Add minnum / maxnum intrinsics

These are named following the IEEE-754 names for these
functions, rather than the libm fmin / fmax to avoid
possible ambiguities. Some languages may implement something
resembling fmin / fmax which return NaN if either operand is
to propagate errors. These implement the IEEE-754 semantics
of returning the other operand if either is a NaN representing
missing data.

llvm-svn: 220341

llvm/lib/Analysis/ValueTracking.cpp

@@ -2578,6 +2578,8 @@ bool llvm::isSafeToSpeculativelyExecute(const Value *V,
        case Intrinsic::fma:
        case Intrinsic::fmuladd:
        case Intrinsic::fabs:
+       case Intrinsic::minnum:
+       case Intrinsic::maxnum:
          return true;
        // TODO: some fp intrinsics are marked as having the same error handling
        // as libm. They're safe to speculate when they won't error.