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Reg2Mem cleanup and optimizations:

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- enable phi instructions demotion to stack
 - create alloca instructions in the entry block


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@43208 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Anton Korobeynikov
2007-10-21 23:05:16 +00:00
parent c6185038b8
commit a024e8ceda
3 changed files with 75 additions and 27 deletions
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38
lib/Transforms/Utils/DemoteRegToStack.cpp
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@ -29,14 +29,23 @@ using namespace llvm;
/// invalidating the SSA information for the value. It returns the pointer to
/// the alloca inserted to create a stack slot for I.
///
AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads) {
if (I.use_empty()) return 0; // nothing to do!
AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
Instruction *AllocaPoint) {
if (I.use_empty()) {
I.eraseFromParent();
return 0;
}
// Create a stack slot to hold the value.
Function *F = I.getParent()->getParent();
AllocaInst *Slot = new AllocaInst(I.getType(), 0, I.getName(),
F->getEntryBlock().begin());
AllocaInst *Slot;
if (AllocaPoint) {
Slot = new AllocaInst(I.getType(), 0, I.getName()+".reg2mem", AllocaPoint);
} else {
Function *F = I.getParent()->getParent();
Slot = new AllocaInst(I.getType(), 0, I.getName()+".reg2mem",
F->getEntryBlock().begin());
}
// Change all of the users of the instruction to read from the stack slot
// instead.
while (!I.use_empty()) {
@ -98,16 +107,21 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads) {
/// DemotePHIToStack - This function takes a virtual register computed by a phi
/// node and replaces it with a slot in the stack frame, allocated via alloca.
/// The phi node is deleted and it returns the pointer to the alloca inserted.
AllocaInst* llvm::DemotePHIToStack(PHINode *P) {
AllocaInst* llvm::DemotePHIToStack(PHINode *P, Instruction *AllocaPoint) {
if (P->use_empty()) {
P->eraseFromParent();
return 0;
}
// Create a stack slot to hold the value.
Function *F = P->getParent()->getParent();
AllocaInst *Slot = new AllocaInst(P->getType(), 0, P->getName(),
F->getEntryBlock().begin());
AllocaInst *Slot;
if (AllocaPoint) {
Slot = new AllocaInst(P->getType(), 0, P->getName()+".reg2mem", AllocaPoint);
} else {
Function *F = P->getParent()->getParent();
Slot = new AllocaInst(P->getType(), 0, P->getName()+".reg2mem",
F->getEntryBlock().begin());
}
// Iterate over each operand, insert store in each predecessor.
for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {