On 10/10/19 1:53 PM, Jakub Jelinek wrote:
On Thu, Oct 10, 2019 at 06:12:02PM +0200, Paolo Carlini wrote:
while working on cp_build_binary_op I noticed that the testsuite wasn't
exercising the warnings in case RROTATE_EXPR / LROTATE_EXPR, even more the
code handling those tree codes seemed completely unused. Turned out that the
C front-end doesn't handle those tree codes at all: I'm coming to the
conclusion that the C++ front-end bits too are now obsolete and may be
removed, because only the middle-end generates those codes in order to
implement optimizations. Anything I'm missing? Any additional testing?
I guess it depends on where.
fold_binary_loc certainly has code to create {L,R}ROTATE_EXPR,
just look at
unsigned foo (unsigned x)
{
return (x << 3) + (x >> (__SIZEOF_INT__ * __CHAR_BIT__ - 3));
}
unsigned bar (unsigned x, unsigned y)
{
return (x << y) | (x >> (__SIZEOF_INT__ * __CHAR_BIT__ - y));
}
and the *.original dump.
The cp_build_binary_op case is unlikely to ever trigger, unless we'd rerun
it on cp_folded trees.
cxx_eval_constant_expression is unlikely, because recently we've switched to
performing constexpr evaluation on pre-cp_folded bodies, not sure if we
never encounter folded trees though.
cp_fold itself depends on whether we ever reprocess the already folded
trees, I'd be afraid we could.
True, and the failure mode there is silent. Let's leave the codes in
that switch.
Jason
