Enable Windows build and refine code

Author: xiaolil1

CMakeLists.txt

@@ -232,6 +232,9 @@ elseif(BUILD_XPU)
     add_compile_definitions(BUILD_XPU)
     set(CMAKE_C_COMPILER icx)
     set(CMAKE_CXX_COMPILER icpx)
+    if(WIN32)
+        set(CMAKE_CXX_COMPILER icx)
+    endif()
 else()
     string(APPEND BNB_OUTPUT_NAME "_cpu")
     set(GPU_SOURCES)

bitsandbytes/backends/xpu/ops.py

@@ -145,7 +145,7 @@ def _(
         shape: Sequence[int],
         dtype: torch.dtype,
     ) -> torch.Tensor:
-        out = torch.zeros(shape, dtype=dtype, device=A.device)
+        out = torch.empty(shape, dtype=dtype, device=A.device)
         _dequantize_4bit_impl(A, absmax, blocksize, quant_type, dtype, out=out)
         return out
 

csrc/xpu_kernels.cpp

@@ -2,11 +2,10 @@
 #include <bit>
 #include <cmath>
 #include <iostream>
-#include <unistd.h>
 
 #include <sycl/sycl.hpp>
 
-inline float dDequantizeFP4Tree(unsigned char val) {
+inline float dDequantizeFP4(unsigned char val) {
   if ((val & 0b1000) == 8)
     if ((val & 0b0100) == 4)
       if ((val & 0b0010) == 2)
@@ -144,8 +143,8 @@ kDequantizeBlockwise<T, TILE_SIZE, NUM_PER_TH, DATA_TYPE>::operator()(
   case FP4:
 #pragma unroll NUM_PER_TH
     for (int j = 0; j < NUM_PER_TH; j++) {
-      vals[j * 2] = dDequantizeFP4Tree(qvals[j] >> 4) * local_abs_max;
-      vals[j * 2 + 1] = dDequantizeFP4Tree(qvals[j] & 0x0F) * local_abs_max;
+      vals[j * 2] = dDequantizeFP4(qvals[j] >> 4) * local_abs_max;
+      vals[j * 2 + 1] = dDequantizeFP4(qvals[j] & 0x0F) * local_abs_max;
     }
     break;
   case NF4: