forked from illumos/gcc
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fold-const.c
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fold-const.c
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/* Fold a constant sub-tree into a single node for C-compiler
Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
This file is part of GCC.
GCC is free software; you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation; either version 2, or (at your option) any later
version.
GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING. If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA. */
/*@@ This file should be rewritten to use an arbitrary precision
@@ representation for "struct tree_int_cst" and "struct tree_real_cst".
@@ Perhaps the routines could also be used for bc/dc, and made a lib.
@@ The routines that translate from the ap rep should
@@ warn if precision et. al. is lost.
@@ This would also make life easier when this technology is used
@@ for cross-compilers. */
/* The entry points in this file are fold, size_int_wide, size_binop
and force_fit_type.
fold takes a tree as argument and returns a simplified tree.
size_binop takes a tree code for an arithmetic operation
and two operands that are trees, and produces a tree for the
result, assuming the type comes from `sizetype'.
size_int takes an integer value, and creates a tree constant
with type from `sizetype'.
force_fit_type takes a constant and prior overflow indicator, and
forces the value to fit the type. It returns an overflow indicator. */
#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "flags.h"
#include "tree.h"
#include "real.h"
#include "rtl.h"
#include "expr.h"
#include "tm_p.h"
#include "toplev.h"
#include "ggc.h"
#include "hashtab.h"
#include "langhooks.h"
#include "md5.h"
static void encode (HOST_WIDE_INT *, unsigned HOST_WIDE_INT, HOST_WIDE_INT);
static void decode (HOST_WIDE_INT *, unsigned HOST_WIDE_INT *, HOST_WIDE_INT *);
static bool negate_mathfn_p (enum built_in_function);
static bool negate_expr_p (tree);
static tree negate_expr (tree);
static tree split_tree (tree, enum tree_code, tree *, tree *, tree *, int);
static tree associate_trees (tree, tree, enum tree_code, tree);
static tree int_const_binop (enum tree_code, tree, tree, int);
static tree const_binop (enum tree_code, tree, tree, int);
static hashval_t size_htab_hash (const void *);
static int size_htab_eq (const void *, const void *);
static tree fold_convert_const (enum tree_code, tree, tree);
static tree fold_convert (tree, tree);
static enum tree_code invert_tree_comparison (enum tree_code);
static enum tree_code swap_tree_comparison (enum tree_code);
static int comparison_to_compcode (enum tree_code);
static enum tree_code compcode_to_comparison (int);
static int truth_value_p (enum tree_code);
static int operand_equal_for_comparison_p (tree, tree, tree);
static int twoval_comparison_p (tree, tree *, tree *, int *);
static tree eval_subst (tree, tree, tree, tree, tree);
static tree pedantic_omit_one_operand (tree, tree, tree);
static tree distribute_bit_expr (enum tree_code, tree, tree, tree);
static tree make_bit_field_ref (tree, tree, int, int, int);
static tree optimize_bit_field_compare (enum tree_code, tree, tree, tree);
static tree decode_field_reference (tree, HOST_WIDE_INT *, HOST_WIDE_INT *,
enum machine_mode *, int *, int *,
tree *, tree *);
static int all_ones_mask_p (tree, int);
static tree sign_bit_p (tree, tree);
static int simple_operand_p (tree);
static tree range_binop (enum tree_code, tree, tree, int, tree, int);
static tree make_range (tree, int *, tree *, tree *);
static tree build_range_check (tree, tree, int, tree, tree);
static int merge_ranges (int *, tree *, tree *, int, tree, tree, int, tree,
tree);
static tree fold_range_test (tree);
static tree unextend (tree, int, int, tree);
static tree fold_truthop (enum tree_code, tree, tree, tree);
static tree optimize_minmax_comparison (tree);
static tree extract_muldiv (tree, tree, enum tree_code, tree);
static tree extract_muldiv_1 (tree, tree, enum tree_code, tree);
static tree strip_compound_expr (tree, tree);
static int multiple_of_p (tree, tree, tree);
static tree constant_boolean_node (int, tree);
static int count_cond (tree, int);
static tree fold_binary_op_with_conditional_arg (enum tree_code, tree, tree,
tree, int);
static bool fold_real_zero_addition_p (tree, tree, int);
static tree fold_mathfn_compare (enum built_in_function, enum tree_code,
tree, tree, tree);
static tree fold_inf_compare (enum tree_code, tree, tree, tree);
static bool reorder_operands_p (tree, tree);
static bool tree_swap_operands_p (tree, tree, bool);
/* The following constants represent a bit based encoding of GCC's
comparison operators. This encoding simplifies transformations
on relational comparison operators, such as AND and OR. */
#define COMPCODE_FALSE 0
#define COMPCODE_LT 1
#define COMPCODE_EQ 2
#define COMPCODE_LE 3
#define COMPCODE_GT 4
#define COMPCODE_NE 5
#define COMPCODE_GE 6
#define COMPCODE_TRUE 7
/* We know that A1 + B1 = SUM1, using 2's complement arithmetic and ignoring
overflow. Suppose A, B and SUM have the same respective signs as A1, B1,
and SUM1. Then this yields nonzero if overflow occurred during the
addition.
Overflow occurs if A and B have the same sign, but A and SUM differ in
sign. Use `^' to test whether signs differ, and `< 0' to isolate the
sign. */
#define OVERFLOW_SUM_SIGN(a, b, sum) ((~((a) ^ (b)) & ((a) ^ (sum))) < 0)
/* To do constant folding on INTEGER_CST nodes requires two-word arithmetic.
We do that by representing the two-word integer in 4 words, with only
HOST_BITS_PER_WIDE_INT / 2 bits stored in each word, as a positive
number. The value of the word is LOWPART + HIGHPART * BASE. */
#define LOWPART(x) \
((x) & (((unsigned HOST_WIDE_INT) 1 << (HOST_BITS_PER_WIDE_INT / 2)) - 1))
#define HIGHPART(x) \
((unsigned HOST_WIDE_INT) (x) >> HOST_BITS_PER_WIDE_INT / 2)
#define BASE ((unsigned HOST_WIDE_INT) 1 << HOST_BITS_PER_WIDE_INT / 2)
/* Unpack a two-word integer into 4 words.
LOW and HI are the integer, as two `HOST_WIDE_INT' pieces.
WORDS points to the array of HOST_WIDE_INTs. */
static void
encode (HOST_WIDE_INT *words, unsigned HOST_WIDE_INT low, HOST_WIDE_INT hi)
{
words[0] = LOWPART (low);
words[1] = HIGHPART (low);
words[2] = LOWPART (hi);
words[3] = HIGHPART (hi);
}
/* Pack an array of 4 words into a two-word integer.
WORDS points to the array of words.
The integer is stored into *LOW and *HI as two `HOST_WIDE_INT' pieces. */
static void
decode (HOST_WIDE_INT *words, unsigned HOST_WIDE_INT *low,
HOST_WIDE_INT *hi)
{
*low = words[0] + words[1] * BASE;
*hi = words[2] + words[3] * BASE;
}
/* Make the integer constant T valid for its type by setting to 0 or 1 all
the bits in the constant that don't belong in the type.
Return 1 if a signed overflow occurs, 0 otherwise. If OVERFLOW is
nonzero, a signed overflow has already occurred in calculating T, so
propagate it. */
int
force_fit_type (tree t, int overflow)
{
unsigned HOST_WIDE_INT low;
HOST_WIDE_INT high;
unsigned int prec;
if (TREE_CODE (t) == REAL_CST)
{
/* ??? Used to check for overflow here via CHECK_FLOAT_TYPE.
Consider doing it via real_convert now. */
return overflow;
}
else if (TREE_CODE (t) != INTEGER_CST)
return overflow;
low = TREE_INT_CST_LOW (t);
high = TREE_INT_CST_HIGH (t);
if (POINTER_TYPE_P (TREE_TYPE (t))
|| TREE_CODE (TREE_TYPE (t)) == OFFSET_TYPE)
prec = POINTER_SIZE;
else
prec = TYPE_PRECISION (TREE_TYPE (t));
/* First clear all bits that are beyond the type's precision. */
if (prec == 2 * HOST_BITS_PER_WIDE_INT)
;
else if (prec > HOST_BITS_PER_WIDE_INT)
TREE_INT_CST_HIGH (t)
&= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
else
{
TREE_INT_CST_HIGH (t) = 0;
if (prec < HOST_BITS_PER_WIDE_INT)
TREE_INT_CST_LOW (t) &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
}
/* Unsigned types do not suffer sign extension or overflow unless they
are a sizetype. */
if (TREE_UNSIGNED (TREE_TYPE (t))
&& ! (TREE_CODE (TREE_TYPE (t)) == INTEGER_TYPE
&& TYPE_IS_SIZETYPE (TREE_TYPE (t))))
return overflow;
/* If the value's sign bit is set, extend the sign. */
if (prec != 2 * HOST_BITS_PER_WIDE_INT
&& (prec > HOST_BITS_PER_WIDE_INT
? 0 != (TREE_INT_CST_HIGH (t)
& ((HOST_WIDE_INT) 1
<< (prec - HOST_BITS_PER_WIDE_INT - 1)))
: 0 != (TREE_INT_CST_LOW (t)
& ((unsigned HOST_WIDE_INT) 1 << (prec - 1)))))
{
/* Value is negative:
set to 1 all the bits that are outside this type's precision. */
if (prec > HOST_BITS_PER_WIDE_INT)
TREE_INT_CST_HIGH (t)
|= ((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
else
{
TREE_INT_CST_HIGH (t) = -1;
if (prec < HOST_BITS_PER_WIDE_INT)
TREE_INT_CST_LOW (t) |= ((unsigned HOST_WIDE_INT) (-1) << prec);
}
}
/* Return nonzero if signed overflow occurred. */
return
((overflow | (low ^ TREE_INT_CST_LOW (t)) | (high ^ TREE_INT_CST_HIGH (t)))
!= 0);
}
/* Add two doubleword integers with doubleword result.
Each argument is given as two `HOST_WIDE_INT' pieces.
One argument is L1 and H1; the other, L2 and H2.
The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
int
add_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
unsigned HOST_WIDE_INT l2, HOST_WIDE_INT h2,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
unsigned HOST_WIDE_INT l;
HOST_WIDE_INT h;
l = l1 + l2;
h = h1 + h2 + (l < l1);
*lv = l;
*hv = h;
return OVERFLOW_SUM_SIGN (h1, h2, h);
}
/* Negate a doubleword integer with doubleword result.
Return nonzero if the operation overflows, assuming it's signed.
The argument is given as two `HOST_WIDE_INT' pieces in L1 and H1.
The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
int
neg_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
if (l1 == 0)
{
*lv = 0;
*hv = - h1;
return (*hv & h1) < 0;
}
else
{
*lv = -l1;
*hv = ~h1;
return 0;
}
}
/* Multiply two doubleword integers with doubleword result.
Return nonzero if the operation overflows, assuming it's signed.
Each argument is given as two `HOST_WIDE_INT' pieces.
One argument is L1 and H1; the other, L2 and H2.
The value is stored as two `HOST_WIDE_INT' pieces in *LV and *HV. */
int
mul_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
unsigned HOST_WIDE_INT l2, HOST_WIDE_INT h2,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
HOST_WIDE_INT arg1[4];
HOST_WIDE_INT arg2[4];
HOST_WIDE_INT prod[4 * 2];
unsigned HOST_WIDE_INT carry;
int i, j, k;
unsigned HOST_WIDE_INT toplow, neglow;
HOST_WIDE_INT tophigh, neghigh;
encode (arg1, l1, h1);
encode (arg2, l2, h2);
memset (prod, 0, sizeof prod);
for (i = 0; i < 4; i++)
{
carry = 0;
for (j = 0; j < 4; j++)
{
k = i + j;
/* This product is <= 0xFFFE0001, the sum <= 0xFFFF0000. */
carry += arg1[i] * arg2[j];
/* Since prod[p] < 0xFFFF, this sum <= 0xFFFFFFFF. */
carry += prod[k];
prod[k] = LOWPART (carry);
carry = HIGHPART (carry);
}
prod[i + 4] = carry;
}
decode (prod, lv, hv); /* This ignores prod[4] through prod[4*2-1] */
/* Check for overflow by calculating the top half of the answer in full;
it should agree with the low half's sign bit. */
decode (prod + 4, &toplow, &tophigh);
if (h1 < 0)
{
neg_double (l2, h2, &neglow, &neghigh);
add_double (neglow, neghigh, toplow, tophigh, &toplow, &tophigh);
}
if (h2 < 0)
{
neg_double (l1, h1, &neglow, &neghigh);
add_double (neglow, neghigh, toplow, tophigh, &toplow, &tophigh);
}
return (*hv < 0 ? ~(toplow & tophigh) : toplow | tophigh) != 0;
}
/* Shift the doubleword integer in L1, H1 left by COUNT places
keeping only PREC bits of result.
Shift right if COUNT is negative.
ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
void
lshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
HOST_WIDE_INT count, unsigned int prec,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv, int arith)
{
unsigned HOST_WIDE_INT signmask;
if (count < 0)
{
rshift_double (l1, h1, -count, prec, lv, hv, arith);
return;
}
#ifdef SHIFT_COUNT_TRUNCATED
if (SHIFT_COUNT_TRUNCATED)
count %= prec;
#endif
if (count >= 2 * HOST_BITS_PER_WIDE_INT)
{
/* Shifting by the host word size is undefined according to the
ANSI standard, so we must handle this as a special case. */
*hv = 0;
*lv = 0;
}
else if (count >= HOST_BITS_PER_WIDE_INT)
{
*hv = l1 << (count - HOST_BITS_PER_WIDE_INT);
*lv = 0;
}
else
{
*hv = (((unsigned HOST_WIDE_INT) h1 << count)
| (l1 >> (HOST_BITS_PER_WIDE_INT - count - 1) >> 1));
*lv = l1 << count;
}
/* Sign extend all bits that are beyond the precision. */
signmask = -((prec > HOST_BITS_PER_WIDE_INT
? ((unsigned HOST_WIDE_INT) *hv
>> (prec - HOST_BITS_PER_WIDE_INT - 1))
: (*lv >> (prec - 1))) & 1);
if (prec >= 2 * HOST_BITS_PER_WIDE_INT)
;
else if (prec >= HOST_BITS_PER_WIDE_INT)
{
*hv &= ~((HOST_WIDE_INT) (-1) << (prec - HOST_BITS_PER_WIDE_INT));
*hv |= signmask << (prec - HOST_BITS_PER_WIDE_INT);
}
else
{
*hv = signmask;
*lv &= ~((unsigned HOST_WIDE_INT) (-1) << prec);
*lv |= signmask << prec;
}
}
/* Shift the doubleword integer in L1, H1 right by COUNT places
keeping only PREC bits of result. COUNT must be positive.
ARITH nonzero specifies arithmetic shifting; otherwise use logical shift.
Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
void
rshift_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
HOST_WIDE_INT count, unsigned int prec,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv,
int arith)
{
unsigned HOST_WIDE_INT signmask;
signmask = (arith
? -((unsigned HOST_WIDE_INT) h1 >> (HOST_BITS_PER_WIDE_INT - 1))
: 0);
#ifdef SHIFT_COUNT_TRUNCATED
if (SHIFT_COUNT_TRUNCATED)
count %= prec;
#endif
if (count >= 2 * HOST_BITS_PER_WIDE_INT)
{
/* Shifting by the host word size is undefined according to the
ANSI standard, so we must handle this as a special case. */
*hv = 0;
*lv = 0;
}
else if (count >= HOST_BITS_PER_WIDE_INT)
{
*hv = 0;
*lv = (unsigned HOST_WIDE_INT) h1 >> (count - HOST_BITS_PER_WIDE_INT);
}
else
{
*hv = (unsigned HOST_WIDE_INT) h1 >> count;
*lv = ((l1 >> count)
| ((unsigned HOST_WIDE_INT) h1 << (HOST_BITS_PER_WIDE_INT - count - 1) << 1));
}
/* Zero / sign extend all bits that are beyond the precision. */
if (count >= (HOST_WIDE_INT)prec)
{
*hv = signmask;
*lv = signmask;
}
else if ((prec - count) >= 2 * HOST_BITS_PER_WIDE_INT)
;
else if ((prec - count) >= HOST_BITS_PER_WIDE_INT)
{
*hv &= ~((HOST_WIDE_INT) (-1) << (prec - count - HOST_BITS_PER_WIDE_INT));
*hv |= signmask << (prec - count - HOST_BITS_PER_WIDE_INT);
}
else
{
*hv = signmask;
*lv &= ~((unsigned HOST_WIDE_INT) (-1) << (prec - count));
*lv |= signmask << (prec - count);
}
}
/* Rotate the doubleword integer in L1, H1 left by COUNT places
keeping only PREC bits of result.
Rotate right if COUNT is negative.
Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
void
lrotate_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
HOST_WIDE_INT count, unsigned int prec,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
unsigned HOST_WIDE_INT s1l, s2l;
HOST_WIDE_INT s1h, s2h;
count %= prec;
if (count < 0)
count += prec;
lshift_double (l1, h1, count, prec, &s1l, &s1h, 0);
rshift_double (l1, h1, prec - count, prec, &s2l, &s2h, 0);
*lv = s1l | s2l;
*hv = s1h | s2h;
}
/* Rotate the doubleword integer in L1, H1 left by COUNT places
keeping only PREC bits of result. COUNT must be positive.
Store the value as two `HOST_WIDE_INT' pieces in *LV and *HV. */
void
rrotate_double (unsigned HOST_WIDE_INT l1, HOST_WIDE_INT h1,
HOST_WIDE_INT count, unsigned int prec,
unsigned HOST_WIDE_INT *lv, HOST_WIDE_INT *hv)
{
unsigned HOST_WIDE_INT s1l, s2l;
HOST_WIDE_INT s1h, s2h;
count %= prec;
if (count < 0)
count += prec;
rshift_double (l1, h1, count, prec, &s1l, &s1h, 0);
lshift_double (l1, h1, prec - count, prec, &s2l, &s2h, 0);
*lv = s1l | s2l;
*hv = s1h | s2h;
}
/* Divide doubleword integer LNUM, HNUM by doubleword integer LDEN, HDEN
for a quotient (stored in *LQUO, *HQUO) and remainder (in *LREM, *HREM).
CODE is a tree code for a kind of division, one of
TRUNC_DIV_EXPR, FLOOR_DIV_EXPR, CEIL_DIV_EXPR, ROUND_DIV_EXPR
or EXACT_DIV_EXPR
It controls how the quotient is rounded to an integer.
Return nonzero if the operation overflows.
UNS nonzero says do unsigned division. */
int
div_and_round_double (enum tree_code code, int uns,
unsigned HOST_WIDE_INT lnum_orig, /* num == numerator == dividend */
HOST_WIDE_INT hnum_orig,
unsigned HOST_WIDE_INT lden_orig, /* den == denominator == divisor */
HOST_WIDE_INT hden_orig,
unsigned HOST_WIDE_INT *lquo,
HOST_WIDE_INT *hquo, unsigned HOST_WIDE_INT *lrem,
HOST_WIDE_INT *hrem)
{
int quo_neg = 0;
HOST_WIDE_INT num[4 + 1]; /* extra element for scaling. */
HOST_WIDE_INT den[4], quo[4];
int i, j;
unsigned HOST_WIDE_INT work;
unsigned HOST_WIDE_INT carry = 0;
unsigned HOST_WIDE_INT lnum = lnum_orig;
HOST_WIDE_INT hnum = hnum_orig;
unsigned HOST_WIDE_INT lden = lden_orig;
HOST_WIDE_INT hden = hden_orig;
int overflow = 0;
if (hden == 0 && lden == 0)
overflow = 1, lden = 1;
/* Calculate quotient sign and convert operands to unsigned. */
if (!uns)
{
if (hnum < 0)
{
quo_neg = ~ quo_neg;
/* (minimum integer) / (-1) is the only overflow case. */
if (neg_double (lnum, hnum, &lnum, &hnum)
&& ((HOST_WIDE_INT) lden & hden) == -1)
overflow = 1;
}
if (hden < 0)
{
quo_neg = ~ quo_neg;
neg_double (lden, hden, &lden, &hden);
}
}
if (hnum == 0 && hden == 0)
{ /* single precision */
*hquo = *hrem = 0;
/* This unsigned division rounds toward zero. */
*lquo = lnum / lden;
goto finish_up;
}
if (hnum == 0)
{ /* trivial case: dividend < divisor */
/* hden != 0 already checked. */
*hquo = *lquo = 0;
*hrem = hnum;
*lrem = lnum;
goto finish_up;
}
memset (quo, 0, sizeof quo);
memset (num, 0, sizeof num); /* to zero 9th element */
memset (den, 0, sizeof den);
encode (num, lnum, hnum);
encode (den, lden, hden);
/* Special code for when the divisor < BASE. */
if (hden == 0 && lden < (unsigned HOST_WIDE_INT) BASE)
{
/* hnum != 0 already checked. */
for (i = 4 - 1; i >= 0; i--)
{
work = num[i] + carry * BASE;
quo[i] = work / lden;
carry = work % lden;
}
}
else
{
/* Full double precision division,
with thanks to Don Knuth's "Seminumerical Algorithms". */
int num_hi_sig, den_hi_sig;
unsigned HOST_WIDE_INT quo_est, scale;
/* Find the highest nonzero divisor digit. */
for (i = 4 - 1;; i--)
if (den[i] != 0)
{
den_hi_sig = i;
break;
}
/* Insure that the first digit of the divisor is at least BASE/2.
This is required by the quotient digit estimation algorithm. */
scale = BASE / (den[den_hi_sig] + 1);
if (scale > 1)
{ /* scale divisor and dividend */
carry = 0;
for (i = 0; i <= 4 - 1; i++)
{
work = (num[i] * scale) + carry;
num[i] = LOWPART (work);
carry = HIGHPART (work);
}
num[4] = carry;
carry = 0;
for (i = 0; i <= 4 - 1; i++)
{
work = (den[i] * scale) + carry;
den[i] = LOWPART (work);
carry = HIGHPART (work);
if (den[i] != 0) den_hi_sig = i;
}
}
num_hi_sig = 4;
/* Main loop */
for (i = num_hi_sig - den_hi_sig - 1; i >= 0; i--)
{
/* Guess the next quotient digit, quo_est, by dividing the first
two remaining dividend digits by the high order quotient digit.
quo_est is never low and is at most 2 high. */
unsigned HOST_WIDE_INT tmp;
num_hi_sig = i + den_hi_sig + 1;
work = num[num_hi_sig] * BASE + num[num_hi_sig - 1];
if (num[num_hi_sig] != den[den_hi_sig])
quo_est = work / den[den_hi_sig];
else
quo_est = BASE - 1;
/* Refine quo_est so it's usually correct, and at most one high. */
tmp = work - quo_est * den[den_hi_sig];
if (tmp < BASE
&& (den[den_hi_sig - 1] * quo_est
> (tmp * BASE + num[num_hi_sig - 2])))
quo_est--;
/* Try QUO_EST as the quotient digit, by multiplying the
divisor by QUO_EST and subtracting from the remaining dividend.
Keep in mind that QUO_EST is the I - 1st digit. */
carry = 0;
for (j = 0; j <= den_hi_sig; j++)
{
work = quo_est * den[j] + carry;
carry = HIGHPART (work);
work = num[i + j] - LOWPART (work);
num[i + j] = LOWPART (work);
carry += HIGHPART (work) != 0;
}
/* If quo_est was high by one, then num[i] went negative and
we need to correct things. */
if (num[num_hi_sig] < (HOST_WIDE_INT) carry)
{
quo_est--;
carry = 0; /* add divisor back in */
for (j = 0; j <= den_hi_sig; j++)
{
work = num[i + j] + den[j] + carry;
carry = HIGHPART (work);
num[i + j] = LOWPART (work);
}
num [num_hi_sig] += carry;
}
/* Store the quotient digit. */
quo[i] = quo_est;
}
}
decode (quo, lquo, hquo);
finish_up:
/* If result is negative, make it so. */
if (quo_neg)
neg_double (*lquo, *hquo, lquo, hquo);
/* compute trial remainder: rem = num - (quo * den) */
mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
neg_double (*lrem, *hrem, lrem, hrem);
add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);
switch (code)
{
case TRUNC_DIV_EXPR:
case TRUNC_MOD_EXPR: /* round toward zero */
case EXACT_DIV_EXPR: /* for this one, it shouldn't matter */
return overflow;
case FLOOR_DIV_EXPR:
case FLOOR_MOD_EXPR: /* round toward negative infinity */
if (quo_neg && (*lrem != 0 || *hrem != 0)) /* ratio < 0 && rem != 0 */
{
/* quo = quo - 1; */
add_double (*lquo, *hquo, (HOST_WIDE_INT) -1, (HOST_WIDE_INT) -1,
lquo, hquo);
}
else
return overflow;
break;
case CEIL_DIV_EXPR:
case CEIL_MOD_EXPR: /* round toward positive infinity */
if (!quo_neg && (*lrem != 0 || *hrem != 0)) /* ratio > 0 && rem != 0 */
{
add_double (*lquo, *hquo, (HOST_WIDE_INT) 1, (HOST_WIDE_INT) 0,
lquo, hquo);
}
else
return overflow;
break;
case ROUND_DIV_EXPR:
case ROUND_MOD_EXPR: /* round to closest integer */
{
unsigned HOST_WIDE_INT labs_rem = *lrem;
HOST_WIDE_INT habs_rem = *hrem;
unsigned HOST_WIDE_INT labs_den = lden, ltwice;
HOST_WIDE_INT habs_den = hden, htwice;
/* Get absolute values. */
if (*hrem < 0)
neg_double (*lrem, *hrem, &labs_rem, &habs_rem);
if (hden < 0)
neg_double (lden, hden, &labs_den, &habs_den);
/* If (2 * abs (lrem) >= abs (lden)) */
mul_double ((HOST_WIDE_INT) 2, (HOST_WIDE_INT) 0,
labs_rem, habs_rem, <wice, &htwice);
if (((unsigned HOST_WIDE_INT) habs_den
< (unsigned HOST_WIDE_INT) htwice)
|| (((unsigned HOST_WIDE_INT) habs_den
== (unsigned HOST_WIDE_INT) htwice)
&& (labs_den < ltwice)))
{
if (*hquo < 0)
/* quo = quo - 1; */
add_double (*lquo, *hquo,
(HOST_WIDE_INT) -1, (HOST_WIDE_INT) -1, lquo, hquo);
else
/* quo = quo + 1; */
add_double (*lquo, *hquo, (HOST_WIDE_INT) 1, (HOST_WIDE_INT) 0,
lquo, hquo);
}
else
return overflow;
}
break;
default:
abort ();
}
/* Compute true remainder: rem = num - (quo * den) */
mul_double (*lquo, *hquo, lden_orig, hden_orig, lrem, hrem);
neg_double (*lrem, *hrem, lrem, hrem);
add_double (lnum_orig, hnum_orig, *lrem, *hrem, lrem, hrem);
return overflow;
}
/* Return true if built-in mathematical function specified by CODE
preserves the sign of it argument, i.e. -f(x) == f(-x). */
static bool
negate_mathfn_p (enum built_in_function code)
{
switch (code)
{
case BUILT_IN_ASIN:
case BUILT_IN_ASINF:
case BUILT_IN_ASINL:
case BUILT_IN_ATAN:
case BUILT_IN_ATANF:
case BUILT_IN_ATANL:
case BUILT_IN_SIN:
case BUILT_IN_SINF:
case BUILT_IN_SINL:
case BUILT_IN_TAN:
case BUILT_IN_TANF:
case BUILT_IN_TANL:
return true;
default:
break;
}
return false;
}
/* Determine whether an expression T can be cheaply negated using
the function negate_expr. */
static bool
negate_expr_p (tree t)
{
unsigned HOST_WIDE_INT val;
unsigned int prec;
tree type;
if (t == 0)
return false;
type = TREE_TYPE (t);
STRIP_SIGN_NOPS (t);
switch (TREE_CODE (t))
{
case INTEGER_CST:
if (TREE_UNSIGNED (type) || ! flag_trapv)
return true;
/* Check that -CST will not overflow type. */
prec = TYPE_PRECISION (type);
if (prec > HOST_BITS_PER_WIDE_INT)
{
if (TREE_INT_CST_LOW (t) != 0)
return true;
prec -= HOST_BITS_PER_WIDE_INT;
val = TREE_INT_CST_HIGH (t);
}
else
val = TREE_INT_CST_LOW (t);
if (prec < HOST_BITS_PER_WIDE_INT)
val &= ((unsigned HOST_WIDE_INT) 1 << prec) - 1;
return val != ((unsigned HOST_WIDE_INT) 1 << (prec - 1));
case REAL_CST:
case NEGATE_EXPR:
return true;
case COMPLEX_CST:
return negate_expr_p (TREE_REALPART (t))
&& negate_expr_p (TREE_IMAGPART (t));
case MINUS_EXPR:
/* We can't turn -(A-B) into B-A when we honor signed zeros. */
return (! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations)
&& reorder_operands_p (TREE_OPERAND (t, 0),
TREE_OPERAND (t, 1));
case MULT_EXPR:
if (TREE_UNSIGNED (TREE_TYPE (t)))
break;
/* Fall through. */
case RDIV_EXPR:
if (! HONOR_SIGN_DEPENDENT_ROUNDING (TYPE_MODE (TREE_TYPE (t))))
return negate_expr_p (TREE_OPERAND (t, 1))
|| negate_expr_p (TREE_OPERAND (t, 0));
break;
case NOP_EXPR:
/* Negate -((double)float) as (double)(-float). */
if (TREE_CODE (type) == REAL_TYPE)
{
tree tem = strip_float_extensions (t);
if (tem != t)
return negate_expr_p (tem);
}
break;
case CALL_EXPR:
/* Negate -f(x) as f(-x). */
if (negate_mathfn_p (builtin_mathfn_code (t)))
return negate_expr_p (TREE_VALUE (TREE_OPERAND (t, 1)));
break;
default:
break;
}
return false;
}
/* Given T, an expression, return the negation of T. Allow for T to be
null, in which case return null. */
static tree
negate_expr (tree t)
{
tree type;
tree tem;
if (t == 0)
return 0;
type = TREE_TYPE (t);
STRIP_SIGN_NOPS (t);
switch (TREE_CODE (t))
{
case INTEGER_CST:
{
unsigned HOST_WIDE_INT low;
HOST_WIDE_INT high;
int overflow = neg_double (TREE_INT_CST_LOW (t),
TREE_INT_CST_HIGH (t),
&low, &high);
tem = build_int_2 (low, high);
TREE_TYPE (tem) = type;
TREE_OVERFLOW (tem)
= (TREE_OVERFLOW (t)
| force_fit_type (tem, overflow && !TREE_UNSIGNED (type)));
TREE_CONSTANT_OVERFLOW (tem)
= TREE_OVERFLOW (tem) | TREE_CONSTANT_OVERFLOW (t);
}
if (! TREE_OVERFLOW (tem)
|| TREE_UNSIGNED (type)
|| ! flag_trapv)
return tem;
break;
case REAL_CST:
tem = build_real (type, REAL_VALUE_NEGATE (TREE_REAL_CST (t)));
/* Two's complement FP formats, such as c4x, may overflow. */
if (! TREE_OVERFLOW (tem) || ! flag_trapping_math)
return fold_convert (type, tem);
break;
case COMPLEX_CST:
{
tree rpart = negate_expr (TREE_REALPART (t));
tree ipart = negate_expr (TREE_IMAGPART (t));
if ((TREE_CODE (rpart) == REAL_CST
&& TREE_CODE (ipart) == REAL_CST)
|| (TREE_CODE (rpart) == INTEGER_CST
&& TREE_CODE (ipart) == INTEGER_CST))
return build_complex (type, rpart, ipart);
}
break;
case NEGATE_EXPR:
return fold_convert (type, TREE_OPERAND (t, 0));
case MINUS_EXPR:
/* - (A - B) -> B - A */
if ((! FLOAT_TYPE_P (type) || flag_unsafe_math_optimizations)
&& reorder_operands_p (TREE_OPERAND (t, 0), TREE_OPERAND (t, 1)))
return fold_convert (type,
fold (build (MINUS_EXPR, TREE_TYPE (t),
TREE_OPERAND (t, 1),
TREE_OPERAND (t, 0))));
break;
case MULT_EXPR:
if (TREE_UNSIGNED (TREE_TYPE (t)))
break;
/* Fall through. */
case RDIV_EXPR: