From da42ac7bc51006101e94711e6847f561d7b08005 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Wed, 2 Nov 2016 08:29:48 +0000 Subject: [PATCH] re PR tree-optimization/78035 (Inconsistency between address comparison and alias analysis) 2016-11-02 Richard Biener PR tree-optimization/78035 PR tree-optimization/77964 * gimple-pretty-print.c (pp_points_to_solution): Print vars_contains_interposable. * tree-ssa-alias.c: Include varasm.h. (ptrs_compare_unequal): Check vars_contains_interposable and decl_binds_to_current_def_p. (dump_points_to_solution): Dump vars_contains_interposable. * tree-ssa-alias.h (struct pt_solution): Add vars_contains_interposable flag. * tree-ssa-structalias.c: Include varasm.h. (set_uids_in_ptset): Record whether vars contains a not decl_binds_to_current_def_p variable in vars_contains_interposable. (ipa_escaped_pt): Update initializer. * gcc.target/i386/pr78035.c: New testcase. From-SVN: r241776 --- gcc/ChangeLog | 17 +++++++++++++++++ gcc/gimple-pretty-print.c | 6 ++++++ gcc/testsuite/ChangeLog | 6 ++++++ gcc/testsuite/gcc.target/i386/pr78035.c | 24 ++++++++++++++++++++++++ gcc/tree-ssa-alias.c | 17 +++++++++++++---- gcc/tree-ssa-alias.h | 2 ++ gcc/tree-ssa-structalias.c | 12 +++++++++++- 7 files changed, 79 insertions(+), 5 deletions(-) create mode 100644 gcc/testsuite/gcc.target/i386/pr78035.c diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 5fdafbf..be6c059 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,5 +1,22 @@ 2016-11-02 Richard Biener + PR tree-optimization/78035 + PR tree-optimization/77964 + * gimple-pretty-print.c (pp_points_to_solution): Print + vars_contains_interposable. + * tree-ssa-alias.c: Include varasm.h. + (ptrs_compare_unequal): Check vars_contains_interposable and + decl_binds_to_current_def_p. + (dump_points_to_solution): Dump vars_contains_interposable. + * tree-ssa-alias.h (struct pt_solution): Add vars_contains_interposable + flag. + * tree-ssa-structalias.c: Include varasm.h. + (set_uids_in_ptset): Record whether vars contains a + not decl_binds_to_current_def_p variable in vars_contains_interposable. + (ipa_escaped_pt): Update initializer. + +2016-11-02 Richard Biener + PR tree-optimization/78047 * tree-ssa-structalias.c (push_fields_onto_fieldstack): Initialize fake field at offset zero conservatively regarding to may_have_pointers. diff --git a/gcc/gimple-pretty-print.c b/gcc/gimple-pretty-print.c index 10bf801..f588f5e 100644 --- a/gcc/gimple-pretty-print.c +++ b/gcc/gimple-pretty-print.c @@ -728,6 +728,12 @@ pp_points_to_solution (pretty_printer *buffer, struct pt_solution *pt) { pp_string (buffer, comma); pp_string (buffer, "restrict"); + comma = ", "; + } + if (pt->vars_contains_interposable) + { + pp_string (buffer, comma); + pp_string (buffer, "interposable"); } pp_string (buffer, ")"); } diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog index 20ef692..6827c00 100644 --- a/gcc/testsuite/ChangeLog +++ b/gcc/testsuite/ChangeLog @@ -1,5 +1,11 @@ 2016-11-02 Richard Biener + PR tree-optimization/78035 + PR tree-optimization/77964 + * gcc.target/i386/pr78035.c: New testcase. + +2016-11-02 Richard Biener + * gcc.dg/tree-ssa/vrp111.c: New testcase. * gcc.dg/tree-ssa/pr20702.c: Disable EVRP. * gcc.dg/tree-ssa/pr21086.c: Likewise. diff --git a/gcc/testsuite/gcc.target/i386/pr78035.c b/gcc/testsuite/gcc.target/i386/pr78035.c new file mode 100644 index 0000000..2e673a8 --- /dev/null +++ b/gcc/testsuite/gcc.target/i386/pr78035.c @@ -0,0 +1,24 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +extern int a; +extern int b; +extern int c; + +int foo(int choose_a) +{ + int *p; + if (choose_a) + p = &a; + else + p = &b; + return p != &c; +} + +int bar () +{ + return &a != &c; +} + +/* We should not optimize away either comparison. */ +/* { dg-final { scan-assembler-times "cmp" 2 } } */ diff --git a/gcc/tree-ssa-alias.c b/gcc/tree-ssa-alias.c index 26c9f9e..ebae6cf 100644 --- a/gcc/tree-ssa-alias.c +++ b/gcc/tree-ssa-alias.c @@ -32,12 +32,12 @@ along with GCC; see the file COPYING3. If not see #include "tree-pretty-print.h" #include "alias.h" #include "fold-const.h" - #include "langhooks.h" #include "dumpfile.h" #include "tree-eh.h" #include "tree-dfa.h" #include "ipa-reference.h" +#include "varasm.h" /* Broad overview of how alias analysis on gimple works: @@ -373,14 +373,18 @@ ptrs_compare_unequal (tree ptr1, tree ptr2) /* We may not use restrict to optimize pointer comparisons. See PR71062. So we have to assume that restrict-pointed-to may be in fact obj1. */ - if (!pi || pi->pt.vars_contains_restrict) + if (!pi + || pi->pt.vars_contains_restrict + || pi->pt.vars_contains_interposable) return false; if (VAR_P (obj1) && (TREE_STATIC (obj1) || DECL_EXTERNAL (obj1))) { varpool_node *node = varpool_node::get (obj1); /* If obj1 may bind to NULL give up (see below). */ - if (! node || ! node->nonzero_address ()) + if (! node + || ! node->nonzero_address () + || ! decl_binds_to_current_def_p (obj1)) return false; } return !pt_solution_includes (&pi->pt, obj1); @@ -553,7 +557,12 @@ dump_points_to_solution (FILE *file, struct pt_solution *pt) comma = ", "; } if (pt->vars_contains_restrict) - fprintf (file, "%srestrict", comma); + { + fprintf (file, "%srestrict", comma); + comma = ", "; + } + if (pt->vars_contains_interposable) + fprintf (file, "%sinterposable", comma); fprintf (file, ")"); } } diff --git a/gcc/tree-ssa-alias.h b/gcc/tree-ssa-alias.h index 27a06fc..810d83c 100644 --- a/gcc/tree-ssa-alias.h +++ b/gcc/tree-ssa-alias.h @@ -57,6 +57,8 @@ struct GTY(()) pt_solution /* Nonzero if the vars bitmap includes a anonymous variable used to represent storage pointed to by a restrict qualified pointer. */ unsigned int vars_contains_restrict : 1; + /* Nonzero if the vars bitmap includes an interposable variable. */ + unsigned int vars_contains_interposable : 1; /* Set of variables that this pointer may point to. */ bitmap vars; diff --git a/gcc/tree-ssa-structalias.c b/gcc/tree-ssa-structalias.c index a0110bc..2880382 100644 --- a/gcc/tree-ssa-structalias.c +++ b/gcc/tree-ssa-structalias.c @@ -39,6 +39,8 @@ #include "tree-dfa.h" #include "params.h" #include "gimple-walk.h" +#include "varasm.h" + /* The idea behind this analyzer is to generate set constraints from the program, then solve the resulting constraints in order to generate the @@ -6360,6 +6362,13 @@ set_uids_in_ptset (bitmap into, bitmap from, struct pt_solution *pt, && fndecl && ! auto_var_in_fn_p (vi->decl, fndecl))) pt->vars_contains_nonlocal = true; + + /* If we have a variable that is interposable record that fact + for pointer comparison simplification. */ + if (VAR_P (vi->decl) + && (TREE_STATIC (vi->decl) || DECL_EXTERNAL (vi->decl)) + && ! decl_binds_to_current_def_p (vi->decl)) + pt->vars_contains_interposable = true; } else if (TREE_CODE (vi->decl) == FUNCTION_DECL @@ -7592,7 +7601,8 @@ make_pass_build_ealias (gcc::context *ctxt) /* IPA PTA solutions for ESCAPED. */ struct pt_solution ipa_escaped_pt - = { true, false, false, false, false, false, false, false, false, NULL }; + = { true, false, false, false, false, + false, false, false, false, false, NULL }; /* Associate node with varinfo DATA. Worker for cgraph_for_symbol_thunks_and_aliases. */ -- 2.7.4