Fix ARM vector copies of overlapping register tuples.
I have tested the fix, but have not been successfull in generating
a robust unit test. This can only be exposed through particular
register assignments.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162821 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/ARM/ARMBaseInstrInfo.cpp b/lib/Target/ARM/ARMBaseInstrInfo.cpp
index 5191c3e..f3c9cf4 100644
--- a/lib/Target/ARM/ARMBaseInstrInfo.cpp
+++ b/lib/Target/ARM/ARMBaseInstrInfo.cpp
@@ -710,10 +710,23 @@
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.