[Diffusion] rL255600: Instcombine: destructor loads of structs that do not contains padding

[NAKAMURA Takumi via llvm-commits]

chapuni added subscribers: llvm-commits, chapuni.

/llvm/trunk/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp:543 Twine(const StringRef&, const char*) was applied here.
In general, we may avoid instantiating Twine.

I tweaked them to use SmallString in r255637.

http://reviews.llvm.org/rL255600