diff options
Diffstat (limited to 'gcc/tree-ssa-loop-niter.c')
| -rw-r--r-- | gcc/tree-ssa-loop-niter.c | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 7af92d1..7510940 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -1482,7 +1482,7 @@ number_of_iterations_until_wrap (class loop *, tree type, affine_iv *iv0, affine_iv *iv1, class tree_niter_desc *niter) { tree niter_type = unsigned_type_for (type); - tree step, num, assumptions, may_be_zero; + tree step, num, assumptions, may_be_zero, span; wide_int high, low, max, min; may_be_zero = fold_build2 (LE_EXPR, boolean_type_node, iv1->base, iv0->base); @@ -1557,6 +1557,20 @@ number_of_iterations_until_wrap (class loop *, tree type, affine_iv *iv0, niter->control.no_overflow = false; + /* Update bound and exit condition as: + bound = niter * STEP + (IVbase - STEP). + { IVbase - STEP, +, STEP } != bound + Here, biasing IVbase by 1 step makes 'bound' be the value before wrap. + */ + niter->control.base = fold_build2 (MINUS_EXPR, niter_type, + niter->control.base, niter->control.step); + span = fold_build2 (MULT_EXPR, niter_type, niter->niter, + fold_convert (niter_type, niter->control.step)); + niter->bound = fold_build2 (PLUS_EXPR, niter_type, span, + fold_convert (niter_type, niter->control.base)); + niter->bound = fold_convert (type, niter->bound); + niter->cmp = NE_EXPR; + return true; } |