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Strict Aliasing Rule #3390

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Strict Aliasing Rule #3390

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26 changes: 9 additions & 17 deletions tensorflow/lite/kernels/internal/quantization_util.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -127,13 +127,9 @@ int64_t IntegerFrExp(double input, int* shift) {
TFLITE_CHECK_EQ(8, sizeof(double));

// We want to access the bits of the input double value directly, which is
// tricky to do safely, so use a union to handle the casting.
union {
double double_value;
uint64_t double_as_uint;
} cast_union;
cast_union.double_value = input;
const uint64_t u = cast_union.double_as_uint;
// tricky to do safely, so use memcpy to handle the casting.
uint64_t u;
std::memcpy(&u, &input, sizeof(u));

// If the bitfield is all zeros apart from the sign bit, this is a normalized
// zero value, so return standard values for this special case.
Expand Down Expand Up @@ -189,11 +185,6 @@ int64_t IntegerFrExp(double input, int* shift) {
}

double DoubleFromFractionAndShift(int64_t fraction, int shift) {
union {
double double_value;
uint64_t double_as_uint;
} result;

// Detect NaNs and infinities.
if (shift == std::numeric_limits<int>::max()) {
if (fraction == 0) {
Expand All @@ -207,8 +198,7 @@ double DoubleFromFractionAndShift(int64_t fraction, int shift) {

// Return a normalized zero for a zero fraction.
if (fraction == 0) {
result.double_as_uint = 0;
return result.double_value;
return 0.0;
}

bool is_negative = (fraction < 0);
Expand All @@ -230,9 +220,11 @@ double DoubleFromFractionAndShift(int64_t fraction, int shift) {
}
encoded_shift += kExponentBias;
uint64_t encoded_sign = is_negative ? kSignMask : 0;
result.double_as_uint = encoded_sign | (encoded_shift << kExponentShift) |
(encoded_fraction << kFractionShift);
return result.double_value;
uint64_t result_as_uint = encoded_sign | (encoded_shift << kExponentShift) |
(encoded_fraction << kFractionShift);
double result;
std::memcpy(&result, &result_as_uint, sizeof(result));
return result;
}

double IntegerDoubleMultiply(double a, double b) {
Expand Down
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