From 4f2a6ad5a49eec0a1cae15e033329f889f9137b9 Mon Sep 17 00:00:00 2001 From: Kugan Vivekanandarajah Date: Fri, 22 Jun 2018 14:11:28 +1000 Subject: [PATCH 2/3] in niter dont check for zero when it is alrealy checked Change-Id: I98982537bca14cb99a85d0da70d33a6c044385fd --- gcc/tree-ssa-loop-niter.c | 33 ++++++++++++++++++++++++++++++++- 1 file changed, 32 insertions(+), 1 deletion(-) diff --git a/gcc/tree-ssa-loop-niter.c b/gcc/tree-ssa-loop-niter.c index 9365915..2299aca 100644 --- a/gcc/tree-ssa-loop-niter.c +++ b/gcc/tree-ssa-loop-niter.c @@ -2503,6 +2503,7 @@ number_of_iterations_popcount (loop_p loop, edge exit, HOST_WIDE_INT max; adjust = true; tree fn = NULL_TREE; + bool check_zero = true; /* Check loop terminating branch is like if (b != 0). */ @@ -2590,7 +2591,37 @@ number_of_iterations_popcount (loop_p loop, edge exit, niter->niter = iter; niter->assumptions = boolean_true_node; - if (adjust) + if (adjust + && EDGE_COUNT (loop->header->preds) == 2) + { + /* Sometimes, src of the popcount is checked for + zero before entering the loop. In this case we + dont need to check for zero again. */ + edge pred_edge = EDGE_PRED (loop->header, 0); + gimple *stmt = last_stmt (pred_edge->src); + + /* If there is an empty pre-header, go one block + above. */ + if (!stmt + && EDGE_COUNT (pred_edge->src->preds) == 1) + { + pred_edge = EDGE_PRED (pred_edge->src, 0); + stmt = last_stmt (pred_edge->src); + } + + /* If we have the src != 0 check and if we are entering + the loop when the condition is true, we can skip zero + check. */ + if (stmt + && gimple_code (stmt) == GIMPLE_COND + && gimple_cond_code (stmt) == NE_EXPR + && pred_edge->flags & EDGE_TRUE_VALUE + && TREE_CODE (gimple_cond_lhs (stmt)) == SSA_NAME + && (gimple_phi_arg_def (phi, loop_preheader_edge (loop)->dest_idx) + == gimple_cond_lhs (stmt))) + check_zero = false; + } + if (adjust && check_zero) niter->may_be_zero = fold_build2 (EQ_EXPR, boolean_type_node, src, build_zero_cst (TREE_TYPE (src))); -- 2.7.4