Re: C++ PATCH to implement P1064R0, Virtual Function Calls in Constant Expressions (v4)

[Marek Polacek <polacek@redhat.com>]

On Wed, Sep 19, 2018 at 03:25:02PM +0200, Andreas Schwab wrote:
> I'm getting this ICE on ia64:
> 
> libtool: compile:  /usr/local/gcc/gcc-20180919/Build/./gcc/xgcc -shared-libgcc -B/usr/local/gcc/gcc-20180919/Build/./gcc -nostdinc++ -L/usr/local/gcc/gcc-20180919/Build/ia64-suse-linux/libstdc++-v3/src -L/usr/local/gcc/gcc-20180919/Build/ia64-suse-linux/libstdc++-v3/src/.libs -L/usr/local/gcc/gcc-20180919/Build/ia64-suse-linux/libstdc++-v3/libsupc++/.libs -B/usr/ia64-suse-linux/bin/ -B/usr/ia64-suse-linux/lib/ -isystem /usr/ia64-suse-linux/include -isystem /usr/ia64-suse-linux/sys-include -fno-checking -I/usr/local/gcc/gcc-20180919/libstdc++-v3/../libgcc -I/usr/local/gcc/gcc-20180919/Build/ia64-suse-linux/libstdc++-v3/include/ia64-suse-linux -I/usr/local/gcc/gcc-20180919/Build/ia64-suse-linux/libstdc++-v3/include -I/usr/local/gcc/gcc-20180919/libstdc++-v3/libsupc++ -D_GLIBCXX_SHARED -fno-implicit-templates -Wall -Wextra -Wwrite-strings -Wcast-qual -Wabi=2 -fdiagnostics-show-location=once -ffunction-sections -fdata-sections -frandom-seed=bad_typeid.lo -O2 -g -D_GNU_SOURCE -c ../../../../libstdc++-v3/libsupc++/bad_typeid.cc  -fPIC -DPIC -D_GLIBCXX_SHARED -o bad_typeid.o
> ../../../../libstdc++-v3/libsupc++/bad_typeid.cc:36:1: internal compiler error: in output_constructor_regular_field, at varasm.c:5165
> 36 | } // namespace std
>    | ^
> 0x400000000176abaf output_constructor_regular_field
>         ../../gcc/varasm.c:5165
> 0x400000000176d09f output_constructor
>         ../../gcc/varasm.c:5475
> 0x400000000176940f output_constant
>         ../../gcc/varasm.c:4967
> 0x400000000175414f assemble_variable_contents
>         ../../gcc/varasm.c:2143
> 0x400000000175586f assemble_variable(tree_node*, int, int, int)
>         ../../gcc/varasm.c:2319
> 0x40000000017a564f varpool_node::assemble_decl()
>         ../../gcc/varpool.c:586
> 0x40000000017a74cf symbol_table::output_variables()
>         ../../gcc/varpool.c:752
> 0x40000000007b806f symbol_table::compile()
>         ../../gcc/cgraphunit.c:2611
> 0x40000000007bd8ef symbol_table::compile()
>         ../../gcc/cgraphunit.c:2791
> 0x40000000007bd8ef symbol_table::finalize_compilation_unit()
>         ../../gcc/cgraphunit.c:2788
> 
> (gdb) up
> #1  0x400000000176abb0 in output_constructor_regular_field (
>     local=0x600ffffffffee920) at ../../gcc/varasm.c:5165
> 5165            gcc_assert (fieldpos == local->total_bytes);
> (gdb) p fieldpos
> $1 = 16
> (gdb) p local->total_bytes
> $2 = 24

That muset be because ia64 uses TARGET_VTABLE_USES_DESCRIPTORS.
Does this help?

2018-09-19  Marek Polacek  <polacek@redhat.com>

	* class.c (build_vtbl_initializer): Don't mess with *inits for
	TARGET_VTABLE_USES_DESCRIPTORS.

diff --git gcc/cp/class.c gcc/cp/class.c
index 9ca46441871..0239f6ae045 100644
--- gcc/cp/class.c
+++ gcc/cp/class.c
@@ -9370,7 +9370,7 @@ build_vtbl_initializer (tree binfo,
 	  int i;
 	  if (init == size_zero_node)
 	    for (i = 0; i < TARGET_VTABLE_USES_DESCRIPTORS; ++i)
-	      CONSTRUCTOR_APPEND_ELT (*inits, idx, init);
+	      CONSTRUCTOR_APPEND_ELT (*inits, NULL_TREE, init);
 	  else
 	    for (i = 0; i < TARGET_VTABLE_USES_DESCRIPTORS; ++i)
 	      {
@@ -9378,7 +9378,7 @@ build_vtbl_initializer (tree binfo,
 				     fn, build_int_cst (NULL_TREE, i));
 		TREE_CONSTANT (fdesc) = 1;
 
-		CONSTRUCTOR_APPEND_ELT (*inits, idx, fdesc);
+		CONSTRUCTOR_APPEND_ELT (*inits, NULL_TREE, fdesc);
 	      }
 	}
       else