Add cpu model init for Windows.

Author: DanielKristofKiss

compiler-rt/lib/builtins/cpu_model/aarch64.c

@@ -76,6 +76,8 @@ struct {
 #elif defined(__linux__) && __has_include(<sys/auxv.h>)
 #include "aarch64/fmv/mrs.inc"
 #include "aarch64/fmv/getauxval.inc"
+#elif defined(_WIN32)
+#include "aarch64/fmv/windows.inc"
 #else
 #include "aarch64/fmv/unimplemented.inc"
 #endif

compiler-rt/lib/builtins/cpu_model/aarch64/fmv/windows.inc

@@ -0,0 +1,42 @@
+#ifndef _ARM64_
+#define _ARM64_
+#endif
+#include <processthreadsapi.h>
+#include <stdint.h>
+
+void __init_cpu_features_resolver(unsigned long hwcap,
+                                  const __ifunc_arg_t *arg) {}
+
+void  CONSTRUCTOR_ATTRIBUTE __init_cpu_features(void) {
+  if (__atomic_load_n(&__aarch64_cpu_features.features, __ATOMIC_RELAXED))
+    return;
+
+  #define setCPUFeature(F) features |= 1ULL << F
+
+  uint64_t features = 0;
+
+  setCPUFeature(FEAT_INIT);
+  setCPUFeature(FEAT_FP);
+
+  // https://learn.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-isprocessorfeaturepresent
+  if (IsProcessorFeaturePresent(PF_ARM_V8_CRC32_INSTRUCTIONS_AVAILABLE))
+    setCPUFeature(FEAT_CRC);
+  if (IsProcessorFeaturePresent(PF_ARM_V81_ATOMIC_INSTRUCTIONS_AVAILABLE))
+    setCPUFeature(FEAT_LSE);
+  if (IsProcessorFeaturePresent(PF_ARM_V82_DP_INSTRUCTIONS_AVAILABLE))
+    setCPUFeature(FEAT_DOTPROD);
+
+  if (IsProcessorFeaturePresent(PF_ARM_V8_CRYPTO_INSTRUCTIONS_AVAILABLE)) {
+    setCPUFeature(FEAT_AES);
+    setCPUFeature(FEAT_SHA2);
+    setCPUFeature(FEAT_PMULL);
+  }
+  if (IsProcessorFeaturePresent(PF_ARM_V83_JSCVT_INSTRUCTIONS_AVAILABLE))
+    setCPUFeature(FEAT_JSCVT);
+
+  if (IsProcessorFeaturePresent(PF_ARM_V83_LRCPC_INSTRUCTIONS_AVAILABLE))
+    setCPUFeature(FEAT_RCPC);
+
+  __atomic_store(&__aarch64_cpu_features.features, &features,
+                  __ATOMIC_RELAXED);
+}

compiler-rt/lib/builtins/cpu_model/cpu_model.h

@@ -31,7 +31,15 @@
 // We're choosing init priority 90 to force our constructors to run before any
 // constructors in the end user application (starting at priority 101). This
 // value matches the libgcc choice for the same functions.
-#define CONSTRUCTOR_ATTRIBUTE __attribute__((constructor(90)))
+#ifdef _WIN64
+// Contructor that replaces the ifunc runs currently with prio 10, see
+// the LowerIFuncPass. The resolver of FMV depends on the cpu features so set
+// the priority to 9.
+#define CONSTRUCTOR_PRIOTITY 9
+#else
+#define CONSTRUCTOR_PRIOTITY 90
+#endif
+#define CONSTRUCTOR_ATTRIBUTE __attribute__((constructor(CONSTRUCTOR_PRIOTITY)))
 #else
 // FIXME: For MSVC, we should make a function pointer global in .CRT$X?? so that
 // this runs during initialization.