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re PR tree-optimization/48052 (loop not vectorized if index is "unsigned int") 

PR tree-optimization/48052
	* cfgloop.h (struct control_iv): New.
	(struct loop): New field control_ivs.
	* tree-ssa-loop-niter.c : Include "stor-layout.h".
	(number_of_iterations_lt): Set no_overflow information.
	(number_of_iterations_exit): Init control iv in niter struct.
	(record_control_iv): New.
	(estimate_numbers_of_iterations_loop): Call record_control_iv.
	(loop_exits_before_overflow): New.  Interface factored out of
	scev_probably_wraps_p.
	(scev_probably_wraps_p): Factor loop niter related code into
	loop_exits_before_overflow.
	(free_numbers_of_iterations_estimates_loop): Free control ivs.
	* tree-ssa-loop-niter.h (free_loop_control_ivs): New.

	gcc/testsuite/ChangeLog
	PR tree-optimization/48052
	* gcc.dg/tree-ssa/scev-8.c: New.
	* gcc.dg/tree-ssa/scev-9.c: New.
	* gcc.dg/tree-ssa/scev-10.c: New.
	* gcc.dg/vect/pr48052.c: New.

From-SVN: r224020
This commit is contained in:
Bin Cheng 2015-06-02 10:19:18 +00:00 committed by Bin Cheng
parent b47717225b
commit 2f07b722ed
9 changed files with 397 additions and 61 deletions
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17
gcc/ChangeLog
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@ -1,3 +1,20 @@
2015-06-02 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/48052
* cfgloop.h (struct control_iv): New.
(struct loop): New field control_ivs.
* tree-ssa-loop-niter.c : Include "stor-layout.h".
(number_of_iterations_lt): Set no_overflow information.
(number_of_iterations_exit): Init control iv in niter struct.
(record_control_iv): New.
(estimate_numbers_of_iterations_loop): Call record_control_iv.
(loop_exits_before_overflow): New. Interface factored out of
scev_probably_wraps_p.
(scev_probably_wraps_p): Factor loop niter related code into
loop_exits_before_overflow.
(free_numbers_of_iterations_estimates_loop): Free control ivs.
* tree-ssa-loop-niter.h (free_loop_control_ivs): New.
2015-06-02 Eric Botcazou <ebotcazou@adacore.com>
* gimplify.c (gimplify_modify_expr): Do not create a DECL_DEBUG_EXPR if

11
gcc/cfgloop.h
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@ -116,6 +116,14 @@ enum loop_estimation
EST_LAST
};
/* The structure describing non-overflow control induction variable for
loop's exit edge. */
struct GTY ((chain_next ("%h.next"))) control_iv {
tree base;
tree step;
struct control_iv *next;
};
/* Structure to hold information for each natural loop. */
struct GTY ((chain_next ("%h.next"))) loop {
/* Index into loops array. */
@ -203,6 +211,9 @@ struct GTY ((chain_next ("%h.next"))) loop {
/* Upper bound on number of iterations of a loop. */
struct nb_iter_bound *bounds;
/* Non-overflow control ivs of a loop. */
struct control_iv *control_ivs;
/* Head of the cyclic list of the exits of the loop. */
struct loop_exit *exits;

8
gcc/testsuite/ChangeLog
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@ -1,3 +1,11 @@
2015-06-02 Bin Cheng <bin.cheng@arm.com>
PR tree-optimization/48052
* gcc.dg/tree-ssa/scev-8.c: New.
* gcc.dg/tree-ssa/scev-9.c: New.
* gcc.dg/tree-ssa/scev-10.c: New.
* gcc.dg/vect/pr48052.c: New.
2015-06-02 Eric Botcazou <ebotcazou@adacore.com>
* gcc.dg/vect/vec-scal-opt.c: Adjust regexp.

23
gcc/testsuite/gcc.dg/tree-ssa/scev-10.c Normal file
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@ -0,0 +1,23 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-ivopts-details" } */
int *a;
int
foo (signed char s, signed char l)
{
signed char i;
int sum = 0;
for (i = s; i < l; i++)
{
sum += a[i];
}
return sum;
}
/* Address of array reference is scev. */
/* { dg-final { scan-tree-dump-times "use \[0-9\]\n address" 1 "ivopts" } } */

62
gcc/testsuite/gcc.dg/tree-ssa/scev-8.c Normal file
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@ -0,0 +1,62 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-ivopts-details" } */
int *a;
int
foo1 (long long s, long long l)
{
long long i;
for (i = s; i < l; i++)
{
a[(short)i] = 0;
}
return 0;
}
int
foo2 (unsigned char s, unsigned char l, unsigned char c)
{
unsigned char i, step = 1;
int sum = 0;
for (i = s; i < l; i++)
{
sum += a[c];
c += step;
}
return sum;
}
int
foo3 (unsigned char s, unsigned char l, unsigned char c)
{
unsigned char i;
int sum = 0;
for (i = s; i != l; i += c)
{
sum += a[i];
}
return sum;
}
int
foo4 (unsigned char s, unsigned char l)
{
unsigned char i;
int sum = 0;
for (i = s; i != l; i++)
{
sum += a[i];
}
return sum;
}
/* Address of array references are not scevs. */
/* { dg-final { scan-tree-dump-not "use \[0-9\]\n address" "ivopts" } } */

22
gcc/testsuite/gcc.dg/tree-ssa/scev-9.c Normal file
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@ -0,0 +1,22 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-ivopts-details" } */
int *a;
int
foo (unsigned char s, unsigned char l)
{
unsigned char i;
int sum = 0;
for (i = s; i < l; i += 1)
{
sum += a[i];
}
return sum;
}
/* Address of array reference is scev. */
/* { dg-final { scan-tree-dump-times "use \[0-9\]\n address" 1 "ivopts" } } */

26
gcc/testsuite/gcc.dg/vect/pr48052.c Normal file
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@ -0,0 +1,26 @@
/* { dg-do compile } */
/* { dg-additional-options "-O3" } */
int foo(int* A, int* B, unsigned start, unsigned BS)
{
int s;
for (unsigned k = start; k < start + BS; k++)
{
s += A[k] * B[k];
}
return s;
}
int bar(int* A, int* B, unsigned BS)
{
int s;
for (unsigned k = 0; k < BS; k++)
{
s += A[k] * B[k];
}
return s;
}
/* { dg-final { scan-tree-dump-times "vectorized 1 loops" 2 "vect" } } */

288
gcc/tree-ssa-loop-niter.c
View File

@ -31,6 +31,7 @@ along with GCC; see the file COPYING3. If not see
#include "wide-int.h"
#include "inchash.h"
#include "tree.h"
#include "stor-layout.h"
#include "fold-const.h"
#include "calls.h"
#include "hashtab.h"
@ -1184,6 +1185,7 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1,
niter->niter = delta;
niter->max = widest_int::from (wi::from_mpz (niter_type, bnds->up, false),
TYPE_SIGN (niter_type));
niter->control.no_overflow = true;
return true;
}
@ -1965,6 +1967,9 @@ number_of_iterations_exit (struct loop *loop, edge exit,
return false;
niter->assumptions = boolean_false_node;
niter->control.base = NULL_TREE;
niter->control.step = NULL_TREE;
niter->control.no_overflow = false;
last = last_stmt (exit->src);
if (!last)
return false;
@ -2744,6 +2749,29 @@ record_estimate (struct loop *loop, tree bound, const widest_int &i_bound,
record_niter_bound (loop, new_i_bound, realistic, upper);
}
/* Records the control iv analyzed in NITER for LOOP if the iv is valid
and doesn't overflow. */
static void
record_control_iv (struct loop *loop, struct tree_niter_desc *niter)
{
struct control_iv *iv;
if (!niter->control.base || !niter->control.step)
return;
if (!integer_onep (niter->assumptions) || !niter->control.no_overflow)
return;
iv = ggc_alloc<control_iv> ();
iv->base = niter->control.base;
iv->step = niter->control.step;
iv->next = loop->control_ivs;
loop->control_ivs = iv;
return;
}
/* Record the estimate on number of iterations of LOOP based on the fact that
the induction variable BASE + STEP * i evaluated in STMT does not wrap and
its values belong to the range <LOW, HIGH>. REALISTIC is true if the
@ -3467,6 +3495,7 @@ estimate_numbers_of_iterations_loop (struct loop *loop)
record_estimate (loop, niter, niter_desc.max,
last_stmt (ex->src),
true, ex == likely_exit, true);
record_control_iv (loop, &niter_desc);
}
exits.release ();
@ -3773,6 +3802,189 @@ nowrap_type_p (tree type)
return false;
}
/* Return true if we can prove LOOP is exited before evolution of induction
variabled {BASE, STEP} overflows with respect to its type bound. */
static bool
loop_exits_before_overflow (tree base, tree step,
gimple at_stmt, struct loop *loop)
{
widest_int niter;
struct control_iv *civ;
struct nb_iter_bound *bound;
tree e, delta, step_abs, unsigned_base;
tree type = TREE_TYPE (step);
tree unsigned_type, valid_niter;
/* Don't issue signed overflow warnings. */
fold_defer_overflow_warnings ();
/* Compute the number of iterations before we reach the bound of the
type, and verify that the loop is exited before this occurs. */
unsigned_type = unsigned_type_for (type);
unsigned_base = fold_convert (unsigned_type, base);
if (tree_int_cst_sign_bit (step))
{
tree extreme = fold_convert (unsigned_type,
lower_bound_in_type (type, type));
delta = fold_build2 (MINUS_EXPR, unsigned_type, unsigned_base, extreme);
step_abs = fold_build1 (NEGATE_EXPR, unsigned_type,
fold_convert (unsigned_type, step));
}
else
{
tree extreme = fold_convert (unsigned_type,
upper_bound_in_type (type, type));
delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, unsigned_base);
step_abs = fold_convert (unsigned_type, step);
}
valid_niter = fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step_abs);
estimate_numbers_of_iterations_loop (loop);
if (max_loop_iterations (loop, &niter)
&& wi::fits_to_tree_p (niter, TREE_TYPE (valid_niter))
&& (e = fold_binary (GT_EXPR, boolean_type_node, valid_niter,
wide_int_to_tree (TREE_TYPE (valid_niter),
niter))) != NULL
&& integer_nonzerop (e))
{
fold_undefer_and_ignore_overflow_warnings ();
return true;
}
if (at_stmt)
for (bound = loop->bounds; bound; bound = bound->next)
{
if (n_of_executions_at_most (at_stmt, bound, valid_niter))
{
fold_undefer_and_ignore_overflow_warnings ();
return true;
}
}
fold_undefer_and_ignore_overflow_warnings ();
/* Try to prove loop is exited before {base, step} overflows with the
help of analyzed loop control IV. This is done only for IVs with
constant step because otherwise we don't have the information. */
if (TREE_CODE (step) == INTEGER_CST)
for (civ = loop->control_ivs; civ; civ = civ->next)
{
enum tree_code code;
tree stepped, extreme, civ_type = TREE_TYPE (civ->step);
/* Have to consider type difference because operand_equal_p ignores
that for constants. */
if (TYPE_UNSIGNED (type) != TYPE_UNSIGNED (civ_type)
|| element_precision (type) != element_precision (civ_type))
continue;
/* Only consider control IV with same step. */
if (!operand_equal_p (step, civ->step, 0))
continue;
/* Done proving if this is a no-overflow control IV. */
if (operand_equal_p (base, civ->base, 0))
return true;
/* If this is a before stepping control IV, in other words, we have
{civ_base, step} = {base + step, step}
Because civ {base + step, step} doesn't overflow during loop
iterations, {base, step} will not overflow if we can prove the
operation "base + step" does not overflow. Specifically, we try
to prove below conditions are satisfied:
base <= UPPER_BOUND (type) - step ;;step > 0
base >= LOWER_BOUND (type) - step ;;step < 0
by proving the reverse conditions are false using loop's initial
condition. */
stepped = fold_build2 (PLUS_EXPR, TREE_TYPE (base), base, step);
if (operand_equal_p (stepped, civ->base, 0))
{
if (tree_int_cst_sign_bit (step))
{
code = LT_EXPR;
extreme = lower_bound_in_type (type, type);
}
else
{
code = GT_EXPR;
extreme = upper_bound_in_type (type, type);
}
extreme = fold_build2 (MINUS_EXPR, type, extreme, step);
e = fold_build2 (code, boolean_type_node, base, extreme);
e = simplify_using_initial_conditions (loop, e);
if (integer_zerop (e))
return true;
continue;
}
/* Similar to above, only in this case we have:
{civ_base, step} = {(signed T)((unsigned T)base + step), step}
&& TREE_TYPE (civ_base) = signed T.
We prove that below condition is satisfied:
(signed T)((unsigned T)base + step)
== (signed T)(unsigned T)base + step
== base + step
because of exact the same reason as above. This also proves
there is no overflow in the operation "base + step", thus the
induction variable {base, step} during loop iterations.
This is necessary to handle cases as below:
int foo (int *a, signed char s, signed char l)
{
signed char i;
for (i = s; i < l; i++)
a[i] = 0;
return 0;
}
The variable I is firstly converted to type unsigned char,
incremented, then converted back to type signed char. */
if (!CONVERT_EXPR_P (civ->base) || TREE_TYPE (civ->base) != type)
continue;
e = TREE_OPERAND (civ->base, 0);
if (TREE_CODE (e) != PLUS_EXPR
|| TREE_CODE (TREE_OPERAND (e, 1)) != INTEGER_CST
|| !operand_equal_p (step,
fold_convert (type,
TREE_OPERAND (e, 1)), 0))
continue;
e = TREE_OPERAND (e, 0);
if (!CONVERT_EXPR_P (e) || !operand_equal_p (e, unsigned_base, 0))
continue;
e = TREE_OPERAND (e, 0);
gcc_assert (operand_equal_p (e, base, 0));
if (tree_int_cst_sign_bit (step))
{
code = LT_EXPR;
extreme = lower_bound_in_type (type, type);
}
else
{
code = GT_EXPR;
extreme = upper_bound_in_type (type, type);
}
extreme = fold_build2 (MINUS_EXPR, type, extreme, step);
e = fold_build2 (code, boolean_type_node, base, extreme);
e = simplify_using_initial_conditions (loop, e);
if (integer_zerop (e))
return true;
}
return false;
}
/* Return false only when the induction variable BASE + STEP * I is
known to not overflow: i.e. when the number of iterations is small
enough with respect to the step and initial condition in order to
@ -3788,13 +4000,6 @@ scev_probably_wraps_p (tree base, tree step,
gimple at_stmt, struct loop *loop,
bool use_overflow_semantics)
{
tree delta, step_abs;
tree unsigned_type, valid_niter;
tree type = TREE_TYPE (step);
tree e;
widest_int niter;
struct nb_iter_bound *bound;
/* FIXME: We really need something like
http://gcc.gnu.org/ml/gcc-patches/2005-06/msg02025.html.
@ -3828,56 +4033,8 @@ scev_probably_wraps_p (tree base, tree step,
if (TREE_CODE (step) != INTEGER_CST)
return true;
/* Don't issue signed overflow warnings. */
fold_defer_overflow_warnings ();
/* Otherwise, compute the number of iterations before we reach the
bound of the type, and verify that the loop is exited before this
occurs. */
unsigned_type = unsigned_type_for (type);
base = fold_convert (unsigned_type, base);
if (tree_int_cst_sign_bit (step))
{
tree extreme = fold_convert (unsigned_type,
lower_bound_in_type (type, type));
delta = fold_build2 (MINUS_EXPR, unsigned_type, base, extreme);
step_abs = fold_build1 (NEGATE_EXPR, unsigned_type,
fold_convert (unsigned_type, step));
}
else
{
tree extreme = fold_convert (unsigned_type,
upper_bound_in_type (type, type));
delta = fold_build2 (MINUS_EXPR, unsigned_type, extreme, base);
step_abs = fold_convert (unsigned_type, step);
}
valid_niter = fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step_abs);
estimate_numbers_of_iterations_loop (loop);
if (max_loop_iterations (loop, &niter)
&& wi::fits_to_tree_p (niter, TREE_TYPE (valid_niter))
&& (e = fold_binary (GT_EXPR, boolean_type_node, valid_niter,
wide_int_to_tree (TREE_TYPE (valid_niter),
niter))) != NULL
&& integer_nonzerop (e))
{
fold_undefer_and_ignore_overflow_warnings ();
return false;
}
if (at_stmt)
for (bound = loop->bounds; bound; bound = bound->next)
{
if (n_of_executions_at_most (at_stmt, bound, valid_niter))
{
fold_undefer_and_ignore_overflow_warnings ();
return false;
}
}
fold_undefer_and_ignore_overflow_warnings ();
if (loop_exits_before_overflow (base, step, at_stmt, loop))
return false;
/* At this point we still don't have a proof that the iv does not
overflow: give up. */
@ -3889,17 +4046,26 @@ scev_probably_wraps_p (tree base, tree step,
void
free_numbers_of_iterations_estimates_loop (struct loop *loop)
{
struct nb_iter_bound *bound, *next;
struct control_iv *civ;
struct nb_iter_bound *bound;
loop->nb_iterations = NULL;
loop->estimate_state = EST_NOT_COMPUTED;
for (bound = loop->bounds; bound; bound = next)
for (bound = loop->bounds; bound;)
{
next = bound->next;
struct nb_iter_bound *next = bound->next;
ggc_free (bound);
bound = next;
}
loop->bounds = NULL;
for (civ = loop->control_ivs; civ;)
{
struct control_iv *next = civ->next;
ggc_free (civ);
civ = next;
}
loop->control_ivs = NULL;
}
/* Frees the information on upper bounds on numbers of iterations of loops. */

1
gcc/tree-ssa-loop-niter.h
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@ -41,6 +41,7 @@ extern void estimate_numbers_of_iterations (void);
extern bool stmt_dominates_stmt_p (gimple, gimple);
extern bool nowrap_type_p (tree);
extern bool scev_probably_wraps_p (tree, tree, gimple, struct loop *, bool);
extern void free_loop_control_ivs (struct loop *);
extern void free_numbers_of_iterations_estimates_loop (struct loop *);
extern void free_numbers_of_iterations_estimates (void);
extern void substitute_in_loop_info (struct loop *, tree, tree);