Hi! When performing cfg cleanup at the end of cfg pass, if there are any OpenMP regions and some basic blocks are unreachable and contain forced labels, remove_bb moves the labels to previous bb, but if the two bb belong to different OpenMP regions, that means it will end up in a different function from where it was assumed to be and checked e.g. during gimplification or OpenMP region SESE checking.
The following patch will place the labels to some bb from the right OpenMP region if the previous bb is not that. I think it should happen very rarely, normally the bbs from each OpenMP region should be from the before-cfg pass adjacent and the problems will usually be only if the OpenMP regions are no-return, so I hope it isn't fatal that it searches through all bbs on the miss. If it turns out to be a problem, it can always lazily create some better data structure and maintain it through bb removals when it reaches that case the first time. Bootstrapped/regtested on x86_64-linux and i686-linux, committed to trunk. 2021-03-05 Jakub Jelinek <ja...@redhat.com> PR middle-end/99322 * tree-cfg.c (bb_to_omp_idx): New variable. (execute_build_cfg): Release the bb_to_omp_idx vector after cleanup_tree_cfg returns. (handle_abnormal_edges): Remove bb_to_omp_idx argument, adjust for bb_to_omp_idx being a vec<int> instead of pointer to array of ints. (make_edges): Remove bb_to_omp_idx local variable, don't pass it to handle_abnormal_edges, adjust for bb_to_omp_idx being a vec<int> instead of pointer to array of ints and don't free/release it at the end. (remove_bb): When removing a bb and placing forced label somewhere else, ensure it is put into the same OpenMP region during cfg pass if possible or to entry successor as fallback. Unregister bb from bb_to_omp_idx. * c-c++-common/gomp/pr99322.c: New test. --- gcc/tree-cfg.c.jj 2021-02-19 12:14:31.616880014 +0100 +++ gcc/tree-cfg.c 2021-03-05 17:38:23.639195846 +0100 @@ -93,6 +93,9 @@ static hash_map<edge, tree> *edge_to_cas static bitmap touched_switch_bbs; +/* OpenMP region idxs for blocks during cfg pass. */ +static vec<int> bb_to_omp_idx; + /* CFG statistics. */ struct cfg_stats_d { @@ -372,6 +375,9 @@ execute_build_cfg (void) dump_scope_blocks (dump_file, dump_flags); } cleanup_tree_cfg (); + + bb_to_omp_idx.release (); + loop_optimizer_init (AVOID_CFG_MODIFICATIONS); replace_loop_annotate (); return 0; @@ -724,8 +730,7 @@ get_abnormal_succ_dispatcher (basic_bloc if COMPUTED_GOTO is false, otherwise factor the computed gotos. */ static void -handle_abnormal_edges (basic_block *dispatcher_bbs, - basic_block for_bb, int *bb_to_omp_idx, +handle_abnormal_edges (basic_block *dispatcher_bbs, basic_block for_bb, auto_vec<basic_block> *bbs, bool computed_goto) { basic_block *dispatcher = dispatcher_bbs + (computed_goto ? 1 : 0); @@ -733,7 +738,7 @@ handle_abnormal_edges (basic_block *disp basic_block bb; bool inner = false; - if (bb_to_omp_idx) + if (!bb_to_omp_idx.is_empty ()) { dispatcher = dispatcher_bbs + 2 * bb_to_omp_idx[for_bb->index]; if (bb_to_omp_idx[for_bb->index] != 0) @@ -748,7 +753,7 @@ handle_abnormal_edges (basic_block *disp /* Check if there are any basic blocks that need to have abnormal edges to this dispatcher. If there are none, return early. */ - if (bb_to_omp_idx == NULL) + if (bb_to_omp_idx.is_empty ()) { if (bbs->is_empty ()) return; @@ -790,7 +795,7 @@ handle_abnormal_edges (basic_block *disp FOR_EACH_VEC_ELT (*bbs, idx, bb) { - if (bb_to_omp_idx + if (!bb_to_omp_idx.is_empty () && bb_to_omp_idx[bb->index] != bb_to_omp_idx[for_bb->index]) continue; @@ -820,7 +825,7 @@ handle_abnormal_edges (basic_block *disp /* Create predecessor edges of the dispatcher. */ FOR_EACH_VEC_ELT (*bbs, idx, bb) { - if (bb_to_omp_idx + if (!bb_to_omp_idx.is_empty () && bb_to_omp_idx[bb->index] != bb_to_omp_idx[for_bb->index]) continue; make_edge (bb, *dispatcher, EDGE_ABNORMAL); @@ -957,7 +962,6 @@ make_edges (void) struct omp_region *cur_region = NULL; auto_vec<basic_block> ab_edge_goto; auto_vec<basic_block> ab_edge_call; - int *bb_to_omp_idx = NULL; int cur_omp_region_idx = 0; /* Create an edge from entry to the first block with executable @@ -971,7 +975,7 @@ make_edges (void) { int mer; - if (bb_to_omp_idx) + if (!bb_to_omp_idx.is_empty ()) bb_to_omp_idx[bb->index] = cur_omp_region_idx; mer = make_edges_bb (bb, &cur_region, &cur_omp_region_idx); @@ -980,8 +984,8 @@ make_edges (void) else if (mer == 2) ab_edge_call.safe_push (bb); - if (cur_region && bb_to_omp_idx == NULL) - bb_to_omp_idx = XCNEWVEC (int, n_basic_blocks_for_fn (cfun)); + if (cur_region && bb_to_omp_idx.is_empty ()) + bb_to_omp_idx.safe_grow_cleared (n_basic_blocks_for_fn (cfun), true); } /* Computed gotos are hell to deal with, especially if there are @@ -1006,7 +1010,7 @@ make_edges (void) basic_block *dispatcher_bbs = dispatcher_bb_array; int count = n_basic_blocks_for_fn (cfun); - if (bb_to_omp_idx) + if (!bb_to_omp_idx.is_empty ()) dispatcher_bbs = XCNEWVEC (basic_block, 2 * count); FOR_EACH_BB_FN (bb, cfun) @@ -1024,12 +1028,12 @@ make_edges (void) /* Make an edge to every label block that has been marked as a potential target for a computed goto or a non-local goto. */ if (FORCED_LABEL (target)) - handle_abnormal_edges (dispatcher_bbs, bb, bb_to_omp_idx, - &ab_edge_goto, true); + handle_abnormal_edges (dispatcher_bbs, bb, &ab_edge_goto, + true); if (DECL_NONLOCAL (target)) { - handle_abnormal_edges (dispatcher_bbs, bb, bb_to_omp_idx, - &ab_edge_call, false); + handle_abnormal_edges (dispatcher_bbs, bb, &ab_edge_call, + false); break; } } @@ -1044,17 +1048,15 @@ make_edges (void) && ((gimple_call_flags (call_stmt) & ECF_RETURNS_TWICE) || gimple_call_builtin_p (call_stmt, BUILT_IN_SETJMP_RECEIVER))) - handle_abnormal_edges (dispatcher_bbs, bb, bb_to_omp_idx, - &ab_edge_call, false); + handle_abnormal_edges (dispatcher_bbs, bb, &ab_edge_call, + false); } } - if (bb_to_omp_idx) + if (!bb_to_omp_idx.is_empty ()) XDELETE (dispatcher_bbs); } - XDELETE (bb_to_omp_idx); - omp_free_regions (); } @@ -2301,6 +2303,30 @@ remove_bb (basic_block bb) new_bb = single_succ (new_bb); gcc_assert (new_bb != bb); } + if ((unsigned) bb->index < bb_to_omp_idx.length () + && ((unsigned) new_bb->index >= bb_to_omp_idx.length () + || (bb_to_omp_idx[bb->index] + != bb_to_omp_idx[new_bb->index]))) + { + /* During cfg pass make sure to put orphaned labels + into the right OMP region. */ + unsigned int i; + int idx; + new_bb = NULL; + FOR_EACH_VEC_ELT (bb_to_omp_idx, i, idx) + if (i >= NUM_FIXED_BLOCKS + && idx == bb_to_omp_idx[bb->index] + && i != (unsigned) bb->index) + { + new_bb = BASIC_BLOCK_FOR_FN (cfun, i); + break; + } + if (new_bb == NULL) + { + new_bb = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun)); + gcc_assert (new_bb != bb); + } + } new_gsi = gsi_after_labels (new_bb); gsi_remove (&i, false); gsi_insert_before (&new_gsi, stmt, GSI_NEW_STMT); @@ -2319,6 +2345,8 @@ remove_bb (basic_block bb) } } + if ((unsigned) bb->index < bb_to_omp_idx.length ()) + bb_to_omp_idx[bb->index] = -1; remove_phi_nodes_and_edges_for_unreachable_block (bb); bb->il.gimple.seq = NULL; bb->il.gimple.phi_nodes = NULL; --- gcc/testsuite/c-c++-common/gomp/pr99322.c.jj 2021-03-05 17:42:12.869659324 +0100 +++ gcc/testsuite/c-c++-common/gomp/pr99322.c 2021-03-05 17:42:01.785781961 +0100 @@ -0,0 +1,26 @@ +/* PR middle-end/99322 */ +/* { dg-do compile } */ + +void foo (void); +void qux (void *); + +void +bar (void) +{ + #pragma omp parallel + for (;;) + for (int i = 0; i < 8; ++i) + foo (); + { lab:; } + qux (&&lab); +} + +void +baz (void) +{ + qux (&&lab); + #pragma omp parallel + for (;;) + ; + lab:; +} Jakub