From 0daf18c2028e5217cd996522816c3dd2ec1a4198 Mon Sep 17 00:00:00 2001
From: Stefan Weil <sw@weilnetz.de>
Date: Fri, 5 Aug 2022 20:21:15 +0200
Subject: [PATCH] Detect availability of AVX512-VNNI

Signed-off-by: Stefan Weil <sw@weilnetz.de>
---
 src/arch/simddetect.cpp | 4 ++++
 src/arch/simddetect.h   | 5 +++++
 src/tesseract.cpp       | 3 +++
 3 files changed, 12 insertions(+)

diff --git a/src/arch/simddetect.cpp b/src/arch/simddetect.cpp
index 573faa0cc1..1afe5a5d81 100644
--- a/src/arch/simddetect.cpp
+++ b/src/arch/simddetect.cpp
@@ -41,6 +41,7 @@
 #endif
 
 #if defined(HAVE_AVX) || defined(HAVE_AVX2) || defined(HAVE_FMA) || defined(HAVE_SSE4_1)
+// See https://en.wikipedia.org/wiki/CPUID.
 #  define HAS_CPUID
 #endif
 
@@ -94,6 +95,7 @@ bool SIMDDetect::avx_available_;
 bool SIMDDetect::avx2_available_;
 bool SIMDDetect::avx512F_available_;
 bool SIMDDetect::avx512BW_available_;
+bool SIMDDetect::avx512VNNI_available_;
 // If true, then FMA has been detected.
 bool SIMDDetect::fma_available_;
 // If true, then SSe4.1 has been detected.
@@ -171,6 +173,7 @@ SIMDDetect::SIMDDetect() {
         avx2_available_ = (ebx & 0x00000020) != 0;
         avx512F_available_ = (ebx & 0x00010000) != 0;
         avx512BW_available_ = (ebx & 0x40000000) != 0;
+        avx512VNNI_available_ = (ecx & 0x00000800) != 0;
       }
 #      endif
     }
@@ -201,6 +204,7 @@ SIMDDetect::SIMDDetect() {
         avx2_available_ = (cpuInfo[1] & 0x00000020) != 0;
         avx512F_available_ = (cpuInfo[1] & 0x00010000) != 0;
         avx512BW_available_ = (cpuInfo[1] & 0x40000000) != 0;
+        avx512VNNI_available_ = (cpuInfo[2] & 0x00000800) != 0;
       }
 #      endif
     }
diff --git a/src/arch/simddetect.h b/src/arch/simddetect.h
index 409319465e..fcb0f53eca 100644
--- a/src/arch/simddetect.h
+++ b/src/arch/simddetect.h
@@ -47,6 +47,10 @@ class SIMDDetect {
   static inline bool IsAVX512BWAvailable() {
     return detector.avx512BW_available_;
   }
+  // Returns true if AVX512 Vector Neural Network Instructions are available.
+  static inline bool IsAVX512VNNIAvailable() {
+    return detector.avx512VNNI_available_;
+  }
   // Returns true if FMA is available on this system.
   static inline bool IsFMAAvailable() {
     return detector.fma_available_;
@@ -75,6 +79,7 @@ class SIMDDetect {
   static TESS_API bool avx2_available_;
   static TESS_API bool avx512F_available_;
   static TESS_API bool avx512BW_available_;
+  static TESS_API bool avx512VNNI_available_;
   // If true, then FMA has been detected.
   static TESS_API bool fma_available_;
   // If true, then SSe4.1 has been detected.
diff --git a/src/tesseract.cpp b/src/tesseract.cpp
index 9154db80a6..0586e08694 100644
--- a/src/tesseract.cpp
+++ b/src/tesseract.cpp
@@ -149,6 +149,9 @@ static void PrintVersionInfo() {
   if (tesseract::SIMDDetect::IsAVX512FAvailable()) {
     printf(" Found AVX512F\n");
   }
+  if (tesseract::SIMDDetect::IsAVX512VNNIAvailable()) {
+    printf(" Found AVX512VNNI\n");
+  }
   if (tesseract::SIMDDetect::IsAVX2Available()) {
     printf(" Found AVX2\n");
   }