Refactor alias check from MISched into common helper. NFC.

Differential Revision: https://reviews.llvm.org/D30598



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@297421 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 1 insertions, 61 deletions

diff --git a/lib/CodeGen/ScheduleDAGInstrs.cpp b/lib/CodeGen/ScheduleDAGInstrs.cpp
index 135e053da4f..18823b74c47 100644
--- a/lib/CodeGen/ScheduleDAGInstrs.cpp
+++ b/lib/CodeGen/ScheduleDAGInstrs.cpp
@@ -537,69 +537,9 @@ static inline bool isGlobalMemoryObject(AliasAnalysis *AA, MachineInstr *MI) {
          (MI->hasOrderedMemoryRef() && !MI->isDereferenceableInvariantLoad(AA));
 }
 
-/// Returns true if the two MIs need a chain edge between them.
-/// This is called on normal stores and loads.
-static bool MIsNeedChainEdge(AliasAnalysis *AA, MachineInstr *MIa,
-                             MachineInstr *MIb) {
-  const MachineFunction *MF = MIa->getParent()->getParent();
-  const TargetInstrInfo *TII = MF->getSubtarget().getInstrInfo();
-
-  assert ((MIa->mayStore() || MIb->mayStore()) &&
-          "Dependency checked between two loads");
-
-  // Let the target decide if memory accesses cannot possibly overlap.
-  if (TII->areMemAccessesTriviallyDisjoint(*MIa, *MIb, AA))
-    return false;
-
-  // To this point analysis is generic. From here on we do need AA.
-  if (!AA)
-    return true;
-
-  // FIXME: Need to handle multiple memory operands to support all targets.
-  if (!MIa->hasOneMemOperand() || !MIb->hasOneMemOperand())
-    return true;
-
-  MachineMemOperand *MMOa = *MIa->memoperands_begin();
-  MachineMemOperand *MMOb = *MIb->memoperands_begin();
-
-  if (!MMOa->getValue() || !MMOb->getValue())
-    return true;
-
-  // The following interface to AA is fashioned after DAGCombiner::isAlias
-  // and operates with MachineMemOperand offset with some important
-  // assumptions:
-  //   - LLVM fundamentally assumes flat address spaces.
-  //   - MachineOperand offset can *only* result from legalization and
-  //     cannot affect queries other than the trivial case of overlap
-  //     checking.
-  //   - These offsets never wrap and never step outside
-  //     of allocated objects.
-  //   - There should never be any negative offsets here.
-  //
-  // FIXME: Modify API to hide this math from "user"
-  // FIXME: Even before we go to AA we can reason locally about some
-  // memory objects. It can save compile time, and possibly catch some
-  // corner cases not currently covered.
-
-  assert ((MMOa->getOffset() >= 0) && "Negative MachineMemOperand offset");
-  assert ((MMOb->getOffset() >= 0) && "Negative MachineMemOperand offset");
-
-  int64_t MinOffset = std::min(MMOa->getOffset(), MMOb->getOffset());
-  int64_t Overlapa = MMOa->getSize() + MMOa->getOffset() - MinOffset;
-  int64_t Overlapb = MMOb->getSize() + MMOb->getOffset() - MinOffset;
-
-  AliasResult AAResult =
-      AA->alias(MemoryLocation(MMOa->getValue(), Overlapa,
-                               UseTBAA ? MMOa->getAAInfo() : AAMDNodes()),
-                MemoryLocation(MMOb->getValue(), Overlapb,
-                               UseTBAA ? MMOb->getAAInfo() : AAMDNodes()));
-
-  return (AAResult != NoAlias);
-}
-
 void ScheduleDAGInstrs::addChainDependency (SUnit *SUa, SUnit *SUb,
                                             unsigned Latency) {
-  if (MIsNeedChainEdge(AAForDep, SUa->getInstr(), SUb->getInstr())) {
+  if (SUa->getInstr()->mayAlias(AAForDep, *SUb->getInstr(), UseTBAA)) {
     SDep Dep(SUa, SDep::MayAliasMem);
     Dep.setLatency(Latency);
     SUb->addPred(Dep);