diff options
Diffstat (limited to 'llvm/lib/Support/APFloat.cpp')
| -rw-r--r-- | llvm/lib/Support/APFloat.cpp | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp index 4b75c9d..2ae28fe 100644 --- a/llvm/lib/Support/APFloat.cpp +++ b/llvm/lib/Support/APFloat.cpp @@ -2213,8 +2213,11 @@ IEEEFloat::opStatus IEEEFloat::convert(const fltSemantics &toSemantics, // when truncating from PowerPC double-double to double format), the // right shift could lose result mantissa bits. Adjust exponent instead // of performing excessive shift. + // Also do a similar trick in case shifting denormal would produce zero + // significand as this case isn't handled correctly by normalize. if (shift < 0 && isFiniteNonZero()) { - int exponentChange = significandMSB() + 1 - fromSemantics.precision; + int omsb = significandMSB() + 1; + int exponentChange = omsb - fromSemantics.precision; if (exponent + exponentChange < toSemantics.minExponent) exponentChange = toSemantics.minExponent - exponent; if (exponentChange < shift) @@ -2222,6 +2225,10 @@ IEEEFloat::opStatus IEEEFloat::convert(const fltSemantics &toSemantics, if (exponentChange < 0) { shift -= exponentChange; exponent += exponentChange; + } else if (omsb <= -shift) { + exponentChange = omsb + shift - 1; // leave at least one bit set + shift -= exponentChange; + exponent += exponentChange; } } |