diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 49 |
1 files changed, 34 insertions, 15 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 6d480c0..67080a3 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -957,13 +957,14 @@ number_of_iterations_ne_max (mpz_t bnd, bool no_overflow, tree c, tree s, bounds on the difference FINAL - IV->base. */ static bool -number_of_iterations_ne (tree type, affine_iv *iv, tree final, - struct tree_niter_desc *niter, bool exit_must_be_taken, - bounds *bnds) +number_of_iterations_ne (struct loop *loop, tree type, affine_iv *iv, + tree final, struct tree_niter_desc *niter, + bool exit_must_be_taken, bounds *bnds) { tree niter_type = unsigned_type_for (type); tree s, c, d, bits, assumption, tmp, bound; mpz_t max; + tree e; niter->control = *iv; niter->bound = final; @@ -998,6 +999,23 @@ number_of_iterations_ne (tree type, affine_iv *iv, tree final, TYPE_SIGN (niter_type)); mpz_clear (max); + /* Compute no-overflow information for the control iv. Note we are + handling NE_EXPR, if iv base equals to final value, the loop exits + immediately, and the iv does not overflow. */ + if (tree_int_cst_sign_bit (iv->step)) + e = fold_build2 (GE_EXPR, boolean_type_node, iv->base, final); + else + e = fold_build2 (LE_EXPR, boolean_type_node, iv->base, final); + e = simplify_using_initial_conditions (loop, e); + if (integer_onep (e) + && (integer_onep (s) + || (TREE_CODE (c) == INTEGER_CST + && TREE_CODE (s) == INTEGER_CST + && wi::mod_trunc (c, s, TYPE_SIGN (type)) == 0))) + { + niter->control.no_overflow = true; + } + /* First the trivial cases -- when the step is 1. */ if (integer_onep (s)) { @@ -1361,8 +1379,8 @@ assert_loop_rolls_lt (tree type, affine_iv *iv0, affine_iv *iv1, that the exit must be taken eventually. */ static bool -number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1, - struct tree_niter_desc *niter, +number_of_iterations_lt (struct loop *loop, tree type, affine_iv *iv0, + affine_iv *iv1, struct tree_niter_desc *niter, bool exit_must_be_taken, bounds *bnds) { tree niter_type = unsigned_type_for (type); @@ -1434,7 +1452,8 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1, zps does not overflow. */ zps.no_overflow = true; - return number_of_iterations_ne (type, &zps, delta, niter, true, bnds); + return number_of_iterations_ne (loop, type, &zps, + delta, niter, true, bnds); } /* Make sure that the control iv does not overflow. */ @@ -1473,9 +1492,9 @@ number_of_iterations_lt (tree type, affine_iv *iv0, affine_iv *iv1, is the case). BNDS bounds the difference IV1->base - IV0->base. */ static bool -number_of_iterations_le (tree type, affine_iv *iv0, affine_iv *iv1, - struct tree_niter_desc *niter, bool exit_must_be_taken, - bounds *bnds) +number_of_iterations_le (struct loop *loop, tree type, affine_iv *iv0, + affine_iv *iv1, struct tree_niter_desc *niter, + bool exit_must_be_taken, bounds *bnds) { tree assumption; tree type1 = type; @@ -1523,7 +1542,7 @@ number_of_iterations_le (tree type, affine_iv *iv0, affine_iv *iv1, bounds_add (bnds, 1, type1); - return number_of_iterations_lt (type, iv0, iv1, niter, exit_must_be_taken, + return number_of_iterations_lt (loop, type, iv0, iv1, niter, exit_must_be_taken, bnds); } @@ -1698,18 +1717,18 @@ number_of_iterations_cond (struct loop *loop, { case NE_EXPR: gcc_assert (integer_zerop (iv1->step)); - ret = number_of_iterations_ne (type, iv0, iv1->base, niter, + ret = number_of_iterations_ne (loop, type, iv0, iv1->base, niter, exit_must_be_taken, &bnds); break; case LT_EXPR: - ret = number_of_iterations_lt (type, iv0, iv1, niter, exit_must_be_taken, - &bnds); + ret = number_of_iterations_lt (loop, type, iv0, iv1, niter, + exit_must_be_taken, &bnds); break; case LE_EXPR: - ret = number_of_iterations_le (type, iv0, iv1, niter, exit_must_be_taken, - &bnds); + ret = number_of_iterations_le (loop, type, iv0, iv1, niter, + exit_must_be_taken, &bnds); break; default: |