1 files changed, 22 insertions, 35 deletions
diff --git a/lib/Transforms/Utils/DemoteRegToStack.cpp b/lib/Transforms/Utils/DemoteRegToStack.cpp
index 8cc2649..99b5830 100644
--- a/lib/Transforms/Utils/DemoteRegToStack.cpp
+++ b/lib/Transforms/Utils/DemoteRegToStack.cpp
@@ -6,21 +6,12 @@
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
-//
-// This file provide the function DemoteRegToStack().  This function takes a
-// virtual register computed by an Instruction and replaces it with a slot in
-// the stack frame, allocated via alloca. It returns the pointer to the
-// AllocaInst inserted.  After this function is called on an instruction, we are
-// guaranteed that the only user of the instruction is a store that is
-// immediately after it.
-//
-//===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Function.h"
 #include "llvm/Instructions.h"
 #include "llvm/Type.h"
-#include <map>
+#include "llvm/ADT/DenseMap.h"
 using namespace llvm;
 
 /// DemoteRegToStack - This function takes a virtual register computed by an
@@ -28,8 +19,7 @@ using namespace llvm;
 /// alloca.  This allows the CFG to be changed around without fear of
 /// 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,
+AllocaInst *llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
                                    Instruction *AllocaPoint) {
   if (I.use_empty()) {
     I.eraseFromParent();
@@ -47,21 +37,20 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
                           F->getEntryBlock().begin());
   }
 
-  // Change all of the users of the instruction to read from the stack slot
-  // instead.
+  // Change all of the users of the instruction to read from the stack slot.
   while (!I.use_empty()) {
     Instruction *U = cast<Instruction>(I.use_back());
     if (PHINode *PN = dyn_cast<PHINode>(U)) {
       // If this is a PHI node, we can't insert a load of the value before the
-      // use.  Instead, insert the load in the predecessor block corresponding
+      // use.  Instead insert the load in the predecessor block corresponding
       // to the incoming value.
       //
       // Note that if there are multiple edges from a basic block to this PHI
-      // node that we cannot multiple loads.  The problem is that the resultant
-      // PHI node will have multiple values (from each load) coming in from the
-      // same block, which is illegal SSA form.  For this reason, we keep track
-      // and reuse loads we insert.
-      std::map<BasicBlock*, Value*> Loads;
+      // node that we cannot have multiple loads. The problem is that the
+      // resulting PHI node will have multiple values (from each load) coming in
+      // from the same block, which is illegal SSA form. For this reason, we
+      // keep track of and reuse loads we insert.
+      DenseMap<BasicBlock*, Value*> Loads;
       for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
         if (PN->getIncomingValue(i) == &I) {
           Value *&V = Loads[PN->getIncomingBlock(i)];
@@ -81,9 +70,9 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
   }
 
 
-  // Insert stores of the computed value into the stack slot.  We have to be
-  // careful is I is an invoke instruction though, because we can't insert the
-  // store AFTER the terminator instruction.
+  // Insert stores of the computed value into the stack slot. We have to be
+  // careful if I is an invoke instruction, because we can't insert the store
+  // AFTER the terminator instruction.
   BasicBlock::iterator InsertPt;
   if (!isa<TerminatorInst>(I)) {
     InsertPt = &I;
@@ -97,18 +86,17 @@ AllocaInst* llvm::DemoteRegToStack(Instruction &I, bool VolatileLoads,
     InsertPt = II.getNormalDest()->begin();
   }
 
-  for (; isa<PHINode>(InsertPt); ++InsertPt)
-  /* empty */;   // Don't insert before any PHI nodes.
-  new StoreInst(&I, Slot, InsertPt);
+  for (; isa<PHINode>(InsertPt) || isa<LandingPadInst>(InsertPt); ++InsertPt)
+    /* empty */;   // Don't insert before PHI nodes or landingpad instrs.
 
+  new StoreInst(&I, Slot, InsertPt);
   return Slot;
 }
 
-
-/// 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, Instruction *AllocaPoint) {
+/// 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. It returns the pointer to the alloca inserted.
+AllocaInst *llvm::DemotePHIToStack(PHINode *P, Instruction *AllocaPoint) {
   if (P->use_empty()) {
     P->eraseFromParent();
     return 0;
@@ -125,7 +113,7 @@ AllocaInst* llvm::DemotePHIToStack(PHINode *P, Instruction *AllocaPoint) {
                           F->getEntryBlock().begin());
   }
 
-  // Iterate over each operand, insert store in each predecessor.
+  // Iterate over each operand inserting a store in each predecessor.
   for (unsigned i = 0, e = P->getNumIncomingValues(); i < e; ++i) {
     if (InvokeInst *II = dyn_cast<InvokeInst>(P->getIncomingValue(i))) {
       assert(II->getParent() != P->getIncomingBlock(i) &&
@@ -135,12 +123,11 @@ AllocaInst* llvm::DemotePHIToStack(PHINode *P, Instruction *AllocaPoint) {
                   P->getIncomingBlock(i)->getTerminator());
   }
 
-  // Insert load in place of the phi and replace all uses.
+  // Insert a load in place of the PHI and replace all uses.
   Value *V = new LoadInst(Slot, P->getName()+".reload", P);
   P->replaceAllUsesWith(V);
 
-  // Delete phi.
+  // Delete PHI.
   P->eraseFromParent();
-
   return Slot;
 }