[InstructionSimplify] Add support for saturating add/sub
Add support for saturating add/sub in InstructionSimplify. In particular, the following simplifications are supported:
sat(X + 0) -> X
sat(X + undef) -> -1
sat(X uadd MAX) -> MAX
(and commutative variants)
sat(X - 0) -> X
sat(X - X) -> 0
sat(X - undef) -> 0
sat(undef - X) -> 0
sat(0 usub X) -> 0
sat(X usub MAX) -> 0
Patch by: @nikic (Nikita Popov)
Differential Revision: https://reviews.llvm.org/D54532
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@347330 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed