| Message ID | Y8WG3g+bAIynpiHC@kam.mff.cuni.cz |
|---|---|
| State | New |
| Headers | show |
| Series | Fix wrong code issues with ipa-sra | expand |
Hello, Coverity flagged a real issue in this patch: On Mon, 16 Jan 2023, Jan Hubicka via Gcc-patches wrote: > --- a/gcc/ipa-utils.cc > +++ b/gcc/ipa-utils.cc [...] > +bitmap > +find_always_executed_bbs (function *fun, bool assume_return_or_eh) > +{ > + auto_vec<basic_block, 20> stack; > + auto_vec<basic_block, 20> terminating_bbs; > + hash_set<basic_block> visited; > + edge e; > + edge_iterator ei; > + > + /* First walk all BBs reachable from entry stopping on statements that may > + terminate execution. Everything past this statement is not going to be executed > + each invocation. */ > + stack.safe_push (ENTRY_BLOCK_PTR_FOR_FN (fun)); > + while (!stack.is_empty ()) > + { > + basic_block bb = stack.pop (); > + bool found = false, found_exit = false; > + if (!assume_return_or_eh > + && (EDGE_COUNT (bb->succs) == 0 || (bb->flags & BB_IRREDUCIBLE_LOOP))) > + found = true; > + FOR_EACH_EDGE (e, ei, bb->succs) > + { > + if (e->dest == EXIT_BLOCK_PTR_FOR_FN (fun)) > + { > + found_exit = true; > + break; > + } > + /* Watch for infinite loops. */ > + if (!found && (assume_return_or_eh & EDGE_DFS_BACK) ^^^^^^^^^^^^^^^ This bitwise 'and' always evaluates to zero, making the entire clause always-false. Alexander
> Hello, > > Coverity flagged a real issue in this patch: > > On Mon, 16 Jan 2023, Jan Hubicka via Gcc-patches wrote: > > --- a/gcc/ipa-utils.cc > > +++ b/gcc/ipa-utils.cc > [...] > > +bitmap > > +find_always_executed_bbs (function *fun, bool assume_return_or_eh) > > +{ > > + auto_vec<basic_block, 20> stack; > > + auto_vec<basic_block, 20> terminating_bbs; > > + hash_set<basic_block> visited; > > + edge e; > > + edge_iterator ei; > > + > > + /* First walk all BBs reachable from entry stopping on statements that may > > + terminate execution. Everything past this statement is not going to be executed > > + each invocation. */ > > + stack.safe_push (ENTRY_BLOCK_PTR_FOR_FN (fun)); > > + while (!stack.is_empty ()) > > + { > > + basic_block bb = stack.pop (); > > + bool found = false, found_exit = false; > > + if (!assume_return_or_eh > > + && (EDGE_COUNT (bb->succs) == 0 || (bb->flags & BB_IRREDUCIBLE_LOOP))) > > + found = true; > > + FOR_EACH_EDGE (e, ei, bb->succs) > > + { > > + if (e->dest == EXIT_BLOCK_PTR_FOR_FN (fun)) > > + { > > + found_exit = true; > > + break; > > + } > > + /* Watch for infinite loops. */ > > + if (!found && (assume_return_or_eh & EDGE_DFS_BACK) > ^^^^^^^^^^^^^^^ > This bitwise 'and' always evaluates to zero, making the entire clause always-false. Hi, that is a good catch. This patch fixes the stupid typo info find_always_executed_bbs which made all edges to be considered as ones closing infinite loops. This fix has somewhat snowballed as, comparing it to finite_function_p, I noticed a divergence in handling of volatile asms (find_always_executed_bbs is conservative and thinks that volatile statement may return or do EH, but it is really impossible and elsewhere we expects that we dont) and I also noticed a bug in handling early returns which made some loops to be missed. I also noticed that function assumes that irreducible loops are marked in CFG which is not necessarily true and it is easy to detect them during the walk. Bootstrapped/regtested x86_64-linux, comitted. gcc/ChangeLog: 2023-01-29 Jan Hubicka <hubicka@ucw.cz> * ipa-utils.cc: Include calls.h, cfgloop.h and cfganal.h (stmt_may_terminate_function_p): If assuming return or EH volatile asm is safe. (find_always_executed_bbs): Fix handling of terminating BBS and infinite loops; add debug output. * tree-ssa-alias.cc (stmt_kills_ref_p): Fix debug output gcc/testsuite/ChangeLog: 2023-01-29 Jan Hubicka <hubicka@ucw.cz> * gcc.dg/ipa/ipa-sra-30.c: New test. * gcc.dg/ipa/ipa-sra-31.c: New test. * gcc.dg/tree-ssa/modref-dse-7.c: New test. diff --git a/gcc/ipa-utils.cc b/gcc/ipa-utils.cc index 3d5633340f1..8badcc2c110 100644 --- a/gcc/ipa-utils.cc +++ b/gcc/ipa-utils.cc @@ -40,6 +40,9 @@ along with GCC; see the file COPYING3. If not see #include "ipa-modref-tree.h" #include "ipa-modref.h" #include "tree-ssa-loop-niter.h" +#include "calls.h" +#include "cfgloop.h" +#include "cfganal.h" /* Debugging function for postorder and inorder code. NOTE is a string that is printed before the nodes are printed. ORDER is an array of @@ -796,11 +799,11 @@ stmt_may_terminate_function_p (function *fun, gimple *stmt, bool assume_return_o { if (stmt_can_throw_external (fun, stmt)) return true; + if (assume_return_or_eh) + return false; gasm *astmt = dyn_cast <gasm *> (stmt); if (astmt && gimple_asm_volatile_p (astmt)) return true; - if (assume_return_or_eh) - return false; if (gimple_could_trap_p (stmt)) return true; if (gcall *call = dyn_cast <gcall *> (stmt)) @@ -832,8 +835,14 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) auto_vec<basic_block, 20> stack; auto_vec<basic_block, 20> terminating_bbs; hash_set<basic_block> visited; + hash_set<basic_block> terminating_bbs_set; edge e; edge_iterator ei; + int flags = flags_from_decl_or_type (fun->decl); + /* PUre and const functions always return. */ + assume_return_or_eh |= (flags & (ECF_CONST|ECF_PURE)) && !(flags & ECF_LOOPING_CONST_OR_PURE); + if (!assume_return_or_eh) + mark_dfs_back_edges (fun); /* First walk all BBs reachable from entry stopping on statements that may terminate execution. Everything past this statement is not going to be executed @@ -843,9 +852,8 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) { basic_block bb = stack.pop (); bool found = false, found_exit = false; - if (!assume_return_or_eh - && (EDGE_COUNT (bb->succs) == 0 || (bb->flags & BB_IRREDUCIBLE_LOOP))) - found = true; + if (bb->index == EXIT_BLOCK) + continue; FOR_EACH_EDGE (e, ei, bb->succs) { if (e->dest == EXIT_BLOCK_PTR_FOR_FN (fun)) @@ -854,10 +862,28 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) break; } /* Watch for infinite loops. */ - if (!found && (assume_return_or_eh & EDGE_DFS_BACK) - && !finite_loop_p (e->src->loop_father)) - found = true; + if (!found + && !assume_return_or_eh && (e->flags & EDGE_DFS_BACK)) + { + if (!dom_info_available_p (CDI_DOMINATORS)) + calculate_dominance_info (CDI_DOMINATORS); + /* If this is not a loop latch edge it is an irreducible region. + Assume that it is infinite. + TODO: with C++ forced progression we can still walk the + irreducible region and see if it contains any side effects. + Similarly for loops. -ffinite-loops does not really imply + this since we allow inlining across -ffinite-loops bondary + and thus it can be used only as a loop flag. */ + if (e->dest->loop_father->header != e->dest + || !dominated_by_p (CDI_DOMINATORS, bb, e->dest)) + found = true; + else if (!finite_loop_p (e->dest->loop_father)) + found = true; + } } + if (!assume_return_or_eh + && (EDGE_COUNT (bb->succs) == 0 || (bb->flags & BB_IRREDUCIBLE_LOOP))) + found = true; for (gimple_stmt_iterator si = gsi_start_nondebug_after_labels_bb (bb); !gsi_end_p (si) && !found; gsi_next_nondebug (&si)) if (stmt_may_terminate_function_p (fun, gsi_stmt (si), assume_return_or_eh)) @@ -869,7 +895,10 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) { visited.add (EXIT_BLOCK_PTR_FOR_FN (fun)); if (!found_exit) - terminating_bbs.safe_push (bb); + { + terminating_bbs.safe_push (bb); + terminating_bbs_set.add (bb); + } } else FOR_EACH_EDGE (e, ei, bb->succs) @@ -883,8 +912,7 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) bitmap ret = BITMAP_ALLOC (NULL); /* A degenerated case when there is no path to exit. */ - if (!visited.contains (EXIT_BLOCK_PTR_FOR_FN (fun)) - && terminating_bbs.is_empty ()) + if (!visited.contains (EXIT_BLOCK_PTR_FOR_FN (fun))) { bitmap_set_bit (ret, single_succ_edge @@ -945,7 +973,7 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) } /* DFS is visiting BB for first time. */ *slot = cstate = XOBNEW (&state_obstack, struct astate); - cstate->low = cstate->dfs_preorder = next_dfs_num++; + cstate->low = cstate->high = cstate->dfs_preorder = next_dfs_num++; w.cstate = cstate; /* Exit block is special; process all fake edges we identified. */ if (bb == EXIT_BLOCK_PTR_FOR_FN (fun)) @@ -981,25 +1009,38 @@ find_always_executed_bbs (function *fun, bool assume_return_or_eh) if (!cstate2) { if (e->src != ENTRY_BLOCK_PTR_FOR_FN (fun)) - cstate->low = 0; + cstate->low = 0; continue; } cstate->low = MIN (cstate->low, (*cstate2)->low); cstate->high = MAX (cstate->high, (*cstate2)->high); } + if (dump_file && (dump_flags & TDF_DETAILS) && bb != EXIT_BLOCK_PTR_FOR_FN (fun)) + fprintf (dump_file, "BB %i %s preorder %i posorder %i low %i high %i\n", + bb->index, terminating_bbs_set.contains (bb) ? "(terminating)": "", + cstate->dfs_preorder, cstate->dfs_postorder, cstate->low, cstate->high); if (cstate->low == cstate->dfs_preorder && cstate->high == cstate->dfs_postorder && bb != EXIT_BLOCK_PTR_FOR_FN (fun)) bitmap_set_bit (ret, bb->index); - FOR_EACH_EDGE (e, ei, bb->succs) - { - astate **cstate2 = state.get (e->dest); - if (!cstate2) - continue; - cstate->low = MIN (cstate->low, (*cstate2)->low); - cstate->high = MAX (cstate->high, (*cstate2)->high); - } - } + if (terminating_bbs_set.contains (bb)) + cstate->low = 0; + else + FOR_EACH_EDGE (e, ei, bb->succs) + { + astate **cstate2 = state.get (e->dest); + if (!cstate2) + continue; + cstate->low = MIN (cstate->low, (*cstate2)->low); + cstate->high = MAX (cstate->high, (*cstate2)->high); + } + } obstack_free (&state_obstack, NULL); + if (dump_file) + { + fprintf (dump_file, "Always executed bbbs %s: ", + assume_return_or_eh ? "(assuming return or EH)": ""); + bitmap_print (dump_file, ret, "", "\n"); + } return ret; } diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-sra-30.c b/gcc/testsuite/gcc.dg/ipa/ipa-sra-30.c new file mode 100644 index 00000000000..5c8e8ed8ca1 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/ipa-sra-30.c @@ -0,0 +1,31 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-ipa-sra" } */ +struct list +{ + struct list *next; + int val; +}; +__attribute__ ((noinline)) +static int reta (int *a) +{ + return *a; +} +__attribute__ ((noinline)) +static int +kill(struct list *l, int *a) +{ + int v; + while (l) + { + v = l->val; + l=l->next; + } + return reta (a) + v; +} +int +test(struct list *l, int *a) +{ + return kill (l, a); +} +/* Loop in kill may be infinite; do not SRA. */ +/* { dg-final { scan-ipa-dump-not "Created new node kill.isra" "sra" } } */ diff --git a/gcc/testsuite/gcc.dg/ipa/ipa-sra-31.c b/gcc/testsuite/gcc.dg/ipa/ipa-sra-31.c new file mode 100644 index 00000000000..0a636d66872 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/ipa-sra-31.c @@ -0,0 +1,4 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-ipa-sra -ffinite-loops" } */ +#include "ipa-sra-30.c" +/* { dg-final { scan-ipa-dump "Created new node kill.isra" "sra" } } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-7.c b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-7.c new file mode 100644 index 00000000000..85a01d30cea --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-dse-7.c @@ -0,0 +1,22 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-optimized" } */ +struct list +{ + struct list *next; +}; +__attribute__ ((noinline)) +void +kill(struct list *l, int *a) +{ + while (l) + l=l->next; + *a = 0; +} +void +test(struct list *l, int *a) +{ + *a=12345; + kill (l, a); + return; +} +/* { dg-final { scan-tree-dump-not "12345" "optimized"} } */ diff --git a/gcc/tree-ssa-alias.cc b/gcc/tree-ssa-alias.cc index b8f107dfa52..7089e8b5bf3 100644 --- a/gcc/tree-ssa-alias.cc +++ b/gcc/tree-ssa-alias.cc @@ -3522,6 +3522,7 @@ stmt_kills_ref_p (gimple *stmt, ao_ref *ref) "ipa-modref: call to %s kills ", node->dump_name ()); print_generic_expr (dump_file, ref->base); + fprintf (dump_file, "\n"); } ++alias_stats.modref_kill_yes; return true;
diff --git a/gcc/ipa-modref.cc b/gcc/ipa-modref.cc index 16e8bfb97a6..e3196df8aa9 100644 --- a/gcc/ipa-modref.cc +++ b/gcc/ipa-modref.cc @@ -1875,11 +1875,11 @@ modref_access_analysis::analyze () statement cannot be analyzed (for any reason), the entire function cannot be analyzed by modref. */ basic_block bb; + bitmap always_executed_bbs = find_always_executed_bbs (cfun, true); FOR_EACH_BB_FN (bb, cfun) { gimple_stmt_iterator si; - bool always_executed - = bb == single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->dest; + bool always_executed = bitmap_bit_p (always_executed_bbs, bb->index); for (si = gsi_start_nondebug_after_labels_bb (bb); !gsi_end_p (si); gsi_next_nondebug (&si)) @@ -1926,6 +1926,7 @@ modref_access_analysis::analyze () && !finite_function_p ()) m_summary_lto->side_effects = true; } + BITMAP_FREE (always_executed_bbs); } /* Return true if OP accesses memory pointed to by SSA_NAME. */ diff --git a/gcc/ipa-sra.cc b/gcc/ipa-sra.cc index 4d7c25c8784..81b75910db1 100644 --- a/gcc/ipa-sra.cc +++ b/gcc/ipa-sra.cc @@ -2529,7 +2529,8 @@ process_scan_results (cgraph_node *node, struct function *fun, TODO: Measure the overhead and the effect of just being pessimistic. Maybe this is only -O3 material? */ - bool pdoms_calculated = false; + hash_map<gimple *, bool> analyzed_stmts; + bitmap always_executed_bbs = NULL; if (check_pass_throughs) for (cgraph_edge *cs = node->callees; cs; cs = cs->next_callee) { @@ -2566,27 +2567,46 @@ process_scan_results (cgraph_node *node, struct function *fun, continue; } - /* Post-dominator check placed last, hoping that it usually won't - be needed. */ - if (!pdoms_calculated) + /* Walk basic block and see if its execution can terminate earlier. + Keep the info for later re-use to avoid quadratic behavoiur here. */ + gimple_stmt_iterator gsi = gsi_for_stmt (call_stmt); + bool safe = true; + int n = 0; + for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi)) { - gcc_checking_assert (cfun); - connect_infinite_loops_to_exit (); - calculate_dominance_info (CDI_POST_DOMINATORS); - pdoms_calculated = true; + bool *b = analyzed_stmts.get (gsi_stmt (gsi)); + if (b) + { + safe = *b; + gsi_next (&gsi); + break; + } + n++; + if (stmt_may_terminate_function_p (fun, gsi_stmt (gsi), false)) + { + safe = false; + break; + } } - if (dominated_by_p (CDI_POST_DOMINATORS, - gimple_bb (call_stmt), - single_succ (ENTRY_BLOCK_PTR_FOR_FN (fun)))) + if (n) + { + if (gsi_end_p (gsi)) + gsi = gsi_start_bb (gimple_bb (call_stmt)); + for (; gsi_stmt (gsi) != call_stmt; gsi_next (&gsi)) + analyzed_stmts.get_or_insert (gsi_stmt (gsi)) = safe; + } + + if (safe && !always_executed_bbs) + { + mark_dfs_back_edges (); + always_executed_bbs = find_always_executed_bbs (fun, false); + } + if (safe && bitmap_bit_p (always_executed_bbs, gimple_bb (call_stmt)->index)) csum->m_arg_flow[argidx].safe_to_import_accesses = true; } } - if (pdoms_calculated) - { - free_dominance_info (CDI_POST_DOMINATORS); - remove_fake_exit_edges (); - } + BITMAP_FREE (always_executed_bbs); /* TODO: Add early exit if we disqualified everything. This also requires that we either relax the restriction that diff --git a/gcc/ipa-utils.cc b/gcc/ipa-utils.cc index 163899af6af..3d5633340f1 100644 --- a/gcc/ipa-utils.cc +++ b/gcc/ipa-utils.cc @@ -35,6 +35,11 @@ along with GCC; see the file COPYING3. If not see #include "tree-vrp.h" #include "ipa-prop.h" #include "ipa-fnsummary.h" +#include "tree-eh.h" +#include "gimple-iterator.h" +#include "ipa-modref-tree.h" +#include "ipa-modref.h" +#include "tree-ssa-loop-niter.h" /* Debugging function for postorder and inorder code. NOTE is a string that is printed before the nodes are printed. ORDER is an array of @@ -781,3 +786,220 @@ recursive_call_p (tree func, tree dest) return false; return true; } + +/* Return true if stmt may terminate execution of function. + If assume_return_or_eh we can further assume that the function ends + either by retrn statement or EH (no trapping or infinite loops). */ + +bool +stmt_may_terminate_function_p (function *fun, gimple *stmt, bool assume_return_or_eh) +{ + if (stmt_can_throw_external (fun, stmt)) + return true; + gasm *astmt = dyn_cast <gasm *> (stmt); + if (astmt && gimple_asm_volatile_p (astmt)) + return true; + if (assume_return_or_eh) + return false; + if (gimple_could_trap_p (stmt)) + return true; + if (gcall *call = dyn_cast <gcall *> (stmt)) + { + int flags = gimple_call_flags (call); + if (flags & (ECF_PURE | ECF_CONST) && ! (flags & ECF_LOOPING_CONST_OR_PURE)) + return false; + modref_summary *s = get_modref_function_summary (call, NULL); + if (s && !s->side_effects) + return false; + return true; + } + return false; +} + +/* Return bitmap of all basic blocks whose first statements are known to + execute on every invocation of the function. + + If assume_return_or_eh we can further assume that the function ends + either by retrn statement or EH (no trapping or infinite loops). + This is useful when sumarizing function in passes like ipa-modref. + + Seeing assume_return_or_eh to false is used to prove that given + statmeent will be executed even if the function gets into infinite + loop or trap. */ +bitmap +find_always_executed_bbs (function *fun, bool assume_return_or_eh) +{ + auto_vec<basic_block, 20> stack; + auto_vec<basic_block, 20> terminating_bbs; + hash_set<basic_block> visited; + edge e; + edge_iterator ei; + + /* First walk all BBs reachable from entry stopping on statements that may + terminate execution. Everything past this statement is not going to be executed + each invocation. */ + stack.safe_push (ENTRY_BLOCK_PTR_FOR_FN (fun)); + while (!stack.is_empty ()) + { + basic_block bb = stack.pop (); + bool found = false, found_exit = false; + if (!assume_return_or_eh + && (EDGE_COUNT (bb->succs) == 0 || (bb->flags & BB_IRREDUCIBLE_LOOP))) + found = true; + FOR_EACH_EDGE (e, ei, bb->succs) + { + if (e->dest == EXIT_BLOCK_PTR_FOR_FN (fun)) + { + found_exit = true; + break; + } + /* Watch for infinite loops. */ + if (!found && (assume_return_or_eh & EDGE_DFS_BACK) + && !finite_loop_p (e->src->loop_father)) + found = true; + } + for (gimple_stmt_iterator si = gsi_start_nondebug_after_labels_bb (bb); + !gsi_end_p (si) && !found; gsi_next_nondebug (&si)) + if (stmt_may_terminate_function_p (fun, gsi_stmt (si), assume_return_or_eh)) + { + found = true; + break; + } + if (found) + { + visited.add (EXIT_BLOCK_PTR_FOR_FN (fun)); + if (!found_exit) + terminating_bbs.safe_push (bb); + } + else + FOR_EACH_EDGE (e, ei, bb->succs) + if (!visited.add (e->dest)) + stack.safe_push (e->dest); + } + + /* Next walk from exit block and find all articulations in the CFG. + Add all terminating basic blocks as "fake" predecessors of the + exit block. */ + + bitmap ret = BITMAP_ALLOC (NULL); + /* A degenerated case when there is no path to exit. */ + if (!visited.contains (EXIT_BLOCK_PTR_FOR_FN (fun)) + && terminating_bbs.is_empty ()) + { + bitmap_set_bit (ret, + single_succ_edge + (ENTRY_BLOCK_PTR_FOR_FN (fun))->dest->index); + return ret; + } + + struct astate + { + unsigned int dfs_preorder; + unsigned int dfs_postorder; + + unsigned int low, high; + }; + + struct worklist + { + basic_block bb; + astate *cstate; + }; + + struct obstack state_obstack; + gcc_obstack_init (&state_obstack); + hash_map<basic_block, astate *> state; + auto_vec<worklist, 32> worklist_vec; + unsigned int next_dfs_num = 1; + + /* Always executed blocks are blocks that are on every path from entry to exit. + We proceed in two steps. First we do backward DFS walk (so we know that entry + is always reached) and record preorder and postorder visiting times. + + In second step we proceed in postorder and for every block A we compute + minimal preorder (A.low) and maximal postorder (A.high) of block reachable + from the BBs in DFS subtree of A. If A is always executed there are no + edges out of this subtree. This can be tested by checking that A.low == A.preorder + and B.high == A.postorder. + + This is first step. Do backward DFS walk and record preorder, postorder + and predecessor info. Initialize stack in postorder. */ + worklist we = {EXIT_BLOCK_PTR_FOR_FN (fun), NULL}; + worklist_vec.safe_push (we); + while (!worklist_vec.is_empty ()) + { + worklist &w = worklist_vec.last (); + basic_block bb = w.bb; + astate *cstate = w.cstate; + + if (!cstate) + { + astate **slot = &state.get_or_insert (bb); + + cstate = *slot; + /* Already processed by DFS? */ + if (cstate) + { + worklist_vec.pop (); + continue; + } + /* DFS is visiting BB for first time. */ + *slot = cstate = XOBNEW (&state_obstack, struct astate); + cstate->low = cstate->dfs_preorder = next_dfs_num++; + w.cstate = cstate; + /* Exit block is special; process all fake edges we identified. */ + if (bb == EXIT_BLOCK_PTR_FOR_FN (fun)) + for (basic_block bb2 : terminating_bbs) + { + worklist we = {bb2, NULL}; + worklist_vec.safe_push (we); + } + FOR_EACH_EDGE (e, ei, bb->preds) + if (visited.contains (e->src)) + { + worklist we = {e->src, NULL}; + worklist_vec.safe_push (we); + } + /* Keep BB on worklist so we process it last time. */ + continue; + } + /* We are finished with processing reachable BBs, see if we have articulation. */ + worklist_vec.pop (); + cstate->high = cstate->dfs_postorder = next_dfs_num++; + stack.safe_push (bb); + } + /* This is the final postorder walk. Determine low and high values and mark + always executed blocks. */ + for (basic_block bb : stack) + { + astate *cstate = *state.get (bb); + FOR_EACH_EDGE (e, ei, bb->preds) + { + astate **cstate2 = state.get (e->src); + /* We skip walking part of CFG reached only after first edge to exit. + No BB reachable from the skipped part is always executed */ + if (!cstate2) + { + if (e->src != ENTRY_BLOCK_PTR_FOR_FN (fun)) + cstate->low = 0; + continue; + } + cstate->low = MIN (cstate->low, (*cstate2)->low); + cstate->high = MAX (cstate->high, (*cstate2)->high); + } + if (cstate->low == cstate->dfs_preorder && cstate->high == cstate->dfs_postorder + && bb != EXIT_BLOCK_PTR_FOR_FN (fun)) + bitmap_set_bit (ret, bb->index); + FOR_EACH_EDGE (e, ei, bb->succs) + { + astate **cstate2 = state.get (e->dest); + if (!cstate2) + continue; + cstate->low = MIN (cstate->low, (*cstate2)->low); + cstate->high = MAX (cstate->high, (*cstate2)->high); + } + } + obstack_free (&state_obstack, NULL); + + return ret; +} diff --git a/gcc/ipa-utils.h b/gcc/ipa-utils.h index e7322e1bf4c..0eefcf40d44 100644 --- a/gcc/ipa-utils.h +++ b/gcc/ipa-utils.h @@ -46,6 +46,8 @@ tree get_base_var (tree); void ipa_merge_profiles (struct cgraph_node *dst, struct cgraph_node *src, bool preserve_body = false); bool recursive_call_p (tree, tree); +bool stmt_may_terminate_function_p (function *fun, gimple *stmt, bool assume_return_or_eh); +bitmap find_always_executed_bbs (function *fun, bool assume_return_or_eh); /* In ipa-pure-const.cc */ bool finite_function_p (); diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr106077.C b/gcc/testsuite/g++.dg/tree-ssa/pr106077.C new file mode 100644 index 00000000000..2c2f7293fa0 --- /dev/null +++ b/gcc/testsuite/g++.dg/tree-ssa/pr106077.C @@ -0,0 +1,22 @@ +// { dg-do compile } +// { dg-options "-O2 -fno-ipa-cp -fdump-tree-optimized" } +short e,f; +static __attribute__ ((noinline)) +int a(int *b) +{ + return *b; +} +static __attribute__ ((noinline)) +__attribute__ ((optimize("non-call-exceptions"))) +int wrap(int *b,int e, int f) +{ + e/=f; + return a(b)+e; +} + +int +t() +{ + return wrap(0,1,0); +} +// { dg-final { scan-tree-dump-not "builtin_trap" "optimized" } }