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Fix a bug in merged condition handling (CodeGen/Generic/2006-10-27-CondFolding.ll).

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Add many fewer CFG edges and PHI node entries.  If there is a switch which has
the same block as multiple destinations, only add that block once as a successor/phi
node (in the jumptable case)


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31242 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Chris Lattner 2006-10-27 23:50:33 +00:00
parent 0d824c3fe1
commit 8c494ab759
1 changed files with 110 additions and 67 deletions
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177
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -282,24 +282,24 @@ FunctionLoweringInfo::FunctionLoweringInfo(TargetLowering &tli,
// Create Machine PHI nodes for LLVM PHI nodes, lowering them as
// appropriate.
PHINode *PN;
for (BasicBlock::iterator I = BB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
MVT::ValueType VT = TLI.getValueType(PN->getType());
unsigned NumElements;
if (VT != MVT::Vector)
NumElements = TLI.getNumElements(VT);
else {
MVT::ValueType VT1,VT2;
NumElements =
TLI.getPackedTypeBreakdown(cast<PackedType>(PN->getType()),
VT1, VT2);
}
unsigned PHIReg = ValueMap[PN];
assert(PHIReg &&"PHI node does not have an assigned virtual register!");
for (unsigned i = 0; i != NumElements; ++i)
BuildMI(MBB, TargetInstrInfo::PHI, PN->getNumOperands(), PHIReg+i);
for (BasicBlock::iterator I = BB->begin();(PN = dyn_cast<PHINode>(I)); ++I){
if (PN->use_empty()) continue;
MVT::ValueType VT = TLI.getValueType(PN->getType());
unsigned NumElements;
if (VT != MVT::Vector)
NumElements = TLI.getNumElements(VT);
else {
MVT::ValueType VT1,VT2;
NumElements =
TLI.getPackedTypeBreakdown(cast<PackedType>(PN->getType()),
VT1, VT2);
}
unsigned PHIReg = ValueMap[PN];
assert(PHIReg && "PHI node does not have an assigned virtual register!");
for (unsigned i = 0; i != NumElements; ++i)
BuildMI(MBB, TargetInstrInfo::PHI, PN->getNumOperands(), PHIReg+i);
}
}
}
@ -497,6 +497,7 @@ public:
void FindMergedConditions(Value *Cond, MachineBasicBlock *TBB,
MachineBasicBlock *FBB, MachineBasicBlock *CurBB,
unsigned Opc);
bool isExportableFromCurrentBlock(Value *V, const BasicBlock *FromBB);
void ExportFromCurrentBlock(Value *V);
// Terminator instructions.
@ -798,15 +799,39 @@ void SelectionDAGLowering::ExportFromCurrentBlock(Value *V) {
PendingLoads.push_back(CopyValueToVirtualRegister(V, Reg));
}
bool SelectionDAGLowering::isExportableFromCurrentBlock(Value *V,
const BasicBlock *FromBB) {
// The operands of the setcc have to be in this block. We don't know
// how to export them from some other block.
if (Instruction *VI = dyn_cast<Instruction>(V)) {
// Can export from current BB.
if (VI->getParent() == FromBB)
return true;
// Is already exported, noop.
return FuncInfo.isExportedInst(V);
}
// If this is an argument, we can export it if the BB is the entry block or
// if it is already exported.
if (isa<Argument>(V)) {
if (FromBB == &FromBB->getParent()->getEntryBlock())
return true;
// Otherwise, can only export this if it is already exported.
return FuncInfo.isExportedInst(V);
}
// Otherwise, constants can always be exported.
return true;
}
/// FindMergedConditions - If Cond is an expression like
void SelectionDAGLowering::FindMergedConditions(Value *Cond,
MachineBasicBlock *TBB,
MachineBasicBlock *FBB,
MachineBasicBlock *CurBB,
unsigned Opc) {
// FIXME: HANDLE AND.
// FIXME: HANDLE NOT
// If this node is not part of the or/and tree, emit it as a branch.
BinaryOperator *BOp = dyn_cast<BinaryOperator>(Cond);
@ -819,12 +844,8 @@ void SelectionDAGLowering::FindMergedConditions(Value *Cond,
if (BOp && isa<SetCondInst>(BOp) &&
// The operands of the setcc have to be in this block. We don't know
// how to export them from some other block.
(!isa<Instruction>(BOp->getOperand(0)) ||
cast<Instruction>(BOp->getOperand(0))->getParent() == BB ||
FuncInfo.isExportedInst(BOp->getOperand(0))) &&
(!isa<Instruction>(BOp->getOperand(1)) ||
cast<Instruction>(BOp->getOperand(1))->getParent() == BB ||
FuncInfo.isExportedInst(BOp->getOperand(1)))) {
isExportableFromCurrentBlock(BOp->getOperand(0), BB) &&
isExportableFromCurrentBlock(BOp->getOperand(1), BB)) {
ExportFromCurrentBlock(BOp->getOperand(0));
ExportFromCurrentBlock(BOp->getOperand(1));
@ -1222,10 +1243,18 @@ void SelectionDAGLowering::visitSwitch(SwitchInst &I) {
DestBBs.push_back(Default);
}
// Update successor info
// Update successor info. Add one edge to each unique successor.
// Vector bool would be better, but vector<bool> is really slow.
std::vector<unsigned char> SuccsHandled;
SuccsHandled.resize(CurMBB->getParent()->getNumBlockIDs());
for (std::vector<MachineBasicBlock*>::iterator I = DestBBs.begin(),
E = DestBBs.end(); I != E; ++I)
JumpTableBB->addSuccessor(*I);
E = DestBBs.end(); I != E; ++I) {
if (!SuccsHandled[(*I)->getNumber()]) {
SuccsHandled[(*I)->getNumber()] = true;
JumpTableBB->addSuccessor(*I);
}
}
// Create a jump table index for this jump table, or return an existing
// one.
@ -3710,63 +3739,77 @@ void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
// BB. As such, the start of the BB might correspond to a different MBB than
// the end.
//
TerminatorInst *TI = LLVMBB->getTerminator();
// Emit constants only once even if used by multiple PHI nodes.
std::map<Constant*, unsigned> ConstantsOut;
// Vector bool would be better, but vector<bool> is really slow.
std::vector<unsigned char> SuccsHandled;
if (TI->getNumSuccessors())
SuccsHandled.resize(BB->getParent()->getNumBlockIDs());
// Check successor nodes PHI nodes that expect a constant to be available from
// this block.
TerminatorInst *TI = LLVMBB->getTerminator();
for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
BasicBlock *SuccBB = TI->getSuccessor(succ);
if (!isa<PHINode>(SuccBB->begin())) continue;
MachineBasicBlock *SuccMBB = FuncInfo.MBBMap[SuccBB];
MachineBasicBlock::iterator MBBI = FuncInfo.MBBMap[SuccBB]->begin();
// If this terminator has multiple identical successors (common for
// switches), only handle each succ once.
unsigned SuccMBBNo = SuccMBB->getNumber();
if (SuccsHandled[SuccMBBNo]) continue;
SuccsHandled[SuccMBBNo] = true;
MachineBasicBlock::iterator MBBI = SuccMBB->begin();
PHINode *PN;
// At this point we know that there is a 1-1 correspondence between LLVM PHI
// nodes and Machine PHI nodes, but the incoming operands have not been
// emitted yet.
for (BasicBlock::iterator I = SuccBB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
unsigned Reg;
Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
if (Constant *C = dyn_cast<Constant>(PHIOp)) {
unsigned &RegOut = ConstantsOut[C];
if (RegOut == 0) {
RegOut = FuncInfo.CreateRegForValue(C);
UnorderedChains.push_back(
SDL.CopyValueToVirtualRegister(C, RegOut));
}
Reg = RegOut;
} else {
Reg = FuncInfo.ValueMap[PHIOp];
if (Reg == 0) {
assert(isa<AllocaInst>(PHIOp) &&
FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(PHIOp)) &&
"Didn't codegen value into a register!??");
Reg = FuncInfo.CreateRegForValue(PHIOp);
UnorderedChains.push_back(
SDL.CopyValueToVirtualRegister(PHIOp, Reg));
}
(PN = dyn_cast<PHINode>(I)); ++I) {
// Ignore dead phi's.
if (PN->use_empty()) continue;
unsigned Reg;
Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
if (Constant *C = dyn_cast<Constant>(PHIOp)) {
unsigned &RegOut = ConstantsOut[C];
if (RegOut == 0) {
RegOut = FuncInfo.CreateRegForValue(C);
UnorderedChains.push_back(
SDL.CopyValueToVirtualRegister(C, RegOut));
}
// Remember that this register needs to added to the machine PHI node as
// the input for this MBB.
MVT::ValueType VT = TLI.getValueType(PN->getType());
unsigned NumElements;
if (VT != MVT::Vector)
NumElements = TLI.getNumElements(VT);
else {
MVT::ValueType VT1,VT2;
NumElements =
TLI.getPackedTypeBreakdown(cast<PackedType>(PN->getType()),
VT1, VT2);
Reg = RegOut;
} else {
Reg = FuncInfo.ValueMap[PHIOp];
if (Reg == 0) {
assert(isa<AllocaInst>(PHIOp) &&
FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(PHIOp)) &&
"Didn't codegen value into a register!??");
Reg = FuncInfo.CreateRegForValue(PHIOp);
UnorderedChains.push_back(
SDL.CopyValueToVirtualRegister(PHIOp, Reg));
}
for (unsigned i = 0, e = NumElements; i != e; ++i)
PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg+i));
}
// Remember that this register needs to added to the machine PHI node as
// the input for this MBB.
MVT::ValueType VT = TLI.getValueType(PN->getType());
unsigned NumElements;
if (VT != MVT::Vector)
NumElements = TLI.getNumElements(VT);
else {
MVT::ValueType VT1,VT2;
NumElements =
TLI.getPackedTypeBreakdown(cast<PackedType>(PN->getType()),
VT1, VT2);
}
for (unsigned i = 0, e = NumElements; i != e; ++i)
PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg+i));
}
}
ConstantsOut.clear();