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Avoid __popcnt and __popcnt64 intrinsics for MSC #2944

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Merged
kripken merged 3 commits into from
Jul 6, 2020
Merged

Avoid __popcnt and __popcnt64 intrinsics for MSC #2944

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45308c0
avoid __popcnt and __popcnt64 intrinsics for MSVC
MaxGraey Jul 5, 2020
e5fd0e5
more faster and trivial version for popcnt(x + 1) != 1
MaxGraey Jul 6, 2020
4ca1a5f
reflect changes in comments
MaxGraey Jul 6, 2020
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6 changes: 3 additions & 3 deletions src/ir/bits.h
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Original file line number Diff line number Diff line change
Expand Up @@ -43,9 +43,9 @@ struct Bits {
if (mask == 0) {
return 0; // trivially not a mask
}
// otherwise, see if adding one turns this into a 1-bit thing, 00011111 + 1
// => 00100000
if (PopCount(mask + 1) != 1) {
// otherwise, see if x & (x + 1) turns this into non-zero value
// 00011111 & (00011111 + 1) => 0
if (mask & (mask + 1)) {
return 0;
}
// this is indeed a mask
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14 changes: 6 additions & 8 deletions src/support/bits.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -21,8 +21,6 @@

#ifdef _MSC_VER
#include <intrin.h>
#define __builtin_popcount __popcnt
#define __builtin_popcountll __popcnt64
#endif

namespace wasm {
Expand All @@ -36,16 +34,16 @@ template<> int PopCount<uint8_t>(uint8_t v) {
}

template<> int PopCount<uint16_t>(uint16_t v) {
#if __has_builtin(__builtin_popcount) || defined(__GNUC__) || defined(_MSC_VER)
return (int)__builtin_popcount(v);
#if __has_builtin(__builtin_popcount) || defined(__GNUC__)
return __builtin_popcount(v);
#else
return PopCount((uint8_t)(v & 0xFF)) + PopCount((uint8_t)(v >> 8));
#endif
}

template<> int PopCount<uint32_t>(uint32_t v) {
#if __has_builtin(__builtin_popcount) || defined(__GNUC__) || defined(_MSC_VER)
return (int)__builtin_popcount(v);
#if __has_builtin(__builtin_popcount) || defined(__GNUC__)
return __builtin_popcount(v);
#else
// See Stanford bithacks, counting bits set in parallel, "best method":
// http://graphics.stanford.edu/~seander/bithacks.html#CountBitsSetParallel
Expand All @@ -56,8 +54,8 @@ template<> int PopCount<uint32_t>(uint32_t v) {
}

template<> int PopCount<uint64_t>(uint64_t v) {
#if __has_builtin(__builtin_popcount) || defined(__GNUC__) || defined(_MSC_VER)
return (int)__builtin_popcountll(v);
#if __has_builtin(__builtin_popcount) || defined(__GNUC__)
return __builtin_popcountll(v);
#else
return PopCount((uint32_t)v) + PopCount((uint32_t)(v >> 32));
#endif
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