Fixed constexpr-ness of bx::bitCast.

bkaradzic · Nov 15, 2024 · cf3b711 · cf3b711
1 parent 109637a
commit cf3b711
Show file tree

Hide file tree

Showing 4 changed files with 21 additions and 101 deletions.
diff --git a/include/bx/bx.h b/include/bx/bx.h
@@ -223,7 +223,7 @@ namespace bx
 	/// Performs `static_cast` of value `_from`, and in debug build runtime verifies/asserts
 	/// that the value didn't change.
 	template<typename Ty, typename FromT>
-	constexpr Ty narrowCast(const FromT& _from, Location _location = Location::current() );
+	Ty narrowCast(const FromT& _from, Location _location = Location::current() );
 
 	/// Copy memory block.
 	///

diff --git a/include/bx/inline/bx.inl b/include/bx/inline/bx.inl
@@ -153,18 +153,21 @@ namespace bx
 		static_assert(sizeof(Ty) == sizeof(FromT)
 			, "bx::bitCast failed! Ty and FromT must be the same size."
 			);
+		static_assert(isTriviallyCopyable<FromT>()
+			, "bx::bitCast failed! FromT must be trivially copyable."
+			);
+		static_assert(isTriviallyCopyable<Ty>()
+			, "bx::bitCast failed! Ty must be trivially copyable."
+			);
 		static_assert(isTriviallyConstructible<Ty>()
-			, "bx::bitCast failed! Destination target must be trivially constructible."
+			, "bx::bitCast failed! Ty must be trivially constructible."
 			);
 
-		Ty to;
-		memCopy(&to, &_from, sizeof(Ty) );
-
-		return to;
+		return __builtin_bit_cast(Ty, _from);
 	}
 
 	template<typename Ty, typename FromT>
-	inline constexpr Ty narrowCast(const FromT& _from, Location _location)
+	inline Ty narrowCast(const FromT& _from, Location _location)
 	{
 		Ty to = static_cast<Ty>(_from);
 		BX_ASSERT_LOC(_location, static_cast<FromT>(to) == _from

diff --git a/include/bx/platform.h b/include/bx/platform.h
@@ -342,18 +342,6 @@
 #		define BX_COMPILER_NAME "MSVC 17.0"
 #	elif BX_COMPILER_MSVC >= 1920 // Visual Studio 2019
 #		define BX_COMPILER_NAME "MSVC 16.0"
-#	elif BX_COMPILER_MSVC >= 1910 // Visual Studio 2017
-#		define BX_COMPILER_NAME "MSVC 15.0"
-#	elif BX_COMPILER_MSVC >= 1900 // Visual Studio 2015
-#		define BX_COMPILER_NAME "MSVC 14.0"
-#	elif BX_COMPILER_MSVC >= 1800 // Visual Studio 2013
-#		define BX_COMPILER_NAME "MSVC 12.0"
-#	elif BX_COMPILER_MSVC >= 1700 // Visual Studio 2012
-#		define BX_COMPILER_NAME "MSVC 11.0"
-#	elif BX_COMPILER_MSVC >= 1600 // Visual Studio 2010
-#		define BX_COMPILER_NAME "MSVC 10.0"
-#	elif BX_COMPILER_MSVC >= 1500 // Visual Studio 2008
-#		define BX_COMPILER_NAME "MSVC 9.0"
 #	else
 #		define BX_COMPILER_NAME "MSVC"
 #	endif //
@@ -481,6 +469,12 @@ static_assert(!BX_COMPILER_GCC || BX_COMPILER_GCC >= 80400, "\n\n"
 	"\tMinimum supported GCC version is 8.4 (March 4, 2020).\n"
 	"\t\n");
 
+// https://learn.microsoft.com/en-us/visualstudio/releases/2019/history
+static_assert(!BX_COMPILER_MSVC || BX_COMPILER_MSVC >= 1927, "\n\n"
+	"\t** IMPORTANT! **\n\n"
+	"\tMinimum supported MSVC 19.27 / Visual Studio 2019 version 16.7 (August 5, 2020).\n"
+	"\t\n");
+
 static_assert(!BX_CPU_ENDIAN_BIG, "\n\n"
 	"\t** IMPORTANT! **\n\n"
 	"\tThe code was not tested for big endian, and big endian CPU is considered unsupported.\n"

diff --git a/tests/cast_test.cpp b/tests/cast_test.cpp
@@ -7,89 +7,12 @@
 #include <bx/bx.h>
 #include <string.h>
 
-namespace bx
+TEST_CASE("Bit cast", "[cast]")
 {
-	extern void memCopyRef(void* _dst, const void* _src, size_t _numBytes);
-}
-
-TEST_CASE("Bit cast round trip test using double to uint64_t", "[cast]")
-{
-	constexpr double d64v = 19880124.0;
-	REQUIRE(sizeof(double) == sizeof(uint64_t) );
-
-	SECTION("bx::bitCast")
-	{
-		const uint64_t u64v = bx::bitCast<uint64_t>(d64v);
-		const double result = bx::bitCast<double>(u64v);
-		REQUIRE(result == d64v);
-	}
-
-	SECTION("bx::memCopy")
-	{
-		uint64_t u64v = 0;
-		double result = 0;
-		bx::memCopy(&u64v, &d64v, sizeof(uint64_t) );
-		bx::memCopy(&result, &u64v, sizeof(double) );
-		REQUIRE(result == d64v);
-	}
-
-	SECTION("bx::memCopyRef")
-	{
-		uint64_t u64v = 0;
-		double result = 0;
-		bx::memCopyRef(&u64v, &d64v, sizeof(uint64_t) );
-		bx::memCopyRef(&result, &u64v, sizeof(double) );
-		REQUIRE(result == d64v);
-	}
-
-	SECTION("::memcpy")
-	{
-		uint64_t u64v = 0;
-		double result = 0;
-		::memcpy(&u64v, &d64v, sizeof(uint64_t) );
-		::memcpy(&result, &u64v, sizeof(double) );
-		REQUIRE(result == d64v);
-	}
-}
-
-TEST_CASE("Bit cast round trip test using uint64_t to double", "[cast]")
-{
-	constexpr uint64_t u64v = 0x3fe9000000000000ull;
-	REQUIRE(sizeof(uint64_t) == sizeof(double) );
-
-	SECTION("bx::bitCast")
-	{
-		const double d64v = bx::bitCast<double>(u64v);
-		const uint64_t result = bx::bitCast<uint64_t>(d64v);
-		REQUIRE(result == u64v);
-	}
-
-	SECTION("bx::memCopy")
-	{
-		double d64v = 0;
-		uint64_t result = 0;
-		bx::memCopy(&d64v, &u64v, sizeof(double) );
-		bx::memCopy(&result, &d64v, sizeof(uint64_t) );
-		REQUIRE(result == u64v);
-	}
-
-	SECTION("bx::memCopyRef")
-	{
-		double d64v = 0;
-		uint64_t result = 0;
-		bx::memCopyRef(&d64v, &u64v, sizeof(double) );
-		bx::memCopyRef(&result, &d64v, sizeof(uint64_t) );
-		REQUIRE(result == u64v);
-	}
-
-	SECTION("::memcpy")
-	{
-		double d64v = 0;
-		uint64_t result = 0;
-		::memcpy(&d64v, &u64v, sizeof(double) );
-		::memcpy(&result, &d64v, sizeof(uint64_t) );
-		REQUIRE(result == u64v);
-	}
+	STATIC_REQUIRE(0x4172f58bc0000000ull == bx::bitCast<uint64_t>(19880124.0) );
+	STATIC_REQUIRE(0x3fe9000000000000ull == bx::bitCast<uint64_t>(0.781250) );
+	STATIC_REQUIRE(19880124.0            == bx::bitCast<double>(0x4172f58bc0000000ull) );
+	STATIC_REQUIRE(0.781250              == bx::bitCast<double>(0x3fe9000000000000ull) );
 }
 
 TEST_CASE("Narrow cast", "[cast]")