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path: root/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
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-rw-r--r--lib/Transforms/Utils/PromoteMemoryToRegister.cpp107
1 files changed, 54 insertions, 53 deletions
diff --git a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
index 23dd2865a0..5cd811d6f2 100644
--- a/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
+++ b/lib/Transforms/Utils/PromoteMemoryToRegister.cpp
@@ -38,21 +38,20 @@ protected:
vector<AllocaInst*> Allocas; // the alloca instruction..
map<Instruction*, unsigned> AllocaLookup; // reverse mapping of above
- vector<vector<BasicBlock*> > WriteSets; // index corresponds to Allocas
vector<vector<BasicBlock*> > PhiNodes; // index corresponds to Allocas
- vector<vector<Value*> > CurrentValue; // the current value stack
//list of instructions to remove at end of pass :)
vector<Instruction *> KillList;
- set<BasicBlock*> visited; // the basic blocks we've already visited
map<BasicBlock*, vector<PHINode*> > NewPhiNodes; // the phinodes we're adding
- void traverse(BasicBlock *f, BasicBlock * predecessor);
+ bool didchange;
+
+ void traverse(BasicBlock *BB, BasicBlock *Pred, vector<Value*> &IncVals,
+ set<BasicBlock*> &Visited);
bool PromoteFunction(Function *F, DominanceFrontier &DF);
bool QueuePhiNode(BasicBlock *bb, unsigned alloca_index);
void findSafeAllocas(Function *M);
- bool didchange;
public:
// I do this so that I can force the deconstruction of the local variables
PromoteInstance(Function *F, DominanceFrontier &DF) {
@@ -65,6 +64,29 @@ public:
} // end of anonymous namespace
+// isSafeAlloca - This predicate controls what types of alloca instructions are
+// allowed to be promoted...
+//
+static inline bool isSafeAlloca(const AllocaInst *AI) {
+ if (AI->isArrayAllocation()) return false;
+
+ for (Value::use_iterator UI = AI->use_begin(), UE = AI->use_end();
+ UI != UE; ++UI) { // Loop over all of the uses of the alloca
+
+ // Only allow nonindexed memory access instructions...
+ if (MemAccessInst *MAI = dyn_cast<MemAccessInst>(*UI)) {
+ if (MAI->hasIndices()) { // indexed?
+ // Allow the access if there is only one index and the index is
+ // zero.
+ if (*MAI->idx_begin() != ConstantUInt::get(Type::UIntTy, 0) ||
+ MAI->idx_begin()+1 != MAI->idx_end())
+ return false;
+ }
+ } else {
+ return false; // Not a load or store?
+ }
+ }
+}
// findSafeAllocas - Find allocas that are safe to promote
//
@@ -74,30 +96,9 @@ void PromoteInstance::findSafeAllocas(Function *F) {
// Look at all instructions in the entry node
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (AllocaInst *AI = dyn_cast<AllocaInst>(*I)) // Is it an alloca?
- if (!AI->isArrayAllocation()) {
- bool isSafe = true;
- for (Value::use_iterator UI = AI->use_begin(), UE = AI->use_end();
- UI != UE; ++UI) { // Loop over all of the uses of the alloca
-
- // Only allow nonindexed memory access instructions...
- if (MemAccessInst *MAI = dyn_cast<MemAccessInst>(*UI)) {
- if (MAI->hasIndices()) { // indexed?
- // Allow the access if there is only one index and the index is
- // zero.
- if (*MAI->idx_begin() != ConstantUInt::get(Type::UIntTy, 0) ||
- MAI->idx_begin()+1 != MAI->idx_end()) {
- isSafe = false;
- break;
- }
- }
- } else {
- isSafe = false; break; // Not a load or store?
- }
- }
- if (isSafe) { // If all checks pass, add alloca to safe list
- AllocaLookup[AI] = Allocas.size();
- Allocas.push_back(AI);
- }
+ if (isSafeAlloca(AI)) { // If safe alloca, add alloca to safe list
+ AllocaLookup[AI] = Allocas.size(); // Keep reverse mapping
+ Allocas.push_back(AI);
}
}
@@ -113,6 +114,7 @@ bool PromoteInstance::PromoteFunction(Function *F, DominanceFrontier &DF) {
// Calculate the set of write-locations for each alloca. This is analogous to
// counting the number of 'redefinitions' of each variable.
+ vector<vector<BasicBlock*> > WriteSets; // index corresponds to Allocas
WriteSets.resize(Allocas.size());
for (unsigned i = 0; i != Allocas.size(); ++i) {
AllocaInst *AI = Allocas[i];
@@ -150,15 +152,15 @@ bool PromoteInstance::PromoteFunction(Function *F, DominanceFrontier &DF) {
// the alloca's. We do this in case there is a load of a value that has not
// been stored yet. In this case, it will get this null value.
//
- CurrentValue.push_back(vector<Value *>(Allocas.size()));
+ vector<Value *> Values(Allocas.size());
for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
- CurrentValue[0][i] =
- Constant::getNullValue(Allocas[i]->getType()->getElementType());
+ Values[i] = Constant::getNullValue(Allocas[i]->getType()->getElementType());
// Walks all basic blocks in the function performing the SSA rename algorithm
// and inserting the phi nodes we marked as necessary
//
- traverse(F->front(), 0); // there is no predecessor of the root node
+ set<BasicBlock*> Visited; // The basic blocks we've already visited
+ traverse(F->front(), 0, Values, Visited);
// Remove all instructions marked by being placed in the KillList...
//
@@ -178,29 +180,29 @@ bool PromoteInstance::PromoteFunction(Function *F, DominanceFrontier &DF) {
// QueuePhiNode - queues a phi-node to be added to a basic-block for a specific
// Alloca returns true if there wasn't already a phi-node for that variable
//
-bool PromoteInstance::QueuePhiNode(BasicBlock *BB, unsigned i /*the alloca*/) {
+bool PromoteInstance::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo) {
// Look up the basic-block in question
vector<PHINode*> &BBPNs = NewPhiNodes[BB];
if (BBPNs.empty()) BBPNs.resize(Allocas.size());
// If the BB already has a phi node added for the i'th alloca then we're done!
- if (BBPNs[i]) return false;
+ if (BBPNs[AllocaNo]) return false;
// Create a phi-node using the dereferenced type...
- PHINode *PN = new PHINode(Allocas[i]->getType()->getElementType(),
- Allocas[i]->getName()+".mem2reg");
- BBPNs[i] = PN;
+ PHINode *PN = new PHINode(Allocas[AllocaNo]->getType()->getElementType(),
+ Allocas[AllocaNo]->getName()+".mem2reg");
+ BBPNs[AllocaNo] = PN;
// Add the phi-node to the basic-block
BB->getInstList().push_front(PN);
- PhiNodes[i].push_back(BB);
+ PhiNodes[AllocaNo].push_back(BB);
return true;
}
-void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred) {
- vector<Value *> &TOS = CurrentValue.back(); // look at top
-
+void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred,
+ vector<Value*> &IncomingVals,
+ set<BasicBlock*> &Visited) {
// If this is a BB needing a phi node, lookup/create the phinode for each
// variable we need phinodes for.
vector<PHINode *> &BBPNs = NewPhiNodes[BB];
@@ -208,17 +210,17 @@ void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred) {
if (PHINode *PN = BBPNs[k]) {
// at this point we can assume that the array has phi nodes.. let's add
// the incoming data
- PN->addIncoming(TOS[k], Pred);
+ PN->addIncoming(IncomingVals[k], Pred);
// also note that the active variable IS designated by the phi node
- TOS[k] = PN;
+ IncomingVals[k] = PN;
}
// don't revisit nodes
- if (visited.count(BB)) return;
+ if (Visited.count(BB)) return;
// mark as visited
- visited.insert(BB);
+ Visited.insert(BB);
// keep track of the value of each variable we're watching.. how?
for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II) {
@@ -228,9 +230,9 @@ void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred) {
Value *Ptr = LI->getPointerOperand();
if (AllocaInst *Src = dyn_cast<AllocaInst>(Ptr)) {
- map<Instruction*, unsigned>::iterator ai = AllocaLookup.find(Src);
- if (ai != AllocaLookup.end()) {
- Value *V = TOS[ai->second];
+ map<Instruction*, unsigned>::iterator AI = AllocaLookup.find(Src);
+ if (AI != AllocaLookup.end()) {
+ Value *V = IncomingVals[AI->second];
// walk the use list of this load and replace all uses with r
LI->replaceAllUsesWith(V);
@@ -245,7 +247,7 @@ void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred) {
map<Instruction *, unsigned>::iterator ai = AllocaLookup.find(Dest);
if (ai != AllocaLookup.end()) {
// what value were we writing?
- TOS[ai->second] = SI->getOperand(0);
+ IncomingVals[ai->second] = SI->getOperand(0);
KillList.push_back(SI); // Mark the store to be deleted
}
}
@@ -253,9 +255,8 @@ void PromoteInstance::traverse(BasicBlock *BB, BasicBlock *Pred) {
} else if (TerminatorInst *TI = dyn_cast<TerminatorInst>(I)) {
// Recurse across our successors
for (unsigned i = 0; i != TI->getNumSuccessors(); i++) {
- CurrentValue.push_back(CurrentValue.back());
- traverse(TI->getSuccessor(i), BB); // This node becomes the predecessor
- CurrentValue.pop_back();
+ vector<Value*> OutgoingVals(IncomingVals);
+ traverse(TI->getSuccessor(i), BB, OutgoingVals, Visited);
}
}
}
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-04-30 07:03:11 +0000