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-rw-r--r--lib/Target/ARM/ARMBaseInstrInfo.cpp13
1 files changed, 13 insertions, 0 deletions
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 5191c3eabe..f3c9cf4e43 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -710,10 +710,23 @@ void ARMBaseInstrInfo::copyPhysReg(MachineBasicBlock &MBB,
const TargetRegisterInfo *TRI = &getRegisterInfo();
MachineInstrBuilder Mov;
+
+ // Copy register tuples backward when the first Dest reg overlaps with SrcReg.
+ if (TRI->regsOverlap(SrcReg, TRI->getSubReg(DestReg, BeginIdx))) {
+ BeginIdx = BeginIdx + ((SubRegs-1)*Spacing);
+ Spacing = -Spacing;
+ }
+#ifndef NDEBUG
+ SmallSet<unsigned, 4> DstRegs;
+#endif
for (unsigned i = 0; i != SubRegs; ++i) {
unsigned Dst = TRI->getSubReg(DestReg, BeginIdx + i*Spacing);
unsigned Src = TRI->getSubReg(SrcReg, BeginIdx + i*Spacing);
assert(Dst && Src && "Bad sub-register");
+#ifndef NDEBUG
+ DstRegs.insert(Dst);
+ assert(!DstRegs.count(Src) && "destructive vector copy");
+#endif
Mov = BuildMI(MBB, I, I->getDebugLoc(), get(Opc), Dst)
.addReg(Src);
// VORR takes two source operands.