Message ID | 20171109200315.GF14653@tucnak |
---|---|
State | New |
Headers | show |
Series | Fix profiledbootstrap - store-merging aliasing issue (PR bootstrap/82916) | expand |
On Thu, 9 Nov 2017, Jakub Jelinek wrote: > Hi! > > We want to terminate a chain if a chain with different base (or insn > outside of any chain) has a store that the current stmt might use, or > overwrite. The functions it used didn't cover the store after store > case which in the middle-end aliasing model needs to avoid tbaa, because > the latter store might be after a placement new or might otherwise change > the dynamic object type of the object. > > The following patch does that. Bootstrapped/regtested on x86_64-linux and > i686-linux, additionally profiledbootstrapped with the configure options > Markus mentioned in the PR. Ok for trunk? > > 2017-11-09 Jakub Jelinek <jakub@redhat.com> > > PR bootstrap/82916 > * gimple-ssa-store-merging.c > (pass_store_merging::terminate_all_aliasing_chains): For > gimple_store_p stmts also call refs_output_dependent_p. > > * gcc.dg/store_merging_2.c: Only expect 2 successful mergings instead > of 3. > * gcc.dg/pr82916.c: New test. > > --- gcc/gimple-ssa-store-merging.c.jj 2017-11-09 15:51:08.000000000 +0100 > +++ gcc/gimple-ssa-store-merging.c 2017-11-09 18:01:20.789236951 +0100 > @@ -945,6 +945,7 @@ pass_store_merging::terminate_all_aliasi > if (!gimple_vuse (stmt)) > return false; > > + tree store_lhs = gimple_store_p (stmt) ? gimple_get_lhs (stmt) : NULL_TREE; > for (imm_store_chain_info *next = m_stores_head, *cur = next; cur; cur = next) > { > next = cur->next; > @@ -958,8 +959,10 @@ pass_store_merging::terminate_all_aliasi > unsigned int i; > FOR_EACH_VEC_ELT (cur->m_store_info, i, info) > { > - if (ref_maybe_used_by_stmt_p (stmt, gimple_assign_lhs (info->stmt)) > - || stmt_may_clobber_ref_p (stmt, gimple_assign_lhs (info->stmt))) > + tree lhs = gimple_assign_lhs (info->stmt); > + if (ref_maybe_used_by_stmt_p (stmt, lhs) > + || stmt_may_clobber_ref_p (stmt, lhs) > + || (store_lhs && refs_output_dependent_p (store_lhs, lhs))) Looks good but may do redundant work for store_lhs? So rather || (! store_lhs && stmt_may_clobber_ref_p (stmt, lhs) || (store_lhs && refs_output_dependent_p (store_lhs, lhs) ? Fails to handle storing calls (in case those can appear in the chains). Looks like we miss some convenient stmt_output/anti_dependent_p (you can follow stmt_may_clobbers_ref_p[_1] for cut&pasting and/or add a bool tbaa flag we can pass down to stmt_may_clobber_ref_p_1). That said - the patch is ok, any improvements can be done as followup. Thanks, Richard. > { > if (dump_file && (dump_flags & TDF_DETAILS)) > { > --- gcc/testsuite/gcc.dg/store_merging_2.c.jj 2017-11-08 16:46:19.000000000 +0100 > +++ gcc/testsuite/gcc.dg/store_merging_2.c 2017-11-09 18:16:33.482344795 +0100 > @@ -77,4 +77,4 @@ main (void) > return 0; > } > > -/* { dg-final { scan-tree-dump-times "Merging successful" 3 "store-merging" } } */ > +/* { dg-final { scan-tree-dump-times "Merging successful" 2 "store-merging" } } */ > --- gcc/testsuite/gcc.dg/pr82916.c.jj 2017-11-09 18:12:40.707128841 +0100 > +++ gcc/testsuite/gcc.dg/pr82916.c 2017-11-09 18:12:19.000000000 +0100 > @@ -0,0 +1,47 @@ > +/* PR bootstrap/82916 */ > +/* { dg-do run } */ > +/* { dg-options "-O2 -fno-tree-dse" } */ > + > +struct A { struct A *next; }; > +struct C > +{ > + int *of; > + struct C *parent, *prev, *next; > + int depth; > + int min; > + struct C *min_occ; > +}; > + > +__attribute__((noipa)) struct C * > +foo (int *node) > +{ > + struct A *p = __builtin_malloc (sizeof (struct C)); > + if (!p) > + return 0; > + p->next = 0; > + /* Originally placement new. */ > + struct C *nw = (struct C *)(void *)p; > + nw->of = node; > + nw->parent = 0; > + nw->prev = 0; > + nw->next = 0; > + nw->depth = 0; > + nw->min_occ = nw; > + nw->min = 0; > + return nw; > +} > + > +int > +main () > +{ > + int o; > + struct C *p = foo (&o); > + if (p) > + { > + if (p->of != &o || p->parent || p->prev || p->next || p->depth > + || p->min || p->min_occ != p) > + __builtin_abort (); > + } > + __builtin_free (p); > + return 0; > +} > > Jakub > >
On Fri, Nov 10, 2017 at 08:52:16AM +0100, Richard Biener wrote: > > @@ -958,8 +959,10 @@ pass_store_merging::terminate_all_aliasi > > unsigned int i; > > FOR_EACH_VEC_ELT (cur->m_store_info, i, info) > > { > > - if (ref_maybe_used_by_stmt_p (stmt, gimple_assign_lhs (info->stmt)) > > - || stmt_may_clobber_ref_p (stmt, gimple_assign_lhs (info->stmt))) > > + tree lhs = gimple_assign_lhs (info->stmt); > > + if (ref_maybe_used_by_stmt_p (stmt, lhs) > > + || stmt_may_clobber_ref_p (stmt, lhs) > > + || (store_lhs && refs_output_dependent_p (store_lhs, lhs))) > > Looks good but may do redundant work for store_lhs? So rather > > || (! store_lhs && stmt_may_clobber_ref_p (stmt, lhs) > || (store_lhs && refs_output_dependent_p (store_lhs, lhs) > > ? Fails to handle storing calls (in case those can appear in the chains). info->stmt is known to be a store, but stmt is not, it can be any other stmt, including calls, so the above would miss the calls handling. > Looks like we miss some convenient stmt_output/anti_dependent_p (you can > follow stmt_may_clobbers_ref_p[_1] for cut&pasting and/or add a > bool tbaa flag we can pass down to stmt_may_clobber_ref_p_1). So perhaps bool tbaa = true argument to both stmt_may_clobber_ref_p_1 and stmt_may_clobber_ref_p, or just stmt_may_clobber_ref_p_1 and add some differently named alternative to stmt_may_clobber_ref_p (in that case, any suggestions on a good name?)? > That said - the patch is ok, any improvements can be done as followup. Jakub
On Fri, 10 Nov 2017, Jakub Jelinek wrote: > On Fri, Nov 10, 2017 at 08:52:16AM +0100, Richard Biener wrote: > > > @@ -958,8 +959,10 @@ pass_store_merging::terminate_all_aliasi > > > unsigned int i; > > > FOR_EACH_VEC_ELT (cur->m_store_info, i, info) > > > { > > > - if (ref_maybe_used_by_stmt_p (stmt, gimple_assign_lhs (info->stmt)) > > > - || stmt_may_clobber_ref_p (stmt, gimple_assign_lhs (info->stmt))) > > > + tree lhs = gimple_assign_lhs (info->stmt); > > > + if (ref_maybe_used_by_stmt_p (stmt, lhs) > > > + || stmt_may_clobber_ref_p (stmt, lhs) > > > + || (store_lhs && refs_output_dependent_p (store_lhs, lhs))) > > > > Looks good but may do redundant work for store_lhs? So rather > > > > || (! store_lhs && stmt_may_clobber_ref_p (stmt, lhs) > > || (store_lhs && refs_output_dependent_p (store_lhs, lhs) > > > > ? Fails to handle storing calls (in case those can appear in the chains). > > info->stmt is known to be a store, but stmt is not, it can be any other > stmt, including calls, so the above would miss the calls handling. > > > Looks like we miss some convenient stmt_output/anti_dependent_p (you can > > follow stmt_may_clobbers_ref_p[_1] for cut&pasting and/or add a > > bool tbaa flag we can pass down to stmt_may_clobber_ref_p_1). > > So perhaps bool tbaa = true argument to both stmt_may_clobber_ref_p_1 > and stmt_may_clobber_ref_p, or just stmt_may_clobber_ref_p_1 and > add some differently named alternative to stmt_may_clobber_ref_p > (in that case, any suggestions on a good name?)? Internally (aka static fn) I'd just add a bool param w/o default. The external API should be stmt_output/anti_dependent_p and I think these days with C++ we could make stmt_may_clobber_ref_p_1 taking ao_ref and stmt_may_clobber_ref_p taking a tree overloads of stmt_may_clobber_ref_p. We'd then have _1 being static and having the extra arg. Richard. > > That said - the patch is ok, any improvements can be done as followup. > > Jakub > >
--- gcc/gimple-ssa-store-merging.c.jj 2017-11-09 15:51:08.000000000 +0100 +++ gcc/gimple-ssa-store-merging.c 2017-11-09 18:01:20.789236951 +0100 @@ -945,6 +945,7 @@ pass_store_merging::terminate_all_aliasi if (!gimple_vuse (stmt)) return false; + tree store_lhs = gimple_store_p (stmt) ? gimple_get_lhs (stmt) : NULL_TREE; for (imm_store_chain_info *next = m_stores_head, *cur = next; cur; cur = next) { next = cur->next; @@ -958,8 +959,10 @@ pass_store_merging::terminate_all_aliasi unsigned int i; FOR_EACH_VEC_ELT (cur->m_store_info, i, info) { - if (ref_maybe_used_by_stmt_p (stmt, gimple_assign_lhs (info->stmt)) - || stmt_may_clobber_ref_p (stmt, gimple_assign_lhs (info->stmt))) + tree lhs = gimple_assign_lhs (info->stmt); + if (ref_maybe_used_by_stmt_p (stmt, lhs) + || stmt_may_clobber_ref_p (stmt, lhs) + || (store_lhs && refs_output_dependent_p (store_lhs, lhs))) { if (dump_file && (dump_flags & TDF_DETAILS)) { --- gcc/testsuite/gcc.dg/store_merging_2.c.jj 2017-11-08 16:46:19.000000000 +0100 +++ gcc/testsuite/gcc.dg/store_merging_2.c 2017-11-09 18:16:33.482344795 +0100 @@ -77,4 +77,4 @@ main (void) return 0; } -/* { dg-final { scan-tree-dump-times "Merging successful" 3 "store-merging" } } */ +/* { dg-final { scan-tree-dump-times "Merging successful" 2 "store-merging" } } */ --- gcc/testsuite/gcc.dg/pr82916.c.jj 2017-11-09 18:12:40.707128841 +0100 +++ gcc/testsuite/gcc.dg/pr82916.c 2017-11-09 18:12:19.000000000 +0100 @@ -0,0 +1,47 @@ +/* PR bootstrap/82916 */ +/* { dg-do run } */ +/* { dg-options "-O2 -fno-tree-dse" } */ + +struct A { struct A *next; }; +struct C +{ + int *of; + struct C *parent, *prev, *next; + int depth; + int min; + struct C *min_occ; +}; + +__attribute__((noipa)) struct C * +foo (int *node) +{ + struct A *p = __builtin_malloc (sizeof (struct C)); + if (!p) + return 0; + p->next = 0; + /* Originally placement new. */ + struct C *nw = (struct C *)(void *)p; + nw->of = node; + nw->parent = 0; + nw->prev = 0; + nw->next = 0; + nw->depth = 0; + nw->min_occ = nw; + nw->min = 0; + return nw; +} + +int +main () +{ + int o; + struct C *p = foo (&o); + if (p) + { + if (p->of != &o || p->parent || p->prev || p->next || p->depth + || p->min || p->min_occ != p) + __builtin_abort (); + } + __builtin_free (p); + return 0; +}