[llvm] AMDGPU/NewPM: Fill out addPreISelPasses (PR #102814)

[Matt Arsenault via llvm-commits]

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@@ -28,8 +36,51 @@ AMDGPUCodeGenPassBuilder::AMDGPUCodeGenPassBuilder(
 }
 
 void AMDGPUCodeGenPassBuilder::addPreISel(AddIRPass &addPass) const {
-  // TODO: Add passes pre instruction selection.
-  // Test only, convert to real IR passes in future.
+  const bool LateCFGStructurize = AMDGPUTargetMachine::EnableLateStructurizeCFG;
+  const bool DisableStructurizer = AMDGPUTargetMachine::DisableStructurizer;
+  const bool EnableStructurizerWorkarounds =
+      AMDGPUTargetMachine::EnableStructurizerWorkarounds;
+
+  if (TM.getOptLevel() > CodeGenOptLevel::None)
+    addPass(FlattenCFGPass());
+
+  if (TM.getOptLevel() > CodeGenOptLevel::None)
+    addPass(SinkingPass());
+
+  addPass(AMDGPULateCodeGenPreparePass(TM));
+
+  // Merge divergent exit nodes. StructurizeCFG won't recognize the multi-exit
+  // regions formed by them.
+
+  addPass(AMDGPUUnifyDivergentExitNodesPass());
+
+  if (!LateCFGStructurize && !DisableStructurizer) {
+    if (EnableStructurizerWorkarounds) {
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arsenm wrote:

Which one? The LateCFGStructurize was never enabled (and I'd need to look if the underlying pass is still there anymore) 

https://github.com/llvm/llvm-project/pull/102814