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[vm] Don't use popcount intrinsic on both x86s.

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Bug: https://github.com/dart-lang/sdk/issues/32314
Change-Id: I5589a22de5777af664c83f221758ba5b35d8678a
Reviewed-on: https://dart-review.googlesource.com/43886
Reviewed-by: Vyacheslav Egorov <vegorov@google.com>
Commit-Queue: Ryan Macnak <rmacnak@google.com>
This commit is contained in:
Ryan Macnak 2018-02-28 17:48:16 +00:00 committed by commit-bot@chromium.org
parent d002e2f6f3
commit b5966dbddc
1 changed files with 13 additions and 12 deletions
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25
runtime/platform/utils.h
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@ -105,27 +105,28 @@ class Utils {
static uintptr_t RoundUpToPowerOfTwo(uintptr_t x);
static int CountOneBits32(uint32_t x) {
#ifdef _MSC_VER
return __popcnt(x);
#elif __GNUC__
// Apparently there are x64 chips without popcount.
#if __GNUC__ && !defined(HOST_ARCH_IA32) && !defined(HOST_ARCH_X64)
return __builtin_popcount(x);
#else
#error CountOneBits32 not implemented for this compiler
// Implementation is from "Hacker's Delight" by Henry S. Warren, Jr.,
// figure 5-2, page 66, where the function is called pop.
x = x - ((x >> 1) & 0x55555555);
x = (x & 0x33333333) + ((x >> 2) & 0x33333333);
x = (x + (x >> 4)) & 0x0F0F0F0F;
x = x + (x >> 8);
x = x + (x >> 16);
return static_cast<int>(x & 0x0000003F);
#endif
}
static int CountOneBits64(uint64_t x) {
#ifdef _MSC_VER
#ifdef ARCH_IS_64_BIT
return __popcnt64(x);
// Apparently there are x64 chips without popcount.
#if __GNUC__ && !defined(HOST_ARCH_IA32) && !defined(HOST_ARCH_X64)
return __builtin_popcountll(x);
#else
return CountOneBits32(static_cast<uint32_t>(x)) +
CountOneBits32(static_cast<uint32_t>(x >> 32));
#endif
#elif __GNUC__
return __builtin_popcountll(x);
#else
#error CountOneBits64 not implemented for this compiler
#endif
}