[AMDGPU] Add Reset function to GCNHazardRecognizer

[kerbowa]

Summary

Reset the tracked emitted instructions when starting scheduling on a new
region.

[rampitec]

Thank you!

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h

public:
   void EmitInstruction(MachineInstr *MI) override;
   HazardType getHazardType(SUnit *SU, int Stalls) override;
   void EmitNoop() override;
   unsigned PreEmitNoops(MachineInstr *) override;
   unsigned PreEmitNoopsCommon(MachineInstr *);
   void AdvanceCycle() override;
   void RecedeCycle() override;
   bool ShouldPreferAnother(SUnit *SU) override;
+  void Reset() override;
 };
 
 } // end namespace llvm
 
 #endif //LLVM_LIB_TARGET_AMDGPUHAZARDRECOGNIZERS_H

llvm/lib/Target/AMDGPU/GCNHazardRecognizer.cpp

GCNHazardRecognizer::GCNHazardRecognizer(const MachineFunction &MF) :
   TII(*ST.getInstrInfo()),
   TRI(TII.getRegisterInfo()),
   ClauseUses(TRI.getNumRegUnits()),
   ClauseDefs(TRI.getNumRegUnits()) {
   MaxLookAhead = MF.getRegInfo().isPhysRegUsed(AMDGPU::AGPR0) ? 18 : 5;
   TSchedModel.init(&ST);
 }
 
+void GCNHazardRecognizer::Reset() {
+  EmittedInstrs.clear();
+}
+
 void GCNHazardRecognizer::EmitInstruction(SUnit *SU) {
   EmitInstruction(SU->getInstr());
 }
 
 void GCNHazardRecognizer::EmitInstruction(MachineInstr *MI) {
   CurrCycleInstr = MI;
 }
 

llvm/test/CodeGen/AMDGPU/post-ra-sched-reset.mir

+# RUN: llc -march=amdgcn -mcpu=gfx900 -run-pass=post-RA-sched -verify-machineinstrs -debug-only=post-RA-sched -o - %s 2>&1 | FileCheck %s
+
+# REQUIRES: asserts
+
+# CHECK-NOT: Stall in cycle
+---
+name:            hazard_rec_reset
+tracksRegLiveness: true
+body:             |
+  bb.0:
+    successors: %bb.1
+
+    $m0 = S_MOV_B32 0
+
+  bb.1:
+    liveins: $vgpr4
+
+    S_SETREG_IMM32_B32 0, 1, implicit-def $mode, implicit $mode
+    $vgpr0 = V_INTERP_P1_F32 killed $vgpr4, 0, 0, implicit $mode, implicit $m0, implicit $exec
+    S_ENDPGM 0
+
+...