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Allow implicit conversion from bfloat16 to float and double

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Conversion from `bfloat16` to `float` and `double` is lossless. It seems natural to allow the conversion to be implicit, as the C++ language also support implicit conversion from a smaller to a larger floating point type.

Intel's OneDLL bfloat16 implementation also has an implicit `operator float()`: https://github.com/oneapi-src/oneDNN/blob/v1.5/src/common/bfloat16.hpp
This commit is contained in:
Niels Dekker
2020-07-11 12:50:46 +02:00
parent dcf7655b3d
commit 4ab32e2de2
2 changed files with 5 additions and 5 deletions
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6
test/bfloat16_float.cpp
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@@ -53,9 +53,9 @@ void test_conversion()
VERIFY_IS_EQUAL(bfloat16(3.40e38f).value, 0x7f80); // Becomes infinity.
// Verify round-to-nearest-even behavior.
float val1 = static_cast<float>(bfloat16(__bfloat16_raw(0x3c00)));
float val2 = static_cast<float>(bfloat16(__bfloat16_raw(0x3c01)));
float val3 = static_cast<float>(bfloat16(__bfloat16_raw(0x3c02)));
float val1 = bfloat16(__bfloat16_raw(0x3c00));
float val2 = bfloat16(__bfloat16_raw(0x3c01));
float val3 = bfloat16(__bfloat16_raw(0x3c02));
VERIFY_IS_EQUAL(bfloat16(0.5f * (val1 + val2)).value, 0x3c00);
VERIFY_IS_EQUAL(bfloat16(0.5f * (val2 + val3)).value, 0x3c02);