icf: Check return type of internal fn calls [PR99517]

icf: Check return type of internal fn calls [PR99517]

The following testcase is miscompiled, because IPA-ICF considers the two
functions identical.  They aren't, the types of the .VEC_CONVERT call
lhs is different.  But for calls to internal functions, there is no
fntype nor callee with a function type to compare, so all we compare
is just the ifn, arguments and some call flags.

The following patch fixes it by checking the internal fn calls like e.g. gimple
assignments where the type of the lhs is checked too.

2021-03-11  Jakub Jelinek  <jakub@redhat.com>

	PR ipa/99517
	* ipa-icf-gimple.c (func_checker::compare_gimple_call): For internal
	function calls with lhs fail if the lhs don't have compatible types.

	* gcc.target/i386/avx2-pr99517-1.c: New test.
	* gcc.target/i386/avx2-pr99517-2.c: New test.