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v8/test/unittests/base/bits-unittest.cc
Clemens Backes fa056cd088 [utils] Move {WhichPowerOf2} to base::bits 
{WhichPowerOf2} is basically the same as {CountTrailingZeros}, with a
restriction to powers of two. Since it does not use or depend on any v8
internals, it can be moved to src/base/bits.h.
This CL also changes the implementation to use the CTZ builtin if
available, and falls back to popcnt otherwise.

Drive-by: Make it constexpr, and rename to {WhichPowerOfTwo}.

R=sigurds@chromium.org

Bug: v8:9810, v8:8912
Change-Id: I8368d098f9ab1247f3b9f036f1385a38de10cc6a
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1903966
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64851}
2019-11-08 09:45:50 +00:00

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// Copyright 2014 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <limits>
#include "src/base/bits.h"
#include "src/base/macros.h"
#include "testing/gtest-support.h"
#ifdef DEBUG
#define DISABLE_IN_RELEASE(Name) Name
#else
#define DISABLE_IN_RELEASE(Name) DISABLED_##Name
#endif
namespace v8 {
namespace base {
namespace bits {
TEST(Bits, CountPopulation16) {
EXPECT_EQ(0u, CountPopulation(uint16_t{0}));
EXPECT_EQ(1u, CountPopulation(uint16_t{1}));
EXPECT_EQ(4u, CountPopulation(uint16_t{0x1111}));
EXPECT_EQ(8u, CountPopulation(uint16_t{0xF0F0}));
EXPECT_EQ(12u, CountPopulation(uint16_t{0xF0FF}));
EXPECT_EQ(16u, CountPopulation(uint16_t{0xFFFF}));
}
TEST(Bits, CountPopulation32) {
EXPECT_EQ(0u, CountPopulation(uint32_t{0}));
EXPECT_EQ(1u, CountPopulation(uint32_t{1}));
EXPECT_EQ(8u, CountPopulation(uint32_t{0x11111111}));
EXPECT_EQ(16u, CountPopulation(uint32_t{0xF0F0F0F0}));
EXPECT_EQ(24u, CountPopulation(uint32_t{0xFFF0F0FF}));
EXPECT_EQ(32u, CountPopulation(uint32_t{0xFFFFFFFF}));
}
TEST(Bits, CountPopulation64) {
EXPECT_EQ(0u, CountPopulation(uint64_t{0}));
EXPECT_EQ(1u, CountPopulation(uint64_t{1}));
EXPECT_EQ(2u, CountPopulation(uint64_t{0x8000000000000001}));
EXPECT_EQ(8u, CountPopulation(uint64_t{0x11111111}));
EXPECT_EQ(16u, CountPopulation(uint64_t{0xF0F0F0F0}));
EXPECT_EQ(24u, CountPopulation(uint64_t{0xFFF0F0FF}));
EXPECT_EQ(32u, CountPopulation(uint64_t{0xFFFFFFFF}));
EXPECT_EQ(16u, CountPopulation(uint64_t{0x1111111111111111}));
EXPECT_EQ(32u, CountPopulation(uint64_t{0xF0F0F0F0F0F0F0F0}));
EXPECT_EQ(48u, CountPopulation(uint64_t{0xFFF0F0FFFFF0F0FF}));
EXPECT_EQ(64u, CountPopulation(uint64_t{0xFFFFFFFFFFFFFFFF}));
}
TEST(Bits, CountLeadingZeros16) {
EXPECT_EQ(16u, CountLeadingZeros(uint16_t{0}));
EXPECT_EQ(15u, CountLeadingZeros(uint16_t{1}));
TRACED_FORRANGE(uint16_t, shift, 0, 15) {
EXPECT_EQ(15u - shift,
CountLeadingZeros(static_cast<uint16_t>(1 << shift)));
}
EXPECT_EQ(4u, CountLeadingZeros(uint16_t{0x0F0F}));
}
TEST(Bits, CountLeadingZeros32) {
EXPECT_EQ(32u, CountLeadingZeros(uint32_t{0}));
EXPECT_EQ(31u, CountLeadingZeros(uint32_t{1}));
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(31u - shift, CountLeadingZeros(uint32_t{1} << shift));
}
EXPECT_EQ(4u, CountLeadingZeros(uint32_t{0x0F0F0F0F}));
}
TEST(Bits, CountLeadingZeros64) {
EXPECT_EQ(64u, CountLeadingZeros(uint64_t{0}));
EXPECT_EQ(63u, CountLeadingZeros(uint64_t{1}));
TRACED_FORRANGE(uint32_t, shift, 0, 63) {
EXPECT_EQ(63u - shift, CountLeadingZeros(uint64_t{1} << shift));
}
EXPECT_EQ(36u, CountLeadingZeros(uint64_t{0x0F0F0F0F}));
EXPECT_EQ(4u, CountLeadingZeros(uint64_t{0x0F0F0F0F00000000}));
}
TEST(Bits, CountTrailingZeros16) {
EXPECT_EQ(16u, CountTrailingZeros(uint16_t{0}));
EXPECT_EQ(15u, CountTrailingZeros(uint16_t{0x8000}));
TRACED_FORRANGE(uint16_t, shift, 0, 15) {
EXPECT_EQ(shift, CountTrailingZeros(static_cast<uint16_t>(1 << shift)));
}
EXPECT_EQ(4u, CountTrailingZeros(uint16_t{0xF0F0u}));
}
TEST(Bits, CountTrailingZerosu32) {
EXPECT_EQ(32u, CountTrailingZeros(uint32_t{0}));
EXPECT_EQ(31u, CountTrailingZeros(uint32_t{0x80000000}));
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(shift, CountTrailingZeros(uint32_t{1} << shift));
}
EXPECT_EQ(4u, CountTrailingZeros(uint32_t{0xF0F0F0F0u}));
}
TEST(Bits, CountTrailingZerosi32) {
EXPECT_EQ(32u, CountTrailingZeros(int32_t{0}));
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(shift, CountTrailingZeros(int32_t{1} << shift));
}
EXPECT_EQ(4u, CountTrailingZeros(int32_t{0x70F0F0F0u}));
EXPECT_EQ(2u, CountTrailingZeros(int32_t{-4}));
EXPECT_EQ(0u, CountTrailingZeros(int32_t{-1}));
}
TEST(Bits, CountTrailingZeros64) {
EXPECT_EQ(64u, CountTrailingZeros(uint64_t{0}));
EXPECT_EQ(63u, CountTrailingZeros(uint64_t{0x8000000000000000}));
TRACED_FORRANGE(uint32_t, shift, 0, 63) {
EXPECT_EQ(shift, CountTrailingZeros(uint64_t{1} << shift));
}
EXPECT_EQ(4u, CountTrailingZeros(uint64_t{0xF0F0F0F0}));
EXPECT_EQ(36u, CountTrailingZeros(uint64_t{0xF0F0F0F000000000}));
}
TEST(Bits, IsPowerOfTwo32) {
EXPECT_FALSE(IsPowerOfTwo(0U));
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_TRUE(IsPowerOfTwo(1U << shift));
EXPECT_FALSE(IsPowerOfTwo((1U << shift) + 5U));
EXPECT_FALSE(IsPowerOfTwo(~(1U << shift)));
}
TRACED_FORRANGE(uint32_t, shift, 2, 31) {
EXPECT_FALSE(IsPowerOfTwo((1U << shift) - 1U));
}
EXPECT_FALSE(IsPowerOfTwo(0xFFFFFFFF));
}
TEST(Bits, IsPowerOfTwo64) {
EXPECT_FALSE(IsPowerOfTwo(uint64_t{0}));
TRACED_FORRANGE(uint32_t, shift, 0, 63) {
EXPECT_TRUE(IsPowerOfTwo(uint64_t{1} << shift));
EXPECT_FALSE(IsPowerOfTwo((uint64_t{1} << shift) + 5U));
EXPECT_FALSE(IsPowerOfTwo(~(uint64_t{1} << shift)));
}
TRACED_FORRANGE(uint32_t, shift, 2, 63) {
EXPECT_FALSE(IsPowerOfTwo((uint64_t{1} << shift) - 1U));
}
EXPECT_FALSE(IsPowerOfTwo(uint64_t{0xFFFFFFFFFFFFFFFF}));
}
TEST(Bits, WhichPowerOfTwo32) {
TRACED_FORRANGE(int, shift, 0, 30) {
EXPECT_EQ(shift, WhichPowerOfTwo(int32_t{1} << shift));
}
TRACED_FORRANGE(int, shift, 0, 31) {
EXPECT_EQ(shift, WhichPowerOfTwo(uint32_t{1} << shift));
}
}
TEST(Bits, WhichPowerOfTwo64) {
TRACED_FORRANGE(int, shift, 0, 62) {
EXPECT_EQ(shift, WhichPowerOfTwo(int64_t{1} << shift));
}
TRACED_FORRANGE(int, shift, 0, 63) {
EXPECT_EQ(shift, WhichPowerOfTwo(uint64_t{1} << shift));
}
}
TEST(Bits, RoundUpToPowerOfTwo32) {
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(1u << shift, RoundUpToPowerOfTwo32(1u << shift));
}
EXPECT_EQ(1u, RoundUpToPowerOfTwo32(0));
EXPECT_EQ(1u, RoundUpToPowerOfTwo32(1));
EXPECT_EQ(4u, RoundUpToPowerOfTwo32(3));
EXPECT_EQ(0x80000000u, RoundUpToPowerOfTwo32(0x7FFFFFFFu));
}
TEST(BitsDeathTest, DISABLE_IN_RELEASE(RoundUpToPowerOfTwo32)) {
ASSERT_DEATH_IF_SUPPORTED({ RoundUpToPowerOfTwo32(0x80000001u); },
".*heck failed:.* << 31");
}
TEST(Bits, RoundUpToPowerOfTwo64) {
TRACED_FORRANGE(uint64_t, shift, 0, 63) {
uint64_t value = uint64_t{1} << shift;
EXPECT_EQ(value, RoundUpToPowerOfTwo64(value));
}
EXPECT_EQ(uint64_t{1}, RoundUpToPowerOfTwo64(0));
EXPECT_EQ(uint64_t{1}, RoundUpToPowerOfTwo64(1));
EXPECT_EQ(uint64_t{4}, RoundUpToPowerOfTwo64(3));
EXPECT_EQ(uint64_t{1} << 63, RoundUpToPowerOfTwo64((uint64_t{1} << 63) - 1));
EXPECT_EQ(uint64_t{1} << 63, RoundUpToPowerOfTwo64(uint64_t{1} << 63));
}
TEST(BitsDeathTest, DISABLE_IN_RELEASE(RoundUpToPowerOfTwo64)) {
ASSERT_DEATH_IF_SUPPORTED({ RoundUpToPowerOfTwo64((uint64_t{1} << 63) + 1); },
".*heck failed:.* << 63");
}
TEST(Bits, RoundDownToPowerOfTwo32) {
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(1u << shift, RoundDownToPowerOfTwo32(1u << shift));
}
EXPECT_EQ(0u, RoundDownToPowerOfTwo32(0));
EXPECT_EQ(4u, RoundDownToPowerOfTwo32(5));
EXPECT_EQ(0x80000000u, RoundDownToPowerOfTwo32(0x80000001u));
}
TEST(Bits, RotateRight32) {
TRACED_FORRANGE(uint32_t, shift, 0, 31) {
EXPECT_EQ(0u, RotateRight32(0u, shift));
}
EXPECT_EQ(1u, RotateRight32(1, 0));
EXPECT_EQ(1u, RotateRight32(2, 1));
EXPECT_EQ(0x80000000u, RotateRight32(1, 1));
}
TEST(Bits, RotateRight64) {
TRACED_FORRANGE(uint64_t, shift, 0, 63) {
EXPECT_EQ(0u, RotateRight64(0u, shift));
}
EXPECT_EQ(1u, RotateRight64(1, 0));
EXPECT_EQ(1u, RotateRight64(2, 1));
EXPECT_EQ(uint64_t{0x8000000000000000}, RotateRight64(1, 1));
}
TEST(Bits, SignedAddOverflow32) {
int32_t val = 0;
EXPECT_FALSE(SignedAddOverflow32(0, 0, &val));
EXPECT_EQ(0, val);
EXPECT_TRUE(
SignedAddOverflow32(std::numeric_limits<int32_t>::max(), 1, &val));
EXPECT_EQ(std::numeric_limits<int32_t>::min(), val);
EXPECT_TRUE(
SignedAddOverflow32(std::numeric_limits<int32_t>::min(), -1, &val));
EXPECT_EQ(std::numeric_limits<int32_t>::max(), val);
EXPECT_TRUE(SignedAddOverflow32(std::numeric_limits<int32_t>::max(),
std::numeric_limits<int32_t>::max(), &val));
EXPECT_EQ(-2, val);
TRACED_FORRANGE(int32_t, i, 1, 50) {
TRACED_FORRANGE(int32_t, j, 1, i) {
EXPECT_FALSE(SignedAddOverflow32(i, j, &val));
EXPECT_EQ(i + j, val);
}
}
}
TEST(Bits, SignedSubOverflow32) {
int32_t val = 0;
EXPECT_FALSE(SignedSubOverflow32(0, 0, &val));
EXPECT_EQ(0, val);
EXPECT_TRUE(
SignedSubOverflow32(std::numeric_limits<int32_t>::min(), 1, &val));
EXPECT_EQ(std::numeric_limits<int32_t>::max(), val);
EXPECT_TRUE(
SignedSubOverflow32(std::numeric_limits<int32_t>::max(), -1, &val));
EXPECT_EQ(std::numeric_limits<int32_t>::min(), val);
TRACED_FORRANGE(int32_t, i, 1, 50) {
TRACED_FORRANGE(int32_t, j, 1, i) {
EXPECT_FALSE(SignedSubOverflow32(i, j, &val));
EXPECT_EQ(i - j, val);
}
}
}
TEST(Bits, SignedMulHigh32) {
EXPECT_EQ(0, SignedMulHigh32(0, 0));
TRACED_FORRANGE(int32_t, i, 1, 50) {
TRACED_FORRANGE(int32_t, j, 1, i) { EXPECT_EQ(0, SignedMulHigh32(i, j)); }
}
EXPECT_EQ(-1073741824, SignedMulHigh32(std::numeric_limits<int32_t>::max(),
std::numeric_limits<int32_t>::min()));
EXPECT_EQ(-1073741824, SignedMulHigh32(std::numeric_limits<int32_t>::min(),
std::numeric_limits<int32_t>::max()));
EXPECT_EQ(1, SignedMulHigh32(1024 * 1024 * 1024, 4));
EXPECT_EQ(2, SignedMulHigh32(8 * 1024, 1024 * 1024));
}
TEST(Bits, SignedMulHighAndAdd32) {
TRACED_FORRANGE(int32_t, i, 1, 50) {
EXPECT_EQ(i, SignedMulHighAndAdd32(0, 0, i));
TRACED_FORRANGE(int32_t, j, 1, i) {
EXPECT_EQ(i, SignedMulHighAndAdd32(j, j, i));
}
EXPECT_EQ(i + 1, SignedMulHighAndAdd32(1024 * 1024 * 1024, 4, i));
}
}
TEST(Bits, SignedDiv32) {
EXPECT_EQ(std::numeric_limits<int32_t>::min(),
SignedDiv32(std::numeric_limits<int32_t>::min(), -1));
EXPECT_EQ(std::numeric_limits<int32_t>::max(),
SignedDiv32(std::numeric_limits<int32_t>::max(), 1));
TRACED_FORRANGE(int32_t, i, 0, 50) {
EXPECT_EQ(0, SignedDiv32(i, 0));
TRACED_FORRANGE(int32_t, j, 1, i) {
EXPECT_EQ(1, SignedDiv32(j, j));
EXPECT_EQ(i / j, SignedDiv32(i, j));
EXPECT_EQ(-i / j, SignedDiv32(i, -j));
}
}
}
TEST(Bits, SignedMod32) {
EXPECT_EQ(0, SignedMod32(std::numeric_limits<int32_t>::min(), -1));
EXPECT_EQ(0, SignedMod32(std::numeric_limits<int32_t>::max(), 1));
TRACED_FORRANGE(int32_t, i, 0, 50) {
EXPECT_EQ(0, SignedMod32(i, 0));
TRACED_FORRANGE(int32_t, j, 1, i) {
EXPECT_EQ(0, SignedMod32(j, j));
EXPECT_EQ(i % j, SignedMod32(i, j));
EXPECT_EQ(i % j, SignedMod32(i, -j));
}
}
}
TEST(Bits, UnsignedAddOverflow32) {
uint32_t val = 0;
EXPECT_FALSE(UnsignedAddOverflow32(0, 0, &val));
EXPECT_EQ(0u, val);
EXPECT_TRUE(
UnsignedAddOverflow32(std::numeric_limits<uint32_t>::max(), 1u, &val));
EXPECT_EQ(std::numeric_limits<uint32_t>::min(), val);
EXPECT_TRUE(UnsignedAddOverflow32(std::numeric_limits<uint32_t>::max(),
std::numeric_limits<uint32_t>::max(),
&val));
TRACED_FORRANGE(uint32_t, i, 1, 50) {
TRACED_FORRANGE(uint32_t, j, 1, i) {
EXPECT_FALSE(UnsignedAddOverflow32(i, j, &val));
EXPECT_EQ(i + j, val);
}
}
}
TEST(Bits, UnsignedDiv32) {
TRACED_FORRANGE(uint32_t, i, 0, 50) {
EXPECT_EQ(0u, UnsignedDiv32(i, 0));
TRACED_FORRANGE(uint32_t, j, i + 1, 100) {
EXPECT_EQ(1u, UnsignedDiv32(j, j));
EXPECT_EQ(i / j, UnsignedDiv32(i, j));
}
}
}
TEST(Bits, UnsignedMod32) {
TRACED_FORRANGE(uint32_t, i, 0, 50) {
EXPECT_EQ(0u, UnsignedMod32(i, 0));
TRACED_FORRANGE(uint32_t, j, i + 1, 100) {
EXPECT_EQ(0u, UnsignedMod32(j, j));
EXPECT_EQ(i % j, UnsignedMod32(i, j));
}
}
}
} // namespace bits
} // namespace base
} // namespace v8
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