[CodeGen] Add "const" to MachineInstr::mayAlias

Summary:
The basic idea here is to make it possible to use
MachineInstr::mayAlias also when the MachineInstr
is const (or the "Other" MachineInstr is const).

The addition of const in MachineInstr::mayAlias
then rippled down to the need for adding const
in several other places, such as
TargetTransformInfo::getMemOperandWithOffset.

Reviewers: hfinkel

Reviewed By: hfinkel

Subscribers: hfinkel, MatzeB, arsenm, jvesely, nhaehnle, hiraditya, javed.absar, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D60856

llvm-svn: 358744

1 files changed, 9 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/ImplicitNullChecks.cpp b/llvm/lib/CodeGen/ImplicitNullChecks.cpp
index 68110314151..dff6d02b06e 100644
--- a/llvm/lib/CodeGen/ImplicitNullChecks.cpp
+++ b/llvm/lib/CodeGen/ImplicitNullChecks.cpp
@@ -180,7 +180,8 @@ class ImplicitNullChecks : public MachineFunctionPass {
   /// Returns AR_NoAlias if \p MI memory operation does not alias with
   /// \p PrevMI, AR_MayAlias if they may alias and AR_WillAliasEverything if
   /// they may alias and any further memory operation may alias with \p PrevMI.
-  AliasResult areMemoryOpsAliased(MachineInstr &MI, MachineInstr *PrevMI);
+  AliasResult areMemoryOpsAliased(const MachineInstr &MI,
+                                  const MachineInstr *PrevMI) const;
 
   enum SuitabilityResult {
     SR_Suitable,
@@ -194,7 +195,8 @@ class ImplicitNullChecks : public MachineFunctionPass {
   /// no sense to continue lookup due to any other instruction will not be able
   /// to be used. \p PrevInsts is the set of instruction seen since
   /// the explicit null check on \p PointerReg.
-  SuitabilityResult isSuitableMemoryOp(MachineInstr &MI, unsigned PointerReg,
+  SuitabilityResult isSuitableMemoryOp(const MachineInstr &MI,
+                                       unsigned PointerReg,
                                        ArrayRef<MachineInstr *> PrevInsts);
 
   /// Return true if \p FaultingMI can be hoisted from after the
@@ -318,8 +320,8 @@ static bool AnyAliasLiveIn(const TargetRegisterInfo *TRI,
 }
 
 ImplicitNullChecks::AliasResult
-ImplicitNullChecks::areMemoryOpsAliased(MachineInstr &MI,
-                                        MachineInstr *PrevMI) {
+ImplicitNullChecks::areMemoryOpsAliased(const MachineInstr &MI,
+                                        const MachineInstr *PrevMI) const {
   // If it is not memory access, skip the check.
   if (!(PrevMI->mayStore() || PrevMI->mayLoad()))
     return AR_NoAlias;
@@ -356,10 +358,11 @@ ImplicitNullChecks::areMemoryOpsAliased(MachineInstr &MI,
 }
 
 ImplicitNullChecks::SuitabilityResult
-ImplicitNullChecks::isSuitableMemoryOp(MachineInstr &MI, unsigned PointerReg,
+ImplicitNullChecks::isSuitableMemoryOp(const MachineInstr &MI,
+                                       unsigned PointerReg,
                                        ArrayRef<MachineInstr *> PrevInsts) {
   int64_t Offset;
-  MachineOperand *BaseOp;
+  const MachineOperand *BaseOp;
 
   if (!TII->getMemOperandWithOffset(MI, BaseOp, Offset, TRI) ||
       !BaseOp->isReg() || BaseOp->getReg() != PointerReg)