InstCombine: Fix another infinite loop caused by visitFPTrunc

We would attempt to replace an frem's operand with the same operand.
This would cause InstCombine to think real work was done, causing
InstCombine to enter an infinite loop.

This fixes the second part of PR21576.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222265 91177308-0d34-0410-b5e6-96231b3b80d8
Fix an inaccurate comment

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222267 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Also allow folding of sign-/zero-extend and logical
shift-right for booleans (i1).

Logical shift-right immediate with sign-/zero-extensions also works for boolean
values.  Update the assert and the test cases to reflect that fact.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222270 91177308-0d34-0410-b5e6-96231b3b80d8
[FastISel][AArch64] Also allow folding of sign-/zero-extend and arithmetic
shift-right for booleans (i1).

Arithmetic shift-right immediate with sign-/zero-extensions also works for
boolean values.  Update the assert and the test cases to reflect that fact.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222272 91177308-0d34-0410-b5e6-96231b3b80d8
[Hexagon] Adding A2_and instruction.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@222274 91177308-0d34-0410-b5e6-96231b3b80d8