Commit 8cc52245 authored by Michael Beck's avatar Michael Beck
Browse files

added ieee754 exact flag which allows more cases to be optimized

[r15334]
parent 26707e47
......@@ -609,6 +609,11 @@ int tarval_ieee754_get_exponent(tarval *tv);
*/
unsigned tarval_ieee754_set_immediate_precision(unsigned bits);
/**
* Returns non-zero if the result of the last IEEE-754 operation was exact.
*/
unsigned tarval_ieee754_get_exact(void);
/**
* Enable/Disable floating point constant folding.
*/
......
......@@ -2345,22 +2345,21 @@ static ir_node *transform_node_Quot(ir_node *n) {
if (is_Const(b)) {
tarval *tv = get_Const_tarval(b);
if (tarval_ieee754_zero_mantissa(tv)) {
tv = tarval_quo(get_mode_one(mode), tv);
if (tv != tarval_bad) {
ir_node *blk = get_irn_n(n, -1);
ir_node *c = new_r_Const(current_ir_graph, blk, mode, tv);
ir_node *a = get_Quot_left(n);
ir_node *m = new_rd_Mul(get_irn_dbg_info(n), current_ir_graph, blk, a, c, mode);
ir_node *mem = get_Quot_mem(n);
turn_into_tuple(n, pn_Quot_max);
set_Tuple_pred(n, pn_Quot_M, mem);
set_Tuple_pred(n, pn_Quot_X_regular, new_r_Jmp(current_ir_graph, blk));
set_Tuple_pred(n, pn_Quot_X_except, new_r_Bad(current_ir_graph));
set_Tuple_pred(n, pn_Quot_res, m);
DBG_OPT_ALGSIM1(oldn, a, b, m, FS_OPT_FP_INV_MUL);
}
tv = tarval_quo(get_mode_one(mode), tv);
if (tv != tarval_bad && tarval_ieee754_get_exact()) {
ir_node *blk = get_irn_n(n, -1);
ir_node *c = new_r_Const(current_ir_graph, blk, mode, tv);
ir_node *a = get_Quot_left(n);
ir_node *m = new_rd_Mul(get_irn_dbg_info(n), current_ir_graph, blk, a, c, mode);
ir_node *mem = get_Quot_mem(n);
turn_into_tuple(n, pn_Quot_max);
set_Tuple_pred(n, pn_Quot_M, mem);
set_Tuple_pred(n, pn_Quot_X_regular, new_r_Jmp(current_ir_graph, blk));
set_Tuple_pred(n, pn_Quot_X_except, new_r_Bad(current_ir_graph));
set_Tuple_pred(n, pn_Quot_res, m);
DBG_OPT_ALGSIM1(oldn, a, b, m, FS_OPT_FP_INV_MUL);
}
}
}
......
......@@ -154,6 +154,9 @@ static int calc_buffer_size;
static int value_size;
static int max_precision;
/** Exact flag. */
static int fc_exact = 1;
#if 0
static void fail_char(const char *str, unsigned int len, int pos) {
if (*(str+pos))
......@@ -221,7 +224,13 @@ static void *pack(const fp_value *int_float, void *packed) {
return packed;
}
static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
/**
* Normalize a fp_value.
*
* @return non-zero if result is exact
*/
static int normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
int exact = 1;
int hsb;
char lsb, guard, round, round_dir = 0;
char *temp = alloca(value_size);
......@@ -236,7 +245,7 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
out_val->desc.clss = NORMAL;
/* mantissa all zeros, so zero exponent (because of explicit one)*/
/* mantissa all zeros, so zero exponent (because of explicit one) */
if (hsb == 2 + in_val->desc.mantissa_size) {
sc_val_from_ulong(0, _exp(out_val));
hsb = -1;
......@@ -250,8 +259,10 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
_shift_right(_mant(in_val), temp, _mant(out_val));
/* remember if some bits were shifted away */
if (!sticky) sticky = sc_had_carry();
if (sc_had_carry()) {
exact = 0;
sticky = 1;
}
sc_add(_exp(in_val), temp, _exp(out_val));
} else if (hsb > -1) {
/* shift left */
......@@ -271,7 +282,10 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
sc_sub(temp, _exp(out_val), NULL);
_shift_right(_mant(out_val), sc_get_buffer(), _mant(out_val));
if (!sticky) sticky = sc_had_carry();
if (sc_had_carry()) {
exact = 0;
sticky = 1;
}
/* denormalized means exponent of zero */
sc_val_from_ulong(0, _exp(out_val));
......@@ -317,6 +331,7 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
if (lsb != 0) {
sc_val_from_long(lsb, temp);
sc_add(_mant(out_val), temp, _mant(out_val));
exact = 0;
}
/* could have rounded down to zero */
......@@ -328,7 +343,8 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
if ((out_val->desc.clss != SUBNORMAL) && (hsb < -1)) {
sc_val_from_ulong(1, temp);
_shift_right(_mant(out_val), temp, _mant(out_val));
if (exact && sc_had_carry())
exact = 0;
sc_add(_exp(out_val), temp, _exp(out_val));
} else if ((out_val->desc.clss == SUBNORMAL) && (hsb == -1)) {
/* overflow caused the mantissa to be normal again,
......@@ -389,6 +405,7 @@ static void normalize(const fp_value *in_val, fp_value *out_val, int sticky) {
}
}
}
return exact;
}
/**
......@@ -417,6 +434,8 @@ static void _fadd(const fp_value *a, const fp_value *b, fp_value *result) {
char sign, res_sign;
char sticky;
fc_exact = 1;
handle_NAN(a, b, result);
/* make sure result has a descriptor */
......@@ -487,6 +506,7 @@ static void _fadd(const fp_value *a, const fp_value *b, fp_value *result) {
_shift_right(_mant(b), exp_diff, temp);
sticky = sc_had_carry();
fc_exact &= !sticky;
if (sticky && sign) {
/* if subtracting a little more than the represented value or adding a little
......@@ -516,16 +536,19 @@ static void _fadd(const fp_value *a, const fp_value *b, fp_value *result) {
/* resulting exponent is the bigger one */
memmove(_exp(result), _exp(a), value_size);
normalize(result, result, sticky);
fc_exact &= normalize(result, result, sticky);
}
/**
* calculate a * b
*/
static void _fmul(const fp_value *a, const fp_value *b, fp_value *result) {
int sticky;
char *temp;
char res_sign;
fc_exact = 1;
handle_NAN(a, b, result);
temp = alloca(value_size);
......@@ -592,17 +615,22 @@ static void _fmul(const fp_value *a, const fp_value *b, fp_value *result) {
sc_val_from_ulong(2 + result->desc.mantissa_size, temp);
_shift_right(_mant(result), temp, _mant(result));
sticky = sc_had_carry();
fc_exact &= !sticky;
normalize(result, result, sc_had_carry());
fc_exact &= normalize(result, result, sticky);
}
/**
* calculate a / b
*/
static void _fdiv(const fp_value *a, const fp_value *b, fp_value *result) {
int sticky;
char *temp, *dividend;
char res_sign;
fc_exact = 1;
handle_NAN(a, b, result);
temp = alloca(value_size);
......@@ -683,9 +711,11 @@ static void _fdiv(const fp_value *a, const fp_value *b, fp_value *result) {
sc_val_from_ulong(1, divisor);
_shift_right(_mant(b), divisor, divisor);
sc_div(dividend, divisor, _mant(result));
sticky = sc_had_carry();
fc_exact &= !sticky;
}
normalize(result, result, sc_had_carry());
fc_exact &= normalize(result, result, sticky);
}
#if 0
......@@ -747,6 +777,9 @@ static void _trunc(const fp_value *a, fp_value *result) {
int exp_bias, exp_val;
char *temp;
/* fixme: can be exact */
fc_exact = 0;
temp = alloca(value_size);
if (a != result)
......@@ -1600,3 +1633,7 @@ unsigned fc_set_immediate_precision(unsigned bits) {
immediate_prec = bits;
return old;
}
int fc_is_exact(void) {
return fc_exact;
}
......@@ -256,6 +256,11 @@ unsigned char fc_sub_bits(const fp_value *val, unsigned num_bit, unsigned byte_o
*/
unsigned fc_set_immediate_precision(unsigned bits);
/**
* Returns non-zero if the result of the last operation was exact.
*/
int fc_is_exact(void);
void init_fltcalc(int precision);
void finish_fltcalc(void);
......
......@@ -1579,9 +1579,9 @@ void sc_mul(const void *value1, const void *value2, void *buffer) {
}
}
int sc_div(const void *value1, const void *value2, void *buffer) {
void sc_div(const void *value1, const void *value2, void *buffer) {
/* temp buffer holding unused result of divmod */
char *mod_res = alloca(calc_buffer_size);
char *unused_res = alloca(calc_buffer_size);
CLEAR_BUFFER(calc_buffer);
carry_flag = 0;
......@@ -1589,14 +1589,13 @@ int sc_div(const void *value1, const void *value2, void *buffer) {
DEBUGPRINTF_COMPUTATION(("%s / ", sc_print_hex(value1)));
DEBUGPRINTF_COMPUTATION(("%s -> ", sc_print_hex(value2)));
_divmod(value1, value2, calc_buffer, mod_res);
_divmod(value1, value2, calc_buffer, unused_res);
DEBUGPRINTF_COMPUTATION(("%s\n", sc_print_hex(calc_buffer)));
if ((buffer != NULL) && (buffer != calc_buffer)) {
memcpy(buffer, calc_buffer, calc_buffer_size);
}
return sc_is_zero(mod_res);
}
void sc_mod(const void *value1, const void *value2, void *buffer) {
......
......@@ -129,10 +129,8 @@ void sc_mul(const void *value1, const void *value2, void *buffer);
/**
* buffer = value1 / value2
*
* @return non-zero if the remainder is null.
*/
int sc_div(const void *value1, const void *value2, void *buffer);
void sc_div(const void *value1, const void *value2, void *buffer);
/**
* buffer = value1 % value2
......
......@@ -1580,6 +1580,11 @@ unsigned tarval_ieee754_set_immediate_precision(unsigned bits) {
return fc_set_immediate_precision(bits);
}
/* Returns non-zero if the result of the last IEEE-754 operation was exact. */
unsigned tarval_ieee754_get_exact(void) {
return fc_is_exact();
}
/*
* Sets the overflow mode for integer operations.
*/
......
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