[Alignment][NFC] TargetLowering::allowsMisalignedMemoryAccesses

Summary:
Note to downstream target maintainers: this might silently change the semantics of your code if you override `TargetLowering::allowsMisalignedMemoryAccesses` without marking it override.

This patch is part of a series to introduce an Alignment type.
See this thread for context: http://lists.llvm.org/pipermail/llvm-dev/2019-July/133851.html
See this patch for the introduction of the type: https://reviews.llvm.org/D64790

Reviewers: courbet

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D81374

include/llvm/CodeGen/TargetLowering.h

@@ -1578,7 +1578,7 @@ public:
 
   /// LLT handling variant.
   virtual bool allowsMisalignedMemoryAccesses(
-      LLT, unsigned AddrSpace = 0, unsigned Align = 1,
+      LLT, unsigned AddrSpace = 0, Align Alignment = Align(1),
       MachineMemOperand::Flags Flags = MachineMemOperand::MONone,
       bool * /*Fast*/ = nullptr) const {
     return false;

lib/CodeGen/GlobalISel/CombinerHelper.cpp

@@ -867,8 +867,7 @@ static bool findGISelOptimalMemOpLowering(std::vector<LLT> &MemOps,
     Ty = LLT::scalar(64);
     if (Op.isFixedDstAlign())
       while (Op.getDstAlign() < Ty.getSizeInBytes() &&
-             !TLI.allowsMisalignedMemoryAccesses(Ty, DstAS,
-                                                 Op.getDstAlign().value()))
+             !TLI.allowsMisalignedMemoryAccesses(Ty, DstAS, Op.getDstAlign()))
         Ty = LLT::scalar(Ty.getSizeInBytes());
     assert(Ty.getSizeInBits() > 0 && "Could not find valid type");
     // FIXME: check for the largest legal type we can load/store to.

lib/Target/AArch64/AArch64ISelLowering.cpp

@@ -1256,7 +1256,7 @@ bool AArch64TargetLowering::allowsMisalignedMemoryAccesses(
 
 // Same as above but handling LLTs instead.
 bool AArch64TargetLowering::allowsMisalignedMemoryAccesses(
-    LLT Ty, unsigned AddrSpace, unsigned Align, MachineMemOperand::Flags Flags,
+    LLT Ty, unsigned AddrSpace, Align Alignment, MachineMemOperand::Flags Flags,
     bool *Fast) const {
   if (Subtarget->requiresStrictAlign())
     return false;
@@ -1271,7 +1271,7 @@ bool AArch64TargetLowering::allowsMisalignedMemoryAccesses(
             // Code that uses clang vector extensions can mark that it
             // wants unaligned accesses to be treated as fast by
             // underspecifying alignment to be 1 or 2.
-            Align <= 2 ||
+            Alignment <= 2 ||
 
             // Disregard v2i64. Memcpy lowering produces those and splitting
             // them regresses performance on micro-benchmarks and olden/bh.

lib/Target/AArch64/AArch64ISelLowering.h

@@ -413,9 +413,10 @@ public:
       MachineMemOperand::Flags Flags = MachineMemOperand::MONone,
       bool *Fast = nullptr) const override;
   /// LLT variant.
-  bool allowsMisalignedMemoryAccesses(
-    LLT Ty, unsigned AddrSpace, unsigned Align, MachineMemOperand::Flags Flags,
-    bool *Fast = nullptr) const override;
+  bool allowsMisalignedMemoryAccesses(LLT Ty, unsigned AddrSpace,
+                                      Align Alignment,
+                                      MachineMemOperand::Flags Flags,
+                                      bool *Fast = nullptr) const override;
 
   /// Provide custom lowering hooks for some operations.
   SDValue LowerOperation(SDValue Op, SelectionDAG &DAG) const override;