c: Add folding of nullptr_t in some cases [PR121478]

The middle-end does not fully understand NULLPTR_TYPE. So it
gets confused a lot of the time when dealing with it.
This adds the folding that is similarly done in the C++ front-end already.
In some cases it should produce slightly better code as there is no
reason to load from a nullptr_t variable as it is always NULL.

The following is handled:
nullptr_v ==/!= nullptr_v -> true/false
(ptr)nullptr_v -> (ptr)0, nullptr_v
f(nullptr_v) -> f ((nullptr, nullptr_v))

The last one is for conversion inside ... .

Bootstrapped and tested on x86_64-linux-gnu.

	PR c/121478
gcc/c/ChangeLog:

	* c-fold.cc (c_fully_fold_internal): Fold nullptr_t ==/!= nullptr_t.
	* c-typeck.cc (convert_arguments): Handle conversion from nullptr_t
	for varargs.
	(convert_for_assignment): Handle conversions from nullptr_t to
	pointer type specially.

gcc/testsuite/ChangeLog:

	* gcc.dg/torture/pr121478-1.c: New test.

Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>

0 files changed, 0 insertions, 0 deletions