1 //===- DemoteRegToStack.cpp - Move a virtual register to the stack --------===//
8 //===----------------------------------------------------------------------===//
10 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
16 #include "llvm/Transforms/Utils/Local.h"
19 /// DemoteRegToStack - This function takes a virtual register computed by an
20 /// Instruction and replaces it with a slot in the stack frame, allocated via
23 /// the alloca inserted to create a stack slot for I.
31   // Create a stack slot to hold the value.  in DemoteRegToStack()
37     Function *F = I.getParent()->getParent();  in DemoteRegToStack()
39                           &F->getEntryBlock().front());  in DemoteRegToStack()
42   // We cannot demote invoke instructions to the stack if their normal edge  in DemoteRegToStack()
46     if (!II->getNormalDest()->getSinglePredecessor()) {  in DemoteRegToStack()
47       unsigned SuccNum = GetSuccessorNumber(II->getParent(), II->getNormalDest());  in DemoteRegToStack()
55   // Change all of the users of the instruction to read from the stack slot.  in DemoteRegToStack()
69       for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)  in DemoteRegToStack()
70         if (PN->getIncomingValue(i) == &I) {  in DemoteRegToStack()
71           Value *&V = Loads[PN->getIncomingBlock(i)];  in DemoteRegToStack()
75                              PN->getIncomingBlock(i)->getTerminator());  in DemoteRegToStack()
77           PN->setIncomingValue(i, V);  in DemoteRegToStack()
83       U->replaceUsesOfWith(&I, V);  in DemoteRegToStack()
87   // Insert stores of the computed value into the stack slot. We have to be  in DemoteRegToStack()
93     for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)  in DemoteRegToStack()
97     InsertPt = II.getNormalDest()->getFirstInsertionPt();  in DemoteRegToStack()
104 /// DemotePHIToStack - This function takes a virtual register computed by a PHI
105 /// node and replaces it with a slot in the stack frame allocated via alloca.
108   if (P->use_empty()) {  in DemotePHIToStack()
109     P->eraseFromParent();  in DemotePHIToStack()
113   // Create a stack slot to hold the value.  in DemotePHIToStack()
116     Slot = new AllocaInst(P->getType(), nullptr,  in DemotePHIToStack()
117                           P->getName()+".reg2mem", AllocaPoint);  in DemotePHIToStack()
119     Function *F = P->getParent()->getParent();  in DemotePHIToStack()
120     Slot = new AllocaInst(P->getType(), nullptr, P->getName() + ".reg2mem",  in DemotePHIToStack()
121                           &F->getEntryBlock().front());  in DemotePHIToStack()
125   for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {  in DemotePHIToStack()
126     if (InvokeInst *II = dyn_cast<InvokeInst>(P->getIncomingValue(i))) {  in DemotePHIToStack()
127       assert(II->getParent() != P->getIncomingBlock(i) &&  in DemotePHIToStack()
130     new StoreInst(P->getIncomingValue(i), Slot,  in DemotePHIToStack()
131                   P->getIncomingBlock(i)->getTerminator());  in DemotePHIToStack()
135   BasicBlock::iterator InsertPt = P->getIterator();  in DemotePHIToStack()
137   for (; isa<PHINode>(InsertPt) || InsertPt->isEHPad(); ++InsertPt)  in DemotePHIToStack()
140   Value *V = new LoadInst(Slot, P->getName() + ".reload", &*InsertPt);  in DemotePHIToStack()
141   P->replaceAllUsesWith(V);  in DemotePHIToStack()
144   P->eraseFromParent();  in DemotePHIToStack()