[inductor][quant]Enable inductor vec codegen for quantization (#98489)
**Summary**
Enable the `decomposed dequant - pointwise ops - decomposed quant` vectorization code gen inside inductor.
Here is the example in the UT and the generated code:
Example:
* `decomposed dequant - relu - decomposed quant` pattern.
* Using `uint8` as the quantized tensor data type.
Generated Code:
```
kernel_cpp_0 = async_compile.cpp('''
#include "/tmp/torchinductor_root/hw/chwr6vy6e6sd25sfh42qtywkuf2emodexm2aomp3lbrcxwznfwyi.h"
extern "C" void kernel(const unsigned char* in_ptr0,
unsigned char* out_ptr0)
{
#pragma omp parallel num_threads(56)
{
{
#pragma omp for
for(long i0=static_cast<long>(0); i0<static_cast<long>(27); i0+=static_cast<long>(1))
{
auto tmp0 = at::vec::load_uint8_as_float(in_ptr0 + static_cast<long>(16*i0));
auto tmp1 = (tmp0);
auto tmp2 = at::vec::Vectorized<float>(static_cast<float>(100));
auto tmp3 = tmp1 - tmp2;
auto tmp4 = at::vec::Vectorized<float>(static_cast<float>(0.01));
auto tmp5 = tmp3 * tmp4;
auto tmp6 = at::vec::clamp_min(tmp5, decltype(tmp5)(0));
auto tmp7 = at::vec::Vectorized<float>(static_cast<float>(100.0));
auto tmp8 = tmp6 * tmp7;
auto tmp9 = tmp8.round();
auto tmp10 = tmp9 + tmp2;
auto tmp11 = at::vec::Vectorized<float>(static_cast<float>(0));
auto tmp12 = at::vec::maximum(tmp10, tmp11);
auto tmp13 = at::vec::Vectorized<float>(static_cast<float>(255));
auto tmp14 = at::vec::minimum(tmp12, tmp13);
auto tmp15 = (tmp14);
tmp15.store_float_as_uint8(out_ptr0 + static_cast<long>(16*i0));
}
#pragma omp for simd simdlen(8)
for(long i0=static_cast<long>(432); i0<static_cast<long>(441); i0+=static_cast<long>(1))
{
auto tmp0 = in_ptr0[static_cast<long>(i0)];
auto tmp1 = static_cast<float>(tmp0);
auto tmp2 = static_cast<float>(100);
auto tmp3 = tmp1 - tmp2;
auto tmp4 = static_cast<float>(0.01);
auto tmp5 = tmp3 * tmp4;
auto tmp6 = tmp5 * (tmp5>0);
auto tmp7 = static_cast<float>(100.0);
auto tmp8 = tmp6 * tmp7;
auto tmp9 = std::nearbyint(tmp8);
auto tmp10 = tmp9 + tmp2;
auto tmp11 = static_cast<float>(0);
auto tmp12 = (tmp11 != tmp11) ? tmp11 : std::max(tmp10, tmp11);
auto tmp13 = static_cast<float>(255);
auto tmp14 = (tmp13 != tmp13) ? tmp13 : std::min(tmp12, tmp13);
auto tmp15 = static_cast<unsigned char>(tmp14);
out_ptr0[static_cast<long>(i0)] = tmp15;
}
}
}
}
''')
```
**Test Plan**
```
cd test/inductor && python -m pytest test_cpu_repro.py -k test_decomposed_dequant_relu_quant
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/98489
Approved by: https://github.com/jgong5, https://github.com/jansel
pytorch
91279f94 - [inductor][quant]Enable inductor vec codegen for quantization (#98489)
