2014-11-03 Marc Glisse <marc.glisse@inria.fr>

	PR tree-optimization/60770
gcc/
	* tree-into-ssa.c (rewrite_update_stmt): Return whether the
	statement should be removed.
	(maybe_register_def): Likewise. Replace clobbers with default
	definitions.
	(rewrite_dom_walker::before_dom_children): Remove statement if
	rewrite_update_stmt says so.
	* tree-ssa-live.c: Include tree-ssa.h.
	(set_var_live_on_entry): Do not mark undefined variables as live.
	(verify_live_on_entry): Do not check undefined variables.
	* tree-ssa.h (ssa_undefined_value_p): New parameter for the case
	of partially undefined variables.
	* tree-ssa.c (ssa_undefined_value_p): Likewise.
	(execute_update_addresses_taken): Do not drop clobbers.

gcc/testsuite/
	* gcc.dg/tree-ssa/pr60770-1.c: New file.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@217034 138bc75d-0d04-0410-961f-82ee72b054a4

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index f31c42b..41a4f57 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,5 +1,22 @@
 2014-11-03  Marc Glisse  <marc.glisse@inria.fr>
 
+       PR tree-optimization/60770
+       * tree-into-ssa.c (rewrite_update_stmt): Return whether the
+       statement should be removed.
+       (maybe_register_def): Likewise. Replace clobbers with default
+       definitions.
+       (rewrite_dom_walker::before_dom_children): Remove statement if
+       rewrite_update_stmt says so.
+       * tree-ssa-live.c: Include tree-ssa.h.
+       (set_var_live_on_entry): Do not mark undefined variables as live.
+       (verify_live_on_entry): Do not check undefined variables.
+       * tree-ssa.h (ssa_undefined_value_p): New parameter for the case
+       of partially undefined variables.
+       * tree-ssa.c (ssa_undefined_value_p): Likewise.
+       (execute_update_addresses_taken): Do not drop clobbers.
+
+2014-11-03  Marc Glisse  <marc.glisse@inria.fr>
+
        PR tree-optimization/63666
        * fold-const.c: Include "optabs.h".
        (fold_ternary_loc) <VEC_PERM_EXPR>: Avoid canonicalizing a

diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 06e9bee..7e97d61 100644 (file)
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2014-11-03  Marc Glisse  <marc.glisse@inria.fr>
+
+       PR tree-optimization/60770
+       * gcc.dg/tree-ssa/pr60770-1.c: New file.
+
 2014-11-03  Jan Beulich  <jbeulich@suse.com>
 
        * gcc.target/i386/i386.exp: Extend option set to test

diff --git a/gcc/testsuite/gcc.dg/tree-ssa/pr60770-1.c b/gcc/testsuite/gcc.dg/tree-ssa/pr60770-1.c
new file mode 100644 (file)
index 0000000..021d884
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/tree-ssa/pr60770-1.c
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -Wall" } */
+
+int f(int n){
+  int*p;
+  {
+    int yyy=n;
+    p=&yyy;
+  }
+  return *p; /* { dg-warning "yyy" } */
+}

diff --git a/gcc/tree-into-ssa.c b/gcc/tree-into-ssa.c
index bf99160..d86efe4 100644 (file)
--- a/gcc/tree-into-ssa.c
+++ b/gcc/tree-into-ssa.c
@@ -1833,14 +1833,15 @@ maybe_replace_use_in_debug_stmt (use_operand_p use_p)
 /* If the operand pointed to by DEF_P is an SSA name in NEW_SSA_NAMES
    or OLD_SSA_NAMES, or if it is a symbol marked for renaming,
    register it as the current definition for the names replaced by
-   DEF_P.  */
+   DEF_P.  Returns whether the statement should be removed.  */
 
-static inline void
+static inline bool
 maybe_register_def (def_operand_p def_p, gimple stmt,
                    gimple_stmt_iterator gsi)
 {
   tree def = DEF_FROM_PTR (def_p);
   tree sym = DECL_P (def) ? def : SSA_NAME_VAR (def);
+  bool to_delete = false;
 
   /* If DEF is a naked symbol that needs renaming, create a new
      name for it.  */
@@ -1848,12 +1849,21 @@ maybe_register_def (def_operand_p def_p, gimple stmt,
     {
       if (DECL_P (def))
        {
-         tree tracked_var;
-
-         def = make_ssa_name (def, stmt);
+         if (gimple_clobber_p (stmt) && is_gimple_reg (sym))
+           {
+             gcc_checking_assert (TREE_CODE (sym) == VAR_DECL);
+             /* Replace clobber stmts with a default def. This new use of a
+                default definition may make it look like SSA_NAMEs have
+                conflicting lifetimes, so we need special code to let them
+                coalesce properly.  */
+             to_delete = true;
+             def = get_or_create_ssa_default_def (cfun, sym);
+           }
+         else
+           def = make_ssa_name (def, stmt);
          SET_DEF (def_p, def);
 
-         tracked_var = target_for_debug_bind (sym);
+         tree tracked_var = target_for_debug_bind (sym);
          if (tracked_var)
            {
              gimple note = gimple_build_debug_bind (tracked_var, def, stmt);
@@ -1911,6 +1921,8 @@ maybe_register_def (def_operand_p def_p, gimple stmt,
       if (is_old_name (def))
        register_new_update_single (def, def);
     }
+
+  return to_delete;
 }
 
 
@@ -1919,9 +1931,9 @@ maybe_register_def (def_operand_p def_p, gimple stmt,
    OLD_SSA_NAMES used by SI will be updated to their current reaching
    definition.  Names in OLD_SSA_NAMES or NEW_SSA_NAMES defined by SI
    will be registered as a new definition for their corresponding name
-   in OLD_SSA_NAMES.  */
+   in OLD_SSA_NAMES.  Returns whether STMT should be removed.  */
 
-static void
+static bool
 rewrite_update_stmt (gimple stmt, gimple_stmt_iterator gsi)
 {
   use_operand_p use_p;
@@ -1930,7 +1942,7 @@ rewrite_update_stmt (gimple stmt, gimple_stmt_iterator gsi)
 
   /* Only update marked statements.  */
   if (!rewrite_uses_p (stmt) && !register_defs_p (stmt))
-    return;
+    return false;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
@@ -1981,9 +1993,12 @@ rewrite_update_stmt (gimple stmt, gimple_stmt_iterator gsi)
   /* Register definitions of names in NEW_SSA_NAMES and OLD_SSA_NAMES.
      Also register definitions for names whose underlying symbol is
      marked for renaming.  */
+  bool to_delete = false;
   if (register_defs_p (stmt))
     FOR_EACH_SSA_DEF_OPERAND (def_p, stmt, iter, SSA_OP_ALL_DEFS)
-      maybe_register_def (def_p, stmt, gsi);
+      to_delete |= maybe_register_def (def_p, stmt, gsi);
+
+  return to_delete;
 }
 
 
@@ -2149,8 +2164,11 @@ rewrite_update_dom_walker::before_dom_children (basic_block bb)
   if (bitmap_bit_p (interesting_blocks, bb->index))
     {
       gcc_checking_assert (bitmap_bit_p (blocks_to_update, bb->index));
-      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
-        rewrite_update_stmt (gsi_stmt (gsi), gsi);
+      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
+       if (rewrite_update_stmt (gsi_stmt (gsi), gsi))
+         gsi_remove (&gsi, true);
+       else
+         gsi_next (&gsi);
     }
 
   /* Step 3.  Update PHI nodes.  */

diff --git a/gcc/tree-ssa-live.c b/gcc/tree-ssa-live.c
index 1effb43..22013e0 100644 (file)
--- a/gcc/tree-ssa-live.c
+++ b/gcc/tree-ssa-live.c
@@ -57,6 +57,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "diagnostic-core.h"
 #include "debug.h"
 #include "flags.h"
+#include "tree-ssa.h"
 
 #ifdef ENABLE_CHECKING
 static void  verify_live_on_entry (tree_live_info_p);
@@ -1103,6 +1104,10 @@ set_var_live_on_entry (tree ssa_name, tree_live_info_p live)
   else
     def_bb = ENTRY_BLOCK_PTR_FOR_FN (cfun);
 
+  /* An undefined local variable does not need to be very alive.  */
+  if (ssa_undefined_value_p (ssa_name, false))
+    return;
+
   /* Visit each use of SSA_NAME and if it isn't in the same block as the def,
      add it to the list of live on entry blocks.  */
   FOR_EACH_IMM_USE_FAST (use, imm_iter, ssa_name)
@@ -1439,6 +1444,11 @@ verify_live_on_entry (tree_live_info_p live)
          else
            if (d == var)
              {
+               /* An undefined local variable does not need to be very
+                  alive.  */
+               if (ssa_undefined_value_p (var, false))
+                 continue;
+
                /* The only way this var shouldn't be marked live on entry is
                   if it occurs in a PHI argument of the block.  */
                size_t z;

diff --git a/gcc/tree-ssa.c b/gcc/tree-ssa.c
index bcf65e1..2535461 100644 (file)
--- a/gcc/tree-ssa.c
+++ b/gcc/tree-ssa.c
@@ -1188,10 +1188,11 @@ tree_ssa_strip_useless_type_conversions (tree exp)
 }
 
 
-/* Return true if T, an SSA_NAME, has an undefined value.  */
+/* Return true if T, an SSA_NAME, has an undefined value.  PARTIAL is what
+   should be returned if the value is only partially undefined.  */
 
 bool
-ssa_undefined_value_p (tree t)
+ssa_undefined_value_p (tree t, bool partial)
 {
   gimple def_stmt;
   tree var = SSA_NAME_VAR (t);
@@ -1215,7 +1216,7 @@ ssa_undefined_value_p (tree t)
     return true;
 
   /* Check if the complex was not only partially defined.  */
-  if (is_gimple_assign (def_stmt)
+  if (partial && is_gimple_assign (def_stmt)
       && gimple_assign_rhs_code (def_stmt) == COMPLEX_EXPR)
     {
       tree rhs1, rhs2;
@@ -1561,18 +1562,6 @@ execute_update_addresses_taken (void)
                if (gimple_assign_lhs (stmt) != lhs)
                  gimple_assign_set_lhs (stmt, lhs);
 
-               /* For var ={v} {CLOBBER}; where var lost
-                  TREE_ADDRESSABLE just remove the stmt.  */
-               if (DECL_P (lhs)
-                   && TREE_CLOBBER_P (rhs)
-                   && bitmap_bit_p (suitable_for_renaming, DECL_UID (lhs)))
-                 {
-                   unlink_stmt_vdef (stmt);
-                   gsi_remove (&gsi, true);
-                   release_defs (stmt);
-                   continue;
-                 }
-
                if (gimple_assign_rhs1 (stmt) != rhs)
                  {
                    gimple_stmt_iterator gsi = gsi_for_stmt (stmt);

diff --git a/gcc/tree-ssa.h b/gcc/tree-ssa.h
index 835686c..ed1ff6e 100644 (file)
--- a/gcc/tree-ssa.h
+++ b/gcc/tree-ssa.h
@@ -51,7 +51,7 @@ extern void delete_tree_ssa (void);
 extern bool tree_ssa_useless_type_conversion (tree);
 extern tree tree_ssa_strip_useless_type_conversions (tree);
 
-extern bool ssa_undefined_value_p (tree);
+extern bool ssa_undefined_value_p (tree, bool = true);
 extern void execute_update_addresses_taken (void);
 
 /* Given an edge_var_map V, return the PHI arg definition.  */