On Mon, May 19, 2014 at 11:27 AM, Richard Sandiford <rdsandif...@googlemail.com> wrote: > Richard Biener <richard.guent...@gmail.com> writes: >> On Sat, May 17, 2014 at 10:15 AM, Richard Sandiford >> <rdsandif...@googlemail.com> wrote: >>> The main thing keeping zero-precision wide-ints alive was void_zero_node, >>> a tree used in the C and C++ frontends that has type VOID_TYPE but code >>> INTEGER_CST. >>> >>> Richard B. asked me to replace the INTEGER_CST with a new constant type, >>> here called VOID_CST. Most of it is straight-forward. The one perhaps >>> controversial bit is that C++ uses void_(zero_)node to represent dummy >>> objects when e.g. taking the address of a member function without an >>> associated object. IIUC the node used in this situation needs to be >>> distinct from anything that could occur in user code and therefore couldn't >>> be a simple null pointer. >>> >>> This reaches the gimplifier in cases like >>> g++.old-deja/g++.brendan/operators4.C. I chose to handle it in the >>> gimplifier, since void_zero_node was previously handled there too, >>> although perhaps by accident. If you object strongly to this then >>> I'll need pretty detailed instructions about what to do instead, >>> i.e. exactly which parts of the C++ front end need to be changed >>> in order for dummy objects never to escape. >> >> I suppose it reaches the gimplifier because it's not handled in >> fold-const.c:fold_convert_loc while the INTEGER_CST void_zero_node >> was (through fold_convert_const). > > But like I said, void_zero_node reached the gimplifier too. Try adding: > > gcc_assert (TREE_TYPE (TREE_OPERAND (*expr_p, 0)) != void_type_node > || TREE_CODE (TREE_OPERAND (*expr_p, 0)) != INTEGER_CST); > > to gimplify_conversion and running g++.old-deja/g++.brendan/operators4.C > to see what I mean. > >> That said, only handling (T)void_cst in gimplification looks like >> a hack. If necessary we'd want to treat it as construct-T-with-zero-value >> consistently. > > OK, so just remove the gcc_checking_assert?
Which one? I'd add VOID_CST handling to fold_convert_const. Richard. > Thanks, > Richard
