From af443edca17649a6f2e66707746f482caefe3d1a Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Sun, 1 Mar 2026 17:54:07 +0000
Subject: Enable arch on windows

---
 README.md            |  6 +++---
 build.bat            | 20 +++++++++++++++-----
 src/utils/prefetch.h | 16 ++++------------
 3 files changed, 22 insertions(+), 20 deletions(-)

diff --git a/README.md b/README.md
index 338a280..64871b5 100644
--- a/README.md
+++ b/README.md
@@ -64,9 +64,9 @@ can be used to build the basic shell, while
 Builds and runs the unit tests. See `build.bat help` for a list of
 all available options.
 
-Note: At the moment certain optimizations, such as multithreading and
-advanced CPU instructions, are not supported on Windows.
-Work is ongoing to improve Windows support.
+Note: The build script for Windows does not support all the options
+available with build.sh. If you want to tune the build options, you'll
+have to manually edit the build script.
 
 ## Running tests
 
diff --git a/build.bat b/build.bat
index 91cc4db..b082e03 100644
--- a/build.bat
+++ b/build.bat
@@ -9,15 +9,25 @@ if [%1]==[/d] (
 
 SET CC=clang
 SET CXX=clang++
-SET ARCH=PORTABLE
 SET THREADS=16
 SET SANITIZE=
 
-:: TODO depends on ARCH variable
-SET ARCHOPTS=
-:: TODO depends on SANITIZE variable
-SET DFLAGS=-g3 -DDEBUG
+SET ARCH=PORTABLE
+clang -march=native -dM -E - < NUL | findstr /C:"__AVX2__" >NUL 2>&1
+if %ERRORLEVEL% EQU 0 (
+    SET ARCH=AVX2
+    SET ARCHOPTS=-mavx2
+    goto :ArchDone
+)
+clang -march=native -dM -E - < NUL | findstr /C:"__ARM_NEON" >NUL 2>&1
+if %ERRORLEVEL% EQU 0 (
+    SET ARCH=NEON
+    goto :ArchDone
+)
+:ArchDone
+
 
+SET DFLAGS=-g3 -DDEBUG
 SET WARNINGS=-Wno-deprecated-declarations
 SET VARIABLES=-DTHREADS=%THREADS% -D%ARCH%
 SET OFLAGS=-O3
diff --git a/src/utils/prefetch.h b/src/utils/prefetch.h
index 89b14e8..a2c41ef 100644
--- a/src/utils/prefetch.h
+++ b/src/utils/prefetch.h
@@ -1,15 +1,7 @@
-#if defined(AVX2)
-
-#define prefetch(a, i) _mm_prefetch(a+i, _MM_HINT_T0)
-
-#else
 #if defined(__GNUC__) || defined(__clang__)
-
-#define prefetch(a, i) __builtin_prefetch(a+i, 0, 0)
-
+    #define prefetch(a, i) __builtin_prefetch(a+i, 0, 0)
+#elif defined(AVX2)
+    #define prefetch(a, i) _mm_prefetch((char *)(a+i), _MM_HINT_T0)
 #else
-
-#define prefetch(a, i) (void)i
-
-#endif
+    #define prefetch(a, i) (void)i
 #endif
-- 
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