Recommit "[DSE] Preserve basic block ordering using OrderedBasicBlock."

Recommitting after addressing a buildbot failure.

This reverts commit c87869ebea000dd6483de7c7451cb36c1d36f866.

llvm-svn: 357222

1 files changed, 24 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/OrderedBasicBlock.cpp b/llvm/lib/Analysis/OrderedBasicBlock.cpp
index 3cc6319028d..401f818f12d 100644
--- a/llvm/lib/Analysis/OrderedBasicBlock.cpp
+++ b/llvm/lib/Analysis/OrderedBasicBlock.cpp
@@ -85,3 +85,27 @@ bool OrderedBasicBlock::dominates(const Instruction *A, const Instruction *B) {
 
   return comesBefore(A, B);
 }
+
+void OrderedBasicBlock::eraseInstruction(const Instruction *I) {
+  if (LastInstFound != BB->end() && I == &*LastInstFound) {
+    if (LastInstFound == BB->begin()) {
+      LastInstFound = BB->end();
+      NextInstPos = 0;
+    } else
+      LastInstFound--;
+  }
+
+  NumberedInsts.erase(I);
+}
+
+void OrderedBasicBlock::replaceInstruction(const Instruction *Old,
+                                           const Instruction *New) {
+  auto OI = NumberedInsts.find(Old);
+  if (OI == NumberedInsts.end())
+    return;
+
+  NumberedInsts[New] = OI->second;
+  if (LastInstFound != BB->end() && Old == &*LastInstFound)
+    LastInstFound = New->getIterator();
+  NumberedInsts.erase(Old);
+}