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Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes (bug 34579) 

Patch IEEEFloat::isSignificandAllZeros and IEEEFloat::isSignificandAllOnes to behave correctly in the case that the size of the significand is a multiple of the width of the integerParts making up the significand.

The patch to IEEEFloat::isSignificandAllOnes fixes bug 34579, and the patch to IEEE:Float:isSignificandAllZeros fixes the unit test "APFloatTest.x87Next" I added here. I have included both in this diff since the changes are very similar.

Patch by Andrew Briand
This commit is contained in:
Craig Topper 2020-09-30 13:55:01 -07:00
parent 66d2e3f495
commit b23916504a
2 changed files with 13 additions and 2 deletions
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4
llvm/lib/Support/APFloat.cpp
View File

@ -842,7 +842,7 @@ bool IEEEFloat::isSignificandAllOnes() const {
// Test if the significand excluding the integral bit is all ones. This allows
// us to test for binade boundaries.
const integerPart *Parts = significandParts();
const unsigned PartCount = partCount();
const unsigned PartCount = partCountForBits(semantics->precision);
for (unsigned i = 0; i < PartCount - 1; i++)
if (~Parts[i])
return false;
@ -864,7 +864,7 @@ bool IEEEFloat::isSignificandAllZeros() const {
// Test if the significand excluding the integral bit is all zeros. This
// allows us to test for binade boundaries.
const integerPart *Parts = significandParts();
const unsigned PartCount = partCount();
const unsigned PartCount = partCountForBits(semantics->precision);
for (unsigned i = 0; i < PartCount - 1; i++)
if (Parts[i])

11
llvm/unittests/ADT/APFloatTest.cpp
View File

@ -4696,4 +4696,15 @@ TEST(APFloatTest, PPCDoubleDoubleFrexp) {
EXPECT_EQ(0x3fe8000000000000ull, Result.bitcastToAPInt().getRawData()[0]);
EXPECT_EQ(0x3c98000000000000ull, Result.bitcastToAPInt().getRawData()[1]);
}
TEST(APFloatTest, x87Largest) {
APFloat MaxX87Val = APFloat::getLargest(APFloat::x87DoubleExtended());
EXPECT_TRUE(MaxX87Val.isLargest());
}
TEST(APFloatTest, x87Next) {
APFloat F(APFloat::x87DoubleExtended(), "-1.0");
F.next(false);
EXPECT_TRUE(ilogb(F) == -1);
}
}