[llvm] Use getSignedTargetConstant for offset (PR #141149)

[Shimin Cui via llvm-commits]

================
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py UTC_ARGS: --version 5
+; RUN: llc -verify-machineinstrs < %s -mcpu=ppc -mtriple powerpc-ibm-aix-xcoff | FileCheck %s
----------------
scui-ibm wrote:

For the reduced case and the original case I worked on, they are ok at 64-bit. I tried to construct a 64-bit case with no success so won't test 64-bit with this PR.

https://github.com/llvm/llvm-project/pull/141149