Detect endianness without boost help

libevmjit/Endianness.cpp

@@ -12,12 +12,21 @@ namespace eth
 namespace jit
 {
 
-llvm::Value* Endianness::bswap(llvm::IRBuilder<>& _builder, llvm::Value* _word)
+llvm::Value* Endianness::bswapIfLE(llvm::IRBuilder<>& _builder, llvm::Value* _word)
 {
-	// TODO: Native is Little Endian
-	assert(_word->getType() == Type::Word);
-	auto bswap = llvm::Intrinsic::getDeclaration(_builder.GetInsertBlock()->getParent()->getParent(), llvm::Intrinsic::bswap, Type::Word);
-	return _builder.CreateCall(bswap, _word);
+	union tester
+	{
+		unsigned int  x;
+		unsigned char isLE;
+	};
+
+	if (tester{1}.isLE)
+	{
+		// OPT: Cache func declaration?
+		auto bswapFunc = llvm::Intrinsic::getDeclaration(_builder.GetInsertBlock()->getParent()->getParent(), llvm::Intrinsic::bswap, Type::Word);
+		return _builder.CreateCall(bswapFunc, _word);
+	}
+	return _word;
 }
 
 }

libevmjit/Endianness.h

@@ -1,8 +1,6 @@
 
 #pragma once
 
-#include <boost/detail/endian.hpp>
-
 #include <llvm/IR/IRBuilder.h>
 
 namespace dev
@@ -14,19 +12,11 @@ namespace jit
 
 struct Endianness
 {
-
-#if defined(BOOST_LITTLE_ENDIAN)
-	static llvm::Value* toBE(llvm::IRBuilder<>& _builder, llvm::Value* _word) { return bswap(_builder, _word); }
-	static llvm::Value* toNative(llvm::IRBuilder<>& _builder, llvm::Value* _word) { return bswap(_builder, _word); }
-
-#elif defined(BOOST_BIG_ENDIAN)
-	static llvm::Value* toBE(llvm::IRBuilder<>&, llvm::Value* _word) { return _word; }
-	static llvm::Value* toNative(llvm::IRBuilder<>&, llvm::Value* _word) { return _word; }
-
-#endif	// Add support for PDP endianness if needed
+	static llvm::Value* toBE(llvm::IRBuilder<>& _builder, llvm::Value* _word) { return bswapIfLE(_builder, _word); }
+	static llvm::Value* toNative(llvm::IRBuilder<>& _builder, llvm::Value* _word) { return bswapIfLE(_builder, _word); }
 
 private:
-	static llvm::Value* bswap(llvm::IRBuilder<>& _builder, llvm::Value* _word);
+	static llvm::Value* bswapIfLE(llvm::IRBuilder<>& _builder, llvm::Value* _word);
 };
 
 }