X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FUtils%2FUnifyFunctionExitNodes.cpp;h=0c2fc0a972b53c931706a5f9fd82bb13563a9e67;hb=7d8f1710a314e5bbc580a9e210d7dc6fa1b50510;hp=b56cee9379e05e5637d690929e2eb814a375c167;hpb=6c0e0496dc8f901a282ae1f591b8af2ecf095b97;p=oota-llvm.git

diff --git a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index b56cee9379e..0c2fc0a972b 100644
--- a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
+++ b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
@@ -1,5 +1,12 @@
 //===- UnifyFunctionExitNodes.cpp - Make all functions have a single exit -===//
 //
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
 // This pass is used to ensure that functions have at most one return
 // instruction in them.  Additionally, it keeps track of which node is the new
 // exit node of the CFG.  If there are no exit nodes in the CFG, the getExitNode
@@ -8,20 +15,28 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Type.h"
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Function.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iPHINode.h"
-#include "llvm/Type.h"
-using std::vector;
+using namespace llvm;
 
-static RegisterOpt<UnifyFunctionExitNodes>
-X("mergereturn", "Unify function exit nodes");
+char UnifyFunctionExitNodes::ID = 0;
+INITIALIZE_PASS(UnifyFunctionExitNodes, "mergereturn",
+                "Unify function exit nodes", false, false)
+
+Pass *llvm::createUnifyFunctionExitNodesPass() {
+  return new UnifyFunctionExitNodes();
+}
 
 void UnifyFunctionExitNodes::getAnalysisUsage(AnalysisUsage &AU) const{
   // We preserve the non-critical-edgeness property
   AU.addPreservedID(BreakCriticalEdgesID);
+  // This is a cluster of orthogonal Transforms
+  AU.addPreserved("mem2reg");
+  AU.addPreservedID(LowerSwitchID);
 }
 
 // UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
@@ -34,51 +49,74 @@ bool UnifyFunctionExitNodes::runOnFunction(Function &F) {
   // Loop over all of the blocks in a function, tracking all of the blocks that
   // return.
   //
-  vector<BasicBlock*> ReturningBlocks;
+  std::vector<BasicBlock*> ReturningBlocks;
+  std::vector<BasicBlock*> UnreachableBlocks;
   for(Function::iterator I = F.begin(), E = F.end(); I != E; ++I)
     if (isa<ReturnInst>(I->getTerminator()))
       ReturningBlocks.push_back(I);
+    else if (isa<UnreachableInst>(I->getTerminator()))
+      UnreachableBlocks.push_back(I);
 
+  // Then unreachable blocks.
+  if (UnreachableBlocks.empty()) {
+    UnreachableBlock = nullptr;
+  } else if (UnreachableBlocks.size() == 1) {
+    UnreachableBlock = UnreachableBlocks.front();
+  } else {
+    UnreachableBlock = BasicBlock::Create(F.getContext(), 
+                                          "UnifiedUnreachableBlock", &F);
+    new UnreachableInst(F.getContext(), UnreachableBlock);
+
+    for (std::vector<BasicBlock*>::iterator I = UnreachableBlocks.begin(),
+           E = UnreachableBlocks.end(); I != E; ++I) {
+      BasicBlock *BB = *I;
+      BB->getInstList().pop_back();  // Remove the unreachable inst.
+      BranchInst::Create(UnreachableBlock, BB);
+    }
+  }
+
+  // Now handle return blocks.
   if (ReturningBlocks.empty()) {
-    ExitNode = 0;
+    ReturnBlock = nullptr;
     return false;                          // No blocks return
   } else if (ReturningBlocks.size() == 1) {
-    ExitNode = ReturningBlocks.front();    // Already has a single return block
+    ReturnBlock = ReturningBlocks.front(); // Already has a single return block
     return false;
   }
 
   // Otherwise, we need to insert a new basic block into the function, add a PHI
-  // node (if the function returns a value), and convert all of the return 
+  // nodes (if the function returns values), and convert all of the return
   // instructions into unconditional branches.
   //
-  BasicBlock *NewRetBlock = new BasicBlock("UnifiedExitNode", &F);
+  BasicBlock *NewRetBlock = BasicBlock::Create(F.getContext(),
+                                               "UnifiedReturnBlock", &F);
 
-  PHINode *PN = 0;
-  if (F.getReturnType() != Type::VoidTy) {
+  PHINode *PN = nullptr;
+  if (F.getReturnType()->isVoidTy()) {
+    ReturnInst::Create(F.getContext(), nullptr, NewRetBlock);
+  } else {
     // If the function doesn't return void... add a PHI node to the block...
-    PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+    PN = PHINode::Create(F.getReturnType(), ReturningBlocks.size(),
+                         "UnifiedRetVal");
     NewRetBlock->getInstList().push_back(PN);
-    NewRetBlock->getInstList().push_back(new ReturnInst(PN));
-  } else {
-    // If it returns void, just add a return void instruction to the block
-    NewRetBlock->getInstList().push_back(new ReturnInst());
+    ReturnInst::Create(F.getContext(), PN, NewRetBlock);
   }
 
   // Loop over all of the blocks, replacing the return instruction with an
   // unconditional branch.
   //
-  for (vector<BasicBlock*>::iterator I = ReturningBlocks.begin(), 
-                                     E = ReturningBlocks.end(); I != E; ++I) {
+  for (std::vector<BasicBlock*>::iterator I = ReturningBlocks.begin(),
+         E = ReturningBlocks.end(); I != E; ++I) {
     BasicBlock *BB = *I;
 
     // Add an incoming element to the PHI node for every return instruction that
     // is merging into this new block...
-    if (PN) PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
+    if (PN)
+      PN->addIncoming(BB->getTerminator()->getOperand(0), BB);
 
     BB->getInstList().pop_back();  // Remove the return insn
-    BB->getInstList().push_back(new BranchInst(NewRetBlock));
+    BranchInst::Create(NewRetBlock, BB);
   }
-  ExitNode = NewRetBlock;
-
+  ReturnBlock = NewRetBlock;
   return true;
 }