[ADT] Add the scalbn function for APFloat.
llvm-svn: 219473
diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp
index 659914a..3063a07 100644
--- a/llvm/lib/Support/APFloat.cpp
+++ b/llvm/lib/Support/APFloat.cpp
@@ -3906,3 +3906,20 @@
exponent = semantics->minExponent-1;
APInt::tcSet(significandParts(), 0, partCount());
}
+
+APFloat llvm::scalbn(APFloat X, int Exp) {
+ if (X.isInfinity() || X.isZero() || X.isNaN())
+ return std::move(X);
+
+ auto MaxExp = X.getSemantics().maxExponent;
+ auto MinExp = X.getSemantics().minExponent;
+ if (Exp > (MaxExp - X.exponent))
+ // Overflow saturates to infinity.
+ return APFloat::getInf(X.getSemantics(), X.isNegative());
+ if (Exp < (MinExp - X.exponent))
+ // Underflow saturates to zero.
+ return APFloat::getZero(X.getSemantics(), X.isNegative());
+
+ X.exponent += Exp;
+ return std::move(X);
+}