re PR target/65697 (__atomic memory barriers not strong enough for __sync builtins)

[gcc.git] / gcc / tree-ssa-dce.c

diff --git a/gcc/tree-ssa-dce.c b/gcc/tree-ssa-dce.c
index 1d887c28f866bf67b20926e49af7b18c58661b48..181626cf979d18eba9464ee881b139924e2b1c60 100644 (file)
--- a/gcc/tree-ssa-dce.c
+++ b/gcc/tree-ssa-dce.c
@@ -1,5 +1,5 @@
 /* Dead code elimination pass for the GNU compiler.
-   Copyright (C) 2002-2014 Free Software Foundation, Inc.
+   Copyright (C) 2002-2015 Free Software Foundation, Inc.
    Contributed by Ben Elliston <bje@redhat.com>
    and Andrew MacLeod <amacleod@redhat.com>
    Adapted to use control dependence by Steven Bosscher, SUSE Labs.
@@ -46,17 +46,14 @@ along with GCC; see the file COPYING3.  If not see
 #include "system.h"
 #include "coretypes.h"
 #include "tm.h"
-
+#include "alias.h"
+#include "symtab.h"
 #include "tree.h"
+#include "fold-const.h"
 #include "calls.h"
 #include "gimple-pretty-print.h"
 #include "predict.h"
-#include "vec.h"
-#include "hashtab.h"
-#include "hash-set.h"
-#include "machmode.h"
 #include "hard-reg-set.h"
-#include "input.h"
 #include "function.h"
 #include "dominance.h"
 #include "cfg.h"
@@ -66,7 +63,6 @@ along with GCC; see the file COPYING3.  If not see
 #include "internal-fn.h"
 #include "tree-eh.h"
 #include "gimple-expr.h"
-#include "is-a.h"
 #include "gimple.h"
 #include "gimplify.h"
 #include "gimple-iterator.h"
@@ -78,10 +74,18 @@ along with GCC; see the file COPYING3.  If not see
 #include "tree-ssanames.h"
 #include "tree-ssa-loop-niter.h"
 #include "tree-into-ssa.h"
+#include "rtl.h"
+#include "flags.h"
+#include "insn-config.h"
+#include "expmed.h"
+#include "dojump.h"
+#include "explow.h"
+#include "emit-rtl.h"
+#include "varasm.h"
+#include "stmt.h"
 #include "expr.h"
 #include "tree-dfa.h"
 #include "tree-pass.h"
-#include "flags.h"
 #include "cfgloop.h"
 #include "tree-scalar-evolution.h"
 #include "tree-chkp.h"
@@ -292,8 +296,7 @@ mark_stmt_if_obviously_necessary (gimple stmt, bool aggressive)
       break;
 
     case GIMPLE_ASSIGN:
-      if (TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
-         && TREE_CLOBBER_P (gimple_assign_rhs1 (stmt)))
+      if (gimple_clobber_p (stmt))
        return;
       break;
 
@@ -1134,7 +1137,12 @@ remove_dead_stmt (gimple_stmt_iterator *i, basic_block bb)
        if (e != e2)
          {
            cfg_altered = true;
-            remove_edge (e2);
+           /* If we made a BB unconditionally exit a loop then this
+              transform alters the set of BBs in the loop.  Schedule
+              a fixup.  */
+           if (loop_exit_edge_p (bb->loop_father, e))
+             loops_state_set (LOOPS_NEED_FIXUP);
+           remove_edge (e2);
          }
        else
          ei_next (&ei);
@@ -1362,6 +1370,25 @@ eliminate_unnecessary_stmts (void)
          /* If GSI is not necessary then remove it.  */
          if (!gimple_plf (stmt, STMT_NECESSARY))
            {
+             /* Keep clobbers that we can keep live live.  */
+             if (gimple_clobber_p (stmt))
+               {
+                 ssa_op_iter iter;
+                 use_operand_p use_p;
+                 bool dead = false;
+                 FOR_EACH_SSA_USE_OPERAND (use_p, stmt, iter, SSA_OP_USE)
+                   {
+                     tree name = USE_FROM_PTR (use_p);
+                     if (!SSA_NAME_IS_DEFAULT_DEF (name)
+                         && !bitmap_bit_p (processed, SSA_NAME_VERSION (name)))
+                       {
+                         dead = true;
+                         break;
+                       }
+                   }
+                 if (!dead)
+                   continue;
+               }
              if (!is_gimple_debug (stmt))
                something_changed = true;
              remove_dead_stmt (&gsi, bb);