Move bitcasts into mathlib

Author: solidpixel

Source/astcenc_color_unquantize.cpp

@@ -51,14 +51,11 @@ static ASTCENC_SIMD_INLINE vint4 uncontract_color(
  *
  * @return The shifted value.
  */
-static ASTCENC_SIMD_INLINE int32_t safe_signed_lsh(int32_t val, int shift)
+static ASTCENC_SIMD_INLINE int safe_signed_lsh(int val, int shift)
 {
-	// Future: Can use std:bit_cast with C++20
-	uint32_t uval;
-	std::memcpy(&uval, &val, sizeof(uint32_t));
+	unsigned int uval = astc::int_as_uint(val);
 	uval <<= shift;
-	std::memcpy(&val, &uval, sizeof(uint32_t));
-	return val;
+	return astc::uint_as_int(uval);
 }
 
 void rgba_delta_unpack(

Source/astcenc_mathlib.h

@@ -26,6 +26,7 @@
 #include <cassert>
 #include <cstdint>
 #include <cmath>
+#include <cstring>
 
 #ifndef ASTCENC_POPCNT
   #if defined(__POPCNT__)
@@ -359,9 +360,10 @@ static inline int flt2int_rd(float v)
  */
 static inline int float_as_int(float v)
 {
-	union { int a; float b; } u;
-	u.b = v;
-	return u.a;
+	// Future: Can use std:bit_cast with C++20
+	int iv;
+	std::memcpy(&iv, &v, sizeof(float));
+	return iv;
 }
 
 /**
@@ -373,9 +375,70 @@ static inline int float_as_int(float v)
  */
 static inline float int_as_float(int v)
 {
-	union { int a; float b; } u;
-	u.a = v;
-	return u.b;
+	// Future: Can use std:bit_cast with C++20
+	float fv;
+	std::memcpy(&fv, &v, sizeof(int));
+	return fv;
+}
+
+/**
+ * @brief SP float bit-interpreted as an unsigned integer.
+ *
+ * @param v   The value to bitcast.
+ *
+ * @return The converted value.
+ */
+static inline unsigned int float_as_uint(float v)
+{
+	// Future: Can use std:bit_cast with C++20
+	unsigned int iv;
+	std::memcpy(&iv, &v, sizeof(float));
+	return iv;
+}
+
+/**
+ * @brief Unsigned integer bit-interpreted as an SP float.
+ *
+ * @param v   The value to bitcast.
+ *
+ * @return The converted value.
+ */
+static inline float uint_as_float(unsigned int v)
+{
+	// Future: Can use std:bit_cast with C++20
+	float fv;
+	std::memcpy(&fv, &v, sizeof(unsigned int));
+	return fv;
+}
+
+/**
+ * @brief Signed int bit-interpreted as an unsigned integer.
+ *
+ * @param v   The value to bitcast.
+ *
+ * @return The converted value.
+ */
+static inline unsigned int int_as_uint(int v)
+{
+	// Future: Can use std:bit_cast with C++20
+	unsigned int uv;
+	std::memcpy(&uv, &v, sizeof(int));
+	return uv;
+}
+
+/**
+ * @brief Unsigned integer bit-interpreted as a signed integer.
+ *
+ * @param v   The value to bitcast.
+ *
+ * @return The converted value.
+ */
+static inline int uint_as_int(unsigned int v)
+{
+	// Future: Can use std:bit_cast with C++20git p
+	int sv;
+	std::memcpy(&sv, &v, sizeof(unsigned int));
+	return sv;
 }
 
 /**

Source/astcenccli_error_metrics.cpp

@@ -68,16 +68,10 @@ static float mpsnr_operator(
 	float val,
 	int fstop
 ) {
-	// Future: Can use std:bit_cast with C++20
-
 	// Fast implementation of pow(2.0, fstop), assuming IEEE float layout
 	// Memcpy to uint avoids ubsan complaints shift of negative int
-	unsigned int fstopu;
-	std::memcpy(&fstopu, &fstop, sizeof(int));
-	uint32_t uscale = 0x3f800000 + (fstopu << 23);
-
-	float scale;
-	std::memcpy(&scale, &uscale, sizeof(float));
+	unsigned int uscale = 0x3f800000u + (astc::int_as_uint(fstop) << 23);
+	float scale = astc::uint_as_float(uscale);
 
 	val = powf(val * scale, (1.0f / 2.2f));
 	return astc::clamp(val * 255.0f, 0.0f, 255.0f);

Source/cmake_core.cmake

@@ -199,11 +199,13 @@ macro(astcenc_set_properties ASTCENC_TARGET_NAME ASTCENC_VENEER_TYPE)
     if(${ASTCENC_UBSAN})
         target_compile_options(${ASTCENC_TARGET_NAME}
             PRIVATE
-                $<${is_gnu_fe}:-fsanitize=undefined>)
+                $<${is_gnu_fe}:-fsanitize=undefined>
+                $<${is_gnu_fe}:-fno-sanitize-recover=all>)
 
         target_link_options(${ASTCENC_TARGET_NAME}
             PRIVATE
-                $<${is_gnu_fe}:-fsanitize=undefined>)
+                $<${is_gnu_fe}:-fsanitize=undefined>
+                $<${is_gnu_fe}:-fno-sanitize-recover=all>)
     endif()
 
     if(NOT ${ASTCENC_INVARIANCE})