Reg2Mem cleanup and optimizations:
- 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
diff --git a/lib/Transforms/Utils/DemoteRegToStack.cpp b/lib/Transforms/Utils/DemoteRegToStack.cpp
index 95b28f1..32c1f19 100644
--- a/lib/Transforms/Utils/DemoteRegToStack.cpp
+++ b/lib/Transforms/Utils/DemoteRegToStack.cpp
@@ -29,14 +29,23 @@
/// 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 @@
/// 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) {