* config/alpha/alpha.md (umk_mismatch_args): Don't put a mode on set.

[pf3gnuchains/gcc-fork.git] / gcc / tree-ssa-dse.c

diff --git a/gcc/tree-ssa-dse.c b/gcc/tree-ssa-dse.c
index 37a5481..80c2622 100644 (file)
--- a/gcc/tree-ssa-dse.c
+++ b/gcc/tree-ssa-dse.c
@@ -1,5 +1,5 @@
 /* Dead store elimination
-   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009
+   Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010
    Free Software Foundation, Inc.
 
 This file is part of GCC.
@@ -24,11 +24,10 @@ along with GCC; see the file COPYING3.  If not see
 #include "tm.h"
 #include "ggc.h"
 #include "tree.h"
-#include "rtl.h"
 #include "tm_p.h"
 #include "basic-block.h"
 #include "timevar.h"
-#include "diagnostic.h"
+#include "gimple-pretty-print.h"
 #include "tree-flow.h"
 #include "tree-pass.h"
 #include "tree-dump.h"
@@ -161,7 +160,7 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt)
   temp = stmt;
   do
     {
-      gimple prev, use_stmt;
+      gimple use_stmt;
       imm_use_iterator ui;
       bool fail = false;
       tree defvar;
@@ -175,28 +174,33 @@ dse_possible_dead_store_p (gimple stmt, gimple *use_stmt)
        defvar = PHI_RESULT (temp);
       else
        defvar = gimple_vdef (temp);
-      prev = temp;
       temp = NULL;
       FOR_EACH_IMM_USE_STMT (use_stmt, ui, defvar)
        {
          cnt++;
 
+         /* If we ever reach our DSE candidate stmt again fail.  We
+            cannot handle dead stores in loops.  */
+         if (use_stmt == stmt)
+           {
+             fail = true;
+             BREAK_FROM_IMM_USE_STMT (ui);
+           }
          /* In simple cases we can look through PHI nodes, but we
             have to be careful with loops and with memory references
             containing operands that are also operands of PHI nodes.
             See gcc.c-torture/execute/20051110-*.c.  */
-         if (gimple_code (use_stmt) == GIMPLE_PHI)
+         else if (gimple_code (use_stmt) == GIMPLE_PHI)
            {
              if (temp
-                 /* We can look through PHIs to post-dominated regions
-                    without worrying if the use not also dominates prev
-                    (in which case it would be a loop PHI with the use
-                    in a latch block).  */
-                 || gimple_bb (prev) == gimple_bb (use_stmt)
-                 || !dominated_by_p (CDI_POST_DOMINATORS,
-                                     gimple_bb (prev), gimple_bb (use_stmt))
+                 /* Make sure we are not in a loop latch block.  */
+                 || gimple_bb (stmt) == gimple_bb (use_stmt)
                  || dominated_by_p (CDI_DOMINATORS,
-                                    gimple_bb (prev), gimple_bb (use_stmt)))
+                                    gimple_bb (stmt), gimple_bb (use_stmt))
+                 /* We can look through PHIs to regions post-dominating
+                    the DSE candidate stmt.  */
+                 || !dominated_by_p (CDI_POST_DOMINATORS,
+                                     gimple_bb (stmt), gimple_bb (use_stmt)))
                {
                  fail = true;
                  BREAK_FROM_IMM_USE_STMT (ui);
@@ -297,8 +301,9 @@ dse_optimize_stmt (struct dse_global_data *dse_gd,
         virtual uses from stmt and the stmt which stores to that same
         memory location, then we may have found redundant store.  */
       if (bitmap_bit_p (dse_gd->stores, get_stmt_uid (use_stmt))
-         && operand_equal_p (gimple_assign_lhs (stmt),
-                             gimple_assign_lhs (use_stmt), 0))
+         && (operand_equal_p (gimple_assign_lhs (stmt),
+                              gimple_assign_lhs (use_stmt), 0)
+             || stmt_kills_ref_p (use_stmt, gimple_assign_lhs (stmt))))
        {
          /* If use_stmt is or might be a nop assignment, e.g. for
             struct { ... } S a, b, *p; ...