It's not safe eliminate copies where src and dst have different sub-register indices.

llvm-svn: 103450

1 files changed, 7 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
index 6b0b2d15819..7e13bf72240 100644
--- a/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
+++ b/llvm/lib/CodeGen/SimpleRegisterCoalescing.cpp
@@ -460,7 +460,7 @@ bool SimpleRegisterCoalescing::RemoveCopyByCommutingDef(LiveInterval &IntA,
     unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
     if (!tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx))
       continue;
-    if (DstReg == IntB.reg) {
+    if (DstReg == IntB.reg && DstSubIdx == 0) {
       // This copy will become a noop. If it's defining a new val#,
       // remove that val# as well. However this live range is being
       // extended to the end of the existing live range defined by the copy.
@@ -624,7 +624,7 @@ SimpleRegisterCoalescing::TrimLiveIntervalToLastUse(SlotIndex CopyIdx,
     LR->valno->addKill(LastUseIdx.getDefIndex());
     unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
     if (tii_->isMoveInstr(*LastUseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
-        DstReg == li.reg) {
+        DstReg == li.reg && DstSubIdx == 0) {
       // Last use is itself an identity code.
       int DeadIdx = LastUseMI->findRegisterDefOperandIdx(li.reg, false, tri_);
       LastUseMI->getOperand(DeadIdx).setIsDead();
@@ -810,6 +810,8 @@ SimpleRegisterCoalescing::UpdateRegDefsUses(unsigned SrcReg, unsigned DstReg,
       unsigned CopySrcReg, CopyDstReg, CopySrcSubIdx, CopyDstSubIdx;
       if (tii_->isMoveInstr(*UseMI, CopySrcReg, CopyDstReg,
                             CopySrcSubIdx, CopyDstSubIdx) &&
+          CopySrcSubIdx == 0 &&
+          CopyDstSubIdx == 0 &&
           CopySrcReg != CopyDstReg &&
           CopySrcReg == SrcReg && CopyDstReg != UseDstReg) {
         // If the use is a copy and it won't be coalesced away, and its source
@@ -2637,7 +2639,7 @@ SimpleRegisterCoalescing::lastRegisterUse(SlotIndex Start,
       MachineInstr *UseMI = Use.getParent();
       unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
       if (tii_->isMoveInstr(*UseMI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
-          SrcReg == DstReg)
+          SrcReg == DstReg && SrcSubIdx == DstSubIdx)
         // Ignore identity copies.
         continue;
       SlotIndex Idx = li_->getInstructionIndex(UseMI);
@@ -2666,7 +2668,7 @@ SimpleRegisterCoalescing::lastRegisterUse(SlotIndex Start,
     // Ignore identity copies.
     unsigned SrcReg, DstReg, SrcSubIdx, DstSubIdx;
     if (!(tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx) &&
-          SrcReg == DstReg))
+          SrcReg == DstReg && SrcSubIdx == DstSubIdx))
       for (unsigned i = 0, NumOps = MI->getNumOperands(); i != NumOps; ++i) {
         MachineOperand &Use = MI->getOperand(i);
         if (Use.isReg() && Use.isUse() && Use.getReg() &&
@@ -2797,7 +2799,7 @@ bool SimpleRegisterCoalescing::runOnMachineFunction(MachineFunction &fn) {
 
       // If the move will be an identity move delete it
       bool isMove= tii_->isMoveInstr(*MI, SrcReg, DstReg, SrcSubIdx, DstSubIdx);
-      if (isMove && SrcReg == DstReg) {
+      if (isMove && SrcReg == DstReg && SrcSubIdx == DstSubIdx) {
         if (li_->hasInterval(SrcReg)) {
           LiveInterval &RegInt = li_->getInterval(SrcReg);
           // If def of this move instruction is dead, remove its live range