[IR] IntrinsicInst - silence static analyzer dyn_cast<> null dereference warnings. NFCI.

The static analyzer is warning about a potential null dereference, but we should be able to use cast<> directly and if not assert will fire for us.

llvm-svn: 372733
diff --git a/llvm/lib/IR/IntrinsicInst.cpp b/llvm/lib/IR/IntrinsicInst.cpp
index a426c9b..2996cfb 100644
--- a/llvm/lib/IR/IntrinsicInst.cpp
+++ b/llvm/lib/IR/IntrinsicInst.cpp
@@ -107,7 +107,7 @@
 ConstrainedFPIntrinsic::getRoundingMode() const {
   unsigned NumOperands = getNumArgOperands();
   Metadata *MD =
-      dyn_cast<MetadataAsValue>(getArgOperand(NumOperands - 2))->getMetadata();
+      cast<MetadataAsValue>(getArgOperand(NumOperands - 2))->getMetadata();
   if (!MD || !isa<MDString>(MD))
     return None;
   return StrToRoundingMode(cast<MDString>(MD)->getString());
@@ -153,7 +153,7 @@
 ConstrainedFPIntrinsic::getExceptionBehavior() const {
   unsigned NumOperands = getNumArgOperands();
   Metadata *MD =
-      dyn_cast<MetadataAsValue>(getArgOperand(NumOperands - 1))->getMetadata();
+      cast<MetadataAsValue>(getArgOperand(NumOperands - 1))->getMetadata();
   if (!MD || !isa<MDString>(MD))
     return None;
   return StrToExceptionBehavior(cast<MDString>(MD)->getString());