[AMDGPU] hazard recognizer for fp atomic to s_denorm_mode

This requires 3 wait states unless there is a wait or VALU in
between.

Differential Revision: https://reviews.llvm.org/D63619

llvm-svn: 364074
diff --git a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h
index 0c4c9d9..cf914b3 100644
--- a/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h
+++ b/llvm/lib/Target/AMDGPU/GCNHazardRecognizer.h
@@ -84,6 +84,7 @@
   int checkAnyInstHazards(MachineInstr *MI);
   int checkReadM0Hazards(MachineInstr *SMovRel);
   int checkNSAtoVMEMHazard(MachineInstr *MI);
+  int checkFPAtomicToDenormModeHazard(MachineInstr *MI);
   void fixHazards(MachineInstr *MI);
   bool fixVcmpxPermlaneHazards(MachineInstr *MI);
   bool fixVMEMtoScalarWriteHazards(MachineInstr *MI);