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Re: [patch] for PR28411
- From: Zdenek Dvorak <rakdver at atrey dot karlin dot mff dot cuni dot cz>
- To: Roger Sayle <roger at eyesopen dot com>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 4 Aug 2006 11:58:00 +0200
- Subject: Re: [patch] for PR28411
- References: <20060729114509.GA7416@atrey.karlin.mff.cuni.cz> <Pine.LNX.4.44.0607291540470.29160-100000@www.eyesopen.com>
Hello,
> On Sat, 29 Jul 2006, Zdenek Dvorak wrote:
> >
> > PR tree-optimization/28411
> > * tree-ssa-loop-niter.c (derive_constant_upper_bound): Pass NULL for
> > the remainder argument of double_int_udiv.
> > * double-int.c (double_int_div, double_int_udiv, double_int_sdiv):
> > Return also remainder after division.
> > * double-int.h (double_int_div, double_int_udiv, double_int_sdiv):
> > Declaration changed.
> > * tree-ssa-loop-ivopts.c (constant_multiple_of): Returns the result
> > in double_int.
> > (get_computation_aff, get_computation_cost_at): Handle double_int
> > return type of constant_multiple_of.
>
> I'd prefer that you add a new double_int_divmod if you need one, rather
> than change the div, udiv and sdiv APIs. It makes sense to define/keep
> stable APIs that allow efficient calculation of quotients and remainders
> without the need to calculate both.
>
> void double_int_sdivmod (double_int a, double_int b, unsigned int code,
> double_int *div, double_int *mod);
>
here is the updated version; I still do not understand why you consider
it better that way, though.
Zdenek
PR tree-optimization/28411
* double-int.c (double_int_div): Use double_int_divmod.
(double_int_divmod, double_int_sdivmod, double_int_udivmod,
double_int_mod, double_int_smod, double_int_umod): New functions.
* double-int.h (double_int_divmod, double_int_sdivmod,
double_int_udivmod, double_int_mod, double_int_smod, double_int_umod):
Declare.
* tree-ssa-loop-ivopts.c (constant_multiple_of): Returns the result
in double_int.
(get_computation_aff, get_computation_cost_at): Handle double_int
return type of constant_multiple_of.
Index: double-int.c
===================================================================
*** double-int.c (revision 115851)
--- double-int.c (working copy)
*************** double_int_neg (double_int a)
*** 203,222 ****
/* Returns A / B (computed as unsigned depending on UNS, and rounded as
specified by CODE). CODE is enum tree_code in fact, but double_int.h
! must be included before tree.h. */
double_int
! double_int_div (double_int a, double_int b, bool uns, unsigned code)
{
- unsigned HOST_WIDE_INT rem_lo;
- HOST_WIDE_INT rem_hi;
double_int ret;
div_and_round_double (code, uns, a.low, a.high, b.low, b.high,
! &ret.low, &ret.high, &rem_lo, &rem_hi);
return ret;
}
/* The same as double_int_div with UNS = false. */
double_int
--- 203,250 ----
/* Returns A / B (computed as unsigned depending on UNS, and rounded as
specified by CODE). CODE is enum tree_code in fact, but double_int.h
! must be included before tree.h. The remainder after the division is
! stored to MOD. */
double_int
! double_int_divmod (double_int a, double_int b, bool uns, unsigned code,
! double_int *mod)
{
double_int ret;
div_and_round_double (code, uns, a.low, a.high, b.low, b.high,
! &ret.low, &ret.high, &mod->low, &mod->high);
return ret;
}
+ /* The same as double_int_divmod with UNS = false. */
+
+ double_int
+ double_int_sdivmod (double_int a, double_int b, unsigned code, double_int *mod)
+ {
+ return double_int_divmod (a, b, false, code, mod);
+ }
+
+ /* The same as double_int_divmod with UNS = true. */
+
+ double_int
+ double_int_udivmod (double_int a, double_int b, unsigned code, double_int *mod)
+ {
+ return double_int_divmod (a, b, true, code, mod);
+ }
+
+ /* Returns A / B (computed as unsigned depending on UNS, and rounded as
+ specified by CODE). CODE is enum tree_code in fact, but double_int.h
+ must be included before tree.h. */
+
+ double_int
+ double_int_div (double_int a, double_int b, bool uns, unsigned code)
+ {
+ double_int mod;
+
+ return double_int_divmod (a, b, uns, code, &mod);
+ }
+
/* The same as double_int_div with UNS = false. */
double_int
*************** double_int_udiv (double_int a, double_in
*** 233,238 ****
--- 261,295 ----
return double_int_div (a, b, true, code);
}
+ /* Returns A % B (computed as unsigned depending on UNS, and rounded as
+ specified by CODE). CODE is enum tree_code in fact, but double_int.h
+ must be included before tree.h. */
+
+ double_int
+ double_int_mod (double_int a, double_int b, bool uns, unsigned code)
+ {
+ double_int mod;
+
+ double_int_divmod (a, b, uns, code, &mod);
+ return mod;
+ }
+
+ /* The same as double_int_mod with UNS = false. */
+
+ double_int
+ double_int_smod (double_int a, double_int b, unsigned code)
+ {
+ return double_int_mod (a, b, false, code);
+ }
+
+ /* The same as double_int_mod with UNS = true. */
+
+ double_int
+ double_int_umod (double_int a, double_int b, unsigned code)
+ {
+ return double_int_mod (a, b, true, code);
+ }
+
/* Constructs tree in type TYPE from with value given by CST. */
tree
Index: double-int.h
===================================================================
*** double-int.h (revision 115851)
--- double-int.h (working copy)
*************** unsigned HOST_WIDE_INT double_int_to_uhw
*** 116,121 ****
--- 116,127 ----
double_int double_int_div (double_int, double_int, bool, unsigned);
double_int double_int_sdiv (double_int, double_int, unsigned);
double_int double_int_udiv (double_int, double_int, unsigned);
+ double_int double_int_mod (double_int, double_int, bool, unsigned);
+ double_int double_int_smod (double_int, double_int, unsigned);
+ double_int double_int_umod (double_int, double_int, unsigned);
+ double_int double_int_divmod (double_int, double_int, bool, unsigned, double_int *);
+ double_int double_int_sdivmod (double_int, double_int, unsigned, double_int *);
+ double_int double_int_udivmod (double_int, double_int, unsigned, double_int *);
bool double_int_negative_p (double_int);
int double_int_cmp (double_int, double_int, bool);
int double_int_scmp (double_int, double_int);
Index: tree-ssa-loop-ivopts.c
===================================================================
*** tree-ssa-loop-ivopts.c (revision 115851)
--- tree-ssa-loop-ivopts.c (working copy)
*************** tree_int_cst_sign_bit (tree t)
*** 2554,2574 ****
return (w >> bitno) & 1;
}
! /* If we can prove that TOP = cst * BOT for some constant cst in TYPE,
! return cst. Otherwise return NULL_TREE. */
! static tree
! constant_multiple_of (tree type, tree top, tree bot)
{
! tree res, mby, p0, p1;
enum tree_code code;
! bool negate;
STRIP_NOPS (top);
STRIP_NOPS (bot);
if (operand_equal_p (top, bot, 0))
! return build_int_cst (type, 1);
code = TREE_CODE (top);
switch (code)
--- 2554,2580 ----
return (w >> bitno) & 1;
}
! /* If we can prove that TOP = cst * BOT for some constant cst,
! store cst to MUL and return true. Otherwise return false.
! The returned value is always sign-extended, regardless of the
! signedness of TOP and BOT. */
! static bool
! constant_multiple_of (tree top, tree bot, double_int *mul)
{
! tree mby;
enum tree_code code;
! double_int res, p0, p1;
! unsigned precision = TYPE_PRECISION (TREE_TYPE (top));
STRIP_NOPS (top);
STRIP_NOPS (bot);
if (operand_equal_p (top, bot, 0))
! {
! *mul = double_int_one;
! return true;
! }
code = TREE_CODE (top);
switch (code)
*************** constant_multiple_of (tree type, tree to
*** 2576,2635 ****
case MULT_EXPR:
mby = TREE_OPERAND (top, 1);
if (TREE_CODE (mby) != INTEGER_CST)
! return NULL_TREE;
! res = constant_multiple_of (type, TREE_OPERAND (top, 0), bot);
! if (!res)
! return NULL_TREE;
! return fold_binary_to_constant (MULT_EXPR, type, res,
! fold_convert (type, mby));
case PLUS_EXPR:
case MINUS_EXPR:
! p0 = constant_multiple_of (type, TREE_OPERAND (top, 0), bot);
! if (!p0)
! return NULL_TREE;
! p1 = constant_multiple_of (type, TREE_OPERAND (top, 1), bot);
! if (!p1)
! return NULL_TREE;
! return fold_binary_to_constant (code, type, p0, p1);
case INTEGER_CST:
if (TREE_CODE (bot) != INTEGER_CST)
! return NULL_TREE;
!
! bot = fold_convert (type, bot);
! top = fold_convert (type, top);
!
! /* If BOT seems to be negative, try dividing by -BOT instead, and negate
! the result afterwards. */
! if (tree_int_cst_sign_bit (bot))
! {
! negate = true;
! bot = fold_unary_to_constant (NEGATE_EXPR, type, bot);
! }
! else
! negate = false;
!
! /* Ditto for TOP. */
! if (tree_int_cst_sign_bit (top))
! {
! negate = !negate;
! top = fold_unary_to_constant (NEGATE_EXPR, type, top);
! }
!
! if (!zero_p (fold_binary_to_constant (TRUNC_MOD_EXPR, type, top, bot)))
! return NULL_TREE;
! res = fold_binary_to_constant (EXACT_DIV_EXPR, type, top, bot);
! if (negate)
! res = fold_unary_to_constant (NEGATE_EXPR, type, res);
! return res;
default:
! return NULL_TREE;
}
}
--- 2582,2621 ----
case MULT_EXPR:
mby = TREE_OPERAND (top, 1);
if (TREE_CODE (mby) != INTEGER_CST)
! return false;
! if (!constant_multiple_of (TREE_OPERAND (top, 0), bot, &res))
! return false;
! *mul = double_int_sext (double_int_mul (res, tree_to_double_int (mby)),
! precision);
! return true;
case PLUS_EXPR:
case MINUS_EXPR:
! if (!constant_multiple_of (TREE_OPERAND (top, 0), bot, &p0)
! || !constant_multiple_of (TREE_OPERAND (top, 1), bot, &p1))
! return false;
! if (code == MINUS_EXPR)
! p1 = double_int_neg (p1);
! *mul = double_int_sext (double_int_add (p0, p1), precision);
! return true;
case INTEGER_CST:
if (TREE_CODE (bot) != INTEGER_CST)
! return false;
! p0 = double_int_sext (tree_to_double_int (bot), precision);
! p1 = double_int_sext (tree_to_double_int (top), precision);
! if (double_int_zero_p (p1))
! return false;
! *mul = double_int_sext (double_int_sdivmod (p0, p1, FLOOR_DIV_EXPR, &res),
! precision);
! return double_int_zero_p (res);
default:
! return false;
}
}
*************** get_computation_aff (struct loop *loop,
*** 2964,2969 ****
--- 2950,2956 ----
HOST_WIDE_INT ratioi;
struct affine_tree_combination cbase_aff, expr_aff;
tree cstep_orig = cstep, ustep_orig = ustep;
+ double_int rat;
if (TYPE_PRECISION (utype) > TYPE_PRECISION (ctype))
{
*************** get_computation_aff (struct loop *loop,
*** 3018,3038 ****
}
else
{
! ratio = constant_multiple_of (uutype, ustep_orig, cstep_orig);
! if (!ratio)
return false;
/* Ratioi is only used to detect special cases when the multiplicative
! factor is 1 or -1, so if we cannot convert ratio to HOST_WIDE_INT,
! we may set it to 0. We prefer cst_and_fits_in_hwi/int_cst_value
! to integer_onep/integer_all_onesp, since the former ignores
! TREE_OVERFLOW. */
! if (cst_and_fits_in_hwi (ratio))
! ratioi = int_cst_value (ratio);
! else if (integer_onep (ratio))
! ratioi = 1;
! else if (integer_all_onesp (ratio))
! ratioi = -1;
else
ratioi = 0;
}
--- 3005,3019 ----
}
else
{
! if (!constant_multiple_of (ustep_orig, cstep_orig, &rat))
return false;
+ ratio = double_int_to_tree (uutype, rat);
/* Ratioi is only used to detect special cases when the multiplicative
! factor is 1 or -1, so if rat does not fit to HOST_WIDE_INT, we may
! set it to 0. */
! if (double_int_fits_in_shwi_p (rat))
! ratioi = double_int_to_shwi (rat);
else
ratioi = 0;
}
*************** get_computation_cost_at (struct ivopts_d
*** 3753,3771 ****
}
else
{
! tree rat;
! rat = constant_multiple_of (utype, ustep, cstep);
!
! if (!rat)
return INFTY;
!
! if (cst_and_fits_in_hwi (rat))
! ratio = int_cst_value (rat);
! else if (integer_onep (rat))
! ratio = 1;
! else if (integer_all_onesp (rat))
! ratio = -1;
else
return INFTY;
}
--- 3734,3746 ----
}
else
{
! double_int rat;
! if (!constant_multiple_of (ustep, cstep, &rat))
return INFTY;
!
! if (double_int_fits_in_shwi_p (rat))
! ratio = double_int_to_shwi (rat);
else
return INFTY;
}