turn instruction_set into set (review beauby)

faiss/python/loader.py

@@ -11,42 +11,42 @@
 
 def instruction_set():
     """
-    Returns a dictionary for supported instruction sets, see
+    Returns the set of supported instruction sets, see
     https://github.com/numpy/numpy/blob/master/numpy/core/src/common/npy_cpu_features.h
-    for the list of features that this dictionary contains per architecture.
+    for the list of features that this set may contain per architecture.
 
     Example:
     >>> instruction_set()  # for x86
-    {"SSE2": True, "AVX2": False, ...}
+    {"SSE2", "AVX2", ...}
     >>> instruction_set()  # for PPC
-    {"VSX": True, "VSX2": False, ...}
+    {"VSX", "VSX2", ...}
     >>> instruction_set()  # for ARM
-    {"NEON": True, "ASIMD": False, ...}
+    {"NEON", "ASIMD", ...}
     """
     import numpy
     if LooseVersion(numpy.__version__) >= "1.19":
         # use private API as next-best thing until numpy/numpy#18058 is solved
         from numpy.core._multiarray_umath import __cpu_features__
-        return __cpu_features__
+        # __cpu_features__ is a dictionary with CPU features
+        # as keys, and True / False as values
+        supported = {k for k, v in __cpu_features__.items() if v}
+        return supported
 
     # platform-dependent legacy fallback before numpy 1.19, no windows
     if platform.system() == "Darwin":
         if subprocess.check_output(["/usr/sbin/sysctl", "hw.optional.avx2_0"])[-1] == '1':
-            return {"AVX2": True}
+            return {"AVX2"}
     elif platform.system() == "Linux":
         import numpy.distutils.cpuinfo
         if "avx2" in numpy.distutils.cpuinfo.cpu.info[0].get('flags', ""):
-            return {"AVX2": True}
-    return {"AVX2": False}
+            return {"AVX2"}
+    return set()
 
 
 logger = logging.getLogger(__name__)
 
 try:
-    instr_set = instruction_set()
-    # dict-values of instr_set are True or False, but do not have
-    # uniform keys across arches -> use fallback value of False
-    has_AVX2 = instr_set.get("AVX2", False)
+    has_AVX2 = "AVX2" in instruction_set()
     if has_AVX2:
         logger.info("Loading faiss with AVX2 support.")
         from .swigfaiss_avx2 import *