gh-125022: add support for simple SIMD features detection

Include/internal/pycore_cpuinfo.h

@@ -0,0 +1,170 @@
+/*
+ * Interface for detecting the different CPUID flags in an opaque manner.
+ * See https://en.wikipedia.org/wiki/CPUID for details on the bit values.
+ *
+ * If a module requires to support SIMD instructions, it should determine
+ * the compiler flags and the instruction sets required for the instrinsics
+ * to work.
+ *
+ * For the headers and expected CPUID bits needed by Intel intrinics, see
+ * https://www.intel.com/content/www/us/en/docs/intrinsics-guide/index.html.
+ */
+
+#ifndef Py_INTERNAL_CPUINFO_H
+#define Py_INTERNAL_CPUINFO_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef Py_BUILD_CORE
+#  error "this header requires Py_BUILD_CORE define"
+#endif
+
+#include <stdint.h>         // uint8_t
+
+typedef struct py_cpuid_features {
+    /* Macro to declare a member flag of 'py_cpuid_features' as a uint8_t. */
+#define _Py_CPUID_DECL_FLAG(MEMBER_NAME)    uint8_t MEMBER_NAME:1
+    // --- Streaming SIMD Extensions ------------------------------------------
+    _Py_CPUID_DECL_FLAG(sse);
+    _Py_CPUID_DECL_FLAG(sse2);
+    _Py_CPUID_DECL_FLAG(sse3);
+    _Py_CPUID_DECL_FLAG(ssse3); // Supplemental SSE3 instructions
+    _Py_CPUID_DECL_FLAG(sse41); // SSE4.1
+    _Py_CPUID_DECL_FLAG(sse42); // SSE4.2
+
+    // --- Advanced Vector Extensions -----------------------------------------
+    _Py_CPUID_DECL_FLAG(avx);
+    _Py_CPUID_DECL_FLAG(avx_ifma);
+    _Py_CPUID_DECL_FLAG(avx_ne_convert);
+
+    _Py_CPUID_DECL_FLAG(avx_vnni);
+    _Py_CPUID_DECL_FLAG(avx_vnni_int8);
+    _Py_CPUID_DECL_FLAG(avx_vnni_int16);
+
+    // --- Advanced Vector Extensions 2 ---------------------------------------
+    _Py_CPUID_DECL_FLAG(avx2);
+
+    // --- Advanced Vector Extensions (512-bit) -------------------------------
+    /*
+     * AVX-512 instruction set are grouped by the processor generation
+     * that implements them (see https://en.wikipedia.org/wiki/AVX-512).
+     *
+     * We do not include GFNI, VPCLMULQDQ and VAES instructions since
+     * they are not exactly AVX-512 per se, nor do we include BF16 or
+     * FP16 since they operate on bfloat16 and binary16 (half-float).
+     *
+     * See https://en.wikipedia.org/wiki/AVX-512#Instruction_set for
+     * the suffix meanings (for instance 'f' stands for 'Foundation').
+     */
+    _Py_CPUID_DECL_FLAG(avx512_f);
+    _Py_CPUID_DECL_FLAG(avx512_cd);
+
+    _Py_CPUID_DECL_FLAG(avx512_er);
+    _Py_CPUID_DECL_FLAG(avx512_pf);
+
+    _Py_CPUID_DECL_FLAG(avx512_4fmaps);
+    _Py_CPUID_DECL_FLAG(avx512_4vnniw);
+
+    _Py_CPUID_DECL_FLAG(avx512_vpopcntdq);
+
+    _Py_CPUID_DECL_FLAG(avx512_vl);
+    _Py_CPUID_DECL_FLAG(avx512_dq);
+    _Py_CPUID_DECL_FLAG(avx512_bw);
+
+    _Py_CPUID_DECL_FLAG(avx512_ifma);
+    _Py_CPUID_DECL_FLAG(avx512_vbmi);
+
+    _Py_CPUID_DECL_FLAG(avx512_vnni);
+
+    _Py_CPUID_DECL_FLAG(avx512_vbmi2);
+    _Py_CPUID_DECL_FLAG(avx512_bitalg);
+
+    _Py_CPUID_DECL_FLAG(avx512_vp2intersect);
+
+    // --- Instructions -------------------------------------------------------
+    _Py_CPUID_DECL_FLAG(cmov);
+    _Py_CPUID_DECL_FLAG(fma);
+    _Py_CPUID_DECL_FLAG(popcnt);
+    _Py_CPUID_DECL_FLAG(pclmulqdq);
+
+    _Py_CPUID_DECL_FLAG(xsave);     // XSAVE/XRSTOR/XSETBV/XGETBV
+    _Py_CPUID_DECL_FLAG(os_xsave);  // XSAVE is enabled by the OS
+
+    // --- XCR0 register bits -------------------------------------------------
+    _Py_CPUID_DECL_FLAG(xcr0_sse);
+    // On some Intel CPUs, it is possible for the CPU to support AVX2
+    // instructions even though the underlying OS does not know about
+    // AVX. In particular, only (SSE) XMM registers will be saved and
+    // restored on context-switch, but not (AVX) YMM registers.
+    _Py_CPUID_DECL_FLAG(xcr0_avx);
+    _Py_CPUID_DECL_FLAG(xcr0_avx512_opmask);
+    _Py_CPUID_DECL_FLAG(xcr0_avx512_zmm_hi256);
+    _Py_CPUID_DECL_FLAG(xcr0_avx512_hi16_zmm);
+#undef _Py_CPUID_DECL_FLAG
+    // Whenever a field is added or removed above, update the
+    // number of fields (40) and adjust the bitsize of 'ready'
+    // so that the size of this structure is a multiple of 8.
+    uint8_t ready; // set if the structure is ready for usage
+} py_cpuid_features;
+
+/*
+ * Explicitly initialize all members to zero to guarantee that
+ * we never have an un-initialized attribute at runtime which
+ * could lead to an illegal instruction error.
+ *
+ * This does not mark 'flags' as being ready yet.
+ *
+ * Note: This function does not set any exception and thus never fails.
+ */
+extern void
+_Py_cpuid_disable_features(py_cpuid_features *flags);
+
+/*
+ * Check whether the structure is ready and flags are inter-compatible,
+ * returning 1 on success and 0 otherwise.
+ *
+ * The caller should disable all CPUID detected features if the check
+ * fails to avoid encountering runtime illegal instruction errors.
+ *
+ * Note: This function does not set any exception and thus never fails.
+ */
+extern int
+_Py_cpuid_check_features(const py_cpuid_features *flags);
+
+/*
+ * Return 1 if all expected flags are set in 'actual', 0 otherwise.
+ *
+ * If 'actual' or 'expect' are not ready yet, this also returns 0.
+ *
+ * Note: This function does not set any exception and thus never fails.
+ */
+extern int
+_Py_cpuid_has_features(const py_cpuid_features *actual,
+                       const py_cpuid_features *expect);
+
+/*
+ * Return 1 if 'actual' and 'expect' are identical, 0 otherwise.
+ *
+ * If 'actual' or 'expect' are not ready yet, this also returns 0.
+ *
+ * Note: This function does not set any exception and thus never fails.
+ */
+extern int
+_Py_cpuid_match_features(const py_cpuid_features *actual,
+                         const py_cpuid_features *expect);
+
+/*
+ * Detect the available features on this machine, storing the result in 'flags'.
+ *
+ * Note: This function does not set any exception and thus never fails.
+ */
+extern void
+_Py_cpuid_detect_features(py_cpuid_features *flags);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* !Py_INTERNAL_CPUINFO_H */

Makefile.pre.in

@@ -432,6 +432,7 @@ PYTHON_OBJS=	\
 		Python/codegen.o \
 		Python/compile.o \
 		Python/context.o \
+		Python/cpuinfo.o \
 		Python/critical_section.o \
 		Python/crossinterp.o \
 		Python/dynamic_annotations.o \
@@ -1191,6 +1192,7 @@ PYTHON_HEADERS= \
 		$(srcdir)/Include/internal/pycore_complexobject.h \
 		$(srcdir)/Include/internal/pycore_condvar.h \
 		$(srcdir)/Include/internal/pycore_context.h \
+		$(srcdir)/Include/internal/pycore_cpuinfo.h \
 		$(srcdir)/Include/internal/pycore_critical_section.h \
 		$(srcdir)/Include/internal/pycore_crossinterp.h \
 		$(srcdir)/Include/internal/pycore_descrobject.h \

PCbuild/pythoncore.vcxproj

@@ -225,6 +225,7 @@
     <ClInclude Include="..\Include\internal\pycore_complexobject.h" />
     <ClInclude Include="..\Include\internal\pycore_condvar.h" />
     <ClInclude Include="..\Include\internal\pycore_context.h" />
+    <ClInclude Include="..\Include\internal\pycore_cpuinfo.h" />
     <ClInclude Include="..\Include\internal\pycore_critical_section.h" />
     <ClInclude Include="..\Include\internal\pycore_crossinterp.h" />
     <ClInclude Include="..\Include\internal\pycore_descrobject.h" />
@@ -584,6 +585,7 @@
     <ClCompile Include="..\Python\codegen.c" />
     <ClCompile Include="..\Python\compile.c" />
     <ClCompile Include="..\Python\context.c" />
+    <ClCompile Include="..\Python\cpuinfo.c" />
     <ClCompile Include="..\Python\critical_section.c" />
     <ClCompile Include="..\Python\crossinterp.c" />
     <ClCompile Include="..\Python\dynamic_annotations.c" />

PCbuild/pythoncore.vcxproj.filters

@@ -597,6 +597,9 @@
     <ClInclude Include="..\Include\internal\pycore_context.h">
       <Filter>Include\internal</Filter>
     </ClInclude>
+    <ClInclude Include="..\Include\internal\pycore_cpuinfo.h">
+      <Filter>Include\cpython</Filter>
+    </ClInclude>
     <ClInclude Include="..\Include\internal\pycore_critical_section.h">
       <Filter>Include\internal</Filter>
     </ClInclude>
@@ -1304,6 +1307,9 @@
     <ClCompile Include="..\Python\compile.c">
       <Filter>Python</Filter>
     </ClCompile>
+    <ClCompile Include="..\Python\cpuinfo.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="..\Python\critical_section.c">
       <Filter>Python</Filter>
     </ClCompile>