[AMDGPU] Rmove unnecssary RecedeCycle.

Author: harrisonGPU

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp

@@ -280,39 +280,6 @@ void GCNHazardRecognizer::processBundle() {
   CurrCycleInstr = nullptr;
 }
 
-void GCNHazardRecognizer::processBundleBottomUp() {
-  // Walk through the instructions in this bundle in bottom-up order.
-  // We only use this during post-RA scheduling, so hazard recognizer mode
-  // should never be active here (it always runs top-down).
-  assert(!IsHazardRecognizerMode &&
-         "Bottom-up scheduling shouldn't run in hazard recognizer mode");
-
-  // Step through each instruction in the bundle in bottom-up order.
-  MachineBasicBlock::instr_iterator MI =
-      std::next(CurrCycleInstr->getIterator());
-  MachineBasicBlock::instr_iterator E =
-      CurrCycleInstr->getParent()->instr_end();
-
-  // Evict stale entries to maintain a fixed lookahead window.
-  // TODO: Hazard detection is not yet implemented. This scheduling
-  // is intended for GFX11 and newer.
-  for (; MI != E && MI->isInsideBundle(); ++MI) {
-    CurrCycleInstr = &*MI;
-
-    // Remove up to (MaxLookAhead - 1) oldest entries.
-    for (unsigned I = 0, E = MaxLookAhead - 1; I < E && !EmittedInstrs.empty();
-         ++I)
-      EmittedInstrs.pop_back();
-
-    EmittedInstrs.push_back(CurrCycleInstr);
-
-    // Keep only the most recent MaxLookAhead entries
-    EmittedInstrs.resize(MaxLookAhead);
-  }
-
-  CurrCycleInstr = nullptr;
-}
-
 void GCNHazardRecognizer::runOnInstruction(MachineInstr *MI) {
   assert(IsHazardRecognizerMode);
 
@@ -450,41 +417,9 @@ void GCNHazardRecognizer::AdvanceCycle() {
 }
 
 void GCNHazardRecognizer::RecedeCycle() {
-  // If no instruction was issued this cycle, pop the oldest placeholder.
-  if (!CurrCycleInstr) {
-    if (!EmittedInstrs.empty())
-      EmittedInstrs.pop_back();
-    return;
-  }
-
-  // If this is a bundle header, handle the entire bundle here.
-  if (CurrCycleInstr->isBundle()) {
-    processBundleBottomUp();
-    return;
-  }
-
-  unsigned NumWaitStates = TII.getNumWaitStates(*CurrCycleInstr);
-  if (!NumWaitStates) {
-    CurrCycleInstr = nullptr;
-    return;
-  }
-
-  // Add current instruction to the emitted list.
-  EmittedInstrs.push_back(CurrCycleInstr);
-
-  // Model remaining wait states by removing older placeholders.
-  for (unsigned I = 1, E = std::min(NumWaitStates, getMaxLookAhead()); I < E;
-       ++I) {
-    if (!EmittedInstrs.empty())
-      EmittedInstrs.pop_back();
-  }
-
-  // getMaxLookahead() is the largest number of wait states we will ever need
-  // to insert, so there is no point in keeping track of more than that many
-  // wait states.
-  EmittedInstrs.resize(getMaxLookAhead());
-
-  CurrCycleInstr = nullptr;
+  if (IsHazardRecognizerMode || ST.getGeneration() < AMDGPUSubtarget::GFX11)
+    llvm_unreachable(
+        "hazard recognizer does not support bottom-up scheduling.");
 }
 
 //===----------------------------------------------------------------------===//

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h

@@ -69,10 +69,6 @@ class GCNHazardRecognizer final : public ScheduleHazardRecognizer {
   // Advance over a MachineInstr bundle. Look for hazards in the bundled
   // instructions.
   void processBundle();
-  // Recede over a MachineInstr bundle. Adds bundled instructions to the
-  // EmittedInstrs queue in bottom-up scheduling mode.
-  // TODO: Hazard detection is not yet implemented.
-  void processBundleBottomUp();
 
   // Run on an individual instruction in hazard recognizer mode. This can be
   // used on a newly inserted instruction before returning from PreEmitNoops.