X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FUtils%2FUnifyFunctionExitNodes.cpp;h=848f2b87c4eed2e2ec8c5e9661dafa9fac2992cc;hb=d68a07650cdb2e18f18f362ba533459aa10e01b6;hp=f8e959c38c7d79859e5d24dcae5714faf2191709;hpb=8606d9924b2c1581e45748430be749f1e2934025;p=oota-llvm.git

diff --git a/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp b/lib/Transforms/Utils/UnifyFunctionExitNodes.cpp
index f8e959c38c7..848f2b87c4e 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
@@ -8,16 +15,30 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Transforms/Scalar.h"
 #include "llvm/BasicBlock.h"
 #include "llvm/Function.h"
-#include "llvm/iTerminators.h"
-#include "llvm/iPHINode.h"
+#include "llvm/Instructions.h"
 #include "llvm/Type.h"
-using std::vector;
+#include "llvm/ADT/StringExtras.h"
+using namespace llvm;
 
-static RegisterOpt<UnifyFunctionExitNodes>
+char UnifyFunctionExitNodes::ID = 0;
+static RegisterPass<UnifyFunctionExitNodes>
 X("mergereturn", "Unify function exit nodes");
 
+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.addPreservedID(PromoteMemoryToRegisterID);
+  AU.addPreservedID(LowerSwitchID);
+}
+
 // UnifyAllExitNodes - Unify all exit nodes of the CFG by creating a new
 // BasicBlock, and converting all returns to unconditional branches to this
 // new basic block.  The singular exit node is returned.
@@ -28,51 +49,91 @@ 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*> UnwindingBlocks;
+  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<UnwindInst>(I->getTerminator()))
+      UnwindingBlocks.push_back(I);
+    else if (isa<UnreachableInst>(I->getTerminator()))
+      UnreachableBlocks.push_back(I);
+
+  // Handle unwinding blocks first.
+  if (UnwindingBlocks.empty()) {
+    UnwindBlock = 0;
+  } else if (UnwindingBlocks.size() == 1) {
+    UnwindBlock = UnwindingBlocks.front();
+  } else {
+    UnwindBlock = BasicBlock::Create("UnifiedUnwindBlock", &F);
+    new UnwindInst(UnwindBlock);
+
+    for (std::vector<BasicBlock*>::iterator I = UnwindingBlocks.begin(),
+           E = UnwindingBlocks.end(); I != E; ++I) {
+      BasicBlock *BB = *I;
+      BB->getInstList().pop_back();  // Remove the unwind insn
+      BranchInst::Create(UnwindBlock, BB);
+    }
+  }
+
+  // Then unreachable blocks.
+  if (UnreachableBlocks.empty()) {
+    UnreachableBlock = 0;
+  } else if (UnreachableBlocks.size() == 1) {
+    UnreachableBlock = UnreachableBlocks.front();
+  } else {
+    UnreachableBlock = BasicBlock::Create("UnifiedUnreachableBlock", &F);
+    new UnreachableInst(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 = 0;
     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("UnifiedReturnBlock", &F);
 
-  if (F.getReturnType() != Type::VoidTy) {
+  PHINode *PN = 0;
+  if (F.getReturnType() == Type::VoidTy) {
+    ReturnInst::Create(NULL, NewRetBlock);
+  } else {
     // If the function doesn't return void... add a PHI node to the block...
-    PHINode *PN = new PHINode(F.getReturnType(), "UnifiedRetVal");
+    PN = PHINode::Create(F.getReturnType(), "UnifiedRetVal");
     NewRetBlock->getInstList().push_back(PN);
-
-    // Add an incoming element to the PHI node for every return instruction that
-    // is merging into this new block...
-    for (vector<BasicBlock*>::iterator I = ReturningBlocks.begin(), 
-                                       E = ReturningBlocks.end(); I != E; ++I)
-      PN->addIncoming((*I)->getTerminator()->getOperand(0), *I);
-
-    // Add a return instruction to return the result of the PHI node...
-    NewRetBlock->getInstList().push_back(new ReturnInst(PN));
-  } else {
-    // If it returns void, just add a return void instruction to the block
-    new ReturnInst(0, NewRetBlock->end());
+    ReturnInst::Create(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) {
-    (*I)->getInstList().pop_back();  // Remove the return insn
-    (*I)->getInstList().push_back(new BranchInst(NewRetBlock));
+  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);
+
+    BB->getInstList().pop_back();  // Remove the return insn
+    BranchInst::Create(NewRetBlock, BB);
   }
-  ExitNode = NewRetBlock;
+  ReturnBlock = NewRetBlock;
   return true;
 }