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Modify code that processes delay slots so that it preserves any 

useful instructions already inserted into delay slots.

llvm-svn: 945
This commit is contained in:
Vikram S. Adve 2001-10-22 13:49:27 +00:00
parent 18a9e39214
commit 9a6457388f
1 changed files with 36 additions and 11 deletions
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47
llvm/lib/CodeGen/InstrSched/InstrScheduling.cpp
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@ -1223,24 +1223,49 @@ ReplaceNopsWithUsefulInstr(SchedulingManager& S,
vector<SchedGraphNode*> sdelayNodeVec,
SchedGraph* graph)
{
vector<SchedGraphNode*> nopNodeVec;
vector<SchedGraphNode*> nopNodeVec; // this will hold unused NOPs
const MachineInstrInfo& mii = S.getInstrInfo();
unsigned ndelays= mii.getNumDelaySlots(node->getMachineInstr()->getOpCode());
const MachineInstr* brInstr = node->getMachineInstr();
unsigned ndelays= mii.getNumDelaySlots(brInstr->getOpCode());
assert(ndelays > 0 && "Unnecessary call to replace NOPs");
// Remove the NOPs currently in delay slots from the graph.
// If not enough useful instructions were found, use the NOPs to
// fill delay slots, otherwise, just discard them.
for (sg_succ_iterator I=succ_begin(node); I != succ_end(node); ++I)
if (! (*I)->isDummyNode()
&& mii.isNop((*I)->getMachineInstr()->getOpCode()))
//
MachineCodeForVMInstr& termMvec = node->getInstr()->getMachineInstrVec();
unsigned int firstDelaySlotIdx;
for (unsigned i=0; i < termMvec.size(); ++i)
if (termMvec[i] == brInstr)
{
if (sdelayNodeVec.size() < ndelays)
sdelayNodeVec.push_back(*I);
else
nopNodeVec.push_back(*I);
firstDelaySlotIdx = i+1;
break;
}
assert(sdelayNodeVec.size() == ndelays);
assert(firstDelaySlotIdx <= termMvec.size()-1 &&
"This sucks! Where's that delay slot instruction?");
// First find all useful instructions already in the delay slots
// and USE THEM. We'll throw away the unused alternatives below
//
for (unsigned i=firstDelaySlotIdx; i < firstDelaySlotIdx + ndelays; ++i)
if (! mii.isNop(termMvec[i]->getOpCode()))
sdelayNodeVec.insert(sdelayNodeVec.begin(),
graph->getGraphNodeForInstr(termMvec[i]));
// Then find the NOPs and keep only as many as are needed.
// Put the rest in nopNodeVec to be deleted.
for (unsigned i=firstDelaySlotIdx; i < firstDelaySlotIdx + ndelays; ++i)
if (mii.isNop(termMvec[i]->getOpCode()))
if (sdelayNodeVec.size() < ndelays)
sdelayNodeVec.push_back(graph->getGraphNodeForInstr(termMvec[i]));
else
nopNodeVec.push_back(graph->getGraphNodeForInstr(termMvec[i]));
assert(sdelayNodeVec.size() >= ndelays);
// If some delay slots were already filled, throw away that many new choices
if (sdelayNodeVec.size() > ndelays)
sdelayNodeVec.resize(ndelays);
// Mark the nodes chosen for delay slots. This removes them from the graph.
for (unsigned i=0; i < sdelayNodeVec.size(); i++)
@ -1512,7 +1537,7 @@ ScheduleInstructionsWithSSA(Method* method,
{
cout << endl
<< "*** Machine instructions after INSTRUCTION SCHEDULING" << endl;
PrintMachineInstructions(method);
method->getMachineCode().dump();
}
return false; // no reason to fail yet