As mentioned in the PR and as
https://software.intel.com/sites/landingpage/IntrinsicsGuide/#text=_mask_popcnt_epi
also documents, _mm*_popcnt_epi* intrinsics are consistent with all other
unary AVX512* intrinsics regarding arguments, i.e. the
_mm*_whatever has just single argument (called a in the docs, and __A in the
GCC headers),
_mm*_mask_whatever has 3 arguments (called src, k, a in the docs and
_W, __U, __A in GCC headers) and
_mm*_maskz_whatever 2 arguments (called k, a in the docs and __U, __A in GCC
headers).  Unfortunately, whomever implemented the _mm*_popcnt_epi*
intrinsics got it wrong for the _mm*_mask_popcnt_epi* ones, calling the
args __A, __U, __B and not passing them in the canonical order to the
builtins, making it API incompatible with ICC as well as clang (tested on
godbolts clang 7/8/9/trunk and ICC 19.0.{0,1}, older clang/ICC don't
understand those, so it isn't that it used to be broken even in other
compilers and got changed afterwards).

2020-02-13  Jakub Jelinek  <jakub@redhat.com>

	PR target/93696
	* config/i386/avx512bitalgintrin.h (_mm512_mask_popcnt_epi8,
	_mm512_mask_popcnt_epi16, _mm256_mask_popcnt_epi8,
	_mm256_mask_popcnt_epi16, _mm_mask_popcnt_epi8,
	_mm_mask_popcnt_epi16): Rename __B argument to __A and __A to __W,
	pass __A to the builtin followed by __W instead of __A followed by
	__B.
	* config/i386/avx512vpopcntdqintrin.h (_mm512_mask_popcnt_epi32,
	_mm512_mask_popcnt_epi64): Likewise.
	* config/i386/avx512vpopcntdqvlintrin.h (_mm_mask_popcnt_epi32,
	_mm256_mask_popcnt_epi32, _mm_mask_popcnt_epi64,
	_mm256_mask_popcnt_epi64): Likewise.

	* gcc.target/i386/pr93696-1.c: New test.
	* gcc.target/i386/pr93696-2.c: New test.
	* gcc.target/i386/avx512bitalg-vpopcntw-1.c (TEST): Fix argument order
	of _mm*_mask_popcnt_*.
	* gcc.target/i386/avx512vpopcntdq-vpopcntq-1.c (TEST): Likewise.
	* gcc.target/i386/avx512vpopcntdq-vpopcntd-1.c (TEST): Likewise.
	* gcc.target/i386/avx512bitalg-vpopcntb-1.c (TEST): Likewise.
	* gcc.target/i386/avx512bitalg-vpopcntb.c (foo): Likewise.
	* gcc.target/i386/avx512bitalg-vpopcntbvl.c (foo): Likewise.
	* gcc.target/i386/avx512vpopcntdq-vpopcntd.c (foo): Likewise.
	* gcc.target/i386/avx512bitalg-vpopcntwvl.c (foo): Likewise.
	* gcc.target/i386/avx512bitalg-vpopcntw.c (foo): Likewise.
	* gcc.target/i386/avx512vpopcntdq-vpopcntq.c (foo): Likewise.