[PATCH] D132495: [BOLT] Improve recognition of unknown control flow

[Amir Ayupov via Phabricator via llvm-commits]

Amir created this revision.
Amir added a reviewer: bolt.
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For functions with references to internal offsets from data but with no
recognized jump tables, add externally referenced blocks as entry points and
mark the function as having an unknown control flow.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D132495

Files:
  bolt/lib/Core/BinaryFunction.cpp


Index: bolt/lib/Core/BinaryFunction.cpp
===================================================================
--- bolt/lib/Core/BinaryFunction.cpp
+++ bolt/lib/Core/BinaryFunction.cpp
@@ -1842,6 +1842,16 @@
   if (HasInternalLabelReference)
     return false;
 
+  // If there are references to function internals from data but the function
+  // does not have recognized jump tables, mark it as having unknown control
+  // flow and register externally referenced blocks as entry points.
+  if (hasInternalReference() && JumpTables.empty()) {
+    HasUnknownControlFlow = true;
+    for (uint64_t PossibleDestination : ExternallyReferencedOffsets)
+      if (BinaryBasicBlock *BB = getBasicBlockAtOffset(PossibleDestination))
+        addEntryPoint(*BB);
+  }
+
   // If there's only one jump table, and one indirect jump, and no other
   // references, then we should be able to derive the jump table even if we
   // fail to match the pattern.


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