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[ESIMD] Revise log/exp implementation to be consistent with std/sycl #5211

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Merged
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Dec 30, 2021
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[ESIMD] Revise log/exp implementation to be consistent with std/sycl #5211

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[ESIMD] Revise log/exp implementation to be consistent with std/sycl
sndmitriev Dec 23, 2021
4762bcb
Addressed review comments
sndmitriev Dec 23, 2021
ef205dd
Merge remote-tracking branch 'intel_llvm/sycl' into sndmitriev/esimd-…
sndmitriev Dec 28, 2021
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41 changes: 38 additions & 3 deletions sycl/include/sycl/ext/intel/experimental/esimd/math.hpp
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Expand Up @@ -1379,7 +1379,7 @@ ESIMD_NODEBUG
////////////////////////////////////////////////////////////////////////////////
// ESIMD arithmetic intrinsics:
//
// inv, log, exp, sqrt, rsqrt, sin, cos
// inv, log2, exp2, sqrt, rsqrt, sin, cos
//
// share the same requirements.
//
Expand Down Expand Up @@ -1427,8 +1427,8 @@ ESIMD_NODEBUG
}

ESIMD_INTRINSIC_DEF(float, inv, inv)
ESIMD_INTRINSIC_DEF(float, log, log)
ESIMD_INTRINSIC_DEF(float, exp, exp)
ESIMD_INTRINSIC_DEF(float, log2, log)
ESIMD_INTRINSIC_DEF(float, exp2, exp)
ESIMD_INTRINSIC_DEF(float, sqrt, sqrt)
ESIMD_INTRINSIC_DEF(float, ieee_sqrt, sqrt_ieee)
ESIMD_INTRINSIC_DEF(float, rsqrt, rsqrt)
Expand Down Expand Up @@ -1592,6 +1592,41 @@ asin(T src0, int flag = saturation_off) {
return Result[0];
}

/// Computes the natural logarithm of the given argument. This is an
/// emulated version based on the H/W supported log2.
/// @param the source operand to compute base-e logarithm of.
/// @return the base-e logarithm of \p src0.
template <int SZ>
ESIMD_NODEBUG ESIMD_INLINE simd<float, SZ> log(simd<float, SZ> src0,
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please add a doc comment that this is s/w-emulated version based on h/w supported log2

int flag = saturation_off) {
constexpr float ln2 = 0.69314718f; // std::numbers::ln2_v<float> in c++20
simd<float, SZ> Result = esimd::log2<SZ>(src0) * ln2;

if (flag != saturation_on)
return Result;

return esimd::saturate<float>(Result);
}

ESIMD_NODEBUG ESIMD_INLINE float log(float src0, int flag = saturation_off) {
return esimd::log<1>(src0, flag)[0];
}

/// Computes e raised to the power of the given argument. This is an
/// emulated version based on the H/W supported exp2.
/// @param the source operand to compute base-e exponential of.
/// @return e raised to the power of \p src0.
template <int SZ>
ESIMD_NODEBUG ESIMD_INLINE simd<float, SZ> exp(simd<float, SZ> src0,
int flag = saturation_off) {
constexpr float log2e = 1.442695f; // std::numbers::log2e_v<float> in c++20
return esimd::exp2<SZ>(src0 * log2e, flag);
}

ESIMD_NODEBUG ESIMD_INLINE float exp(float src0, int flag = saturation_off) {
return esimd::exp<1>(src0, flag)[0];
}

////////////////////////////////////////////////////////////////////////////////
// Rounding intrinsics.
////////////////////////////////////////////////////////////////////////////////
Expand Down
16 changes: 14 additions & 2 deletions sycl/test/esimd/math_impl.cpp
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Expand Up @@ -25,7 +25,7 @@ SYCL_ESIMD_FUNCTION SYCL_EXTERNAL simd<float, 16> sycl_math(simd<float, 16> x) {
return v;
}

// Math sin,cos,log,exp functions from esimd namespace are translated
// Math sin,cos,log2,exp2 functions from esimd namespace are translated
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please add E2E test link

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intel/llvm-test-suite#673

// into vector __esimd_ calls, which later translate into GenX intrinsics.
SYCL_ESIMD_FUNCTION SYCL_EXTERNAL simd<float, 16>
esimd_math(simd<float, 16> x) {
Expand All @@ -35,7 +35,19 @@ esimd_math(simd<float, 16> x) {
//CHECK: call spir_func <16 x float> @_Z11__esimd_sin
v = esimd::sin(v);
//CHECK: call spir_func <16 x float> @_Z11__esimd_log
v = esimd::log(v);
v = esimd::log2(v);
//CHECK: call spir_func <16 x float> @_Z11__esimd_exp
v = esimd::exp2(v);
return v;
}

// Math log,exp functions from esimd namespace are emulated with
// __esimd_ log/exp calls, which later translate into GenX intrinsics.
SYCL_ESIMD_FUNCTION SYCL_EXTERNAL simd<float, 16>
esimd_math_emu(simd<float, 16> x) {
simd<float, 16> v = 0;
//CHECK: call spir_func <16 x float> @_Z11__esimd_log
v = esimd::log(x);
//CHECK: call spir_func <16 x float> @_Z11__esimd_exp
v = esimd::exp(v);
return v;
Expand Down