InstructionSimplify.cpp.  Other fixups as needed.
Part of rdar://10500969

llvm-svn: 145559

InstructionSimplify on instructions that didn't change since the
last time round the loop.

llvm-svn: 122745

operands are visited before the instructions themselves.

llvm-svn: 122647

llvm-svn: 122645

visit instructions before their uses, since InstructionSimplify does a
better job in that case.  All this prompted by Frits van Bommel.

llvm-svn: 122343

not very important since the pass is only used for testing, but it does make
it more realistic.  Suggested by Frits van Bommel.

llvm-svn: 122336

llvm-svn: 122265