[llvm] [AMDGPU] Make LowerModuleLDS a noop on an already lowered module (PR #217075)

[Matt Arsenault via llvm-commits]

================
@@ -1078,17 +1078,23 @@ class AMDGPULowerModuleLDS {
   }
 
   bool runOnModuleNormal(Module &M) {
-    CallGraph CG = CallGraph(M);
     bool Changed = superAlignLDSGlobals(M);
----------------
arsenm wrote:

Seems like this alignment optimization should only apply when committing to the lowering?

https://github.com/llvm/llvm-project/pull/217075