diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 30 |
1 files changed, 23 insertions, 7 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 848e812..5a7cab5 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -1668,18 +1668,34 @@ number_of_iterations_cond (struct loop *loop, exit_must_be_taken = true; } - /* We can handle the case when neither of the sides of the comparison is - invariant, provided that the test is NE_EXPR. This rarely occurs in - practice, but it is simple enough to manage. */ + /* We can handle cases which neither of the sides of the comparison is + invariant: + + {iv0.base, iv0.step} cmp_code {iv1.base, iv1.step} + as if: + {iv0.base, iv0.step - iv1.step} cmp_code {iv1.base, 0} + + provided that either below condition is satisfied: + + a) the test is NE_EXPR; + b) iv0.step - iv1.step is positive integer. + + This rarely occurs in practice, but it is simple enough to manage. */ if (!integer_zerop (iv0->step) && !integer_zerop (iv1->step)) { tree step_type = POINTER_TYPE_P (type) ? sizetype : type; - if (code != NE_EXPR) + tree step = fold_binary_to_constant (MINUS_EXPR, step_type, + iv0->step, iv1->step); + + /* No need to check sign of the new step since below code takes care + of this well. */ + if (code != NE_EXPR && TREE_CODE (step) != INTEGER_CST) return false; - iv0->step = fold_binary_to_constant (MINUS_EXPR, step_type, - iv0->step, iv1->step); - iv0->no_overflow = false; + iv0->step = step; + if (!POINTER_TYPE_P (type)) + iv0->no_overflow = false; + iv1->step = build_int_cst (step_type, 0); iv1->no_overflow = true; } |