re PR rtl-optimization/33638 (wrong code with -O2 -fforce-addr)

	PR rtl-optimization/33638
	* dse.c (struct insn_info): Remove 'stack_read' field,
	add 'stack_pointer_based' field.
	(record_store): For a store with non-constant base, record
	whether it is stack pointer based.
	(scan_insn): For the call to a const function, remove stack
	pointer based stores from the list of local active stores.
	(scan_reads_nospill): Delete code dealing with const functions.

From-SVN: r129226

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e659b1ebf7528b7df2760b083fb3a0ff6c2cfb19..f2568d6c5bf019b455c150b86b1831316b437cd3 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2007-10-11  Eric Botcazou  <ebotcazou@libertysurf.fr>
+
+       PR rtl-optimization/33638
+       * dse.c (struct insn_info): Remove 'stack_read' field,
+       add 'stack_pointer_based' field.
+       (record_store): For a store with non-constant base, record
+       whether it is stack pointer based.
+       (scan_insn): For the call to a const function, remove stack
+       pointer based stores from the list of local active stores.
+       (scan_reads_nospill): Delete code dealing with const functions.
+
 2007-10-10  Peter Bergner  <bergner@vnet.ibm.com>
 
        * ra-conflict.c (partial_bitnum, max_bitnum): Change type of variables

diff --git a/gcc/dse.c b/gcc/dse.c
index d031c49a4f02303812b1c4ba2af1018b26ec5dfb..c5e8e26dc62c3e4a6753d996fcddcbc7e4dab7ea 100644 (file)
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -284,12 +284,11 @@ struct insn_info
      contains a wild read, the use_rec will be null.  */
   bool wild_read;
 
-  /* This field is set for const function calls.  Const functions
-     cannot read memory, but they can read the stack because that is
-     where they may get their parms.  So having this set is less
-     severe than a wild read, it just means that all of the stores to
-     the stack are killed rather than all stores.  */
-  bool stack_read;
+  /* This field is only used for the processing of const functions.
+     These functions cannot read memory, but they can read the stack
+     because that is where they may get their parms.  It is set to
+     true if the insn may contain a stack pointer based store.  */
+  bool stack_pointer_based;
 
   /* This is true if any of the sets within the store contains a
      cselib base.  Such stores can only be deleted by the local
@@ -941,8 +940,9 @@ add_wild_read (bb_info_t bb_info)
 }
 
 
-/* Return true if X is a constant or one of the registers that behaves
-   as a constant over the life of a function.  */
+/* Return true if X is a constant or one of the registers that behave
+   as a constant over the life of a function.  This is equivalent to
+   !rtx_varies_p for memory addresses.  */
 
 static bool
 const_or_frame_p (rtx x)
@@ -1245,8 +1245,15 @@ record_store (rtx body, bb_info_t bb_info)
     }
   else
     {
-      store_info = pool_alloc (cse_store_info_pool);
+      rtx base_term = find_base_term (XEXP (mem, 0));
+      if (!base_term
+         || (GET_CODE (base_term) == ADDRESS
+             && GET_MODE (base_term) == Pmode
+             && XEXP (base_term, 0) == stack_pointer_rtx))
+       insn_info->stack_pointer_based = true;
       insn_info->contains_cselib_groups = true;
+
+      store_info = pool_alloc (cse_store_info_pool);
       group_id = -1;
 
       if (dump_file)
@@ -1948,9 +1955,10 @@ scan_insn (bb_info_t bb_info, rtx insn)
   if (CALL_P (insn))
     {
       insn_info->cannot_delete = true;
+
       /* Const functions cannot do anything bad i.e. read memory,
-        however, they can read their parameters which may have been
-        pushed onto the stack.  */
+        however, they can read their parameters which may have
+        been pushed onto the stack.  */
       if (CONST_OR_PURE_CALL_P (insn) && !pure_call_p (insn))
        {
          insn_info_t i_ptr = active_local_stores;
@@ -1961,15 +1969,8 @@ scan_insn (bb_info_t bb_info, rtx insn)
 
          while (i_ptr)
            {
-             store_info_t store_info = i_ptr->store_rec;
-
-             /* Skip the clobbers.  */
-             while (!store_info->is_set)
-               store_info = store_info->next;
-
-             /* Remove the frame related stores.  */
-             if (store_info->group_id >= 0
-                 && VEC_index (group_info_t, rtx_group_vec, store_info->group_id)->frame_related)
+             /* Remove the stack pointer based stores.  */
+             if (i_ptr->stack_pointer_based)
                {
                  if (dump_file)
                    dump_insn_info ("removing from active", i_ptr);
@@ -1983,14 +1984,12 @@ scan_insn (bb_info_t bb_info, rtx insn)
                last = i_ptr;
              i_ptr = i_ptr->next_local_store;
            }
-
-         insn_info->stack_read = true;
-         
-         return;
        }
 
-      /* Every other call, including pure functions may read memory.  */
-      add_wild_read (bb_info);
+      else
+       /* Every other call, including pure functions, may read memory.  */
+       add_wild_read (bb_info);
+
       return;
     }
 
@@ -2492,18 +2491,6 @@ scan_reads_nospill (insn_info_t insn_info, bitmap gen, bitmap kill)
   int i;
   group_info_t group;
 
-  /* For const function calls kill the stack related stores.  */
-  if (insn_info->stack_read)
-    {
-      for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)
-       if (group->process_globally && group->frame_related)
-         {
-           if (kill)
-             bitmap_ior_into (kill, group->group_kill);
-           bitmap_and_compl_into (gen, group->group_kill); 
-         }
-    }
-
   while (read_info)
     {
       for (i = 0; VEC_iterate (group_info_t, rtx_group_vec, i, group); i++)