Remove remaining type aliasing though unions

Author: solidpixel

.gitignore

@@ -9,6 +9,7 @@
 *.o
 *.a
 __pycache__
+pve
 Scratch
 Proto
 

Source/astcenc_decompress_symbolic.cpp

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Apache-2.0
 // ----------------------------------------------------------------------------
-// Copyright 2011-2024 Arm Limited
+// Copyright 2011-2025 Arm Limited
 //
 // Licensed under the Apache License, Version 2.0 (the "License"); you may not
 // use this file except in compliance with the License. You may obtain a copy
@@ -163,9 +163,7 @@ void unpack_weights(
  */
 static float error_color_nan()
 {
-	if32 v;
-	v.u = 0xFFFFE000U;
-	return v.f;
+	return astc::uint_as_float(0xFFFFE000u);
 }
 
 /* See header for documentation. */

Source/astcenc_entry.cpp

@@ -136,19 +136,19 @@ static const std::array<astcenc_preset_config, 6> preset_configs_low {{
 /**
  * @brief Validate CPU floating point meets assumptions made in the codec.
  *
- * The codec is written with the assumption that a float threaded through the @c if32 union will be
- * stored and reloaded as a 32-bit IEEE-754 float with round-to-nearest rounding. This is always the
- * case in an IEEE-754 compliant system, however not every system or compilation mode is actually
- * IEEE-754 compliant. This normally fails if the code is compiled with fast math enabled.
+ * The codec is written with the assumption that float bit patterns are valid
+ * IEEE754 values that are stored and reloaded with round-to-nearest rounding.
+ * This is always the case in an IEEE-754 compliant system, however not every
+ * system or compilation mode is actually IEEE-754 compliant. This normally
+ * fails if the code is compiled with fast math enabled, for example.
  *
- * @return Return @c ASTCENC_SUCCESS if validated, otherwise an error on failure.
+ * @return Return @c ASTCENC_SUCCESS if validated, an error on failure.
  */
 static astcenc_error validate_cpu_float()
 {
-	if32 p;
 	volatile float xprec_testval = 2.51f;
-	p.f = xprec_testval + 12582912.0f;
-	float q = p.f - 12582912.0f;
+	float store = xprec_testval + 12582912.0f;
+	float q = store - 12582912.0f;
 
 	if (q != 3.0f)
 	{

Source/astcenc_mathlib.h

@@ -124,14 +124,6 @@
   to future vectorization.
 ============================================================================ */
 
-// Union for manipulation of float bit patterns
-typedef union
-{
-	uint32_t u;
-	int32_t s;
-	float f;
-} if32;
-
 // These are namespaced to avoid colliding with C standard library functions.
 namespace astc
 {
@@ -475,11 +467,10 @@ static inline float sqrt(float v)
  */
 static inline float frexp(float v, int* expo)
 {
-	if32 p;
-	p.f = v;
-	*expo = ((p.u >> 23) & 0xFF) - 126;
-	p.u = (p.u & 0x807fffff) | 0x3f000000;
-	return p.f;
+	unsigned int iv = astc::float_as_uint(v);
+	*expo = ((iv >> 23) & 0xFF) - 126;
+	iv = (iv & 0x807fffff) | 0x3f000000;
+	return astc::uint_as_float(iv);
 }
 
 /**

Source/astcenc_mathlib_softfloat.cpp

@@ -395,17 +395,14 @@ static sf16 sf32_to_sf16(sf32 inp, roundmode rmode)
 /* convert from soft-float to native-float */
 float sf16_to_float(uint16_t p)
 {
-	if32 i;
-	i.u = sf16_to_sf32(p);
-	return i.f;
+	return astc::uint_as_float(sf16_to_sf32(p));
 }
 
 /* convert from native-float to soft-float */
 uint16_t float_to_sf16(float p)
 {
-	if32 i;
-	i.f = p;
-	return sf32_to_sf16(i.u, SF_NEARESTEVEN);
+	unsigned int ip = astc::float_as_uint(p);
+	return sf32_to_sf16(ip, SF_NEARESTEVEN);
 }
 
 #endif

Source/cmake_core.cmake

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