APFloat: Make sure that we get a well-formed x87 NaN when converting from a smaller type.
Fixes PR15054.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@173459 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Support/APFloat.cpp b/lib/Support/APFloat.cpp
index 686f91b..5b68fbb 100644
--- a/lib/Support/APFloat.cpp
+++ b/lib/Support/APFloat.cpp
@@ -1913,6 +1913,12 @@
*losesInfo = (fs != opOK);
} else if (category == fcNaN) {
*losesInfo = lostFraction != lfExactlyZero || X86SpecialNan;
+
+ // For x87 extended precision, we want to make a NaN, not a special NaN if
+ // the input wasn't special either.
+ if (!X86SpecialNan && semantics == &APFloat::x87DoubleExtended)
+ APInt::tcSetBit(significandParts(), semantics->precision - 1);
+
// gcc forces the Quiet bit on, which means (float)(double)(float_sNan)
// does not give you back the same bits. This is dubious, and we
// don't currently do it. You're really supposed to get