GlobalISel: Add a note about how we're being a bit loose with memory operands

The logic in r292461 is conservatively correct, but we should revisit
this later. Add a TODO so we don't forget.

llvm-svn: 292553

1 files changed, 4 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 0f23c2f0358..5f23d253f56 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -177,6 +177,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
 
       MIRBuilder.buildConstant(Offset, i * NarrowSize / 8);
       MIRBuilder.buildGEP(SrcReg, MI.getOperand(1).getReg(), Offset);
+      // TODO: This is conservatively correct, but we probably want to split the
+      // memory operands in the future.
       MIRBuilder.buildLoad(DstReg, SrcReg, **MI.memoperands_begin());
 
       DstRegs.push_back(DstReg);
@@ -202,6 +204,8 @@ LegalizerHelper::LegalizeResult LegalizerHelper::narrowScalar(MachineInstr &MI,
       unsigned Offset = MRI.createGenericVirtualRegister(LLT::scalar(64));
       MIRBuilder.buildConstant(Offset, i * NarrowSize / 8);
       MIRBuilder.buildGEP(DstReg, MI.getOperand(1).getReg(), Offset);
+      // TODO: This is conservatively correct, but we probably want to split the
+      // memory operands in the future.
       MIRBuilder.buildStore(SrcRegs[i], DstReg, **MI.memoperands_begin());
     }
     MI.eraseFromParent();