[llvm] [AMDGPU] Support bottom-up postRA scheduing. (PR #135295)

[Matt Arsenault via llvm-commits]

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@@ -417,7 +417,9 @@ void GCNHazardRecognizer::AdvanceCycle() {
 }
 
 void GCNHazardRecognizer::RecedeCycle() {
-  llvm_unreachable("hazard recognizer does not support bottom-up scheduling.");
+  if (IsHazardRecognizerMode || ST.getGeneration() < AMDGPUSubtarget::GFX11)
+    llvm_unreachable(
+        "hazard recognizer does not support bottom-up scheduling.");
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arsenm wrote:

This shouldn't be unreachable, it's a fatal error 

https://github.com/llvm/llvm-project/pull/135295