Account for PATCHABLE instrs in Branch Relaxation

PATCHABLE_* instructions expand to up to 36-byte
sleds. Updating the size of PATCHABLE instructions
causes them to be outlined, so we need to add a
check to prevent the outliner from considering
basic blocks that contain PATCHABLE instructions.

Differential Revision: https://reviews.llvm.org/D147982

1 files changed, 18 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/TargetInstrInfo.cpp b/llvm/lib/CodeGen/TargetInstrInfo.cpp
index 5c5b6a0..9d6c9a6 100644
--- a/llvm/lib/CodeGen/TargetInstrInfo.cpp
+++ b/llvm/lib/CodeGen/TargetInstrInfo.cpp
@@ -1651,10 +1651,25 @@ bool TargetInstrInfo::isMBBSafeToOutlineFrom(MachineBasicBlock &MBB,
   // Some instrumentations create special TargetOpcode at the start which
   // expands to special code sequences which must be present.
   auto First = MBB.getFirstNonDebugInstr();
-  if (First != MBB.end() &&
-      (First->getOpcode() == TargetOpcode::FENTRY_CALL ||
-       First->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_ENTER))
+  if (First == MBB.end())
+    return true;
+
+  if (First->getOpcode() == TargetOpcode::FENTRY_CALL ||
+      First->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_ENTER)
+    return false;
+
+  // Some instrumentations create special pseudo-instructions at or just before
+  // the end that must be present.
+  auto Last = MBB.getLastNonDebugInstr();
+  if (Last->getOpcode() == TargetOpcode::PATCHABLE_RET ||
+      Last->getOpcode() == TargetOpcode::PATCHABLE_TAIL_CALL)
     return false;
 
+  if (Last != First && Last->isReturn()) {
+    --Last;
+    if (Last->getOpcode() == TargetOpcode::PATCHABLE_FUNCTION_EXIT ||
+        Last->getOpcode() == TargetOpcode::PATCHABLE_TAIL_CALL)
+      return false;
+  }
   return true;
 }