From 9684a697d59cdcbe9dff84bdaf3b42cf0465e821 Mon Sep 17 00:00:00 2001
From: Bruno Cardoso Lopes <bruno.cardoso@gmail.com>
Date: Sat, 18 Aug 2007 01:50:47 +0000
Subject: [PATCH] A Pass to insert Nops on intructions with DelaySlot

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@41150 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/Mips/MipsDelaySlotFiller.cpp | 77 +++++++++++++++++++++++++
 1 file changed, 77 insertions(+)
 create mode 100644 lib/Target/Mips/MipsDelaySlotFiller.cpp

diff --git a/lib/Target/Mips/MipsDelaySlotFiller.cpp b/lib/Target/Mips/MipsDelaySlotFiller.cpp
new file mode 100644
index 00000000000..1185abf606a
--- /dev/null
+++ b/lib/Target/Mips/MipsDelaySlotFiller.cpp
@@ -0,0 +1,77 @@
+//===-- DelaySlotFiller.cpp - Mips delay slot filler ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Bruno Cardoso Lopes and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Simple pass to fills delay slots with NOPs.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "delay-slot-filler"
+
+#include "Mips.h"
+#include "MipsTargetMachine.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/ADT/Statistic.h"
+
+using namespace llvm;
+
+STATISTIC(FilledSlots, "Number of delay slots filled");
+
+namespace {
+  struct Filler : public MachineFunctionPass {
+
+    TargetMachine &TM;
+    const TargetInstrInfo *TII;
+
+    static char ID;
+    Filler(TargetMachine &tm) 
+      : MachineFunctionPass((intptr_t)&ID), TM(tm), TII(tm.getInstrInfo()) { }
+
+    virtual const char *getPassName() const {
+      return "Mips Delay Slot Filler";
+    }
+
+    bool runOnMachineBasicBlock(MachineBasicBlock &MBB);
+    bool runOnMachineFunction(MachineFunction &F) {
+      bool Changed = false;
+      for (MachineFunction::iterator FI = F.begin(), FE = F.end();
+           FI != FE; ++FI)
+        Changed |= runOnMachineBasicBlock(*FI);
+      return Changed;
+    }
+
+  };
+  char Filler::ID = 0;
+} // end of anonymous namespace
+
+/// runOnMachineBasicBlock - Fill in delay slots for the given basic block.
+/// Currently, we fill delay slots with NOPs. We assume there is only one
+/// delay slot per delayed instruction.
+bool Filler::
+runOnMachineBasicBlock(MachineBasicBlock &MBB) 
+{
+  bool Changed = false;
+  for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I)
+    if (TII->hasDelaySlot(I->getOpcode())) {
+      MachineBasicBlock::iterator J = I;
+      ++J;
+      BuildMI(MBB, J, TII->get(Mips::NOP));
+      ++FilledSlots;
+      Changed = true;
+    }
+  return Changed;
+}
+
+/// createMipsDelaySlotFillerPass - Returns a pass that fills in delay
+/// slots in Mips MachineFunctions
+FunctionPass *llvm::createMipsDelaySlotFillerPass(MipsTargetMachine &tm) {
+  return new Filler(tm);
+}
+