[compiler-rt] [compiler-rt] Add cpu model init for Windows. (PR #111961)

[Daniel Kiss via llvm-commits]

================
@@ -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);
----------------
DanielKristofKiss wrote:

Thanks, I didn't notice the headers change recently :D 
Now we have a bunch of features, I refactored the code a bit.

https://github.com/llvm/llvm-project/pull/111961