void (*arm_lang_output_object_attributes_hook)(void);
+struct four_ints
+{
+ int i[4];
+};
+
/* Forward function declarations. */
static bool arm_needs_doubleword_align (enum machine_mode, const_tree);
static int arm_compute_static_chain_stack_bytes (void);
static bool arm_legitimate_address_p (enum machine_mode, rtx, bool);
static int thumb_far_jump_used_p (void);
static bool thumb_force_lr_save (void);
-static int const_ok_for_op (HOST_WIDE_INT, enum rtx_code);
static rtx emit_sfm (int, int);
static unsigned arm_size_return_regs (void);
static bool arm_assemble_integer (rtx, unsigned int, int);
static int arm_comp_type_attributes (const_tree, const_tree);
static void arm_set_default_type_attributes (tree);
static int arm_adjust_cost (rtx, rtx, rtx, int);
-static int count_insns_for_constant (HOST_WIDE_INT, int);
+static int optimal_immediate_sequence (enum rtx_code code,
+ unsigned HOST_WIDE_INT val,
+ struct four_ints *return_sequence);
+static int optimal_immediate_sequence_1 (enum rtx_code code,
+ unsigned HOST_WIDE_INT val,
+ struct four_ints *return_sequence,
+ int i);
static int arm_get_strip_length (int);
static bool arm_function_ok_for_sibcall (tree, tree);
static enum machine_mode arm_promote_function_mode (const_tree,
}
/* Return true if I is a valid constant for the operation CODE. */
-static int
+int
const_ok_for_op (HOST_WIDE_INT i, enum rtx_code code)
{
if (const_ok_for_arm (i))
return const_ok_for_arm (ARM_SIGN_EXTEND (~i));
case PLUS:
+ /* See if we can use addw or subw. */
+ if (TARGET_THUMB2
+ && ((i & 0xfffff000) == 0
+ || ((-i) & 0xfffff000) == 0))
+ return 1;
+ /* else fall through. */
+
case COMPARE:
case EQ:
case NE:
1);
}
-/* Return the number of instructions required to synthesize the given
- constant, if we start emitting them from bit-position I. */
+/* Return a sequence of integers, in RETURN_SEQUENCE that fit into
+ ARM/THUMB2 immediates, and add up to VAL.
+ Thr function return value gives the number of insns required. */
static int
-count_insns_for_constant (HOST_WIDE_INT remainder, int i)
-{
- HOST_WIDE_INT temp1;
- int step_size = TARGET_ARM ? 2 : 1;
- int num_insns = 0;
-
- gcc_assert (TARGET_ARM || i == 0);
-
- do
- {
- int end;
-
- if (i <= 0)
- i += 32;
- if (remainder & (((1 << step_size) - 1) << (i - step_size)))
- {
- end = i - 8;
- if (end < 0)
- end += 32;
- temp1 = remainder & ((0x0ff << end)
- | ((i < end) ? (0xff >> (32 - end)) : 0));
- remainder &= ~temp1;
- num_insns++;
- i -= 8 - step_size;
- }
- i -= step_size;
- } while (remainder);
- return num_insns;
-}
-
-static int
-find_best_start (unsigned HOST_WIDE_INT remainder)
+optimal_immediate_sequence (enum rtx_code code, unsigned HOST_WIDE_INT val,
+ struct four_ints *return_sequence)
{
int best_consecutive_zeros = 0;
int i;
int best_start = 0;
+ int insns1, insns2;
+ struct four_ints tmp_sequence;
/* If we aren't targetting ARM, the best place to start is always at
- the bottom. */
- if (! TARGET_ARM)
- return 0;
-
- for (i = 0; i < 32; i += 2)
+ the bottom, otherwise look more closely. */
+ if (TARGET_ARM)
{
- int consecutive_zeros = 0;
-
- if (!(remainder & (3 << i)))
+ for (i = 0; i < 32; i += 2)
{
- while ((i < 32) && !(remainder & (3 << i)))
- {
- consecutive_zeros += 2;
- i += 2;
- }
- if (consecutive_zeros > best_consecutive_zeros)
+ int consecutive_zeros = 0;
+
+ if (!(val & (3 << i)))
{
- best_consecutive_zeros = consecutive_zeros;
- best_start = i - consecutive_zeros;
+ while ((i < 32) && !(val & (3 << i)))
+ {
+ consecutive_zeros += 2;
+ i += 2;
+ }
+ if (consecutive_zeros > best_consecutive_zeros)
+ {
+ best_consecutive_zeros = consecutive_zeros;
+ best_start = i - consecutive_zeros;
+ }
+ i -= 2;
}
- i -= 2;
}
}
the constant starting from `best_start', and also starting from
zero (i.e. with bit 31 first to be output). If `best_start' doesn't
yield a shorter sequence, we may as well use zero. */
+ insns1 = optimal_immediate_sequence_1 (code, val, return_sequence, best_start);
if (best_start != 0
- && ((((unsigned HOST_WIDE_INT) 1) << best_start) < remainder)
- && (count_insns_for_constant (remainder, 0) <=
- count_insns_for_constant (remainder, best_start)))
- best_start = 0;
+ && ((((unsigned HOST_WIDE_INT) 1) << best_start) < val))
+ {
+ insns2 = optimal_immediate_sequence_1 (code, val, &tmp_sequence, 0);
+ if (insns2 <= insns1)
+ {
+ *return_sequence = tmp_sequence;
+ insns1 = insns2;
+ }
+ }
- return best_start;
+ return insns1;
+}
+
+/* As for optimal_immediate_sequence, but starting at bit-position I. */
+static int
+optimal_immediate_sequence_1 (enum rtx_code code, unsigned HOST_WIDE_INT val,
+ struct four_ints *return_sequence, int i)
+{
+ int remainder = val & 0xffffffff;
+ int insns = 0;
+
+ /* Try and find a way of doing the job in either two or three
+ instructions.
+
+ In ARM mode we can use 8-bit constants, rotated to any 2-bit aligned
+ location. We start at position I. This may be the MSB, or
+ optimial_immediate_sequence may have positioned it at the largest block
+ of zeros that are aligned on a 2-bit boundary. We then fill up the temps,
+ wrapping around to the top of the word when we drop off the bottom.
+ In the worst case this code should produce no more than four insns.
+
+ In Thumb2 mode, we can use 32/16-bit replicated constants, and 8-bit
+ constants, shifted to any arbitrary location. We should always start
+ at the MSB. */
+ do
+ {
+ int end;
+ int b1, b2, b3, b4;
+ unsigned HOST_WIDE_INT result;
+ int loc;
+
+ gcc_assert (insns < 4);
+
+ if (i <= 0)
+ i += 32;
+
+ /* First, find the next normal 12/8-bit shifted/rotated immediate. */
+ if (remainder & ((TARGET_ARM ? (3 << (i - 2)) : (1 << (i - 1)))))
+ {
+ loc = i;
+ if (i <= 12 && TARGET_THUMB2 && code == PLUS)
+ /* We can use addw/subw for the last 12 bits. */
+ result = remainder;
+ else
+ {
+ /* Use an 8-bit shifted/rotated immediate. */
+ end = i - 8;
+ if (end < 0)
+ end += 32;
+ result = remainder & ((0x0ff << end)
+ | ((i < end) ? (0xff >> (32 - end))
+ : 0));
+ i -= 8;
+ }
+ }
+ else
+ {
+ /* Arm allows rotates by a multiple of two. Thumb-2 allows
+ arbitrary shifts. */
+ i -= TARGET_ARM ? 2 : 1;
+ continue;
+ }
+
+ /* Next, see if we can do a better job with a thumb2 replicated
+ constant.
+
+ We do it this way around to catch the cases like 0x01F001E0 where
+ two 8-bit immediates would work, but a replicated constant would
+ make it worse.
+
+ TODO: 16-bit constants that don't clear all the bits, but still win.
+ TODO: Arithmetic splitting for set/add/sub, rather than bitwise. */
+ if (TARGET_THUMB2)
+ {
+ b1 = (remainder & 0xff000000) >> 24;
+ b2 = (remainder & 0x00ff0000) >> 16;
+ b3 = (remainder & 0x0000ff00) >> 8;
+ b4 = remainder & 0xff;
+
+ if (loc > 24)
+ {
+ /* The 8-bit immediate already found clears b1 (and maybe b2),
+ but must leave b3 and b4 alone. */
+
+ /* First try to find a 32-bit replicated constant that clears
+ almost everything. We can assume that we can't do it in one,
+ or else we wouldn't be here. */
+ unsigned int tmp = b1 & b2 & b3 & b4;
+ unsigned int tmp2 = tmp + (tmp << 8) + (tmp << 16)
+ + (tmp << 24);
+ unsigned int matching_bytes = (tmp == b1) + (tmp == b2)
+ + (tmp == b3) + (tmp == b4);
+ if (tmp
+ && (matching_bytes >= 3
+ || (matching_bytes == 2
+ && const_ok_for_op (remainder & ~tmp2, code))))
+ {
+ /* At least 3 of the bytes match, and the fourth has at
+ least as many bits set, or two of the bytes match
+ and it will only require one more insn to finish. */
+ result = tmp2;
+ i = tmp != b1 ? 32
+ : tmp != b2 ? 24
+ : tmp != b3 ? 16
+ : 8;
+ }
+
+ /* Second, try to find a 16-bit replicated constant that can
+ leave three of the bytes clear. If b2 or b4 is already
+ zero, then we can. If the 8-bit from above would not
+ clear b2 anyway, then we still win. */
+ else if (b1 == b3 && (!b2 || !b4
+ || (remainder & 0x00ff0000 & ~result)))
+ {
+ result = remainder & 0xff00ff00;
+ i = 24;
+ }
+ }
+ else if (loc > 16)
+ {
+ /* The 8-bit immediate already found clears b2 (and maybe b3)
+ and we don't get here unless b1 is alredy clear, but it will
+ leave b4 unchanged. */
+
+ /* If we can clear b2 and b4 at once, then we win, since the
+ 8-bits couldn't possibly reach that far. */
+ if (b2 == b4)
+ {
+ result = remainder & 0x00ff00ff;
+ i = 16;
+ }
+ }
+ }
+
+ return_sequence->i[insns++] = result;
+ remainder &= ~result;
+
+ if (code == SET || code == MINUS)
+ code = PLUS;
+ }
+ while (remainder);
+
+ return insns;
}
/* Emit an instruction with the indicated PATTERN. If COND is
/* As above, but extra parameter GENERATE which, if clear, suppresses
RTL generation. */
-/* ??? This needs more work for thumb2. */
static int
arm_gen_constant (enum rtx_code code, enum machine_mode mode, rtx cond,
int can_negate = 0;
int final_invert = 0;
int i;
- int num_bits_set = 0;
int set_sign_bit_copies = 0;
int clear_sign_bit_copies = 0;
int clear_zero_bit_copies = 0;
int set_zero_bit_copies = 0;
- int insns = 0;
+ int insns = 0, neg_insns, inv_insns;
unsigned HOST_WIDE_INT temp1, temp2;
unsigned HOST_WIDE_INT remainder = val & 0xffffffff;
- int step_size = TARGET_ARM ? 2 : 1;
+ struct four_ints *immediates;
+ struct four_ints pos_immediates, neg_immediates, inv_immediates;
/* Find out which operations are safe for a given CODE. Also do a quick
check for degenerate cases; these can occur when DImode operations
{
case SET:
can_invert = 1;
- can_negate = 1;
break;
case PLUS:
gen_rtx_NOT (mode, source)));
return 1;
}
+ final_invert = 1;
break;
case MINUS:
source)));
return 1;
}
- can_negate = 1;
break;
break;
}
- for (i = 0; i < 32; i++)
- if (remainder & (1 << i))
- num_bits_set++;
-
- if ((code == AND) || (can_invert && num_bits_set > 16))
- remainder ^= 0xffffffff;
- else if (code == PLUS && num_bits_set > 16)
- remainder = (-remainder) & 0xffffffff;
-
- /* For XOR, if more than half the bits are set and there's a sequence
- of more than 8 consecutive ones in the pattern then we can XOR by the
- inverted constant and then invert the final result; this may save an
- instruction and might also lead to the final mvn being merged with
- some other operation. */
- else if (code == XOR && num_bits_set > 16
- && (count_insns_for_constant (remainder ^ 0xffffffff,
- find_best_start
- (remainder ^ 0xffffffff))
- < count_insns_for_constant (remainder,
- find_best_start (remainder))))
- {
- remainder ^= 0xffffffff;
- final_invert = 1;
+ /* Calculate what the instruction sequences would be if we generated it
+ normally, negated, or inverted. */
+ if (code == AND)
+ /* AND cannot be split into multiple insns, so invert and use BIC. */
+ insns = 99;
+ else
+ insns = optimal_immediate_sequence (code, remainder, &pos_immediates);
+
+ if (can_negate)
+ neg_insns = optimal_immediate_sequence (code, (-remainder) & 0xffffffff,
+ &neg_immediates);
+ else
+ neg_insns = 99;
+
+ if (can_invert || final_invert)
+ inv_insns = optimal_immediate_sequence (code, remainder ^ 0xffffffff,
+ &inv_immediates);
+ else
+ inv_insns = 99;
+
+ immediates = &pos_immediates;
+
+ /* Is the negated immediate sequence more efficient? */
+ if (neg_insns < insns && neg_insns <= inv_insns)
+ {
+ insns = neg_insns;
+ immediates = &neg_immediates;
+ }
+ else
+ can_negate = 0;
+
+ /* Is the inverted immediate sequence more efficient?
+ We must allow for an extra NOT instruction for XOR operations, although
+ there is some chance that the final 'mvn' will get optimized later. */
+ if ((inv_insns + 1) < insns || (!final_invert && inv_insns < insns))
+ {
+ insns = inv_insns;
+ immediates = &inv_immediates;
}
else
{
can_invert = 0;
- can_negate = 0;
+ final_invert = 0;
}
- /* Now try and find a way of doing the job in either two or three
- instructions.
- We start by looking for the largest block of zeros that are aligned on
- a 2-bit boundary, we then fill up the temps, wrapping around to the
- top of the word when we drop off the bottom.
- In the worst case this code should produce no more than four insns.
- Thumb-2 constants are shifted, not rotated, so the MSB is always the
- best place to start. */
+ /* Now output the chosen sequence as instructions. */
+ if (generate)
+ {
+ for (i = 0; i < insns; i++)
+ {
+ rtx new_src, temp1_rtx;
- /* ??? Use thumb2 replicated constants when the high and low halfwords are
- the same. */
- {
- /* Now start emitting the insns. */
- i = find_best_start (remainder);
- do
- {
- int end;
+ temp1 = immediates->i[i];
- if (i <= 0)
- i += 32;
- if (remainder & (3 << (i - 2)))
- {
- end = i - 8;
- if (end < 0)
- end += 32;
- temp1 = remainder & ((0x0ff << end)
- | ((i < end) ? (0xff >> (32 - end)) : 0));
- remainder &= ~temp1;
-
- if (generate)
- {
- rtx new_src, temp1_rtx;
+ if (code == SET || code == MINUS)
+ new_src = (subtargets ? gen_reg_rtx (mode) : target);
+ else if ((final_invert || i < (insns - 1)) && subtargets)
+ new_src = gen_reg_rtx (mode);
+ else
+ new_src = target;
- if (code == SET || code == MINUS)
- {
- new_src = (subtargets ? gen_reg_rtx (mode) : target);
- if (can_invert && code != MINUS)
- temp1 = ~temp1;
- }
- else
- {
- if ((final_invert || remainder) && subtargets)
- new_src = gen_reg_rtx (mode);
- else
- new_src = target;
- if (can_invert)
- temp1 = ~temp1;
- else if (can_negate)
- temp1 = -temp1;
- }
+ if (can_invert)
+ temp1 = ~temp1;
+ else if (can_negate)
+ temp1 = -temp1;
- temp1 = trunc_int_for_mode (temp1, mode);
- temp1_rtx = GEN_INT (temp1);
+ temp1 = trunc_int_for_mode (temp1, mode);
+ temp1_rtx = GEN_INT (temp1);
- if (code == SET)
- ;
- else if (code == MINUS)
- temp1_rtx = gen_rtx_MINUS (mode, temp1_rtx, source);
- else
- temp1_rtx = gen_rtx_fmt_ee (code, mode, source, temp1_rtx);
+ if (code == SET)
+ ;
+ else if (code == MINUS)
+ temp1_rtx = gen_rtx_MINUS (mode, temp1_rtx, source);
+ else
+ temp1_rtx = gen_rtx_fmt_ee (code, mode, source, temp1_rtx);
- emit_constant_insn (cond,
- gen_rtx_SET (VOIDmode, new_src,
- temp1_rtx));
- source = new_src;
- }
+ emit_constant_insn (cond,
+ gen_rtx_SET (VOIDmode, new_src,
+ temp1_rtx));
+ source = new_src;
- if (code == SET)
- {
- can_invert = 0;
- code = PLUS;
- }
- else if (code == MINUS)
+ if (code == SET)
+ {
+ can_invert = 0;
+ can_negate = 1;
code = PLUS;
-
- insns++;
- i -= 8 - step_size;
- }
- /* Arm allows rotates by a multiple of two. Thumb-2 allows arbitrary
- shifts. */
- i -= step_size;
- }
- while (remainder);
- }
+ }
+ else if (code == MINUS)
+ code = PLUS;
+ }
+ }
if (final_invert)
{
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