Title: [259537] trunk/Source/WTF
- Revision
- 259537
- Author
- [email protected]
- Date
- 2020-04-04 14:42:23 -0700 (Sat, 04 Apr 2020)
Log Message
[Clang 10] Fix -Wimplicit-int-float-conversion compilation warnings in WTF
https://bugs.webkit.org/show_bug.cgi?id=209955
Reviewed by Darin Adler.
Clang 10 reports a compilation warning for int to float
conversions losing the precision. The warning is often reported
for code converting a floating point value to an integer value.
For example:
> Optional<int> positive_float_to_int(float f) {
> if (f > INT_MAX)
> return nullopt;
> return static_cast<int>(f);
> }
INT_MAX is implicitly converted float, but float can't keep the
precision of such large value. And, C++ spec doesn't specify
whether it would be rounded up or down. Above code should be
rewritten to:
> Optional<int> positive_float_to_int(float f) {
> if (f >= pow(2, 31))
> return nullopt;
> return static_cast<int>(f);
> }
Instead of using pow, this change added a template variable
maxPlusOne<T>.
* wtf/MathExtras.h:
(powerOfTwo): Added.
(doubleToInteger): Added.
(maxPlusOne): Added.
* wtf/MediaTime.cpp:
(WTF::MediaTime::createWithFloat):
(WTF::MediaTime::createWithDouble):
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (259536 => 259537)
--- trunk/Source/WTF/ChangeLog 2020-04-04 19:36:31 UTC (rev 259536)
+++ trunk/Source/WTF/ChangeLog 2020-04-04 21:42:23 UTC (rev 259537)
@@ -1,3 +1,43 @@
+2020-04-04 Fujii Hironori <[email protected]>
+
+ [Clang 10] Fix -Wimplicit-int-float-conversion compilation warnings in WTF
+ https://bugs.webkit.org/show_bug.cgi?id=209955
+
+ Reviewed by Darin Adler.
+
+ Clang 10 reports a compilation warning for int to float
+ conversions losing the precision. The warning is often reported
+ for code converting a floating point value to an integer value.
+ For example:
+
+ > Optional<int> positive_float_to_int(float f) {
+ > if (f > INT_MAX)
+ > return nullopt;
+ > return static_cast<int>(f);
+ > }
+
+ INT_MAX is implicitly converted float, but float can't keep the
+ precision of such large value. And, C++ spec doesn't specify
+ whether it would be rounded up or down. Above code should be
+ rewritten to:
+
+ > Optional<int> positive_float_to_int(float f) {
+ > if (f >= pow(2, 31))
+ > return nullopt;
+ > return static_cast<int>(f);
+ > }
+
+ Instead of using pow, this change added a template variable
+ maxPlusOne<T>.
+
+ * wtf/MathExtras.h:
+ (powerOfTwo): Added.
+ (doubleToInteger): Added.
+ (maxPlusOne): Added.
+ * wtf/MediaTime.cpp:
+ (WTF::MediaTime::createWithFloat):
+ (WTF::MediaTime::createWithDouble):
+
2020-04-03 David Kilzer <[email protected]>
[Xcode] Replace ASAN_OTHER_CFLAGS and ASAN_OTHER_CPLUSPLUSFLAGS with $(inherited)
Modified: trunk/Source/WTF/wtf/MathExtras.h (259536 => 259537)
--- trunk/Source/WTF/wtf/MathExtras.h 2020-04-04 19:36:31 UTC (rev 259536)
+++ trunk/Source/WTF/wtf/MathExtras.h 2020-04-04 21:42:23 UTC (rev 259537)
@@ -391,6 +391,19 @@
mantissa |= 0x10000000000000ull;
}
+template<typename T> constexpr unsigned countOfBits = sizeof(T) * CHAR_BIT;
+template<typename T> constexpr unsigned countOfMagnitudeBits = countOfBits<T> - std::is_signed_v<T>;
+
+constexpr float powerOfTwo(unsigned e)
+{
+ float p = 1;
+ while (e--)
+ p *= 2;
+ return p;
+}
+
+template<typename T> constexpr float maxPlusOne = powerOfTwo(countOfMagnitudeBits<T>);
+
// Calculate d % 2^{64}.
inline void doubleToInteger(double d, unsigned long long& value)
{
@@ -398,7 +411,7 @@
value = 0;
else {
// -2^{64} < fmodValue < 2^{64}.
- double fmodValue = fmod(trunc(d), std::numeric_limits<unsigned long long>::max() + 1.0);
+ double fmodValue = fmod(trunc(d), maxPlusOne<unsigned long long>);
if (fmodValue >= 0) {
// 0 <= fmodValue < 2^{64}.
// 0 <= value < 2^{64}. This cast causes no loss.
Modified: trunk/Source/WTF/wtf/MediaTime.cpp (259536 => 259537)
--- trunk/Source/WTF/wtf/MediaTime.cpp 2020-04-04 19:36:31 UTC (rev 259536)
+++ trunk/Source/WTF/wtf/MediaTime.cpp 2020-04-04 21:42:23 UTC (rev 259537)
@@ -95,7 +95,7 @@
return invalidTime();
if (std::isinf(floatTime))
return std::signbit(floatTime) ? negativeInfiniteTime() : positiveInfiniteTime();
- if (floatTime > std::numeric_limits<int64_t>::max())
+ if (floatTime >= maxPlusOne<int64_t>)
return positiveInfiniteTime();
if (floatTime < std::numeric_limits<int64_t>::min())
return negativeInfiniteTime();
@@ -102,7 +102,7 @@
if (!timeScale)
return std::signbit(floatTime) ? negativeInfiniteTime() : positiveInfiniteTime();
- while (floatTime * timeScale > std::numeric_limits<int64_t>::max())
+ while (floatTime * timeScale >= maxPlusOne<int64_t>)
timeScale /= 2;
return MediaTime(static_cast<int64_t>(floatTime * timeScale), timeScale, Valid);
}
@@ -125,7 +125,7 @@
return invalidTime();
if (std::isinf(doubleTime))
return std::signbit(doubleTime) ? negativeInfiniteTime() : positiveInfiniteTime();
- if (doubleTime > std::numeric_limits<int64_t>::max())
+ if (doubleTime >= maxPlusOne<int64_t>)
return positiveInfiniteTime();
if (doubleTime < std::numeric_limits<int64_t>::min())
return negativeInfiniteTime();
@@ -132,7 +132,7 @@
if (!timeScale)
return std::signbit(doubleTime) ? negativeInfiniteTime() : positiveInfiniteTime();
- while (doubleTime * timeScale > std::numeric_limits<int64_t>::max())
+ while (doubleTime * timeScale >= maxPlusOne<int64_t>)
timeScale /= 2;
return MediaTime(static_cast<int64_t>(std::round(doubleTime * timeScale)), timeScale, Valid);
}
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