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Optimizations of log2 for ivec4

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This commit is contained in:
Christophe Riccio 2014-11-24 01:56:36 +01:00
parent 117634c7ea
commit e8fbcf76dd
5 changed files with 171 additions and 40 deletions
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32
glm/detail/func_exponential.inl
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@ -35,20 +35,22 @@
namespace glm{
namespace detail
{
template <bool isFloat>
struct compute_log2{};
template <>
struct compute_log2<true>
{
template <typename T>
GLM_FUNC_QUALIFIER T operator() (T Value) const
{
# if GLM_LANG & GLM_LANG_CXX11_FLAG
return std::log2(Value);
using std::log2;
# else
return std::log(Value) * static_cast<T>(1.4426950408889634073599246810019);
template <typename genType>
genType log2(genType Value)
{
return std::log(Value) * static_cast<genType>(1.4426950408889634073599246810019);
}
# endif
template <typename T, precision P, template <class, precision> class vecType, bool isFloat = true>
struct compute_log2
{
GLM_FUNC_QUALIFIER static vecType<T, P> call(vecType<T, P> const & vec)
{
return detail::functor1<T, T, P, vecType>::call(log2, vec);
}
};
@ -121,17 +123,13 @@ namespace detail
template <typename genType>
GLM_FUNC_QUALIFIER genType log2(genType x)
{
GLM_STATIC_ASSERT(std::numeric_limits<genType>::is_iec559 || std::numeric_limits<genType>::is_integer,
"GLM core 'log2' only accept floating-point inputs. Include <glm/gtx/integer.hpp> for additional integer support.");
assert(x > genType(0)); // log2 is only defined on the range (0, inf]
return detail::compute_log2<std::numeric_limits<genType>::is_iec559>()(x);
return log2(tvec1<genType>(x)).x;
}
template <typename T, precision P, template <typename, precision> class vecType>
GLM_FUNC_QUALIFIER vecType<T, P> log2(vecType<T, P> const & x)
{
return detail::functor1<T, T, P, vecType>::call(log2, x);
return detail::compute_log2<T, P, vecType, std::numeric_limits<T>::is_iec559>::call(x);
}
// sqrt

11
glm/detail/setup.hpp
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@ -564,11 +564,12 @@
// User defines: GLM_FORCE_PURE GLM_FORCE_SSE2 GLM_FORCE_SSE3 GLM_FORCE_AVX GLM_FORCE_AVX2
#define GLM_ARCH_PURE 0x0000
#define GLM_ARCH_SSE2 0x0001
#define GLM_ARCH_SSE3 0x0002
#define GLM_ARCH_SSE4 0x0004
#define GLM_ARCH_AVX 0x0008
#define GLM_ARCH_AVX2 0x0010
#define GLM_ARCH_X86 0x0001
#define GLM_ARCH_SSE2 0x0002
#define GLM_ARCH_SSE3 0x0004
#define GLM_ARCH_SSE4 0x0008
#define GLM_ARCH_AVX 0x0010
#define GLM_ARCH_AVX2 0x0020
#if defined(GLM_FORCE_PURE)
# define GLM_ARCH GLM_ARCH_PURE

36
glm/gtc/integer.inl
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@ -29,19 +29,35 @@
namespace glm{
namespace detail
{
GLM_FUNC_QUALIFIER unsigned int nlz(unsigned int x)
template <typename T, precision P, template <class, precision> class vecType>
struct compute_log2<T, P, vecType, false>
{
return 31u - findMSB(x);
}
template <>
struct compute_log2<false>
GLM_FUNC_QUALIFIER static vecType<T, P> call(vecType<T, P> const & vec)
{
template <typename T>
GLM_FUNC_QUALIFIER T operator() (T const & Value) const
{
return Value <= static_cast<T>(1) ? T(0) : T(32) - nlz(Value - T(1));
//Equivalent to return findMSB(vec); but save one function call in ASM with VC
//return findMSB(vec);
return detail::compute_findMSB_vec<T, P, vecType, sizeof(T) * 8>::call(vec);
}
};
# if(GLM_ARCH != GLM_ARCH_PURE) && (GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_APPLE_CLANG | GLM_COMPILER_LLVM))
template <precision P>
struct compute_log2<int, P, tvec4, false>
{
GLM_FUNC_QUALIFIER static tvec4<int, P> call(tvec4<int, P> const & vec)
{
tvec4<int, P> Result(glm::uninitialize);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.x), vec.x);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.y), vec.y);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.z), vec.z);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result.w), vec.w);
return Result;
}
};
# endif//GLM_ARCH != GLM_ARCH_PURE
}//namespace detail
}//namespace glm

6
test/core/core_func_common.cpp
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@ -887,12 +887,6 @@ namespace sign
Error += Data[i].Return == Result ? 0 : 1;
}
for(std::size_t i = 0; i < sizeof(Data) / sizeof(type<glm::int32>); ++i)
{
glm::int32 Result = sign_sub(Data[i].Value);
Error += Data[i].Return == Result ? 0 : 1;
}
return Error;
}

122
test/gtc/gtc_integer.cpp
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@ -7,9 +7,11 @@
// File : test/gtc/integer.cpp
///////////////////////////////////////////////////////////////////////////////////////////////////
#define GLM_FORCE_INLINE
#include <glm/gtc/integer.hpp>
#include <glm/gtc/type_precision.hpp>
#include <glm/gtc/vec1.hpp>
#include <glm/gtx/type_aligned.hpp>
#include <glm/vector_relational.hpp>
#include <glm/vec2.hpp>
#include <glm/vec3.hpp>
@ -48,6 +50,126 @@ namespace log2_
int perf()
{
int Error = 0;
std::size_t const Count(100000000);
{
std::vector<int> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
Result[i] = glm::log2(static_cast<int>(i));
std::clock_t End = clock();
printf("glm::log2<int>: %d clocks\n", End - Begin);
}
{
std::vector<glm::ivec4> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
Result[i] = glm::log2(glm::ivec4(i));
std::clock_t End = clock();
printf("glm::log2<ivec4>: %d clocks\n", End - Begin);
}
# if(GLM_ARCH != GLM_ARCH_PURE) && (GLM_COMPILER & (GLM_COMPILER_VC | GLM_COMPILER_APPLE_CLANG | GLM_COMPILER_LLVM))
{
std::vector<glm::ivec4> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
{
glm::tvec4<unsigned long, glm::defaultp> Tmp(glm::uninitialize);
_BitScanReverse(&Tmp.x, i);
_BitScanReverse(&Tmp.y, i);
_BitScanReverse(&Tmp.z, i);
_BitScanReverse(&Tmp.w, i);
Result[i] = glm::ivec4(Tmp);
}
std::clock_t End = clock();
printf("glm::log2<ivec4> inlined: %d clocks\n", End - Begin);
}
{
std::vector<glm::tvec4<unsigned long, glm::defaultp> > Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
{
_BitScanReverse(&Result[i].x, i);
_BitScanReverse(&Result[i].y, i);
_BitScanReverse(&Result[i].z, i);
_BitScanReverse(&Result[i].w, i);
}
std::clock_t End = clock();
printf("glm::log2<ivec4> inlined no cast: %d clocks\n", End - Begin);
}
{
std::vector<glm::ivec4> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
{
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].x), i);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].y), i);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].z), i);
_BitScanReverse(reinterpret_cast<unsigned long*>(&Result[i].w), i);
}
std::clock_t End = clock();
printf("glm::log2<ivec4> reinterpret: %d clocks\n", End - Begin);
}
# endif//GLM_ARCH != GLM_ARCH_PURE
{
std::vector<float> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
Result[i] = glm::log2(static_cast<float>(i));
std::clock_t End = clock();
printf("glm::log2<float>: %d clocks\n", End - Begin);
}
{
std::vector<glm::vec4> Result;
Result.resize(Count);
std::clock_t Begin = clock();
for(std::size_t i = 0; i < Count; ++i)
Result[i] = glm::log2(glm::vec4(i));
std::clock_t End = clock();
printf("glm::log2<vec4>: %d clocks\n", End - Begin);
}
return Error;
}