[ESIMD] Revise log/exp implementation to be consistent with std/sycl #5211
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- Rename esimd::log/exp to esimd::log2/exp2 since they operate with base 2 - Add esimd::log/exp functions emulated via esimd::log2/exp2 Signed-off-by: Sergey Dmitriev <[email protected]>
sndmitriev
requested review from
kbobrovs,
kychendev and
v-klochkov
as code owners
kbobrovs
reviewed
Dec 23, 2021
| template <int SZ> | ||
| ESIMD_NODEBUG ESIMD_INLINE simd<float, SZ> log(simd<float, SZ> src0, | ||
| int flag = saturation_off) { | ||
| constexpr float ln2 = 0.693147f; // std::numbers::ln2_v<float> in c++20 |
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Nit: is this precision maximum float can reach? If so, could you please add a comment?
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For ln2 looks like it should be possible to add more digits after the dot. But for log2e (below) it seems to be the max precision already.
$ cat test.cpp
#include <stdio.h>
int main() {
float a1 = 0.693147180559945309417232121458176f;
float b1 = 0.69314718f;
int *ai1 = (int *)&a1;
int *bi1 = (int *)&b1;
printf("*ai1 == *bi1 %d\n", (*ai1 == *bi1));
float a2 = 1.442695040888963407359924681001892f;
float b2 = 1.442695f;
int *ai2 = (int *)&a2;
int *bi2 = (int *)&b2;
printf("*ai2 == *bi2 %d\n", (*ai2 == *bi2));
return 0;
}
$ g++ test.cpp; ./a.out
*ai1 == *bi1 1
*ai2 == *bi2 1
$
I can actually add a double initializer and let compiler truncate it to float.
| @@ -25,7 +25,7 @@ SYCL_ESIMD_FUNCTION SYCL_EXTERNAL simd<float, 16> sycl_math(simd<float, 16> x) { | |||
| return v; | |||
| } | |||
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| // 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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kbobrovs
reviewed
Dec 23, 2021
| // log | ||
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| 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
|
/verify with intel/llvm-test-suite#673 |
|
/verify with intel/llvm-test-suite#673 |
kbobrovs
approved these changes
Dec 27, 2021
|
/verify with intel/llvm-test-suite#673 |
|
@vladimirlaz, could you merge this PR, please? |
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Signed-off-by: Sergey Dmitriev [email protected]