Runtime error check elimination

  Hoist runtime checks in the loop nest if they guard an "error" like event.
  Such events are recognized as blocks with an unreachable terminator or a call
  to the ubsan function that deals with out of bound accesses. Other "error"
  events can be added easily.

  We will ignore these blocks when we detect/model/optmize and code generate SCoPs
  but we will make sure that they would not have been executed using the assumption
  framework.

llvm-svn: 247310

1 files changed, 14 insertions, 0 deletions

diff --git a/polly/lib/Support/ScopHelper.cpp b/polly/lib/Support/ScopHelper.cpp
index a535f98aa55..69904f0c241 100644
--- a/polly/lib/Support/ScopHelper.cpp
+++ b/polly/lib/Support/ScopHelper.cpp
@@ -331,3 +331,17 @@ Value *polly::expandCodeFor(Scop &S, ScalarEvolution &SE, const DataLayout &DL,
   ScopExpander Expander(S.getRegion(), SE, DL, Name);
   return Expander.expandCodeFor(E, Ty, IP);
 }
+
+bool polly::isErrorBlock(BasicBlock &BB) {
+
+  for (Instruction &Inst : BB)
+    if (CallInst *CI = dyn_cast<CallInst>(&Inst))
+      if (Function *F = CI->getCalledFunction())
+        if (F->getName().equals("__ubsan_handle_out_of_bounds"))
+          return true;
+
+  if (isa<UnreachableInst>(BB.getTerminator()))
+    return true;
+
+  return false;
+}