[GlobalISel] LegalizerHelper: Fix the incorrect alignment when splitting loads/stores in narrowScalar

Reviewers: dsanders, bogner, jpaquette, aemerson, ab, paquette

Reviewed By: dsanders

Subscribers: rovka, kristof.beyls, javed.absar, llvm-commits

Differential Revision: https://reviews.llvm.org/D53664

llvm-svn: 345292
diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index c9ed97a..516f5ce 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -467,12 +467,12 @@
       unsigned DstReg = MRI.createGenericVirtualRegister(NarrowTy);
       unsigned SrcReg = 0;
       unsigned Adjustment = i * NarrowSize / 8;
+      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
 
       MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
           MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, i == 0 ? MMO.getAlignment() : NarrowSize / 8,
-          MMO.getAAInfo(), MMO.getRanges(), MMO.getSyncScopeID(),
-          MMO.getOrdering(), MMO.getFailureOrdering());
+          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
+          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
 
       MIRBuilder.materializeGEP(SrcReg, MI.getOperand(1).getReg(), OffsetTy,
                                 Adjustment);
@@ -509,12 +509,12 @@
     for (int i = 0; i < NumParts; ++i) {
       unsigned DstReg = 0;
       unsigned Adjustment = i * NarrowSize / 8;
+      unsigned Alignment = MinAlign(MMO.getAlignment(), Adjustment);
 
       MachineMemOperand *SplitMMO = MIRBuilder.getMF().getMachineMemOperand(
           MMO.getPointerInfo().getWithOffset(Adjustment), MMO.getFlags(),
-          NarrowSize / 8, i == 0 ? MMO.getAlignment() : NarrowSize / 8,
-          MMO.getAAInfo(), MMO.getRanges(), MMO.getSyncScopeID(),
-          MMO.getOrdering(), MMO.getFailureOrdering());
+          NarrowSize / 8, Alignment, MMO.getAAInfo(), MMO.getRanges(),
+          MMO.getSyncScopeID(), MMO.getOrdering(), MMO.getFailureOrdering());
 
       MIRBuilder.materializeGEP(DstReg, MI.getOperand(1).getReg(), OffsetTy,
                                 Adjustment);