Hi, this patch adds EAF_NOT_RETURNED_DIRECTLY which works similarly as EAF_NODIRECTESCAPE. Values pointed to by a given argument may be returned but not the argument itself. This helps PTA quite noticeably because we mostly care about tracking points to which given memory location can escape.
I think this is about last reasonable improvement we can get to EAF flags. cc1plus disambiguation counts change from: Alias oracle query stats: refs_may_alias_p: 77976088 disambiguations, 98744590 queries ref_maybe_used_by_call_p: 572845 disambiguations, 79014622 queries call_may_clobber_ref_p: 340823 disambiguations, 344823 queries nonoverlapping_component_refs_p: 0 disambiguations, 26590 queries nonoverlapping_refs_since_match_p: 31626 disambiguations, 65379 must overlaps, 97963 queries aliasing_component_refs_p: 57414 disambiguations, 11434878 queries TBAA oracle: 27749649 disambiguations 91624184 queries 14733408 are in alias set 0 8847139 queries asked about the same object 139 queries asked about the same alias set 0 access volatile 38412201 are dependent in the DAG 1881648 are aritificially in conflict with void * Modref stats: modref use: 23785 disambiguations, 702425 queries modref clobber: 2296391 disambiguations, 22690531 queries 5260226 tbaa queries (0.231825 per modref query) 731741 base compares (0.032249 per modref query) PTA query stats: pt_solution_includes: 12580233 disambiguations, 35854408 queries pt_solutions_intersect: 1409041 disambiguations, 13496899 queries To: Alias oracle query stats: refs_may_alias_p: 78304485 disambiguations, 98830913 queries ref_maybe_used_by_call_p: 630360 disambiguations, 79308222 queries call_may_clobber_ref_p: 381549 disambiguations, 384627 queries nonoverlapping_component_refs_p: 0 disambiguations, 26299 queries nonoverlapping_refs_since_match_p: 29919 disambiguations, 64917 must overlaps, 95781 queries aliasing_component_refs_p: 57250 disambiguations, 11336880 queries TBAA oracle: 27835747 disambiguations 91534430 queries 14884868 are in alias set 0 8933627 queries asked about the same object 123 queries asked about the same alias set 0 access volatile 37974723 are dependent in the DAG 1905342 are aritificially in conflict with void * Modref stats: modref use: 24929 disambiguations, 756294 queries modref clobber: 2334910 disambiguations, 23414495 queries 5359212 tbaa queries (0.228884 per modref query) 754642 base compares (0.032230 per modref query) PTA query stats: pt_solution_includes: 13262256 disambiguations, 36306509 queries pt_solutions_intersect: 1574672 disambiguations, 13638933 queries So about 5% more pt_solution_includes and 11% more pt_solutions_intersect disambiguations. Bootstrapped/regtested x86_64-linux, OK? Honza gcc/ChangeLog: * tree-core.h (EAF_NOT_RETURNED_DIRECTLY): New flag. (EAF_NOREAD): Renumber. * ipa-modref.c (dump_eaf_flags): Dump EAF_NOT_RETURNED_DIRECTLY. (remove_useless_eaf_flags): Handle EAF_NOT_RETURNED_DIRECTLY (deref_flags): Likewise. (modref_lattice::init): Likewise. (modref_lattice::merge): Likewise. (merge_call_lhs_flags): Likewise. (analyze_ssa_name_flags): Likewise. (modref_merge_call_site_flags): Likewise. * tree-ssa-structalias.c (handle_call_arg): Likewise. gcc/testsuite/ChangeLog: * gcc.dg/ipa/modref-3.c: New test. * gcc.dg/tree-ssa/modref-10.c: New test. diff --git a/gcc/ipa-modref.c b/gcc/ipa-modref.c index d866d9ed6b3..c0aae084dbd 100644 --- a/gcc/ipa-modref.c +++ b/gcc/ipa-modref.c @@ -160,6 +160,8 @@ dump_eaf_flags (FILE *out, int flags, bool newline = true) fprintf (out, " unused"); if (flags & EAF_NOT_RETURNED) fprintf (out, " not_returned"); + if (flags & EAF_NOT_RETURNED_DIRECTLY) + fprintf (out, " not_returned_directly"); if (flags & EAF_NOREAD) fprintf (out, " noread"); if (newline) @@ -295,7 +297,7 @@ remove_useless_eaf_flags (int eaf_flags, int ecf_flags, bool returns_void) else if (ecf_flags & ECF_PURE) eaf_flags &= ~implicit_pure_eaf_flags; else if ((ecf_flags & ECF_NORETURN) || returns_void) - eaf_flags &= ~EAF_NOT_RETURNED; + eaf_flags &= ~(EAF_NOT_RETURNED | EAF_NOT_RETURNED_DIRECTLY); return eaf_flags; } @@ -1373,7 +1375,7 @@ memory_access_to (tree op, tree ssa_name) static int deref_flags (int flags, bool ignore_stores) { - int ret = EAF_NODIRECTESCAPE; + int ret = EAF_NODIRECTESCAPE | EAF_NOT_RETURNED_DIRECTLY; /* If argument is unused just account for the read involved in dereference. */ if (flags & EAF_UNUSED) @@ -1458,7 +1460,8 @@ modref_lattice::init () { /* All flags we track. */ int f = EAF_DIRECT | EAF_NOCLOBBER | EAF_NOESCAPE | EAF_UNUSED - | EAF_NODIRECTESCAPE | EAF_NOT_RETURNED | EAF_NOREAD; + | EAF_NODIRECTESCAPE | EAF_NOT_RETURNED | + EAF_NOT_RETURNED_DIRECTLY | EAF_NOREAD; flags = f; /* Check that eaf_flags_t is wide enough to hold all flags. */ gcc_checking_assert (f == flags); @@ -1540,6 +1543,8 @@ modref_lattice::merge (int f) Fnspec machinery does set both so compensate for this. */ if (f & EAF_NOESCAPE) f |= EAF_NODIRECTESCAPE; + if (f & EAF_NOT_RETURNED) + f |= EAF_NOT_RETURNED_DIRECTLY; if ((flags & f) != flags) { flags &= f; @@ -1647,7 +1652,9 @@ merge_call_lhs_flags (gcall *call, int arg, int index, bool deref, && (flags & ERF_RETURN_ARG_MASK) != arg) return; - if (gimple_call_arg_flags (call, arg) & (EAF_NOT_RETURNED | EAF_UNUSED)) + int eaf_flags = gimple_call_arg_flags (call, arg); + + if (eaf_flags & (EAF_NOT_RETURNED | EAF_UNUSED)) return; /* If return value is SSA name determine its flags. */ @@ -1655,12 +1662,14 @@ merge_call_lhs_flags (gcall *call, int arg, int index, bool deref, { tree lhs = gimple_call_lhs (call); analyze_ssa_name_flags (lhs, lattice, depth + 1, ipa); - if (deref) + if (deref || (eaf_flags & EAF_NOT_RETURNED_DIRECTLY)) lattice[index].merge_deref (lattice[SSA_NAME_VERSION (lhs)], false); else lattice[index].merge (lattice[SSA_NAME_VERSION (lhs)]); } /* In the case of memory store we can do nothing. */ + else if (eaf_flags & EAF_NOT_RETURNED_DIRECTLY) + lattice[index].merge (deref_flags (0, false)); else lattice[index].merge (0); } @@ -1731,11 +1740,13 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice> &lattice, int depth, && DECL_BY_REFERENCE (DECL_RESULT (current_function_decl))) ; else if (gimple_return_retval (ret) == name) - lattice[index].merge (~(EAF_UNUSED | EAF_NOT_RETURNED)); + lattice[index].merge (~(EAF_UNUSED | EAF_NOT_RETURNED + | EAF_NOT_RETURNED_DIRECTLY)); else if (memory_access_to (gimple_return_retval (ret), name)) { lattice[index].merge_direct_load (); - lattice[index].merge (~(EAF_UNUSED | EAF_NOT_RETURNED)); + lattice[index].merge (~(EAF_UNUSED | EAF_NOT_RETURNED + | EAF_NOT_RETURNED_DIRECTLY)); } } /* Account for LHS store, arg loads and flags from callee function. */ @@ -1794,7 +1805,8 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice> &lattice, int depth, if (!(ecf_flags & (ECF_CONST | ECF_NOVOPS))) { int call_flags = gimple_call_arg_flags (call, i) - | EAF_NOT_RETURNED; + | EAF_NOT_RETURNED + | EAF_NOT_RETURNED_DIRECTLY; if (ignore_stores) call_flags |= ignore_stores_eaf_flags; @@ -1817,7 +1829,8 @@ analyze_ssa_name_flags (tree name, vec<modref_lattice> &lattice, int depth, { int call_flags = deref_flags (gimple_call_arg_flags (call, i) - | EAF_NOT_RETURNED, ignore_stores); + | EAF_NOT_RETURNED + | EAF_NOT_RETURNED_DIRECTLY, ignore_stores); if (!record_ipa) lattice[index].merge (call_flags); else @@ -3858,14 +3871,18 @@ modref_merge_call_site_flags (escape_summary *sum, flags_lto |= ignore_stores_eaf_flags; } /* Returning the value is already accounted to at local propagation. */ - flags |= ee->min_flags | EAF_NOT_RETURNED; - flags_lto |= ee->min_flags | EAF_NOT_RETURNED; + flags |= ee->min_flags | EAF_NOT_RETURNED | EAF_NOT_RETURNED_DIRECTLY; + flags_lto |= ee->min_flags | EAF_NOT_RETURNED | EAF_NOT_RETURNED_DIRECTLY; /* Noescape implies that value also does not escape directly. Fnspec machinery does set both so compensate for this. */ if (flags & EAF_NOESCAPE) flags |= EAF_NODIRECTESCAPE; if (flags_lto & EAF_NOESCAPE) flags_lto |= EAF_NODIRECTESCAPE; + if (flags & EAF_NOT_RETURNED) + flags |= EAF_NOT_RETURNED_DIRECTLY; + if (flags_lto & EAF_NOT_RETURNED) + flags_lto |= EAF_NOT_RETURNED_DIRECTLY; if (!(flags & EAF_UNUSED) && cur_summary && ee->parm_index < (int)cur_summary->arg_flags.length ()) { diff --git a/gcc/testsuite/gcc.dg/ipa/modref-3.c b/gcc/testsuite/gcc.dg/ipa/modref-3.c new file mode 100644 index 00000000000..c90683bc962 --- /dev/null +++ b/gcc/testsuite/gcc.dg/ipa/modref-3.c @@ -0,0 +1,20 @@ +/* { dg-options "-O2 -fdump-ipa-modref" } */ +/* { dg-do link } */ +int *ptr; +void linker_error (); +int +main () +{ + int a; + __attribute__((noinline)) int test2 () + { + ptr = 0; + return a; + } + a = 1; + test2 (); + if (a != 1) + linker_error (); + return 0; +} +/* { dg-final { scan-ipa-dump "Static chain flags: noclobber noescape nodirectescape" "modref" } */ diff --git a/gcc/testsuite/gcc.dg/tree-ssa/modref-10.c b/gcc/testsuite/gcc.dg/tree-ssa/modref-10.c new file mode 100644 index 00000000000..c608408809d --- /dev/null +++ b/gcc/testsuite/gcc.dg/tree-ssa/modref-10.c @@ -0,0 +1,20 @@ +/* { dg-do link } */ +/* { dg-options "-O2 -fdump-tree-modref1" } */ +void linker_error (); +__attribute__((noinline)) +int * +test (int **a) +{ + return *a; +} +int +main() +{ + int val; + int *a=&val; + int *b = test (&a); + if (b == (int *)&a) + linker_error (); + return 0; +} +/* { dg-final { scan-tree-dump "parm 0 flags: noclobber noescape nodirectescape not_returned_directly" "modref1"} } */ diff --git a/gcc/tree-core.h b/gcc/tree-core.h index d3d2a8d812f..8a55db2b3f5 100644 --- a/gcc/tree-core.h +++ b/gcc/tree-core.h @@ -117,8 +117,12 @@ struct die_struct; /* Nonzero if the argument does not escape to return value. */ #define EAF_NOT_RETURNED (1 << 5) +/* Nonzero if the argument argument itself does not escape + to return value but memory referenced by it may escape. */ +#define EAF_NOT_RETURNED_DIRECTLY (1 << 6) + /* Nonzero if the argument is not read. */ -#define EAF_NOREAD (1 << 6) +#define EAF_NOREAD (1 << 7) /* Call return flags. */ /* Mask for the argument number that is returned. Lower two bits of diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c index 99072df0768..5f24c0171f0 100644 --- a/gcc/tree-ssa-structalias.c +++ b/gcc/tree-ssa-structalias.c @@ -4082,8 +4082,16 @@ handle_call_arg (gcall *stmt, tree arg, vec<ce_s> *results, int flags, { struct constraint_expr cexpr; cexpr.var = tem->id; - cexpr.type = SCALAR; - cexpr.offset = 0; + if (flags & EAF_NOT_RETURNED_DIRECTLY) + { + cexpr.type = DEREF; + cexpr.offset = UNKNOWN_OFFSET; + } + else + { + cexpr.type = SCALAR; + cexpr.offset = 0; + } results->safe_push (cexpr); }