diff options
Diffstat (limited to 'gcc/tree-ssa-loop-ivopts.cc')
| -rw-r--r-- | gcc/tree-ssa-loop-ivopts.cc | 28 |
1 files changed, 24 insertions, 4 deletions
diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc index 544a946..2fe2655 100644 --- a/gcc/tree-ssa-loop-ivopts.cc +++ b/gcc/tree-ssa-loop-ivopts.cc @@ -132,6 +132,7 @@ along with GCC; see the file COPYING3. If not see #include "tree-vectorizer.h" #include "dbgcnt.h" #include "cfganal.h" +#include "gimple-fold.h" /* For lang_hooks.types.type_for_mode. */ #include "langhooks.h" @@ -147,7 +148,7 @@ along with GCC; see the file COPYING3. If not see The average trip count is computed from profile data if it exists. */ -static inline HOST_WIDE_INT +static inline unsigned HOST_WIDE_INT avg_loop_niter (class loop *loop) { HOST_WIDE_INT niter = estimated_stmt_executions_int (loop); @@ -4213,7 +4214,9 @@ adjust_setup_cost (struct ivopts_data *data, int64_t cost, return cost; else if (optimize_loop_for_speed_p (data->current_loop)) { - int64_t niters = (int64_t) avg_loop_niter (data->current_loop); + uint64_t niters = avg_loop_niter (data->current_loop); + if (niters > (uint64_t) cost) + return (round_up_p && cost != 0) ? 1 : 0; return (cost + (round_up_p ? niters - 1 : 0)) / niters; } else @@ -7250,7 +7253,24 @@ create_new_iv (struct ivopts_data *data, struct iv_cand *cand) base = unshare_expr (cand->iv->base); - create_iv (base, PLUS_EXPR, unshare_expr (cand->iv->step), + /* The step computation could invoke UB when the loop does not iterate. + Avoid inserting it on the preheader in its native form but rewrite + it to a well-defined form. This also helps masking SCEV issues + which freely re-associates the IV computations when building up + CHRECs without much regard for signed overflow invoking UB. */ + gimple_seq stmts = NULL; + tree step = force_gimple_operand (unshare_expr (cand->iv->step), &stmts, + true, NULL_TREE); + if (stmts) + { + for (auto gsi = gsi_start (stmts); !gsi_end_p (gsi); gsi_next (&gsi)) + if (gimple_needing_rewrite_undefined (gsi_stmt (gsi))) + rewrite_to_defined_unconditional (&gsi); + gsi_insert_seq_on_edge_immediate + (loop_preheader_edge (data->current_loop), stmts); + } + + create_iv (base, PLUS_EXPR, step, cand->var_before, data->current_loop, &incr_pos, after, &cand->var_before, &cand->var_after); } @@ -7277,7 +7297,7 @@ create_new_ivs (struct ivopts_data *data, class iv_ca *set) if (data->loop_loc != UNKNOWN_LOCATION) fprintf (dump_file, " at %s:%d", LOCATION_FILE (data->loop_loc), LOCATION_LINE (data->loop_loc)); - fprintf (dump_file, ", " HOST_WIDE_INT_PRINT_DEC " avg niters", + fprintf (dump_file, ", " HOST_WIDE_INT_PRINT_UNSIGNED " avg niters", avg_loop_niter (data->current_loop)); fprintf (dump_file, ", %lu IVs:\n", bitmap_count_bits (set->cands)); EXECUTE_IF_SET_IN_BITMAP (set->cands, 0, i, bi) |