
break;
}
pc = next_pc;
}
/* Is the frame size (offset, really) a known constant? */
if (pv_is_register (reg[RX_SP_REGNUM], RX_SP_REGNUM))
result->frame_size = reg[RX_SP_REGNUM].k;
/* Was the frame pointer initialized? */
if (pv_is_register (reg[RX_FP_REGNUM], RX_SP_REGNUM))
{
result->has_frame_ptr = 1;
result->frame_ptr_offset = reg[RX_FP_REGNUM].k;
}
/* Record where all the registers were saved. */
pv_area_scan (stack, check_for_saved, (void *) result);
result->prologue_end = after_last_frame_setup_insn;
do_cleanups (back_to);
}
static void
msp430_analyze_prologue (struct gdbarch *gdbarch, CORE_ADDR start_pc,
CORE_ADDR limit_pc, struct msp430_prologue *result)
{
CORE_ADDR pc, next_pc;
int rn;
pv_t reg[MSP430_NUM_TOTAL_REGS];
struct pv_area *stack;
struct cleanup *back_to;
CORE_ADDR after_last_frame_setup_insn = start_pc;
int code_model = gdbarch_tdep (gdbarch)->code_model;
int sz;
memset (result, 0, sizeof (*result));
for (rn = 0; rn < MSP430_NUM_TOTAL_REGS; rn++)
{
reg[rn] = pv_register (rn, 0);
result->reg_offset[rn] = 1;
}
stack = make_pv_area (MSP430_SP_REGNUM, gdbarch_addr_bit (gdbarch));
back_to = make_cleanup_free_pv_area (stack);
/* The call instruction has saved the return address on the stack. */
sz = code_model == MSP_LARGE_CODE_MODEL ? 4 : 2;
reg[MSP430_SP_REGNUM] = pv_add_constant (reg[MSP430_SP_REGNUM], -sz);
pv_area_store (stack, reg[MSP430_SP_REGNUM], sz, reg[MSP430_PC_REGNUM]);
pc = start_pc;
while (pc < limit_pc)
{
int bytes_read;
struct msp430_get_opcode_byte_handle opcode_handle;
MSP430_Opcode_Decoded opc;
opcode_handle.pc = pc;
bytes_read = msp430_decode_opcode (pc, &opc, msp430_get_opcode_byte,
&opcode_handle);
next_pc = pc + bytes_read;
if (opc.id == MSO_push && opc.op[0].type == MSP430_Operand_Register)
{
int rsrc = opc.op[0].reg;
reg[MSP430_SP_REGNUM] = pv_add_constant (reg[MSP430_SP_REGNUM], -2);
pv_area_store (stack, reg[MSP430_SP_REGNUM], 2, reg[rsrc]);
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == MSO_push /* PUSHM */
&& opc.op[0].type == MSP430_Operand_None
&& opc.op[1].type == MSP430_Operand_Register)
{
int rsrc = opc.op[1].reg;
int count = opc.repeats + 1;
int size = opc.size == 16 ? 2 : 4;
while (count > 0)
{
reg[MSP430_SP_REGNUM]
= pv_add_constant (reg[MSP430_SP_REGNUM], -size);
pv_area_store (stack, reg[MSP430_SP_REGNUM], size, reg[rsrc]);
rsrc--;
count--;
}
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == MSO_sub
&& opc.op[0].type == MSP430_Operand_Register
&& opc.op[0].reg == MSR_SP
&& opc.op[1].type == MSP430_Operand_Immediate)
{
int addend = opc.op[1].addend;
reg[MSP430_SP_REGNUM] = pv_add_constant (reg[MSP430_SP_REGNUM],
-addend);
after_last_frame_setup_insn = next_pc;
}
else if (opc.id == MSO_mov
&& opc.op[0].type == MSP430_Operand_Immediate
&& 12 <= opc.op[0].reg && opc.op[0].reg <= 15)
after_last_frame_setup_insn = next_pc;
else
{
/* Terminate the prologue scan. */
break;
}
pc = next_pc;
}
/* Is the frame size (offset, really) a known constant? */
if (pv_is_register (reg[MSP430_SP_REGNUM], MSP430_SP_REGNUM))
result->frame_size = reg[MSP430_SP_REGNUM].k;
/* Record where all the registers were saved. */
pv_area_scan (stack, check_for_saved, result);
result->prologue_end = after_last_frame_setup_insn;
do_cleanups (back_to);
}
