From f7e1faa2e8afa354903cc5dec3b96ec3216fd610 Mon Sep 17 00:00:00 2001
From: Khem Raj <raj.khem@gmail.com>
Date: Tue, 17 Sep 2024 18:22:36 +0000
Subject: [PATCH] Add cmake check for deducing 32bit or 64bit RISCV

Currently its only compilable for RV64 when RVV is
enabled, this will extend it to build for RV32 with
RVV as well
---
 CMakeLists.txt | 38 +++++++++++++++++++++++++++++++++++---
 1 file changed, 35 insertions(+), 3 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 545e8de878..f8780a0a5b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -59,6 +59,33 @@ if(CHECK_PIE_SUPPORTED)
   endif()
 endif()
 
+if (CMAKE_CXX_COMPILER_ARCHITECTURE_ID MATCHES "RISCV32|RISCV64|RISCV128" OR CMAKE_SYSTEM_PROCESSOR MATCHES "riscv32|riscv64|riscv128")
+  include(CheckCSourceCompiles)
+  check_c_source_compiles("
+  #if __riscv_xlen == 64
+  int main() { return 0; }
+  #else
+  #error Not RISCV-64
+  #endif
+  " IS_RISCV_XLEN_64)
+
+  check_c_source_compiles("
+  #if __riscv_xlen == 32
+  int main() { return 0; }
+  #else
+  #error Not RISCV-32
+  #endif
+  " IS_RISCV_XLEN_32)
+
+  if(IS_RISCV_XLEN_32)
+    set(RISCV_XLEN 32)
+  elseif(IS_RISCV_XLEN_64)
+    set(RISCV_XLEN 64)
+  else()
+    message(WARNING "Unable to determine RISC-V XLEN")
+  endif()
+endif()
+
 include(GNUInstallDirs)
 
 if (NOT CMAKE_BUILD_TYPE)
@@ -72,7 +99,7 @@ set(HWY_CMAKE_ARM7 OFF CACHE BOOL "Set copts for Armv7 with NEON (requires vfpv4
 # skipped. For GCC 13.1+, you can also build with -fexcess-precision=standard.
 set(HWY_CMAKE_SSE2 OFF CACHE BOOL "Set SSE2 as baseline for 32-bit x86?")
 
-# Currently this will compile the entire codebase with `-march=rv64gcv1p0`:
+# Currently this will compile the entire codebase with `-march=rv<XLEN>gcv1p0`:
 set(HWY_CMAKE_RVV ON CACHE BOOL "Set copts for RISCV with RVV?")
 
 # Unconditionally adding -Werror risks breaking the build when new warnings
@@ -384,8 +411,13 @@ else()
     # we add the gcv compiler flag, which then requires the CPU (now when using
     # either compiler) to support V.
     if(HWY_CMAKE_RVV)
-      list(APPEND HWY_FLAGS -march=rv64gcv1p0)
-      add_link_options(-march=rv64gcv1p0)
+      if(RISCV_XLEN EQUAL 64)
+        list(APPEND HWY_FLAGS -march=rv64gcv1p0)
+        add_link_options(-march=rv64gcv1p0)
+      elseif(RISCV_XLEN EQUAL 32)
+        list(APPEND HWY_FLAGS -march=rv32gcv1p0)
+        add_link_options(-march=rv32gcv1p0)
+      endif()
       if(${CMAKE_CXX_COMPILER_ID} MATCHES "Clang")
         list(APPEND HWY_FLAGS -menable-experimental-extensions)
       endif()