re PR middle-end/36509 (gcc.dg/Wstrict-aliasing-float-ptr-int-obj.c)

2008-12-04  Richard Guenther  <rguenther@suse.de>

	PR middle-end/36509
	PR c++/38334
	* Makefile.in (tree-ssa-alias-warnings.o): Remove.
	(tree-ssa-structalias.o): Remove errors.h dependency.
	(tree-ssa-reassoc.o): Likewise.
	* tree-ssa-reassoc.c: Do not include errors.h.
	* tree-ssa-alias-warnings.c: Remove.
	* tree-ssa-alias.c (compute_may_aliases): Remove call to
	strict_aliasing_warning_backend.
	* tree-ssa-structalias.c (emit_pointer_definition): New function.
	(emit_alias_warning): Likewise.
	(set_uids_in_ptset): Warn for clear cases of type-punning.
	* tree-inline.c (remap_gimple_op_r): Preserve TREE_NO_WARNING
	on INDIRECT_REFs.

	cp/
	* typeck.c (get_member_function_from_ptrfunc): Mark the vtbl
	pointer access with TREE_NO_WARNING.

	* gcc.dg/Wstrict-aliasing-float-ptr-int-obj.c: Adjust, remove XFAIL.
	* gcc.dg/Wstrict-aliasing-converted-assigned.c: Adjust.
	* g++.dg/warn/Wstrict-aliasing-float-ref-int-obj.C: Likewise.

From-SVN: r142437

gcc/ChangeLog

+2008-12-04  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/36509
+	* Makefile.in (tree-ssa-alias-warnings.o): Remove.
+	(tree-ssa-structalias.o): Remove errors.h dependency.
+	(tree-ssa-reassoc.o): Likewise.
+	* tree-ssa-reassoc.c: Do not include errors.h.
+	* tree-ssa-alias-warnings.c: Remove.
+	* tree-ssa-alias.c (compute_may_aliases): Remove call to
+	strict_aliasing_warning_backend.
+	* tree-ssa-structalias.c (emit_pointer_definition): New function.
+	(emit_alias_warning): Likewise.
+	(set_uids_in_ptset): Warn for clear cases of type-punning.
+	* tree-inline.c (remap_gimple_op_r): Preserve TREE_NO_WARNING
+	on INDIRECT_REFs.
+
 2008-12-04  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* cse.c (equiv_constant): Fix pasto.

gcc/Makefile.in

@@ -1243,7 +1243,6 @@ OBJS-common = \
 	tree-switch-conversion.o \
 	tree-ssa-address.o \
 	tree-ssa-alias.o \
-	tree-ssa-alias-warnings.o \
 	tree-ssa-ccp.o \
 	tree-ssa-coalesce.o \
 	tree-ssa-copy.o \
@@ -2089,7 +2088,7 @@ stor-layout.o : stor-layout.c $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) \
    $(TOPLEV_H)
 tree-ssa-structalias.o: tree-ssa-structalias.c tree-ssa-structalias.h \
    $(SYSTEM_H) $(CONFIG_H) coretypes.h $(TM_H) $(GGC_H) $(OBSTACK_H) $(BITMAP_H) \
-   $(FLAGS_H) $(RTL_H) $(TM_P_H) hard-reg-set.h $(BASIC_BLOCK_H) output.h errors.h \
+   $(FLAGS_H) $(RTL_H) $(TM_P_H) hard-reg-set.h $(BASIC_BLOCK_H) output.h \
    $(DIAGNOSTIC_H) $(TREE_H) $(C_COMMON_H) $(TREE_FLOW_H) $(TREE_INLINE_H) varray.h \
    $(C_TREE_H) $(GIMPLE_H) $(HASHTAB_H) $(FUNCTION_H) $(CGRAPH_H) tree-pass.h \
    $(TIMEVAR_H) alloc-pool.h $(SPLAY_TREE_H) $(PARAMS_H) gt-tree-ssa-structalias.h \
@@ -2309,11 +2308,6 @@ tree-ssa-loop-im.o : tree-ssa-loop-im.c $(TREE_FLOW_H) $(CONFIG_H) \
 tree-ssa-math-opts.o : tree-ssa-math-opts.c $(CONFIG_H) $(SYSTEM_H) coretypes.h \
    $(TM_H) $(FLAGS_H) $(TREE_H) $(TREE_FLOW_H) $(REAL_H) $(TIMEVAR_H) tree-pass.h \
    alloc-pool.h $(BASIC_BLOCK_H) $(TARGET_H)
-tree-ssa-alias-warnings.o : tree-ssa-alias-warnings.c \
-   $(CONFIG_H) $(SYSTEM_H) coretypes.h $(TM_H) $(TREE_H) $(TREE_DUMP_H) \
-   $(TREE_FLOW_H) $(PARAMS_H) $(FUNCTION_H) $(EXPR_H) $(TOPLEV_H) \
-   tree-ssa-structalias.h tree-ssa-propagate.h langhooks.h alloc-pool.h \
-   $(DIAGNOSTIC_H)
 tree-ssa-alias.o : tree-ssa-alias.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
    $(RTL_H) $(TREE_H) $(TM_P_H) $(EXPR_H) $(GGC_H) $(TREE_INLINE_H) $(FLAGS_H) \
    $(FUNCTION_H) $(TIMEVAR_H) convert.h $(TM_H) coretypes.h langhooks.h \
@@ -2321,7 +2315,7 @@ tree-ssa-alias.o : tree-ssa-alias.c $(TREE_FLOW_H) $(CONFIG_H) $(SYSTEM_H) \
    hard-reg-set.h $(GIMPLE_H) vec.h tree-ssa-structalias.h \
    $(IPA_TYPE_ESCAPE_H) vecprim.h pointer-set.h alloc-pool.h
 tree-ssa-reassoc.o : tree-ssa-reassoc.c $(TREE_FLOW_H) $(CONFIG_H) \
-   $(SYSTEM_H) $(TREE_H) $(GGC_H) $(DIAGNOSTIC_H) errors.h $(TIMEVAR_H) \
+   $(SYSTEM_H) $(TREE_H) $(GGC_H) $(DIAGNOSTIC_H) $(TIMEVAR_H) \
    $(TM_H) coretypes.h $(TREE_DUMP_H) tree-pass.h $(FLAGS_H) tree-iterator.h\
    $(BASIC_BLOCK_H) $(GIMPLE_H) $(TREE_INLINE_H) vec.h langhooks.h \
    alloc-pool.h pointer-set.h $(CFGLOOP_H)

gcc/cp/ChangeLog

+2008-12-04  Richard Guenther  <rguenther@suse.de>
+
+	PR c++/38334
+	* typeck.c (get_member_function_from_ptrfunc): Mark the vtbl
+	pointer access with TREE_NO_WARNING.
+
 2008-12-03  Jason Merrill  <jason@redhat.com>
 
 	PR c++/38232

gcc/cp/typeck.c

@@ -2790,6 +2790,10 @@ get_member_function_from_ptrfunc (tree *instance_ptrptr, tree function)
       vtbl = build1 (NOP_EXPR, build_pointer_type (vtbl_ptr_type_node),
 		     instance_ptr);
       vtbl = cp_build_indirect_ref (vtbl, NULL, tf_warning_or_error);
+      /* If the object is not dynamic the access invokes undefined
+	 behavior.  As it is not executed in this case silence the
+	 spurious warnings it may provoke.  */
+      TREE_NO_WARNING (vtbl) = 1;
 
       /* Finally, extract the function pointer from the vtable.  */
       e2 = fold_build2 (POINTER_PLUS_EXPR, TREE_TYPE (vtbl), vtbl,

gcc/testsuite/ChangeLog

+2008-12-04  Richard Guenther  <rguenther@suse.de>
+
+	PR middle-end/36509
+	* gcc.dg/Wstrict-aliasing-float-ptr-int-obj.c: Adjust, remove XFAIL.
+	* gcc.dg/Wstrict-aliasing-converted-assigned.c: Adjust.
+	* g++.dg/warn/Wstrict-aliasing-float-ref-int-obj.C: Likewise.
+
 2008-12-04  Eric Botcazou  <ebotcazou@adacore.com>
 
 	* gcc.dg/union-4.c: New test.

gcc/testsuite/g++.dg/warn/Wstrict-aliasing-float-ref-int-obj.C

@@ -4,7 +4,9 @@
 
 int foo() {
   int x;
-  float& q = reinterpret_cast<float&> (x);  /* { dg-warning "type-punn" } */
-  q = 1.0;
+  float& q = reinterpret_cast<float&> (x);  /* { dg-message "initialized" } */
+  q = 1.0; /* { dg-warning "does break strict-aliasing" } */
   return x;
 }
+
+/* { dg-message "dereferencing type-punned" "" { target *-*-* } 7 } */

gcc/testsuite/gcc.dg/Wstrict-aliasing-converted-assigned.c

@@ -8,3 +8,6 @@ int foo()
   *(long*)&i = 0;  /* { dg-warning "type-punn" } */
   return i;
 }
+
+/* { dg-message "does break strict-aliasing" "" { target *-*-* } 8 } */
+/* { dg-message "initialized" "" { target *-*-* } 8 } */

gcc/testsuite/gcc.dg/Wstrict-aliasing-float-ptr-int-obj.c

@@ -11,12 +11,12 @@ int foo() {
   float* r;
 
   if (flag) {
-    q = (float*) &x;  /* { dg-warning "type-punn" "" { xfail *-*-* } } */
+    q = (float*) &x;  /* { dg-message "initialized" } */
   } else {
-    q = (float*) &y;  /* { dg-warning "type-punn" "" { xfail *-*-* } } */
+    q = (float*) &y;  /* { dg-message "initialized" } */
   }
 
-  *q = 1.0;
+  *q = 1.0;  /* { dg-warning "does break strict-aliasing" } */
 
   return x;
 

gcc/tree-inline.c

@@ -710,6 +710,7 @@ remap_gimple_op_r (tree *tp, int *walk_subtrees, void *data)
 		    {
 	              *tp = build1 (INDIRECT_REF, type, new_tree);
 		      TREE_THIS_VOLATILE (*tp) = TREE_THIS_VOLATILE (old);
+		      TREE_NO_WARNING (*tp) = TREE_NO_WARNING (old);
 		    }
 		}
 	      *walk_subtrees = 0;

gcc/tree-ssa-alias.c

@@ -1825,9 +1825,6 @@ compute_may_aliases (void)
 	dump_referenced_vars (dump_file);
     }
 
-  /* Report strict aliasing violations.  */
-  strict_aliasing_warning_backend ();
-
   /* Deallocate memory used by aliasing data structures.  */
   delete_alias_info (ai);
 

gcc/tree-ssa-reassoc.c

@@ -22,7 +22,6 @@ along with GCC; see the file COPYING3.  If not see
 #include "system.h"
 #include "coretypes.h"
 #include "tm.h"
-#include "errors.h"
 #include "ggc.h"
 #include "tree.h"
 #include "basic-block.h"

gcc/tree-ssa-structalias.c

@@ -31,14 +31,14 @@
 #include "hard-reg-set.h"
 #include "basic-block.h"
 #include "output.h"
-#include "errors.h"
-#include "diagnostic.h"
 #include "tree.h"
 #include "c-common.h"
 #include "tree-flow.h"
 #include "tree-inline.h"
 #include "varray.h"
 #include "c-tree.h"
+#include "diagnostic.h"
+#include "toplev.h"
 #include "gimple.h"
 #include "hashtab.h"
 #include "function.h"
@@ -4648,14 +4648,15 @@ shared_bitmap_add (bitmap pt_vars)
    IS_DEREFED is true if PTR was directly dereferenced, which we use to
    help determine whether we are we are allowed to prune using TBAA.
    If NO_TBAA_PRUNING is true, we do not perform any TBAA pruning of
-   the from set.  */
+   the from set.  Returns the number of pruned variables.  */
 
-static void
+static unsigned
 set_uids_in_ptset (tree ptr, bitmap into, bitmap from, bool is_derefed,
 		   bool no_tbaa_pruning)
 {
   unsigned int i;
   bitmap_iterator bi;
+  unsigned pruned = 0;
 
   gcc_assert (POINTER_TYPE_P (TREE_TYPE (ptr)));
 
@@ -4688,14 +4689,97 @@ set_uids_in_ptset (tree ptr, bitmap into, bitmap from, bool is_derefed,
 	      if (may_alias_p (SSA_NAME_VAR (ptr), mem_alias_set,
 			       vi->decl, var_alias_set, true))
 	        bitmap_set_bit (into, DECL_UID (vi->decl));
+	      else
+		++pruned;
 	    }
 	}
     }
+
+  return pruned;
 }
 
 
 static bool have_alias_info = false;
 
+/* Emit a note for the pointer initialization point DEF.  */
+
+static void
+emit_pointer_definition (gimple def)
+{
+  if (gimple_code (def) == GIMPLE_PHI)
+    {
+      use_operand_p argp;
+      ssa_op_iter oi;
+
+      FOR_EACH_PHI_ARG (argp, def, oi, SSA_OP_USE)
+	{
+	  tree arg = USE_FROM_PTR (argp);
+	  if (TREE_CODE (arg) == SSA_NAME)
+	    emit_pointer_definition (SSA_NAME_DEF_STMT (arg));
+	  else
+	    inform (0, "initialized from %qE", arg);
+	}
+    }
+  else if (!gimple_nop_p (def))
+    inform (gimple_location (def), "initialized from here");
+}
+
+/* Emit a strict aliasing warning for dereferencing the pointer PTR.  */
+
+static void
+emit_alias_warning (tree ptr)
+{
+  gimple def = SSA_NAME_DEF_STMT (ptr);
+  gimple use;
+  imm_use_iterator ui;
+  unsigned warned = 0;
+
+  FOR_EACH_IMM_USE_STMT (use, ui, ptr)
+    {
+      tree deref = NULL_TREE;
+
+      if (gimple_has_lhs (use))
+	{
+	  tree lhs = get_base_address (gimple_get_lhs (use));
+	  if (lhs
+	      && INDIRECT_REF_P (lhs)
+	      && TREE_OPERAND (lhs, 0) == ptr)
+	    deref = lhs;
+	}
+      if (gimple_assign_single_p (use))
+	{
+	  tree rhs = get_base_address (gimple_assign_rhs1 (use));
+	  if (rhs
+	      && INDIRECT_REF_P (rhs)
+	      && TREE_OPERAND (rhs, 0) == ptr)
+	    deref = rhs;
+	}
+      else if (is_gimple_call (use))
+	{
+	  unsigned i;
+	  for (i = 0; i < gimple_call_num_args (use); ++i)
+	    {
+	      tree op = get_base_address (gimple_call_arg (use, i));
+	      if (op
+		  && INDIRECT_REF_P (op)
+		  && TREE_OPERAND (op, 0) == ptr)
+		deref = op;
+	    }
+	}
+      if (deref
+	  && !TREE_NO_WARNING (deref))
+	{
+	  TREE_NO_WARNING (deref) = 1;
+	  warning_at (gimple_location (use), OPT_Wstrict_aliasing,
+		      "dereferencing pointer %qD does break strict-aliasing "
+		      "rules", SSA_NAME_VAR (ptr));
+	  ++warned;
+	}
+    }
+  if (warned > 0)
+    emit_pointer_definition (def);
+}
+
 /* Given a pointer variable P, fill in its points-to set, or return
    false if we can't.
    Rather than return false for variables that point-to anything, we
@@ -4740,7 +4824,7 @@ find_what_p_points_to (tree p)
       else
 	{
 	  struct ptr_info_def *pi = get_ptr_info (p);
-	  unsigned int i;
+	  unsigned int i, pruned;
 	  bitmap_iterator bi;
 	  bool was_pt_anything = false;
 	  bitmap finished_solution;
@@ -4792,9 +4876,9 @@ find_what_p_points_to (tree p)
 	  finished_solution = BITMAP_GGC_ALLOC ();
 	  stats.points_to_sets_created++;
 
-	  set_uids_in_ptset (p, finished_solution, vi->solution,
-			     pi->is_dereferenced,
-			     vi->no_tbaa_pruning);
+	  pruned = set_uids_in_ptset (p, finished_solution, vi->solution,
+				      pi->is_dereferenced,
+				      vi->no_tbaa_pruning);
 	  result = shared_bitmap_lookup (finished_solution);
 
 	  if (!result)
@@ -4809,7 +4893,22 @@ find_what_p_points_to (tree p)
 	    }
 
 	  if (bitmap_empty_p (pi->pt_vars))
-	    pi->pt_vars = NULL;
+	    {
+	      pi->pt_vars = NULL;
+	      if (pruned > 0
+		  && pi->is_dereferenced
+		  && warn_strict_aliasing > 0
+		  && !SSA_NAME_IS_DEFAULT_DEF (p))
+		{
+		  if (dump_file && dump_flags & TDF_DETAILS)
+		    {
+		      fprintf (dump_file, "alias warning for ");
+		      print_generic_expr (dump_file, p, 0);
+		      fprintf (dump_file, "\n");
+		    }
+		  emit_alias_warning (p);
+		}
+	    }
 
 	  return true;
 	}