Add utility routines to remove dead debug info.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@59011 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 60 insertions, 0 deletions

diff --git a/lib/Transforms/Utils/DbgInfoUtils.cpp b/lib/Transforms/Utils/DbgInfoUtils.cpp
new file mode 100644
index 0000000000..4bd116a6e5
--- /dev/null
+++ b/lib/Transforms/Utils/DbgInfoUtils.cpp
@@ -0,0 +1,60 @@
+//===-- DbgInfoUtils.cpp - DbgInfo Utilities -------------------------------==//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// Utility functions to manipulate debugging information.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/DbgInfoUtils.h"
+#include "llvm/IntrinsicInst.h"
+
+using namespace llvm;
+
+/// RemoveDeadDbgIntrinsics - Remove dead dbg intrinsics from this 
+/// basic block.
+void llvm::RemoveDeadDbgIntrinsics(BasicBlock &BB) {
+  BasicBlock::iterator BI = BB.begin(), BE = BB.end();
+  if (BI == BE) return;
+
+  Instruction *Prev = BI; ++BI;
+  while (BI != BE) {
+    Instruction *Next = BI; ++BI;
+    DbgInfoIntrinsic *DBI_Prev = dyn_cast<DbgInfoIntrinsic>(Prev);
+    if (!DBI_Prev) {
+      Prev = Next;
+      continue;
+    }
+    
+    // If there are two consecutive llvm.dbg.stoppoint calls then
+    // it is likely that the optimizer deleted code in between these
+    // two intrinsics. 
+    DbgInfoIntrinsic *DBI_Next = dyn_cast<DbgInfoIntrinsic>(Next);
+    if (DBI_Next 
+        && DBI_Prev->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint
+        && DBI_Next->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint)
+      Prev->eraseFromParent();
+    
+    // If a llvm.dbg.stoppoint is placed just before an unconditional
+    // branch then remove the llvm.dbg.stoppoint intrinsic.
+    else if (BranchInst *UC = dyn_cast<BranchInst>(Next)) {
+      if (UC->isUnconditional() 
+          && DBI_Prev->getIntrinsicID() == llvm::Intrinsic::dbg_stoppoint)
+        Prev->eraseFromParent();
+    }
+
+    Prev = Next;
+  }
+}
+
+/// RemoveDeadDbgIntrinsics - Remove dead dbg intrinsics from this function.
+void llvm::RemoveDeadDbgIntrinsics(Function &F) {
+  for (Function::iterator FI = F.begin(), FE = F.end();
+       FI != FE; ++FI) 
+    RemoveDeadDbgIntrinsics(*FI);
+}