tree-optimization/104373 - early diagnostic on unreachable code
The following improves early uninit diagnostics by computing edge reachability using VN and ignoring unreachable blocks when looking for uninitialized uses. To not ICE with -fdump-tree-all the early uninit pass needs a dumpfile since VN tries to dump statistics. 2022-02-04 Richard Biener <rguenther@suse.de> PR tree-optimization/104373 * tree-ssa-sccvn.h (do_rpo_vn): New export exposing the walk kind. * tree-ssa-sccvn.cc (do_rpo_vn): Export, get the default walk kind as argument. (run_rpo_vn): Adjust. (pass_fre::execute): Likewise. * tree-ssa-uninit.cc (warn_uninitialized_vars): Skip blocks not reachable. (execute_late_warn_uninitialized): Mark all edges as executable. (execute_early_warn_uninitialized): Use VN to compute executable edges. (pass_data_early_warn_uninitialized): Enable a dump file, change dump name to warn_uninit. * g++.dg/warn/Wuninitialized-32.C: New testcase. * gcc.dg/uninit-pr20644-O0.c: Remove XFAIL.
This commit is contained in:
Richard Biener
parent
4a8083285c
commit
0f58ba4dd6
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@ -0,0 +1,14 @@
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// { dg-do compile }
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// { dg-additional-options "-Wall" }
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void* operator new[](unsigned long, void* __p);
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struct allocator
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{
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~allocator();
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};
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void *foo (void *p)
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{
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return p ? new(p) allocator[1] : new allocator[1]; // { dg-bogus "uninitialized" }
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}
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@ -7,7 +7,7 @@ int foo ()
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int j;
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if (1 == i)
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return j; /* { dg-bogus "uninitialized" "uninitialized" { xfail *-*-* } } */
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return j; /* { dg-bogus "uninitialized" "uninitialized" } */
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return 0;
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}
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@ -7034,15 +7034,14 @@ eliminate_with_rpo_vn (bitmap inserted_exprs)
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return walker.eliminate_cleanup ();
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}
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static unsigned
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unsigned
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do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
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bool iterate, bool eliminate);
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bool iterate, bool eliminate, vn_lookup_kind kind);
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void
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run_rpo_vn (vn_lookup_kind kind)
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{
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default_vn_walk_kind = kind;
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do_rpo_vn (cfun, NULL, NULL, true, false);
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do_rpo_vn (cfun, NULL, NULL, true, false, kind);
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/* ??? Prune requirement of these. */
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constant_to_value_id = new hash_table<vn_constant_hasher> (23);
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@ -7740,11 +7739,12 @@ do_unwind (unwind_state *to, rpo_elim &avail)
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executed and iterate. If ELIMINATE is true then perform
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elimination, otherwise leave that to the caller. */
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static unsigned
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unsigned
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do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
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bool iterate, bool eliminate)
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bool iterate, bool eliminate, vn_lookup_kind kind)
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{
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unsigned todo = 0;
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default_vn_walk_kind = kind;
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/* We currently do not support region-based iteration when
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elimination is requested. */
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@ -8164,8 +8164,7 @@ do_rpo_vn (function *fn, edge entry, bitmap exit_bbs,
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unsigned
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do_rpo_vn (function *fn, edge entry, bitmap exit_bbs)
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{
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default_vn_walk_kind = VN_WALKREWRITE;
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unsigned todo = do_rpo_vn (fn, entry, exit_bbs, false, true);
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unsigned todo = do_rpo_vn (fn, entry, exit_bbs, false, true, VN_WALKREWRITE);
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free_rpo_vn ();
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return todo;
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}
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@ -8221,8 +8220,7 @@ pass_fre::execute (function *fun)
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if (iterate_p)
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loop_optimizer_init (AVOID_CFG_MODIFICATIONS);
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default_vn_walk_kind = VN_WALKREWRITE;
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todo = do_rpo_vn (fun, NULL, NULL, iterate_p, true);
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todo = do_rpo_vn (fun, NULL, NULL, iterate_p, true, VN_WALKREWRITE);
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free_rpo_vn ();
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if (iterate_p)
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@ -291,6 +291,7 @@ value_id_constant_p (unsigned int v)
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tree fully_constant_vn_reference_p (vn_reference_t);
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tree vn_nary_simplify (vn_nary_op_t);
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unsigned do_rpo_vn (function *, edge, bitmap, bool, bool, vn_lookup_kind);
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unsigned do_rpo_vn (function *, edge, bitmap);
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void run_rpo_vn (vn_lookup_kind);
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unsigned eliminate_with_rpo_vn (bitmap);
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@ -38,8 +38,9 @@ along with GCC; see the file COPYING3. If not see
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#include "builtins.h"
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#include "calls.h"
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#include "gimple-range.h"
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#include "gimple-predicate-analysis.h"
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#include "domwalk.h"
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#include "tree-ssa-sccvn.h"
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/* This implements the pass that does predicate aware warning on uses of
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possibly uninitialized variables. The pass first collects the set of
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@ -986,7 +987,19 @@ warn_uninitialized_vars (bool wmaybe_uninit)
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basic_block bb;
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FOR_EACH_BB_FN (bb, cfun)
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{
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edge_iterator ei;
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edge e;
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FOR_EACH_EDGE (e, ei, bb->preds)
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if (e->flags & EDGE_EXECUTABLE)
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break;
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/* Skip unreachable blocks. For early analysis we use VN to
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determine edge executability when wmaybe_uninit. */
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if (!e)
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continue;
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basic_block succ = single_succ (ENTRY_BLOCK_PTR_FOR_FN (cfun));
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/* ??? This could be improved when we use a greedy walk and have
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some edges marked as not executable. */
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wlims.always_executed = dominated_by_p (CDI_POST_DOMINATORS, succ, bb);
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if (wlims.always_executed)
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@ -1319,6 +1332,11 @@ execute_late_warn_uninitialized (function *fun)
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calculate_dominance_info (CDI_DOMINATORS);
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calculate_dominance_info (CDI_POST_DOMINATORS);
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/* Mark all edges executable, warn_uninitialized_vars will skip
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unreachable blocks. */
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set_all_edges_as_executable (fun);
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/* Re-do the plain uninitialized variable check, as optimization may have
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straightened control flow. Do this first so that we don't accidentally
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get a "may be" warning when we'd have seen an "is" warning later. */
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@ -1388,7 +1406,7 @@ make_pass_late_warn_uninitialized (gcc::context *ctxt)
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}
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static unsigned int
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execute_early_warn_uninitialized (void)
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execute_early_warn_uninitialized (struct function *fun)
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{
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/* Currently, this pass runs always but
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execute_late_warn_uninitialized only runs with optimization. With
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@ -1398,6 +1416,17 @@ execute_early_warn_uninitialized (void)
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calculate_dominance_info (CDI_DOMINATORS);
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calculate_dominance_info (CDI_POST_DOMINATORS);
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/* Use VN in its cheapest incarnation and without doing any
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elimination to compute edge reachability. Don't bother when
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we only warn for unconditionally executed code though. */
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if (!optimize)
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{
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do_rpo_vn (fun, NULL, NULL, false, false, VN_NOWALK);
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free_rpo_vn ();
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}
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else
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set_all_edges_as_executable (fun);
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warn_uninitialized_vars (/*warn_maybe_uninitialized=*/!optimize);
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/* Post-dominator information cannot be reliably updated. Free it
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@ -1412,7 +1441,7 @@ namespace {
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const pass_data pass_data_early_warn_uninitialized =
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{
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GIMPLE_PASS, /* type */
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"*early_warn_uninitialized", /* name */
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"early_uninit", /* name */
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OPTGROUP_NONE, /* optinfo_flags */
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TV_TREE_UNINIT, /* tv_id */
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PROP_ssa, /* properties_required */
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@ -1431,9 +1460,9 @@ public:
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/* opt_pass methods: */
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virtual bool gate (function *) { return gate_warn_uninitialized (); }
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virtual unsigned int execute (function *)
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virtual unsigned int execute (function *fun)
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{
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return execute_early_warn_uninitialized ();
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return execute_early_warn_uninitialized (fun);
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}
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}; // class pass_early_warn_uninitialized
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