CodeGen: Remove AliasAnalysis from regalloc

This was stored in LiveIntervals, but not actually used for anything
related to LiveIntervals. It was only used in one check for if a load
instruction is rematerializable. I also don't think this was entirely
correct, since it was implicitly assuming constant loads are also
dereferenceable.

Remove this and rely only on the invariant+dereferenceable flags in
the memory operand. Set the flag based on the AA query upfront. This
should have the same net benefit, but has the possible disadvantage of
making this AA query nonlazy.

Preserve the behavior of assuming pointsToConstantMemory implying
dereferenceable for now, but maybe this should be changed.

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 07f1dce..52501ca 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -706,11 +706,11 @@ static bool isSuccOrder(SUnit *SUa, SUnit *SUb) {
 
 /// Return true if the instruction causes a chain between memory
 /// references before and after it.
-static bool isDependenceBarrier(MachineInstr &MI, AliasAnalysis *AA) {
+static bool isDependenceBarrier(MachineInstr &MI) {
   return MI.isCall() || MI.mayRaiseFPException() ||
          MI.hasUnmodeledSideEffects() ||
          (MI.hasOrderedMemoryRef() &&
-          (!MI.mayLoad() || !MI.isDereferenceableInvariantLoad(AA)));
+          (!MI.mayLoad() || !MI.isDereferenceableInvariantLoad()));
 }
 
 /// Return the underlying objects for the memory references of an instruction.
@@ -743,7 +743,7 @@ void SwingSchedulerDAG::addLoopCarriedDependences(AliasAnalysis *AA) {
     UndefValue::get(Type::getVoidTy(MF.getFunction().getContext()));
   for (auto &SU : SUnits) {
     MachineInstr &MI = *SU.getInstr();
-    if (isDependenceBarrier(MI, AA))
+    if (isDependenceBarrier(MI))
       PendingLoads.clear();
     else if (MI.mayLoad()) {
       SmallVector<const Value *, 4> Objs;