[Bug c++/20280] [4.0/4.1 regression] ICE in create_tmp_var, at gimplify.c:368

aoliva at redhat dot com gcc-bugzilla@gcc.gnu.org
Fri Mar 4 19:23:00 GMT 2005


------- Additional Comments From aoliva at gcc dot gnu dot org  2005-03-04 19:23 -------
Subject: Re: [PR c++/20280] hoist indirect_ref out of addressable cond_exprs

On Mar  4, 2005, Mark Mitchell <mark@codesourcery.com> wrote:

> Your reading is logical, but it depends on exactly what "lvalue for a
> bit-field" means.  (Note that it does not say "lvalue *is* a
> bit-field"; it says "lvalue *for* a bit-field".)

Good point.  Here's an all-new patch, with the comment updated to
reflect our discussion.

Still testing on x86_64-linux-gnu, ok to install if it succeeds?

Index: gcc/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c++/20280
	* gimplify.c (gimplify_cond_expr): Add fallback argument.  Use a
	temporary variable of pointer type if an lvalues is required.
	(gimplify_modify_expr_rhs): Request an rvalue from it.
	(gimplify_expr): Pass fallback on.

Index: gcc/gimplify.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/gimplify.c,v
retrieving revision 2.113
diff -u -p -r2.113 gimplify.c
--- gcc/gimplify.c 18 Feb 2005 19:35:37 -0000 2.113
+++ gcc/gimplify.c 4 Mar 2005 19:18:49 -0000
@@ -2123,7 +2123,8 @@ gimple_boolify (tree expr)
      *EXPR_P should be stored.  */
 
 static enum gimplify_status
-gimplify_cond_expr (tree *expr_p, tree *pre_p, tree *post_p, tree target)
+gimplify_cond_expr (tree *expr_p, tree *pre_p, tree *post_p, tree target,
+		    fallback_t fallback)
 {
   tree expr = *expr_p;
   tree tmp, tmp2, type;
@@ -2137,18 +2138,40 @@ gimplify_cond_expr (tree *expr_p, tree *
      the arms.  */
   else if (! VOID_TYPE_P (type))
     {
+      tree result;
+
       if (target)
 	{
 	  ret = gimplify_expr (&target, pre_p, post_p,
 			       is_gimple_min_lval, fb_lvalue);
 	  if (ret != GS_ERROR)
 	    ret = GS_OK;
-	  tmp = target;
+	  result = tmp = target;
 	  tmp2 = unshare_expr (target);
 	}
+      else if ((fallback & fb_lvalue) == 0)
+	{
+	  result = tmp2 = tmp = create_tmp_var (TREE_TYPE (expr), "iftmp");
+	  ret = GS_ALL_DONE;
+	}
       else
 	{
-	  tmp2 = tmp = create_tmp_var (TREE_TYPE (expr), "iftmp");
+	  tree type = build_pointer_type (TREE_TYPE (expr));
+
+	  if (TREE_TYPE (TREE_OPERAND (expr, 1)) != void_type_node)
+	    TREE_OPERAND (expr, 1) =
+	      build_fold_addr_expr (TREE_OPERAND (expr, 1));
+
+	  if (TREE_TYPE (TREE_OPERAND (expr, 2)) != void_type_node)
+	    TREE_OPERAND (expr, 2) =
+	      build_fold_addr_expr (TREE_OPERAND (expr, 2));
+	  
+	  tmp2 = tmp = create_tmp_var (type, "iftmp");
+
+	  expr = build (COND_EXPR, void_type_node, TREE_OPERAND (expr, 0),
+			TREE_OPERAND (expr, 1), TREE_OPERAND (expr, 2));
+
+	  result = build_fold_indirect_ref (tmp);
 	  ret = GS_ALL_DONE;
 	}
 
@@ -2169,7 +2192,7 @@ gimplify_cond_expr (tree *expr_p, tree *
       /* Move the COND_EXPR to the prequeue.  */
       gimplify_and_add (expr, pre_p);
 
-      *expr_p = tmp;
+      *expr_p = result;
       return ret;
     }
 
@@ -2907,7 +2930,8 @@ gimplify_modify_expr_rhs (tree *expr_p, 
 	if (!is_gimple_reg_type (TREE_TYPE (*from_p)))
 	  {
 	    *expr_p = *from_p;
-	    return gimplify_cond_expr (expr_p, pre_p, post_p, *to_p);
+	    return gimplify_cond_expr (expr_p, pre_p, post_p, *to_p,
+				       fb_rvalue);
 	  }
 	else
 	  ret = GS_UNHANDLED;
@@ -3721,7 +3745,8 @@ gimplify_expr (tree *expr_p, tree *pre_p
 	  break;
 
 	case COND_EXPR:
-	  ret = gimplify_cond_expr (expr_p, pre_p, post_p, NULL_TREE);
+	  ret = gimplify_cond_expr (expr_p, pre_p, post_p, NULL_TREE,
+				    fallback);
 	  break;
 
 	case CALL_EXPR:
Index: gcc/testsuite/ChangeLog
from  Alexandre Oliva  <aoliva@redhat.com>

	PR c++/20280
	* g++.dg/tree-ssa/pr20280.C: New.

Index: gcc/testsuite/g++.dg/tree-ssa/pr20280.C
===================================================================
RCS file: gcc/testsuite/g++.dg/tree-ssa/pr20280.C
diff -N gcc/testsuite/g++.dg/tree-ssa/pr20280.C
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ gcc/testsuite/g++.dg/tree-ssa/pr20280.C 4 Mar 2005 19:19:03 -0000
@@ -0,0 +1,63 @@
+// PR c++/20280
+
+// { dg-do compile }
+
+// Gimplification of the COND_EXPR used to fail because it had an
+// addressable type, and create_tmp_var rejected that.
+
+struct A
+{
+    ~A();
+};
+
+struct B : A {};
+
+A& foo();
+
+void bar(bool b)
+{
+    (B&) (b ? foo() : foo());
+}
+
+// Make sure bit-fields and addressable types don't cause crashes.
+// These were not in the original bug report.
+
+// Added by Alexandre Oliva <aoliva@redhat.com>
+
+// Copyright 2005 Free Software Foundation
+
+struct X
+{
+  long i : 32, j, k : 32;
+};
+
+void g(long&);
+void h(const long&);
+
+void f(X &x, bool b)
+{
+  (b ? x.i : x.j) = 1;
+  (b ? x.j : x.k) = 2;
+  (b ? x.i : x.k) = 3;
+
+  (void)(b ? x.i : x.j);
+  (void)(b ? x.i : x.k);
+  (void)(b ? x.j : x.k);
+
+  g (b ? x.i : x.j); // { dg-error "cannot bind bitfield" }
+  g (b ? x.i : x.k); // { dg-error "cannot bind bitfield" }
+  g (b ? x.j : x.k); // { dg-error "cannot bind bitfield" }
+
+  // It's not entirely clear whether these should be accepted.  The
+  // conditional expressions are lvalues for sure, and 8.5.3/5 exempts
+  // lvalues for bit-fields, but it's not clear that conditional
+  // expressions that are lvalues and that have at least one possible
+  // result that is a bit-field lvalue meets this condition.
+  h (b ? x.i : x.j);
+  h (b ? x.i : x.k);
+  h (b ? x.j : x.k);
+
+  (long &)(b ? x.i : x.j); // { dg-error "address of bit-field" }
+  (long &)(b ? x.i : x.k); // { dg-error "address of bit-field" }
+  (long &)(b ? x.j : x.k); // { dg-error "address of bit-field" }
+}

-- 
Alexandre Oliva             http://www.ic.unicamp.br/~oliva/
Red Hat Compiler Engineer   aoliva@{redhat.com, gcc.gnu.org}
Free Software Evangelist  oliva@{lsd.ic.unicamp.br, gnu.org}


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20280



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