Fix another infinite loop in InstCombine

Summary:
InstCombine infinite-loops for the testcase added
It is because InstCombine is generating instructions that can be
optimized by itself. Fix by not optimizing frem if the optimized
type is the same as original type.
rdar://problem/19150820

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D6634

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224097 91177308-0d34-0410-b5e6-96231b3b80d8
A fix for PR21176. 
 
DW_OP_const <const> doesn't describe a constant value, but a value at a constant address. 
The proper way to describe a constant value is DW_OP_constu <const>, DW_OP_stack_value. 
Added DW_OP_stack_value to the stack. 

Marked incorrect-variable-debugloc1.ll to xfail for PowerPC64, while the the failure (PR21881) 
is being investigated. 



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224098 91177308-0d34-0410-b5e6-96231b3b80d8