Optionally hide symbols from export (#5)

Can instruct cmake to include the -fvisibility=hidden flag

This is necessary to allow multiple versions of the librandomx.a static library to be linked to different shared libraries on OSX/Macos. It doesn't seem to be necessary on linux, but does not hurt.

CMakeLists.txt

@@ -30,6 +30,8 @@ cmake_minimum_required(VERSION 3.5)
 
 project(RandomX)
 
+set(CMAKE_VERBOSE_MAKEFILE ON)
+
 set(randomx_sources
 src/aes_hash.cpp
 src/argon2_ref.c
@@ -212,9 +214,14 @@ endif()
 set(RANDOMX_INCLUDE "${CMAKE_CURRENT_SOURCE_DIR}/src" CACHE STRING "RandomX Include path")
 
 # Define variables for custom preprocessor definitions with default values
+option(USE_HIDDEN_VISIBILITY "Include -fvisibility=hidden flag" OFF)
 set(RANDOMX_ARGON_MEMORY "" CACHE STRING "Set the RANDOMX_ARGON_MEMORY value")
 set(RANDOMX_DATASET_BASE_SIZE "" CACHE STRING "Set the RANDOMX_DATASET_BASE_SIZE value")
 
+if(USE_HIDDEN_VISIBILITY)
+  add_compile_options("-fvisibility=hidden")
+endif()
+
 add_library(randomx ${randomx_sources})
 
 # Apply the custom preprocessor definitions only if they are set

src/randomx.cpp

@@ -145,7 +145,6 @@ extern "C" {
 	}
 
 	randomx_dataset *randomx_alloc_dataset(randomx_flags flags) {
-
 		//fail on 32-bit systems if DatasetSize is >= 4 GiB
 		if (randomx::DatasetSize > std::numeric_limits<size_t>::max()) {
 			return nullptr;

src/vm_interpreted.cpp

@@ -54,7 +54,6 @@ namespace randomx {
 
 	template<class Allocator, bool softAes>
 	void InterpretedVm<Allocator, softAes>::execute() {
-
 		NativeRegisterFile nreg;
 
 		for(unsigned i = 0; i < RegisterCountFlt; ++i)
@@ -71,7 +70,7 @@ namespace randomx {
 			spAddr0 &= ScratchpadL3Mask64;
 			spAddr1 ^= spMix >> 32;
 			spAddr1 &= ScratchpadL3Mask64;
-			
+
 			for (unsigned i = 0; i < RegistersCount; ++i)
 				nreg.r[i] ^= load64(scratchpad + spAddr0 + 8 * i);
 
@@ -85,6 +84,7 @@ namespace randomx {
 
 			mem.mx ^= nreg.r[config.readReg2] ^ nreg.r[config.readReg3];
 			mem.mx &= CacheLineAlignMask;
+
 			datasetPrefetch(datasetOffset + mem.mx);
 			datasetRead(datasetOffset + mem.ma, nreg.r);
 			std::swap(mem.mx, mem.ma);