From eac945a9cb402800154c78b7d1c1d163b0131b6b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E7=8E=8B=E9=98=B3?= <657837019@qq.com>
Date: Thu, 18 Jun 2026 15:22:38 +0800
Subject: [PATCH] Fix riscv generic target detection

---
 CMakeLists.txt | 23 ++++++++++++++++++-----
 README.md      |  2 ++
 src/bmdef.h    | 15 +++++++++++----
 3 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 9e6a7ee7..0a0c1eb9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,6 +72,11 @@ set(BM_HEADERS ${PROJECT_SOURCE_DIR}/src/bm.h
 
 set (CMAKE_CXX_STANDARD 17)
 
+string(TOLOWER "${CMAKE_SYSTEM_PROCESSOR}" BM_SYSTEM_PROCESSOR_LOWER)
+set(BM_TARGET_IS_X86 FALSE)
+if (BM_SYSTEM_PROCESSOR_LOWER MATCHES "^(x86_64|amd64|i[3-6]86|x86)$")
+    set(BM_TARGET_IS_X86 TRUE)
+endif()
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "GNU")
     set(warnopt "-Wno-psabi")
@@ -83,11 +88,19 @@ if (CMAKE_CXX_COMPILER_ID MATCHES "GNU" OR CMAKE_CXX_COMPILER_ID MATCHES "Clang"
     elseif("${BMOPTFLAGS}" STREQUAL "BMAVX2OPT")
         set(bmoptf "-march=skylake -mavx2 -O2 -DBMAVX2OPT")
     else()
-	if (CMAKE_BUILD_TYPE MATCHES "Release")
-		set(bmoptf "-march=native -O2")
-	else()
-		set(bmoptf "-march=native")
-	endif()
+        if (BM_TARGET_IS_X86 AND NOT CMAKE_CROSSCOMPILING)
+	    if (CMAKE_BUILD_TYPE MATCHES "Release")
+		    set(bmoptf "-march=native -O2")
+	    else()
+		    set(bmoptf "-march=native")
+	    endif()
+        else()
+	    if (CMAKE_BUILD_TYPE MATCHES "Release")
+		    set(bmoptf "-O2")
+	    else()
+		    set(bmoptf "")
+	    endif()
+        endif()
     endif()
 
     set(flags "-Wall -Wextra -Wno-ignored-qualifiers -fPIC -fomit-frame-pointer")
diff --git a/README.md b/README.md
index 5b853355..d9113c5b 100644
--- a/README.md
+++ b/README.md
@@ -328,6 +328,8 @@ If you want to change the default you can do that in makefile.in
 Project now comes with a set of makefiles for cmake, you can just build it or generate project files for any 
 cmake-supported environment.
 
+When targeting `riscv64`, use the default portable build unless you add a dedicated RISC-V SIMD backend. Avoid inheriting host-only `-march=native` settings during cross-target or simulated target builds.
+
 
 ###### Windows:
 ---
diff --git a/src/bmdef.h b/src/bmdef.h
index db237cf3..0fbd4d15 100644
--- a/src/bmdef.h
+++ b/src/bmdef.h
@@ -56,20 +56,27 @@ For more information please visit:  http://bitmagic.io
 #endif
 
 
+#if defined(__riscv)
+#define BM_RISCV
+#endif
+
+
 // macro to define/undefine unaligned memory access (x86, PowerPC)
 //
-#if defined(__i386) || defined(__x86_64) || defined(__ppc__) || \
+#if !defined(BM_RISCV) && \
+    (defined(__i386) || defined(__x86_64) || defined(__ppc__) || \
     defined(__ppc64__) || defined(_M_IX86) || defined(_M_AMD64) || \
     defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
     defined(_M_ARM) || defined(_M_ARM64) || \
     defined(__arm__) || defined(__aarch64__) || \
-    (defined(_M_MPPC) && !defined(BM_FORBID_UNALIGNED_ACCESS))
+    (defined(_M_MPPC) && !defined(BM_FORBID_UNALIGNED_ACCESS)))
 #define BM_UNALIGNED_ACCESS_OK 1
 #endif
 
-#if defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
+#if !defined(BM_RISCV) && \
+    (defined(_M_IX86) || defined(_M_AMD64) || defined(_M_X64) || \
     defined(__i386) || defined(__x86_64) || defined(_M_AMD64) || \
-    defined(BMSSE2OPT) || defined(BMSSE42OPT)
+    defined(BMSSE2OPT) || defined(BMSSE42OPT))
 #define BM_x86
 #endif