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Add post-indexed load / store transformations.

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llvm-svn: 31498
This commit is contained in:
Evan Cheng 2006-11-07 09:03:05 +00:00
parent e3c204efe1
commit 3db2b3aab9
1 changed files with 198 additions and 49 deletions
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247
lib/CodeGen/SelectionDAG/DAGCombiner.cpp
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@ -47,6 +47,11 @@ namespace {
static Statistic<> NodesCombined ("dagcombiner", static Statistic<> NodesCombined ("dagcombiner",
"Number of dag nodes combined"); "Number of dag nodes combined");
static Statistic<> PreIndexedNodes ("pre_indexed_ops",
"Number of pre-indexed nodes created");
static Statistic<> PostIndexedNodes ("post_indexed_ops",
"Number of post-indexed nodes created");
static cl::opt<bool> static cl::opt<bool>
CombinerAA("combiner-alias-analysis", cl::Hidden, CombinerAA("combiner-alias-analysis", cl::Hidden,
cl::desc("Turn on alias analysis during testing")); cl::desc("Turn on alias analysis during testing"));
@ -174,13 +179,16 @@ namespace {
return true; return true;
} }
/// CombineToPreIndexedLoadStore - Try turning a load / store into a /// CombineToPreIndexedLoadStore - Try turning a load / store and a
/// pre-indexed load store when the base pointer is a add or subtract /// pre-indexed load / store when the base pointer is a add or subtract
/// and it has other uses besides the load / store. When the /// and it has other uses besides the load / store. After the
/// transformation is done, the new indexed load / store effectively /// transformation, the new indexed load / store has effectively folded
/// folded the add / subtract in and all of its other uses are redirected /// the add / subtract in and all of its other uses are redirected to the
/// to the new load / store. /// new load / store.
bool CombineToPreIndexedLoadStore(SDNode *N) { bool CombineToPreIndexedLoadStore(SDNode *N) {
if (!AfterLegalize)
return false;
bool isLoad = true; bool isLoad = true;
SDOperand Ptr; SDOperand Ptr;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) { if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
@ -191,8 +199,7 @@ namespace {
} else } else
return false; return false;
if (AfterLegalize && if ((Ptr.getOpcode() == ISD::ADD || Ptr.getOpcode() == ISD::SUB) &&
(Ptr.getOpcode() == ISD::ADD || Ptr.getOpcode() == ISD::SUB) &&
Ptr.Val->use_size() > 1) { Ptr.Val->use_size() > 1) {
SDOperand BasePtr; SDOperand BasePtr;
SDOperand Offset; SDOperand Offset;
@ -203,57 +210,56 @@ namespace {
// that would create a cycle. // that would create a cycle.
// 2) All uses are load / store ops that use it as base ptr and offset // 2) All uses are load / store ops that use it as base ptr and offset
// is just an addressing mode immediate. // is just an addressing mode immediate.
// 3) If the would-be new base may not to be dead at N. FIXME: The // 3) If the would-be new base may not to be dead at N.
// proper check is too expensive (in turns of compile time) to
// check. Just make sure other uses of the new base are not also
// themselves use of loads / stores.
bool OffIsAMImm = Offset.getOpcode() == ISD::Constant && bool OffIsAMImm = Offset.getOpcode() == ISD::Constant && TLI.
TLI.isLegalAddressImmediate( isLegalAddressImmediate(cast<ConstantSDNode>(Offset)->getValue());
cast<ConstantSDNode>(Offset)->getValue());
// Check for #3. // Check for #3.
if (OffIsAMImm && BasePtr.Val->use_size() > 1) { for (SDNode::use_iterator I = BasePtr.Val->use_begin(),
for (SDNode::use_iterator I = BasePtr.Val->use_begin(), E = BasePtr.Val->use_end(); I != E; ++I) {
E = BasePtr.Val->use_end(); I != E; ++I) { SDNode *Use = *I;
SDNode *Use = *I; if (Use == Ptr.Val)
if (Use == Ptr.Val) continue;
continue; if (Use->getOpcode() == ISD::CopyToReg)
if (Use->getOpcode() == ISD::ADD || Use->getOpcode() == ISD::SUB){ return false;
for (SDNode::use_iterator II = Use->use_begin(), if (OffIsAMImm && (Use->getOpcode() == ISD::ADD ||
EE = Use->use_end(); II != EE; ++II) { Use->getOpcode() == ISD::SUB)) {
SDNode *UseUse = *II; for (SDNode::use_iterator II = Use->use_begin(),
if (UseUse->getOpcode() == ISD::LOAD && EE = Use->use_end(); II != EE; ++II) {
cast<LoadSDNode>(UseUse)->getBasePtr().Val == Use) SDNode *UseUse = *II;
return false; if (UseUse->getOpcode() == ISD::LOAD &&
else if (UseUse->getOpcode() == ISD::STORE && cast<LoadSDNode>(UseUse)->getBasePtr().Val == Use)
cast<StoreSDNode>(UseUse)->getBasePtr().Val == Use) return false;
return false; else if (UseUse->getOpcode() == ISD::STORE &&
} cast<StoreSDNode>(UseUse)->getBasePtr().Val == Use)
return false;
} }
} }
} }
// Now check for #1 and #2. // Now check for #1 and #2.
unsigned NumRealUses = 0; unsigned NumRealUses = 0;
for (SDNode::use_iterator I = Ptr.Val->use_begin(), if (OffIsAMImm) {
E = Ptr.Val->use_end(); I != E; ++I) { for (SDNode::use_iterator I = Ptr.Val->use_begin(),
SDNode *Use = *I; E = Ptr.Val->use_end(); I != E; ++I) {
if (Use == N) SDNode *Use = *I;
continue; if (Use == N)
if (Use->isPredecessor(N)) continue;
return false; if (Use->isPredecessor(N))
return false;
if (!OffIsAMImm) { if (!OffIsAMImm) {
NumRealUses++;
} else if (Use->getOpcode() == ISD::LOAD) {
if (cast<LoadSDNode>(Use)->getBasePtr().Val != Ptr.Val)
NumRealUses++; NumRealUses++;
} else if (Use->getOpcode() == ISD::STORE) { } else if (Use->getOpcode() == ISD::LOAD) {
if (cast<StoreSDNode>(Use)->getBasePtr().Val != Ptr.Val) if (cast<LoadSDNode>(Use)->getBasePtr().Val != Ptr.Val)
NumRealUses++;
} else if (Use->getOpcode() == ISD::STORE) {
if (cast<StoreSDNode>(Use)->getBasePtr().Val != Ptr.Val)
NumRealUses++;
} else
NumRealUses++; NumRealUses++;
} else }
NumRealUses++;
} }
if (NumRealUses == 0) if (NumRealUses == 0)
return false; return false;
@ -261,6 +267,7 @@ namespace {
SDOperand Result = isLoad SDOperand Result = isLoad
? DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM) ? DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM)
: DAG.getIndexedStore(SDOperand(N,0), BasePtr, Offset, AM); : DAG.getIndexedStore(SDOperand(N,0), BasePtr, Offset, AM);
++PreIndexedNodes;
++NodesCombined; ++NodesCombined;
DEBUG(std::cerr << "\nReplacing.4 "; N->dump(); DEBUG(std::cerr << "\nReplacing.4 "; N->dump();
std::cerr << "\nWith: "; Result.Val->dump(&DAG); std::cerr << "\nWith: "; Result.Val->dump(&DAG);
@ -294,7 +301,149 @@ namespace {
return true; return true;
} }
} }
return false;
}
/// CombineToPostIndexedLoadStore - Try combine a load / store with a
/// add / sub of the base pointer node into a post-indexed load / store.
/// The transformation folded the add / subtract into the new indexed
/// load / store effectively and all of its uses are redirected to the
/// new load / store.
bool CombineToPostIndexedLoadStore(SDNode *N) {
if (!AfterLegalize)
return false;
bool isLoad = true;
SDOperand Ptr;
MVT::ValueType VT;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
Ptr = LD->getBasePtr();
VT = LD->getLoadedVT();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
Ptr = ST->getBasePtr();
VT = ST->getStoredVT();
isLoad = false;
} else
return false;
if (Ptr.Val->use_size() > 1) {
for (SDNode::use_iterator I = Ptr.Val->use_begin(),
E = Ptr.Val->use_end(); I != E; ++I) {
SDNode *Op = *I;
if (Op == N ||
(Op->getOpcode() != ISD::ADD && Op->getOpcode() != ISD::SUB))
continue;
SDOperand BasePtr;
SDOperand Offset;
ISD::MemOpAddrMode AM = ISD::UNINDEXED;
if (TLI.getPostIndexedAddressParts(Op, VT, BasePtr, Offset, AM,DAG) &&
BasePtr.Val == Ptr.Val) {
// Try turning it into a post-indexed load / store except when
// 1) Op must be independent of N, i.e. Op is neither a predecessor
// nor a successor of N. Otherwise, if Op is folded that would
// create a cycle.
// 2) All uses are load / store ops that use it as base ptr and offset
// is just an addressing mode immediate.
// 3) If the would-be new base may not to be dead at N.
bool OffIsAMImm = Offset.getOpcode() == ISD::Constant && TLI.
isLegalAddressImmediate(cast<ConstantSDNode>(Offset)->getValue());
// Check for #3.
bool TryNext = false;
for (SDNode::use_iterator II = BasePtr.Val->use_begin(),
EE = BasePtr.Val->use_end(); II != EE; ++II) {
SDNode *Use = *II;
if (Use == Ptr.Val)
continue;
if (Use->getOpcode() == ISD::CopyToReg) {
TryNext = true;
break;
}
if (OffIsAMImm && (Use->getOpcode() == ISD::ADD ||
Use->getOpcode() == ISD::SUB)) {
for (SDNode::use_iterator III = Use->use_begin(),
EEE = Use->use_end(); III != EEE; ++III) {
SDNode *UseUse = *III;
if (UseUse->getOpcode() == ISD::LOAD &&
cast<LoadSDNode>(UseUse)->getBasePtr().Val == Use) {
TryNext = true;
break;
} else if (UseUse->getOpcode() == ISD::STORE &&
cast<StoreSDNode>(UseUse)->getBasePtr().Val == Use) {
TryNext = true;
break;
}
}
}
}
if (TryNext)
continue;
if (OffIsAMImm) {
// Check for #2.
unsigned NumRealUses = 0;
for (SDNode::use_iterator II = Op->use_begin(), EE = Op->use_end();
II != EE; ++II) {
SDNode *Use = *II;
if (Use->getOpcode() == ISD::LOAD) {
if (cast<LoadSDNode>(Use)->getBasePtr().Val != Op)
NumRealUses++;
} else if (Use->getOpcode() == ISD::STORE) {
if (cast<StoreSDNode>(Use)->getBasePtr().Val != Op)
NumRealUses++;
} else
NumRealUses++;
}
if (NumRealUses == 0)
continue;
}
// Check for #1
if (!Op->isPredecessor(N) && !N->isPredecessor(Op)) {
SDOperand Result = isLoad
? DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM)
: DAG.getIndexedStore(SDOperand(N,0), BasePtr, Offset, AM);
++PostIndexedNodes;
++NodesCombined;
DEBUG(std::cerr << "\nReplacing.5 "; N->dump();
std::cerr << "\nWith: "; Result.Val->dump(&DAG);
std::cerr << '\n');
std::vector<SDNode*> NowDead;
if (isLoad) {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(0),
NowDead);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), Result.getValue(2),
NowDead);
} else {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(1),
NowDead);
}
// Nodes can end up on the worklist more than once. Make sure we do
// not process a node that has been replaced.
for (unsigned i = 0, e = NowDead.size(); i != e; ++i)
removeFromWorkList(NowDead[i]);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
// Replace the uses of Use with uses of the updated base value.
DAG.ReplaceAllUsesOfValueWith(SDOperand(Op, 0),
Result.getValue(isLoad ? 1 : 0),
NowDead);
removeFromWorkList(Op);
for (unsigned i = 0, e = NowDead.size(); i != e; ++i)
removeFromWorkList(NowDead[i]);
DAG.DeleteNode(Op);
return true;
}
}
}
}
return false; return false;
} }
@ -2877,7 +3026,7 @@ SDOperand DAGCombiner::visitLOAD(SDNode *N) {
} }
// Try transforming N to an indexed load. // Try transforming N to an indexed load.
if (CombineToPreIndexedLoadStore(N)) if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDOperand(N, 0); return SDOperand(N, 0);
return SDOperand(); return SDOperand();
@ -2923,7 +3072,7 @@ SDOperand DAGCombiner::visitSTORE(SDNode *N) {
} }
// Try transforming N to an indexed store. // Try transforming N to an indexed store.
if (CombineToPreIndexedLoadStore(N)) if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDOperand(N, 0); return SDOperand(N, 0);
return SDOperand(); return SDOperand();