Inline memove for small constant sizes and refactor memcpy and memset.

src/IceTargetLowering.cpp

Index: src/IceTargetLowering.cpp
diff --git a/src/IceTargetLowering.cpp b/src/IceTargetLowering.cpp
index d1ca570ba7d2a0fe1a70a18a389a1bdfac038d92..3e93b768cfb24d1384090ecf1c9a023dc6f38218 100644
--- a/src/IceTargetLowering.cpp
+++ b/src/IceTargetLowering.cpp
@@ -440,6 +440,11 @@ InstCall *TargetLowering::makeHelperCall(const IceString &Name, Variable *Dest,
   return Call;
 }
 
+bool TargetLowering::shouldOptimizeMemIntrins() {
+  return Ctx->getFlags().getOptLevel() >= Opt_1 ||
+         Ctx->getFlags().getForceMemIntrinOpt();
+}
+
 void TargetLowering::emitWithoutPrefix(const ConstantRelocatable *C) const {
   if (!BuildDefs::dump())
     return;