[Packetizer] Add function to check for aliasing between instructions

llvm-svn: 316243

1 files changed, 32 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/DFAPacketizer.cpp b/llvm/lib/CodeGen/DFAPacketizer.cpp
index 853b9afa102..cf21316ec22 100644
--- a/llvm/lib/CodeGen/DFAPacketizer.cpp
+++ b/llvm/lib/CodeGen/DFAPacketizer.cpp
@@ -336,6 +336,38 @@ void VLIWPacketizerList::PacketizeMIs(MachineBasicBlock *MBB,
   VLIWScheduler->finishBlock();
 }
 
+bool VLIWPacketizerList::alias(const MachineMemOperand &Op1,
+                               const MachineMemOperand &Op2,
+                               bool UseTBAA) const {
+  if (!Op1.getValue() || !Op2.getValue())
+    return true;
+
+  int64_t MinOffset = std::min(Op1.getOffset(), Op2.getOffset());
+  int64_t Overlapa = Op1.getSize() + Op1.getOffset() - MinOffset;
+  int64_t Overlapb = Op2.getSize() + Op2.getOffset() - MinOffset;
+
+  AliasResult AAResult =
+      AA->alias(MemoryLocation(Op1.getValue(), Overlapa,
+                               UseTBAA ? Op1.getAAInfo() : AAMDNodes()),
+                MemoryLocation(Op2.getValue(), Overlapb,
+                               UseTBAA ? Op2.getAAInfo() : AAMDNodes()));
+
+  return AAResult != NoAlias;
+}
+
+bool VLIWPacketizerList::alias(const MachineInstr &MI1,
+                               const MachineInstr &MI2,
+                               bool UseTBAA) const {
+  if (MI1.memoperands_empty() || MI2.memoperands_empty())
+    return true;
+
+  for (const MachineMemOperand *Op1 : MI1.memoperands())
+    for (const MachineMemOperand *Op2 : MI2.memoperands())
+      if (alias(*Op1, *Op2, UseTBAA))
+        return true;
+  return false;
+}
+
 // Add a DAG mutation object to the ordered list.
 void VLIWPacketizerList::addMutation(
       std::unique_ptr<ScheduleDAGMutation> Mutation) {