[CodeGen] Split out the notions of MI invariance and MI dereferenceability.

Summary:
An IR load can be invariant, dereferenceable, neither, or both.  But
currently, MI's notion of invariance is IR-invariant &&
IR-dereferenceable.

This patch splits up the notions of invariance and dereferenceability at
the MI level.  It's NFC, so adds some probably-unnecessary
"is-dereferenceable" checks, which we can remove later if desired.

Reviewers: chandlerc, tstellarAMD

Subscribers: jholewinski, arsenm, nemanjai, llvm-commits

Differential Revision: https://reviews.llvm.org/D23371

llvm-svn: 281151

1 files changed, 6 insertions, 10 deletions

diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
index 028f31a5f8c..170704958d4 100644
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -4444,7 +4444,8 @@ PrepareCall(SelectionDAG &DAG, SDValue &Callee, SDValue &InFlag, SDValue &Chain,
         LDChain = CallSeqStart.getValue(CallSeqStart->getNumValues()-2);
 
       auto MMOFlags = Subtarget.hasInvariantFunctionDescriptors()
-                          ? MachineMemOperand::MOInvariant
+                          ? (MachineMemOperand::MODereferenceable |
+                             MachineMemOperand::MOInvariant)
                           : MachineMemOperand::MONone;
 
       MachinePointerInfo MPI(CS ? CS->getCalledValue() : nullptr);
@@ -6481,10 +6482,7 @@ SDValue PPCTargetLowering::LowerFP_TO_INT(SDValue Op, SelectionDAG &DAG,
   LowerFP_TO_INTForReuse(Op, RLI, DAG, dl);
 
   return DAG.getLoad(Op.getValueType(), dl, RLI.Chain, RLI.Ptr, RLI.MPI,
-                     RLI.Alignment,
-                     RLI.IsInvariant ? MachineMemOperand::MOInvariant
-                                     : MachineMemOperand::MONone,
-                     RLI.AAInfo, RLI.Ranges);
+                     RLI.Alignment, RLI.MMOFlags(), RLI.AAInfo, RLI.Ranges);
 }
 
 // We're trying to insert a regular store, S, and then a load, L. If the
@@ -6527,6 +6525,7 @@ bool PPCTargetLowering::canReuseLoadAddress(SDValue Op, EVT MemVT,
 
   RLI.Chain = LD->getChain();
   RLI.MPI = LD->getPointerInfo();
+  RLI.IsDereferenceable = LD->isDereferenceable();
   RLI.IsInvariant = LD->isInvariant();
   RLI.Alignment = LD->getAlignment();
   RLI.AAInfo = LD->getAAInfo();
@@ -6719,11 +6718,8 @@ SDValue PPCTargetLowering::LowerINT_TO_FP(SDValue Op,
 
     MachineFunction &MF = DAG.getMachineFunction();
     if (canReuseLoadAddress(SINT, MVT::i64, RLI, DAG)) {
-      Bits =
-          DAG.getLoad(MVT::f64, dl, RLI.Chain, RLI.Ptr, RLI.MPI, RLI.Alignment,
-                      RLI.IsInvariant ? MachineMemOperand::MOInvariant
-                                      : MachineMemOperand::MONone,
-                      RLI.AAInfo, RLI.Ranges);
+      Bits = DAG.getLoad(MVT::f64, dl, RLI.Chain, RLI.Ptr, RLI.MPI,
+                         RLI.Alignment, RLI.MMOFlags(), RLI.AAInfo, RLI.Ranges);
       spliceIntoChain(RLI.ResChain, Bits.getValue(1), DAG);
     } else if (Subtarget.hasLFIWAX() &&
                canReuseLoadAddress(SINT, MVT::i32, RLI, DAG, ISD::SEXTLOAD)) {