Re: operator new returns nonzero

[Marc Glisse <marc dot glisse at inria dot fr>]

On Sat, 7 Sep 2013, Mike Stump wrote:

> On Sep 7, 2013, at 12:27 PM, Marc Glisse <marc.glisse@inria.fr> wrote:
> > Now flag_check_new should probably disable this optimization…
>
> Yes, this why my point.

Ok, here it is (again, no proper testing until bootstrap is fixed)

2013-09-07  Marc Glisse  <marc.glisse@inria.fr>

	PR c++/19476
gcc/
	* fold-const.c (tree_expr_nonzero_warnv_p): Handle operator new.
	* tree-vrp.c (gimple_stmt_nonzero_warnv_p, stmt_interesting_for_vrp):
	Likewise.
	(vrp_visit_stmt): Remove duplicated code.

gcc/testsuite/
	* g++.dg/tree-ssa/pr19476-1.C: New file.
	* g++.dg/tree-ssa/pr19476-2.C: Likewise.
	* g++.dg/tree-ssa/pr19476-3.C: Likewise.

--
Marc Glisse

Index: testsuite/g++.dg/tree-ssa/pr19476-1.C
===================================================================
--- testsuite/g++.dg/tree-ssa/pr19476-1.C	(revision 0)
+++ testsuite/g++.dg/tree-ssa/pr19476-1.C	(revision 0)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fdump-tree-ccp1" } */
+
+#include <new>
+
+int f(){
+  return 33 + (0 == new(std::nothrow) int);
+}
+int g(){
+  return 42 + (0 == new int[50]);
+}
+
+/* { dg-final { scan-tree-dump     "return 42" "ccp1" } } */
+/* { dg-final { scan-tree-dump-not "return 33" "ccp1" } } */
+/* { dg-final { cleanup-tree-dump "ccp1" } } */

Property changes on: testsuite/g++.dg/tree-ssa/pr19476-1.C
___________________________________________________________________
Added: svn:keywords
   + Author Date Id Revision URL
Added: svn:eol-style
   + native

Index: testsuite/g++.dg/tree-ssa/pr19476-2.C
===================================================================
--- testsuite/g++.dg/tree-ssa/pr19476-2.C	(revision 0)
+++ testsuite/g++.dg/tree-ssa/pr19476-2.C	(revision 0)
@@ -0,0 +1,17 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+#include <new>
+
+int f(){
+  int *p = new(std::nothrow) int;
+  return 33 + (0 == p);
+}
+int g(){
+  int *p = new int[50];
+  return 42 + (0 == p);
+}
+
+/* { dg-final { scan-tree-dump     "return 42" "optimized" } } */
+/* { dg-final { scan-tree-dump-not "return 33" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

Property changes on: testsuite/g++.dg/tree-ssa/pr19476-2.C
___________________________________________________________________
Added: svn:keywords
   + Author Date Id Revision URL
Added: svn:eol-style
   + native

Index: testsuite/g++.dg/tree-ssa/pr19476-3.C
===================================================================
--- testsuite/g++.dg/tree-ssa/pr19476-3.C	(revision 0)
+++ testsuite/g++.dg/tree-ssa/pr19476-3.C	(revision 0)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O3 -fcheck-new -fdump-tree-optimized" } */
+
+#include <new>
+
+int g(){
+  return 42 + (0 == new int);
+}
+
+/* { dg-final { scan-tree-dump-not "return 42" "optimized" } } */
+/* { dg-final { cleanup-tree-dump "optimized" } } */

Property changes on: testsuite/g++.dg/tree-ssa/pr19476-3.C
___________________________________________________________________
Added: svn:keywords
   + Author Date Id Revision URL
Added: svn:eol-style
   + native

Index: fold-const.c
===================================================================
--- fold-const.c	(revision 202351)
+++ fold-const.c	(working copy)
@@ -16171,21 +16171,31 @@ tree_expr_nonzero_warnv_p (tree t, bool
     case MODIFY_EXPR:
     case BIND_EXPR:
       return tree_expr_nonzero_warnv_p (TREE_OPERAND (t, 1),
 					strict_overflow_p);
 
     case SAVE_EXPR:
       return tree_expr_nonzero_warnv_p (TREE_OPERAND (t, 0),
 					strict_overflow_p);
 
     case CALL_EXPR:
-      return alloca_call_p (t);
+      {
+	tree fn = CALL_EXPR_FN (t);
+	if (TREE_CODE (fn) != ADDR_EXPR) return false;
+	tree fndecl = TREE_OPERAND (fn, 0);
+	if (TREE_CODE (fndecl) != FUNCTION_DECL) return false;
+	if (!flag_check_new
+	    && DECL_IS_OPERATOR_NEW (fndecl)
+	    && !TREE_NOTHROW (fndecl))
+	  return true;
+	return alloca_call_p (t);
+      }
 
     default:
       break;
     }
   return false;
 }
 
 /* Return true when T is an address and is known to be nonzero.
    Handle warnings about undefined signed overflow.  */
 
Index: tree-vrp.c
===================================================================
--- tree-vrp.c	(revision 202351)
+++ tree-vrp.c	(working copy)
@@ -1047,21 +1047,29 @@ gimple_assign_nonzero_warnv_p (gimple st
    *STRICT_OVERFLOW_P.*/
 
 static bool
 gimple_stmt_nonzero_warnv_p (gimple stmt, bool *strict_overflow_p)
 {
   switch (gimple_code (stmt))
     {
     case GIMPLE_ASSIGN:
       return gimple_assign_nonzero_warnv_p (stmt, strict_overflow_p);
     case GIMPLE_CALL:
-      return gimple_alloca_call_p (stmt);
+      {
+	tree fndecl = gimple_call_fndecl (stmt);
+	if (!fndecl) return false;
+	if (!flag_check_new
+	    && DECL_IS_OPERATOR_NEW (fndecl)
+	    && !TREE_NOTHROW (fndecl))
+	  return true;
+	return gimple_alloca_call_p (stmt);
+      }
     default:
       gcc_unreachable ();
     }
 }
 
 /* Like tree_expr_nonzero_warnv_p, but this function uses value ranges
    obtained so far.  */
 
 static bool
 vrp_stmt_computes_nonzero (gimple stmt, bool *strict_overflow_p)
@@ -6486,21 +6494,22 @@ stmt_interesting_for_vrp (gimple stmt)
       tree lhs = gimple_get_lhs (stmt);
 
       /* In general, assignments with virtual operands are not useful
 	 for deriving ranges, with the obvious exception of calls to
 	 builtin functions.  */
       if (lhs && TREE_CODE (lhs) == SSA_NAME
 	  && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
 	      || POINTER_TYPE_P (TREE_TYPE (lhs)))
 	  && ((is_gimple_call (stmt)
 	       && gimple_call_fndecl (stmt) != NULL_TREE
-	       && DECL_BUILT_IN (gimple_call_fndecl (stmt)))
+	       && (DECL_BUILT_IN (gimple_call_fndecl (stmt))
+		   || DECL_IS_OPERATOR_NEW (gimple_call_fndecl (stmt))))
 	      || !gimple_vuse (stmt)))
 	return true;
     }
   else if (gimple_code (stmt) == GIMPLE_COND
 	   || gimple_code (stmt) == GIMPLE_SWITCH)
     return true;
 
   return false;
 }
 
@@ -7407,30 +7416,21 @@ vrp_visit_stmt (gimple stmt, edge *taken
   if (dump_file && (dump_flags & TDF_DETAILS))
     {
       fprintf (dump_file, "\nVisiting statement:\n");
       print_gimple_stmt (dump_file, stmt, 0, dump_flags);
       fprintf (dump_file, "\n");
     }
 
   if (!stmt_interesting_for_vrp (stmt))
     gcc_assert (stmt_ends_bb_p (stmt));
   else if (is_gimple_assign (stmt) || is_gimple_call (stmt))
-    {
-      /* In general, assignments with virtual operands are not useful
-	 for deriving ranges, with the obvious exception of calls to
-	 builtin functions.  */
-      if ((is_gimple_call (stmt)
-	   && gimple_call_fndecl (stmt) != NULL_TREE
-	   && DECL_BUILT_IN (gimple_call_fndecl (stmt)))
-	  || !gimple_vuse (stmt))
-	return vrp_visit_assignment_or_call (stmt, output_p);
-    }
+    return vrp_visit_assignment_or_call (stmt, output_p);
   else if (gimple_code (stmt) == GIMPLE_COND)
     return vrp_visit_cond_stmt (stmt, taken_edge_p);
   else if (gimple_code (stmt) == GIMPLE_SWITCH)
     return vrp_visit_switch_stmt (stmt, taken_edge_p);
 
   /* All other statements produce nothing of interest for VRP, so mark
      their outputs varying and prevent further simulation.  */
   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_DEF)
     set_value_range_to_varying (get_value_range (def));