From: Robin Dapp <[email protected]>
This adds the get_niter_type_bound helper and uses it in
loop_exits_before_overflow as well as derive_simple_iv_with_niters.
We can re-use it in subsequent patches for computing nowrap bounds.
gcc/ChangeLog:
* tree-scalar-evolution.cc (derive_simple_iv_with_niters): Use
new function.
* tree-ssa-loop-niter.cc (loop_exits_before_overflow): Use new
function.
(get_niter_type_bound): New function.
* tree-ssa-loop-niter.h (get_niter_type_bound): Declare.
---
gcc/tree-scalar-evolution.cc | 20 ++++------------
gcc/tree-ssa-loop-niter.cc | 44 ++++++++++++++++++++++--------------
gcc/tree-ssa-loop-niter.h | 1 +
3 files changed, 32 insertions(+), 33 deletions(-)
diff --git a/gcc/tree-scalar-evolution.cc b/gcc/tree-scalar-evolution.cc
index 279ff46474e..b9acdbe9135 100644
--- a/gcc/tree-scalar-evolution.cc
+++ b/gcc/tree-scalar-evolution.cc
@@ -3239,22 +3239,10 @@ derive_simple_iv_with_niters (tree ev, tree *niters)
folded only if inner iv won't overflow. We compute the maximum
number the inner iv can iterate before overflowing and return the
simplified affine iv. */
- tree delta;
- init = fold_convert (type, init);
- step = fold_convert (type, step);
- ev = build_polynomial_chrec (CHREC_VARIABLE (inner_ev), init, step);
- if (tree_int_cst_sign_bit (step))
- {
- tree bound = lower_bound_in_type (inner_type, inner_type);
- delta = fold_build2 (MINUS_EXPR, type, init, fold_convert (type, bound));
- step = fold_build1 (NEGATE_EXPR, type, step);
- }
- else
- {
- tree bound = upper_bound_in_type (inner_type, inner_type);
- delta = fold_build2 (MINUS_EXPR, type, fold_convert (type, bound), init);
- }
- *niters = fold_build2 (FLOOR_DIV_EXPR, type, delta, step);
+ ev = build_polynomial_chrec (CHREC_VARIABLE (inner_ev),
+ fold_convert (type, init),
+ fold_convert (type, step));
+ *niters = get_niter_type_bound (inner_type, init, step);
return ev;
}
diff --git a/gcc/tree-ssa-loop-niter.cc b/gcc/tree-ssa-loop-niter.cc
index 0c1ebd1c7d5..fe179b69b05 100644
--- a/gcc/tree-ssa-loop-niter.cc
+++ b/gcc/tree-ssa-loop-niter.cc
@@ -5357,24 +5357,15 @@ nowrap_type_p (tree type)
return false;
}
-/* Return true if we can prove LOOP is exited before evolution of induction
- variable {BASE, STEP} overflows with respect to its type bound. */
+/* Return an upper bound on the number of times the affine IV {BASE, +, STEP}
+ of type TYPE can step while staying within TYPE's range. */
-static bool
-loop_exits_before_overflow (tree base, tree step,
- gimple *at_stmt, class loop *loop)
+tree
+get_niter_type_bound (tree type, tree base, tree step)
{
- widest_int niter;
- struct control_iv *civ;
- class nb_iter_bound *bound;
- tree e, delta, step_abs, unsigned_base;
- tree type = TREE_TYPE (step);
- tree unsigned_type, valid_niter;
-
- /* 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);
+ tree unsigned_type = unsigned_type_for (type);
+ tree unsigned_base = fold_convert (unsigned_type, base);
+ tree delta, step_abs;
if (tree_int_cst_sign_bit (step))
{
@@ -5392,7 +5383,26 @@ loop_exits_before_overflow (tree base, tree step,
step_abs = fold_convert (unsigned_type, step);
}
- valid_niter = fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step_abs);
+ return fold_build2 (FLOOR_DIV_EXPR, unsigned_type, delta, step_abs);
+}
+
+/* Return true if we can prove LOOP is exited before evolution of induction
+ variable {BASE, STEP} overflows with respect to its type bound. */
+
+static bool
+loop_exits_before_overflow (tree base, tree step,
+ gimple *at_stmt, class loop *loop)
+{
+ widest_int niter;
+ struct control_iv *civ;
+ class nb_iter_bound *bound;
+ tree e;
+ tree type = TREE_TYPE (step);
+ tree valid_niter;
+
+ /* Compute the number of iterations before we reach the bound of the
+ type, and verify that the loop is exited before this occurs. */
+ valid_niter = get_niter_type_bound (type, base, step);
estimate_numbers_of_iterations (loop);
diff --git a/gcc/tree-ssa-loop-niter.h b/gcc/tree-ssa-loop-niter.h
index 643ac1d7f7f..24e458f08db 100644
--- a/gcc/tree-ssa-loop-niter.h
+++ b/gcc/tree-ssa-loop-niter.h
@@ -52,6 +52,7 @@ extern void estimate_numbers_of_iterations (function *);
extern void estimate_numbers_of_iterations (class loop *);
extern bool stmt_dominates_stmt_p (gimple *, gimple *);
extern bool nowrap_type_p (tree);
+extern tree get_niter_type_bound (tree, tree, tree);
extern bool scev_probably_wraps_p (tree, tree, tree, gimple *,
class loop *, bool);
extern void free_numbers_of_iterations_estimates (class loop *);
--
2.54.0
