> 2005-06-02 Steven Bosscher <stevenb@suse.de>

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

diff --git a/gcc/tree-ssa-operands.c b/gcc/tree-ssa-operands.c
index ccc2033..83ec21b 100644 (file)
--- a/gcc/tree-ssa-operands.c
+++ b/gcc/tree-ssa-operands.c
@@ -26,12 +26,12 @@ Boston, MA 02111-1307, USA.  */
 #include "flags.h"
 #include "function.h"
 #include "diagnostic.h"
-#include "errors.h"
 #include "tree-flow.h"
 #include "tree-inline.h"
 #include "tree-pass.h"
 #include "ggc.h"
 #include "timevar.h"
+#include "toplev.h"
 
 #include "langhooks.h"
 
@@ -99,6 +99,10 @@ Boston, MA 02111-1307, USA.  */
    VUSE for 'b'.  */
 #define opf_no_vops    (1 << 2)
 
+/* Operand is a "non-specific" kill for call-clobbers and such.  This is used
+   to distinguish "reset the world" events from explicit MODIFY_EXPRs.  */
+#define opf_non_specific  (1 << 3)
+
 /* This structure maintain a sorted list of operands which is created by
    parse_ssa_operand.  */
 struct opbuild_list_d GTY (())
@@ -1326,7 +1330,7 @@ get_expr_operands (tree stmt, tree *expr_p, int flags)
                bool exact;             
                if (overlap_subvar (offset, size, sv, &exact))
                  {
-                   if (exact)
+                   if (!exact)
                      flags &= ~opf_kill_def;
                    add_stmt_operand (&sv->var, s_ann, flags);
                  }
@@ -1552,7 +1556,7 @@ get_asm_expr_operands (tree stmt)
          EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, i, bi)
              {
                tree var = referenced_var (i);
-               add_stmt_operand (&var, s_ann, opf_is_def);
+               add_stmt_operand (&var, s_ann, opf_is_def | opf_non_specific);
              }
 
        /* Now clobber all addressables.  */
@@ -1570,7 +1574,7 @@ get_asm_expr_operands (tree stmt)
                  && get_subvars_for_var (var) != NULL)
                continue;               
 
-             add_stmt_operand (&var, s_ann, opf_is_def);
+             add_stmt_operand (&var, s_ann, opf_is_def | opf_non_specific);
            }
 
        break;
@@ -1755,20 +1759,21 @@ add_stmt_operand (tree *var_p, stmt_ann_t s_ann, int flags)
 
   /* If the variable cannot be modified and this is a V_MAY_DEF change
      it into a VUSE.  This happens when read-only variables are marked
-     call-clobbered and/or aliased to writeable variables.  So we only
-     check that this only happens on stores, and not writes to GIMPLE
-     registers.
-     
-     FIXME: The C++ FE is emitting assignments in the IL stream for
-     read-only globals.  This is wrong, but for the time being disable
-     this transformation on V_MUST_DEF operands (otherwise, we
-     mis-optimize SPEC2000's eon).  */
-  if ((flags & opf_is_def)
-      && !(flags & opf_kill_def)
-      && unmodifiable_var_p (var))
+     call-clobbered and/or aliased to writable variables.  So we only
+     check that this only happens on non-specific stores.
+
+     Note that if this is a specific store, i.e. associated with a
+     modify_expr, then we can't suppress the V_DEF, lest we run into
+     validation problems.
+
+     This can happen when programs cast away const, leaving us with a
+     store to read-only memory.  If the statement is actually executed
+     at runtime, then the program is ill formed.  If the statement is
+     not executed then all is well.  At the very least, we cannot ICE.  */
+  if ((flags & opf_non_specific) && unmodifiable_var_p (var))
     {
       gcc_assert (!is_real_op);
-      flags &= ~opf_is_def;
+      flags &= ~(opf_is_def | opf_kill_def);
     }
 
   if (is_real_op)
@@ -1886,35 +1891,14 @@ add_stmt_operand (tree *var_p, stmt_ann_t s_ann, int flags)
 static void
 note_addressable (tree var, stmt_ann_t s_ann)
 {
-  tree ref;
   subvar_t svars;
-  HOST_WIDE_INT offset;
-  HOST_WIDE_INT size;
 
   if (!s_ann)
     return;
   
-  /* If this is a COMPONENT_REF, and we know exactly what it touches, we only
-     take the address of the subvariables it will touch.
-     Otherwise, we take the address of all the subvariables, plus the real
-     ones.  */
-
-  if (var && TREE_CODE (var) == COMPONENT_REF 
-      && (ref = okay_component_ref_for_subvars (var, &offset, &size)))
-    {
-      subvar_t sv;
-      svars = get_subvars_for_var (ref);
-      
-      if (s_ann->addresses_taken == NULL)
-       s_ann->addresses_taken = BITMAP_GGC_ALLOC ();      
-      
-      for (sv = svars; sv; sv = sv->next)
-       {
-         if (overlap_subvar (offset, size, sv, NULL))
-           bitmap_set_bit (s_ann->addresses_taken, var_ann (sv->var)->uid);
-       }
-      return;
-    }
+  /* Note that it is *NOT OKAY* to use the target of a COMPONENT_REF
+     as the only thing we take the address of.
+     See PR 21407 and the ensuing mailing list discussion.  */
   
   var = get_base_address (var);
   if (var && SSA_VAR_P (var))
@@ -1997,7 +1981,7 @@ add_call_clobber_ops (tree stmt)
       if (unmodifiable_var_p (var))
        add_stmt_operand (&var, &empty_ann, opf_none);
       else
-       add_stmt_operand (&var, &empty_ann, opf_is_def);
+       add_stmt_operand (&var, &empty_ann, opf_is_def | opf_non_specific);
     }
 
   clobbered_aliased_loads = empty_ann.makes_aliased_loads;
@@ -2082,7 +2066,7 @@ add_call_read_ops (tree stmt)
   EXECUTE_IF_SET_IN_BITMAP (call_clobbered_vars, 0, u, bi)
     {
       tree var = referenced_var (u);
-      add_stmt_operand (&var, &empty_ann, opf_none);
+      add_stmt_operand (&var, &empty_ann, opf_none | opf_non_specific);
     }
 
   ro_call_aliased_loads = empty_ann.makes_aliased_loads;