Working on optimisation but I'm still losing to std::to_string()

CMakeLists.txt

@@ -41,6 +41,10 @@ target_compile_definitions(${PROJECT_NAME}
 	INTERFACE SPROUT_USE_TEMPLATE_ALIASES
 )
 
+target_compile_options(${PROJECT_NAME}
+	INTERFACE -mprfchw
+)
+
 if (BUILD_TESTING)
 	add_subdirectory(test/unit)
 endif()

include/duckhandy/implem/int_conv.hpp

@@ -104,11 +104,26 @@ namespace dhandy {
 
 			template <typename L>
 			[[gnu::pure,gnu::always_inline]]
-			static constexpr L abs(L in) { return (not BecomesUnsigned and std::numeric_limits<L>::is_signed and in < L(0) ? -in : in); }
+			static constexpr L abs(L v);
 			[[gnu::pure,gnu::always_inline]]
 			static constexpr CastedType cast (I in) { return static_cast<CastedType>(in); }
 		};
 
+		template <typename I, std::size_t Base, bool IsSigned, bool ForceUnsigned>
+		template <typename L>
+		[[gnu::const,gnu::always_inline]]
+		inline constexpr L NumberAdaptation<I, Base, IsSigned, ForceUnsigned>::abs(L v) {
+			if constexpr (not BecomesUnsigned and std::numeric_limits<L>::is_signed) {
+				//https://graphics.stanford.edu/~seander/bithacks.html#IntegerAbs
+				const L mask = v >> (sizeof(L) * CHAR_BIT - 1);
+				const UnsignedType r = (v + mask) ^ mask;
+				return static_cast<L>(r);
+			}
+			else {
+				return v;
+			}
+		}
+
 		template <typename I, unsigned int Base, typename Tr, typename=void>
 		struct IntConversion {
 			static constexpr RevArray<I, Base, Tr> to_ary (I in) {
@@ -156,18 +171,21 @@ namespace dhandy {
 				const bool was_negative = implem::is_negative<I, 10>(in);
 
 				RetType arr;
+				if (not std::is_constant_evaluated())
+					__builtin_prefetch(arr.base_ptr(), 1, 3);
 				arr.push_front(Tr::NullChar);
-				while (Num::abs(in) >= static_cast<I>(100)) {
-					const auto index = (Num::abs(in) % 100) * 2;
+				in = Num::abs(in);
+				while (in >= static_cast<I>(100)) {
+					const auto index = (in % 100) * 2;
 					arr.push_front(Tr::to_digit(static_cast<int>(lookup[index + 1])));
 					arr.push_front(Tr::to_digit(static_cast<int>(lookup[index + 0])));
 					in = static_cast<I>(in / static_cast<I>(100));
 				};
-				if (Num::abs(in) < static_cast<I>(10)) {
-					arr.push_front(Tr::to_digit(static_cast<int>(Num::abs(in))));
+				if (in < static_cast<I>(10)) {
+					arr.push_front(Tr::to_digit(static_cast<int>(in)));
 				}
 				else {
-					const auto index = Num::abs(in) * 2;
+					const auto index = in * 2;
 					arr.push_front(Tr::to_digit(static_cast<int>(lookup[index + 1])));
 					arr.push_front(Tr::to_digit(static_cast<int>(lookup[index + 0])));
 				}
@@ -301,17 +319,24 @@ namespace dhandy {
 		static const constexpr unsigned int DigitCount = DCount;
 
 		static constexpr C to_digit (unsigned int num) {
-			return (num < DigitCount ?
-				static_cast<C>(num + FirstDigit) :
-				static_cast<C>(num + FirstLetter - DigitCount)
-			);
+			constexpr const C ret[2] = {FirstDigit, FirstLetter - DigitCount};
+#if 0
+			//https://graphics.stanford.edu/~seander/bithacks.html#ConditionalSetOrClearBitsWithoutBranching
+			const bool f = num >= DigitCount;
+			constexpr const unsigned int m = 1;
+			const unsigned int w = (-f & m);
+#else
+			const auto w = (DigitCount - 1 - num) >> (sizeof(unsigned int) * CHAR_BIT - 1);
+#endif
+			return num + ret[w];
 		}
 
 		static constexpr int from_digit (C dig) {
-			return (dig < FirstLetter ?
-				dig - FirstDigit :
-				dig - FirstLetter + DigitCount
-			);
+			//return (dig < FirstLetter ?  dig - FirstDigit : dig - FirstLetter + DigitCount);
+			typedef typename std::make_unsigned<C>::type UC;
+			constexpr const C ret[2] = {FirstLetter - DigitCount, FirstDigit};
+			const auto w = static_cast<UC>(dig - FirstLetter) >> (sizeof(UC) * CHAR_BIT - 1);
+			return dig - ret[w];
 		}
 	};
 	template <typename C>

include/duckhandy/implem/reversed_sized_array_bt.hpp

@@ -46,6 +46,7 @@ namespace dhandy {
 		constexpr T& operator[] (std::size_t idx) { if (idx >= size()) throw std::out_of_range("Out of bound array access"); return m_data[idx + m_curr + 1]; }
 		constexpr void push_front (const T& itm) { if (size() == S) throw std::length_error("ReversedSizedArray is full"); m_data[m_curr--] = itm; }
 		constexpr const T* data() const { return m_data.data() + m_curr + 1; }
+		constexpr const T* base_ptr() const { return m_data.data(); }
 		constexpr iterator begin() { return m_data.begin() + m_curr + 1; }
 		constexpr iterator end() { return m_data.end(); }
 		constexpr const T& back() const { return *(m_data.data() + S - 1); }
@@ -62,6 +63,8 @@ namespace dhandy {
 		bool operator!= (const std::basic_string<T>& other) const { return not operator==(other); }
 		bool operator== (const T* other) const { return to_string_view() == std::basic_string_view<T>(other); }
 		bool operator!= (const T* other) const { return not operator==(other); }
+
+		std::string to_string() const { return to<std::basic_string<T>>(); }
 #endif
 
 	private:

include/duckhandy/int_conv.hpp

@@ -91,9 +91,9 @@ namespace dhandy {
 		};
 	} //namespace implem
 
-	template <typename To, typename From>
-	constexpr inline To int_conv (const From& from, bool all_caps=false) {
-		if (all_caps)
+	template <typename To, typename From, bool AllCaps=false>
+	constexpr inline To int_conv (const From& from, std::integral_constant<bool, AllCaps> = std::integral_constant<bool, AllCaps>{}) {
+		if constexpr (AllCaps)
 			return implem::IntConv<To, From, ASCIITranslatorUpcase<char>>::conv(from);
 		else
 			return implem::IntConv<To, From, ASCIITranslator<char>>::conv(from);

test/unit/CMakeLists.txt

@@ -1,9 +1,9 @@
 project(dhandy_unit_test CXX)
 
 add_executable(${PROJECT_NAME}
+	int_conv_test.cpp
 	main.cpp
 	endianness_test.cpp
-	int_conv_test.cpp
 	reversed_sized_array_test.cpp
 	bitfield_pack_test.cpp
 	resource_pool_test.cpp

test/unit/int_conv_test.cpp

@@ -266,11 +266,11 @@ TEST_CASE ("Check upcase/downcase int to array conversions", "[i2s][int_conv]")
 }
 
 TEST_CASE ("Try int conv with non-char", "[s2i][int_conv]") {
-	using dhandy::int_to_ary;
+	using dhandy::buildtime_int_to_ary;
 	using dhandy::ASCIITranslator;
 
 	std::wstring_view exp1(L"235713");
-	auto val1 = int_to_ary<int, 10, ASCIITranslator<wchar_t>>(235713).to_string_view();
+	auto val1 = buildtime_int_to_ary<int, 235713, 10, ASCIITranslator<wchar_t>>().to_string_view();
 	CHECK(exp1 == val1);
 }