From ca3bc1bd80fdff511e83d563a4ee94d6cd885473 Mon Sep 17 00:00:00 2001
From: Chris Robinson <chris.kcat@gmail.com>
Date: Fri, 25 Aug 2023 11:28:05 -0700
Subject: Use a bit_cast instead of a union for type-punning
---
common/alnumeric.h | 47 ++++++++++++++++-------------------------------
1 file changed, 16 insertions(+), 31 deletions(-)
(limited to 'common/alnumeric.h')
diff --git a/common/alnumeric.h b/common/alnumeric.h
index 8220d3e5..620a9bcb 100644
--- a/common/alnumeric.h
+++ b/common/alnumeric.h
@@ -12,6 +12,7 @@
#include <xmmintrin.h>
#endif
+#include "albit.h"
#include "altraits.h"
#include "opthelpers.h"
@@ -159,21 +160,16 @@ inline int float2int(float f) noexcept
#elif (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP == 0) \
|| ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) \
&& !defined(__SSE_MATH__))
- int sign, shift, mant;
- union {
- float f;
- int i;
- } conv;
+ const int conv_i{al::bit_cast<int>(f)};
- conv.f = f;
- sign = (conv.i>>31) | 1;
- shift = ((conv.i>>23)&0xff) - (127+23);
+ const int sign{(conv_i>>31) | 1};
+ const int shift{((conv_i>>23)&0xff) - (127+23)};
/* Over/underflow */
if(shift >= 31 || shift < -23) UNLIKELY
return 0;
- mant = (conv.i&0x7fffff) | 0x800000;
+ const int mant{(conv_i&0x7fffff) | 0x800000};
if(shift < 0) LIKELY
return (mant >> -shift) * sign;
return (mant << shift) * sign;
@@ -195,25 +191,19 @@ inline int double2int(double d) noexcept
#elif (defined(_MSC_VER) && defined(_M_IX86_FP) && _M_IX86_FP < 2) \
|| ((defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__)) \
&& !defined(__SSE2_MATH__))
- int sign, shift;
- int64_t mant;
- union {
- double d;
- int64_t i64;
- } conv;
+ const int64_t conv_i64{al::bit_cast<int64_t>(d)};
- conv.d = d;
- sign = (conv.i64 >> 63) | 1;
- shift = ((conv.i64 >> 52) & 0x7ff) - (1023 + 52);
+ const int sign{static_cast<int>(conv_i64 >> 63) | 1};
+ const int shift{(static_cast<int>(conv_i64 >> 52) & 0x7ff) - (1023 + 52)};
/* Over/underflow */
if(shift >= 63 || shift < -52) UNLIKELY
return 0;
- mant = (conv.i64 & 0xfffffffffffff_i64) | 0x10000000000000_i64;
+ const int64_t mant{(conv_i64 & 0xfffffffffffff_i64) | 0x10000000000000_i64};
if(shift < 0) LIKELY
- return (int)(mant >> -shift) * sign;
- return (int)(mant << shift) * sign;
+ return static_cast<int>(mant >> -shift) * sign;
+ return static_cast<int>(mant << shift) * sign;
#else
@@ -246,19 +236,14 @@ inline float fast_roundf(float f) noexcept
/* Integral limit, where sub-integral precision is not available for
* floats.
*/
- static const float ilim[2]{
+ static constexpr float ilim[2]{
8388608.0f /* 0x1.0p+23 */,
-8388608.0f /* -0x1.0p+23 */
};
- unsigned int sign, expo;
- union {
- float f;
- unsigned int i;
- } conv;
-
- conv.f = f;
- sign = (conv.i>>31)&0x01;
- expo = (conv.i>>23)&0xff;
+ const unsigned int conv_i{al::bit_cast<unsigned int>(f)};
+
+ const unsigned int sign{(conv_i>>31)&0x01};
+ const unsigned int expo{(conv_i>>23)&0xff};
if(expo >= 150/*+23*/) UNLIKELY
{
--
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