[PATCH] Fix PR45860

[Richard Guenther]

Conditional store-elimination is confused when a non-register typed
constant is stored (such as any STRING_CST).

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.

Richard.

2010-10-20  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/45860
	* tree-ssa-phiopt.c (cond_store_replacement): Do not do
	conditional store replacement for non-register type stores.

	* gcc.dg/torture/pr45860.c: New testcase.

Index: gcc/tree-ssa-phiopt.c
===================================================================
*** gcc/tree-ssa-phiopt.c	(revision 165712)
--- gcc/tree-ssa-phiopt.c	(working copy)
*************** cond_store_replacement (basic_block midd
*** 1204,1213 ****
        || TREE_CODE (TREE_OPERAND (lhs, 0)) != SSA_NAME)
      return false;
  
!   /* RHS is either a single SSA_NAME or a constant. */
    code = gimple_assign_rhs_code (assign);
    if (get_gimple_rhs_class (code) != GIMPLE_SINGLE_RHS
!       || (code != SSA_NAME && !is_gimple_min_invariant (rhs)))
      return false;
    /* Prove that we can move the store down.  We could also check
       TREE_THIS_NOTRAP here, but in that case we also could move stores,
--- 1204,1214 ----
        || TREE_CODE (TREE_OPERAND (lhs, 0)) != SSA_NAME)
      return false;
  
!   /* RHS is either a single SSA_NAME or a constant of register type. */
    code = gimple_assign_rhs_code (assign);
    if (get_gimple_rhs_class (code) != GIMPLE_SINGLE_RHS
!       || (code != SSA_NAME && !is_gimple_min_invariant (rhs))
!       || !is_gimple_reg_type (TREE_TYPE (lhs)))
      return false;
    /* Prove that we can move the store down.  We could also check
       TREE_THIS_NOTRAP here, but in that case we also could move stores,
*************** cond_store_replacement (basic_block midd
*** 1217,1224 ****
  
    /* Now we've checked the constraints, so do the transformation:
       1) Remove the single store.  */
-   mark_symbols_for_renaming (assign);
    gsi = gsi_for_stmt (assign);
    gsi_remove (&gsi, true);
  
    /* 2) Create a temporary where we can store the old content
--- 1218,1225 ----
  
    /* Now we've checked the constraints, so do the transformation:
       1) Remove the single store.  */
    gsi = gsi_for_stmt (assign);
+   unlink_stmt_vdef (assign);
    gsi_remove (&gsi, true);
  
    /* 2) Create a temporary where we can store the old content
*************** cond_store_replacement (basic_block midd
*** 1237,1243 ****
    name = make_ssa_name (condstoretemp, new_stmt);
    gimple_assign_set_lhs (new_stmt, name);
    gimple_set_location (new_stmt, locus);
-   mark_symbols_for_renaming (new_stmt);
    gsi_insert_on_edge (e1, new_stmt);
  
    /* 4) Create a PHI node at the join block, with one argument
--- 1238,1243 ----
*************** cond_store_replacement (basic_block midd
*** 1249,1255 ****
  
    lhs = unshare_expr (lhs);
    new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi));
-   mark_symbols_for_renaming (new_stmt);
  
    /* 5) Insert that PHI node.  */
    gsi = gsi_after_labels (join_bb);
--- 1249,1254 ----
Index: gcc/testsuite/gcc.dg/torture/pr45860.c
===================================================================
*** gcc/testsuite/gcc.dg/torture/pr45860.c	(revision 0)
--- gcc/testsuite/gcc.dg/torture/pr45860.c	(revision 0)
***************
*** 0 ****
--- 1,11 ----
+ /* { dg-do compile } */
+ 
+ void
+ foo (char *str, int i)
+ {
+   static const char text[] = "";
+   str[i] = 0;
+   if (i & 1)
+     __builtin_strcpy (str + i, text);
+ }
+