[AMDGPU][NewPM] Make the pass flow consistent with the legacy pipeline. (llvm#136551)

Author: cdevadas

llvm/lib/Target/AMDGPU/AMDGPUTargetMachine.cpp

@@ -2081,13 +2081,11 @@ void AMDGPUCodeGenPassBuilder::addCodeGenPrepare(AddIRPass &addPass) const {
 
 void AMDGPUCodeGenPassBuilder::addPreISel(AddIRPass &addPass) const {
 
-  if (TM.getOptLevel() > CodeGenOptLevel::None)
+  if (TM.getOptLevel() > CodeGenOptLevel::None) {
     addPass(FlattenCFGPass());
-
-  if (TM.getOptLevel() > CodeGenOptLevel::None)
     addPass(SinkingPass());
-
-  addPass(AMDGPULateCodeGenPreparePass(TM));
+    addPass(AMDGPULateCodeGenPreparePass(TM));
+  }
 
   // Merge divergent exit nodes. StructurizeCFG won't recognize the multi-exit
   // regions formed by them.