Add dump() routines to help debug debug info :)

[oota-llvm.git] / lib / VMCore / BasicBlock.cpp

diff --git a/lib/VMCore/BasicBlock.cpp b/lib/VMCore/BasicBlock.cpp
index 17469d6bdb2f9b1d61f03977eddd909249568ad9..a76f659233d4270f4ed29e1db56a292f1fa8c56c 100644 (file)
--- a/lib/VMCore/BasicBlock.cpp
+++ b/lib/VMCore/BasicBlock.cpp
@@ -15,6 +15,7 @@
 #include "llvm/Constants.h"
 #include "llvm/Instructions.h"
 #include "llvm/Type.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/Support/CFG.h"
 #include "llvm/Support/LeakDetector.h"
 #include "llvm/Support/Compiler.h"
@@ -143,15 +144,14 @@ const TerminatorInst *BasicBlock::getTerminator() const {
   return dyn_cast<TerminatorInst>(&InstList.back());
 }
 
-Instruction* BasicBlock::getFirstNonPHI()
-{
-    BasicBlock::iterator i = begin();
-    // All valid basic blocks should have a terminator,
-    // which is not a PHINode. If we have invalid basic
-    // block we'll get assert when dereferencing past-the-end
-    // iterator.
-    while (isa<PHINode>(i)) ++i;
-    return &*i;
+Instruction* BasicBlock::getFirstNonPHI() {
+  BasicBlock::iterator i = begin();
+  // All valid basic blocks should have a terminator,
+  // which is not a PHINode. If we have an invalid basic
+  // block we'll get an assertion failure when dereferencing
+  // a past-the-end iterator.
+  while (isa<PHINode>(i)) ++i;
+  return &*i;
 }
 
 void BasicBlock::dropAllReferences() {
@@ -169,6 +169,25 @@ BasicBlock *BasicBlock::getSinglePredecessor() {
   return (PI == E) ? ThePred : 0 /*multiple preds*/;
 }
 
+/// getUniquePredecessor - If this basic block has a unique predecessor block,
+/// return the block, otherwise return a null pointer.
+/// Note that unique predecessor doesn't mean single edge, there can be 
+/// multiple edges from the unique predecessor to this block (for example 
+/// a switch statement with multiple cases having the same destination).
+BasicBlock *BasicBlock::getUniquePredecessor() {
+  pred_iterator PI = pred_begin(this), E = pred_end(this);
+  if (PI == E) return 0; // No preds.
+  BasicBlock *PredBB = *PI;
+  ++PI;
+  for (;PI != E; ++PI) {
+    if (*PI != PredBB)
+      return 0;
+    // The same predecessor appears multiple times in the predecessor list.
+    // This is OK.
+  }
+  return PredBB;
+}
+
 /// removePredecessor - This method is used to notify a BasicBlock that the
 /// specified Predecessor of the block is no longer able to reach it.  This is
 /// actually not used to update the Predecessor list, but is actually used to
@@ -261,7 +280,9 @@ BasicBlock *BasicBlock::splitBasicBlock(iterator I, const std::string &BBName) {
   assert(I != InstList.end() &&
          "Trying to get me to create degenerate basic block!");
 
-  BasicBlock *New = BasicBlock::Create(BBName, getParent(), getNext());
+  BasicBlock *InsertBefore = next(Function::iterator(this))
+                               .getNodePtrUnchecked();
+  BasicBlock *New = BasicBlock::Create(BBName, getParent(), InsertBefore);
 
   // Move all of the specified instructions from the original basic block into
   // the new basic block.