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re PR tree-optimization/83255 ([graphite] Wrong code w/ -O1 -floop-nest-optimize)

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2017-12-04  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/83255
	* graphite-isl-ast-to-gimple.c (translate_isl_ast_node_for):
	Re-add zero-iteration check.

	* gcc.dg/graphite/pr83255.c: New testcase.

From-SVN: r255382
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Richard Biener 2017-12-04 14:04:36 +00:00 committed by Richard Biener
parent ca4564f9a4
commit 86502ecfe4
4 changed files with 65 additions and 0 deletions
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6
gcc/ChangeLog
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@ -1,3 +1,9 @@
2017-12-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/83255
* graphite-isl-ast-to-gimple.c (translate_isl_ast_node_for):
Re-add zero-iteration check.
2017-12-04 Segher Boessenkool <segher@kernel.crashing.org>
PR rtl-optimization/83245

26
gcc/graphite-isl-ast-to-gimple.c
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@ -720,6 +720,32 @@ translate_isl_ast_node_for (loop_p context_loop, __isl_keep isl_ast_node *node,
ub = integer_zero_node;
edge last_e = single_succ_edge (split_edge (next_e));
/* Compensate for the fact that we emit a do { } while loop from
a for ISL AST.
??? We often miss constraints on niter because the SESE region
doesn't cover loop header copies. Ideally we'd add constraints
for all relevant dominating conditions. */
if (TREE_CODE (lb) == INTEGER_CST && TREE_CODE (ub) == INTEGER_CST
&& tree_int_cst_compare (lb, ub) <= 0)
;
else
{
tree one = build_one_cst (POINTER_TYPE_P (type) ? sizetype : type);
/* Adding +1 and using LT_EXPR helps with loop latches that have a
loop iteration count of "PARAMETER - 1". For PARAMETER == 0 this
becomes 2^k-1 due to integer overflow, and the condition lb <= ub
is true, even if we do not want this. However lb < ub + 1 is false,
as expected. */
tree ub_one = fold_build2 (POINTER_TYPE_P (type)
? POINTER_PLUS_EXPR : PLUS_EXPR,
type, ub, one);
create_empty_if_region_on_edge (next_e,
fold_build2 (LT_EXPR, boolean_type_node,
lb, ub_one));
next_e = get_true_edge_from_guard_bb (next_e->dest);
}
translate_isl_ast_for_loop (context_loop, node, next_e,
type, lb, ub, ip);
return last_e;

5
gcc/testsuite/ChangeLog
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@ -1,3 +1,8 @@
2017-12-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/83255
* gcc.dg/graphite/pr83255.c: New testcase.
2017-12-04 Richard Biener <rguenther@suse.de>
PR tree-optimization/83238

28
gcc/testsuite/gcc.dg/graphite/pr83255.c Normal file
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@ -0,0 +1,28 @@
/* { dg-do run } */
/* { dg-options "-O -floop-nest-optimize -fdump-tree-graphite-details" } */
int rx, in;
int
main (void)
{
const int tj = 3;
int as[tj];
static int l4;
while (l4 < 1)
{
for (rx = 0; rx < tj; ++rx)
{
for (in = 0; in < tj; ++in)
as[in] = 1;
as[rx] = 0;
}
++l4;
}
if (as[tj - 1] != 0)
__builtin_abort ();
}
/* { dg-final { scan-tree-dump "loop nest optimized" "graphite" } } */