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Re: Tree VRP bug: internal compiler error: in build_int_cst_wide, at tree.c:886


On 3/19/07, Andrew Haley <aph@redhat.com> wrote:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31264

This happens because we have a VIEW_CONVERT EXPR(double->long) that is
used in a conditional.  VRP tries to register an edge assertion for
this expression:

<view_convert_expr 0x2aaaae08c6c0
    type <integer_type 0x2aaaadfee3c0 long public DI
        size <integer_cst 0x2aaaadfe19f0 constant invariant 64>
        unit size <integer_cst 0x2aaaadfe1a20 constant invariant 8>
        align 64 symtab 0 alias set -1 canonical type 0x2aaaadfee3c0 precision 64 min <integer_cst 0x2aaaadfe1930 -9223372036854775808> max <integer_cst 0x2aaaadfe1990 9223372036854775807>
        pointer_to_this <pointer_type 0x2aaaae00e300> chain <type_decl 0x2aaaadff2270 long>>

    arg 0 <ssa_name 0x2aaaae0a8f00
        type <real_type 0x2aaaadffa6c0 double DF size <integer_cst 0x2aaaadfe19f0 64> unit size <integer_cst 0x2aaaadfe1a20 8>
            align 64 symtab 0 alias set -1 canonical type 0x2aaaadffa6c0 precision 64
            chain <type_decl 0x2aaaadff2d00 double>>
        visited var <parm_decl 0x2aaaadfe7960 D.774> def_stmt <phi_node 0x2aaaae0b2d00>

Which eventually works its way down to:

  if (!has_single_use (op))
    {
      val = build_int_cst (TREE_TYPE (op), 0);
      register_new_assert_for (op, code, val, NULL, e, bsi);
      retval = true;
    }

and this fails with an ICE because TREE_TYPE (op) is real_type, and
you can't build_int_cst with a real_type.

The simplest way of fixing this is simply to disallow
VIEW_CONVERT_EXPR in this context.  Comments?

Index: tree-vrp.c
===================================================================
--- tree-vrp.c  (revision 122839)
+++ tree-vrp.c  (working copy)
@@ -3485,7 +3485,6 @@
     }
   else if (TREE_CODE (rhs) == NOP_EXPR
           || TREE_CODE (rhs) == CONVERT_EXPR
-          || TREE_CODE (rhs) == VIEW_CONVERT_EXPR
           || TREE_CODE (rhs) == NON_LVALUE_EXPR)
     {
       /* Recurse through the type conversion.  */

It's indeed broken to look through VIEW_CONVERT_EXPRs here. The patch looks obviously correct.

Thanks,
Richard.


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