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[flang] Correct off-by-one error in SET_EXPONENT

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SET_EXPONENT is returning values that are too large by a factor
of two.

Differential Revision: https://reviews.llvm.org/D107986
This commit is contained in:
peter klausler 2021-08-12 11:10:53 -07:00
parent a2556bf44c
commit a05bae6163
2 changed files with 5 additions and 5 deletions
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2
flang/runtime/numeric.cpp
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@ -109,7 +109,7 @@ template <typename T> inline T SetExponent(T x, std::int64_t p) {
} else if (x == 0) {
return 0; // 0 -> 0
} else {
int expo{std::ilogb(x)};
int expo{std::ilogb(x) + 1};
auto ip{static_cast<int>(p - expo)};
if (ip != p - expo) {
ip = p < 0 ? std::numeric_limits<int>::min()

8
flang/unittests/Runtime/Numeric.cpp
View file

@ -142,10 +142,10 @@ TEST(Numeric, Scale) {
TEST(Numeric, SetExponent) {
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{0}, 0), 0);
EXPECT_EQ(RTNAME(SetExponent8)(Real<8>{0}, 666), 0);
EXPECT_EQ(RTNAME(SetExponent8)(Real<8>{3.0}, 0), 1.5);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, 0), 1.0);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, 1), 2.0);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, -1), 0.5);
EXPECT_EQ(RTNAME(SetExponent8)(Real<8>{3.0}, 0), 0.75);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, 0), 0.5);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, 1), 1.0);
EXPECT_EQ(RTNAME(SetExponent4)(Real<4>{1.0}, -1), 0.25);
EXPECT_TRUE(std::isnan(
RTNAME(SetExponent4)(std::numeric_limits<Real<4>>::infinity(), 1)));
EXPECT_TRUE(std::isnan(