[llvm-bugs] [Bug 40716] New: Missed opportunity vectorization with __uint128_t
via llvm-bugs
llvm-bugs at lists.llvm.org
Wed Feb 13 04:26:16 PST 2019
https://bugs.llvm.org/show_bug.cgi?id=40716
Bug ID: 40716
Summary: Missed opportunity vectorization with __uint128_t
Product: clang
Version: trunk
Hardware: All
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: C++
Assignee: unassignedclangbugs at nondot.org
Reporter: gchatelet at google.com
CC: blitzrakete at gmail.com, dgregor at apple.com,
erik.pilkington at gmail.com, llvm-bugs at lists.llvm.org,
richard-llvm at metafoo.co.uk
Bitwise operations on __uint128_t do not take advantage of vector operations:
__uint128_t xor_512_128(const __uint128_t* a, const __uint128_t* b) {
return (a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2]) | (a[3] ^ b[3]);
}
xor_512_128(unsigned __int128 const*, unsigned __int128 const*):
mov rax, qword ptr [rsi]
mov rdx, qword ptr [rsi + 8]
xor rdx, qword ptr [rdi + 8]
xor rax, qword ptr [rdi]
mov r8, qword ptr [rsi + 16]
mov rcx, qword ptr [rsi + 24]
xor rcx, qword ptr [rdi + 24]
or rcx, rdx
xor r8, qword ptr [rdi + 16]
or r8, rax
mov r9, qword ptr [rsi + 40]
mov r10, qword ptr [rsi + 32]
xor r10, qword ptr [rdi + 32]
xor r9, qword ptr [rdi + 40]
mov rax, qword ptr [rsi + 48]
mov rdx, qword ptr [rsi + 56]
xor rdx, qword ptr [rdi + 56]
or rdx, r9
or rdx, rcx
xor rax, qword ptr [rdi + 48]
or rax, r10
or rax, r8
ret
Whereas uint64_t do vectorize
__uint128_t xor_512_64(const uint64_t* a, const uint64_t* b) {
return (a[0] ^ b[0]) | (a[1] ^ b[1]) | (a[2] ^ b[2]) | (a[3] ^ b[3]) |
(a[4] ^ b[4]) | (a[5] ^ b[5]) | (a[6] ^ b[6]) | (a[7] ^ b[7]);
}
xor_512_64(unsigned long const*, unsigned long const*):
vmovdqu ymm0, ymmword ptr [rsi]
vmovdqu ymm1, ymmword ptr [rsi + 32]
vpxor ymm1, ymm1, ymmword ptr [rdi + 32]
vpxor ymm0, ymm0, ymmword ptr [rdi]
vpor ymm0, ymm0, ymm1
vextracti128 xmm1, ymm0, 1
vpor xmm0, xmm0, xmm1
vpshufd xmm1, xmm0, 78 # xmm1 = xmm0[2,3,0,1]
vpor xmm0, xmm0, xmm1
vmovq rax, xmm0
xor edx, edx
vzeroupper
ret
https://godbolt.org/z/mwOeNm
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