[llvm] [AMDGPU] [DO NOT MERGE] Nonsuccessful Attempt At Using SelectionDAG Hooks for abs i8/i16 (PR #167064)

[Matt Arsenault via llvm-commits]

================
@@ -0,0 +1,1478 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=amdgcn -mcpu=tahiti -o - < %s | FileCheck %s --check-prefixes=SDAG6
----------------
arsenm wrote:

Should use explicit -global-isel=0 for the dag run lines 

https://github.com/llvm/llvm-project/pull/167064