1 files changed, 99 insertions, 3 deletions

diff --git a/lib/Target/MBlaze/MBlazeDelaySlotFiller.cpp b/lib/Target/MBlaze/MBlazeDelaySlotFiller.cpp
index b551b79..32424e5 100644
--- a/lib/Target/MBlaze/MBlazeDelaySlotFiller.cpp
+++ b/lib/Target/MBlaze/MBlazeDelaySlotFiller.cpp
@@ -7,7 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// Simple pass to fills delay slots with NOPs.
+// A pass that attempts to fill instructions with delay slots. If no
+// instructions can be moved into the delay slot then a NOP is placed there.
 //
 //===----------------------------------------------------------------------===//
 
@@ -19,6 +20,10 @@
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/Target/TargetInstrInfo.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;
 
@@ -31,7 +36,7 @@ namespace {
     const TargetInstrInfo *TII;
 
     static char ID;
-    Filler(TargetMachine &tm) 
+    Filler(TargetMachine &tm)
       : MachineFunctionPass(ID), TM(tm), TII(tm.getInstrInfo()) { }
 
     virtual const char *getPassName() const {
@@ -51,6 +56,91 @@ namespace {
   char Filler::ID = 0;
 } // end of anonymous namespace
 
+static bool hasImmInstruction(MachineBasicBlock::iterator &candidate) {
+    // Any instruction with an immediate mode operand greater than
+    // 16-bits requires an implicit IMM instruction.
+    unsigned numOper = candidate->getNumOperands();
+    for (unsigned op = 0; op < numOper; ++op) {
+        if (candidate->getOperand(op).isImm() &&
+            (candidate->getOperand(op).getImm() & 0xFFFFFFFFFFFF0000LL) != 0)
+            return true;
+
+        // FIXME: we could probably check to see if the FP value happens
+        //        to not need an IMM instruction. For now we just always
+        //        assume that FP values always do.
+        if (candidate->getOperand(op).isFPImm())
+            return true;
+    }
+
+    return false;
+}
+
+static bool delayHasHazard(MachineBasicBlock::iterator &candidate,
+                           MachineBasicBlock::iterator &slot) {
+
+    // Loop over all of the operands in the branch instruction
+    // and make sure that none of them are defined by the
+    // candidate instruction.
+    unsigned numOper = slot->getNumOperands();
+    for (unsigned op = 0; op < numOper; ++op) {
+        if (!slot->getOperand(op).isReg() ||
+            !slot->getOperand(op).isUse() ||
+            slot->getOperand(op).isImplicit())
+            continue;
+
+        unsigned cnumOper = candidate->getNumOperands();
+        for (unsigned cop = 0; cop < cnumOper; ++cop) {
+            if (candidate->getOperand(cop).isReg() &&
+                candidate->getOperand(cop).isDef() &&
+                candidate->getOperand(cop).getReg() ==
+                slot->getOperand(op).getReg())
+                return true;
+        }
+    }
+
+    // There are no hazards between the two instructions
+    return false;
+}
+
+static bool usedBeforeDelaySlot(MachineBasicBlock::iterator &candidate,
+                                MachineBasicBlock::iterator &slot) {
+  MachineBasicBlock::iterator I = candidate;
+  for (++I; I != slot; ++I) {
+        unsigned numOper = I->getNumOperands();
+        for (unsigned op = 0; op < numOper; ++op) {
+            if (I->getOperand(op).isReg() &&
+                I->getOperand(op).isUse()) {
+                unsigned reg = I->getOperand(op).getReg();
+                unsigned cops = candidate->getNumOperands();
+                for (unsigned cop = 0; cop < cops; ++cop) {
+                    if (candidate->getOperand(cop).isReg() &&
+                        candidate->getOperand(cop).isDef() &&
+                        candidate->getOperand(cop).getReg() == reg)
+                        return true;
+                }
+            }
+        }
+  }
+
+  return false;
+}
+
+static MachineBasicBlock::iterator
+findDelayInstr(MachineBasicBlock &MBB,MachineBasicBlock::iterator &slot) {
+  MachineBasicBlock::iterator found = MBB.end();
+  for (MachineBasicBlock::iterator I = MBB.begin(); I != slot; ++I) {
+      TargetInstrDesc desc = I->getDesc();
+      if (desc.hasDelaySlot() || desc.isBranch() ||
+          desc.mayLoad() || desc.    mayStore() ||
+          hasImmInstruction(I) || delayHasHazard(I,slot) ||
+          usedBeforeDelaySlot(I,slot)) continue;
+
+      found = I;
+  }
+
+  return found;
+}
+
 /// 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.
@@ -59,10 +149,16 @@ bool Filler::runOnMachineBasicBlock(MachineBasicBlock &MBB) {
   for (MachineBasicBlock::iterator I = MBB.begin(); I != MBB.end(); ++I)
     if (I->getDesc().hasDelaySlot()) {
       MachineBasicBlock::iterator J = I;
+      MachineBasicBlock::iterator D = findDelayInstr(MBB,I);
+
       ++J;
-      BuildMI(MBB, J, I->getDebugLoc(), TII->get(MBlaze::NOP));
       ++FilledSlots;
       Changed = true;
+
+      if (D == MBB.end())
+        BuildMI(MBB, J, I->getDebugLoc(), TII->get(MBlaze::NOP));
+      else
+        MBB.splice(J, &MBB, D);
     }
   return Changed;
 }