re PR tree-optimization/78035 (Inconsistency between address comparison and alias...

2016-11-02  Richard Biener  <rguenther@suse.de>

	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

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 5fdafbfac06e0e962285ec096dd2b15d7e96deb8..be6c059f26e0e41448e21fd00e43a9cb62a4e535 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,20 @@
+2016-11-02  Richard Biener  <rguenther@suse.de>
+
+       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  <rguenther@suse.de>
 
        PR tree-optimization/78047

diff --git a/gcc/gimple-pretty-print.c b/gcc/gimple-pretty-print.c
index 10bf80139b6806824dd0e8e294712f5ffa933f01..f588f5e445edb22672b8e565cf7ebf1e472e18db 100644 (file)
--- 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 20ef692bb1963d78625cd80a5bbd5415b154b291..6827c0090bcb00d1767215db6c096930895d5794 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2016-11-02  Richard Biener  <rguenther@suse.de>
+
+       PR tree-optimization/78035
+       PR tree-optimization/77964
+       * gcc.target/i386/pr78035.c: New testcase.
+
 2016-11-02  Richard Biener  <rguenther@suse.de>
 
        * gcc.dg/tree-ssa/vrp111.c: New testcase.

diff --git a/gcc/testsuite/gcc.target/i386/pr78035.c b/gcc/testsuite/gcc.target/i386/pr78035.c
new file mode 100644 (file)
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 26c9f9e894b78f2dce72c017f27e2fb84e090019..ebae6cfa6fe073f282de315f8ec41c3887364986 100644 (file)
--- 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 27a06fcca2c20bc1373856efff82afb690e1d7d5..810d83c978e570ec359d7c859baa28ba04d3d6bc 100644 (file)
--- 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 a0110bcfccb682ea1519dc950198dad3a025c30c..28803826b43fddb7661f68315f96de8d1a4604ad 100644 (file)
--- 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.  */