vendor/llvm-project/llvmorg-16-init-18548-gb0daacf58f41

1 files changed, 15 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
index 18507b8fa84f..865add28f781 100644
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -370,8 +370,10 @@ void TailDuplicator::processPHI(
   // Remove PredBB from the PHI node.
   MI->removeOperand(SrcOpIdx + 1);
   MI->removeOperand(SrcOpIdx);
-  if (MI->getNumOperands() == 1)
+  if (MI->getNumOperands() == 1 && !TailBB->hasAddressTaken())
     MI->eraseFromParent();
+  else if (MI->getNumOperands() == 1)
+    MI->setDesc(TII->get(TargetOpcode::IMPLICIT_DEF));
 }
 
 /// Duplicate a TailBB instruction to PredBB and update
@@ -395,7 +397,7 @@ void TailDuplicator::duplicateInstruction(
       if (!MO.isReg())
         continue;
       Register Reg = MO.getReg();
-      if (!Register::isVirtualRegister(Reg))
+      if (!Reg.isVirtual())
         continue;
       if (MO.isDef()) {
         const TargetRegisterClass *RC = MRI->getRegClass(Reg);
@@ -716,8 +718,7 @@ bool TailDuplicator::canCompletelyDuplicateBB(MachineBasicBlock &BB) {
 
 bool TailDuplicator::duplicateSimpleBB(
     MachineBasicBlock *TailBB, SmallVectorImpl<MachineBasicBlock *> &TDBBs,
-    const DenseSet<Register> &UsedByPhi,
-    SmallVectorImpl<MachineInstr *> &Copies) {
+    const DenseSet<Register> &UsedByPhi) {
   SmallPtrSet<MachineBasicBlock *, 8> Succs(TailBB->succ_begin(),
                                             TailBB->succ_end());
   SmallVector<MachineBasicBlock *, 8> Preds(TailBB->predecessors());
@@ -799,6 +800,15 @@ bool TailDuplicator::canTailDuplicate(MachineBasicBlock *TailBB,
     return false;
   if (!PredCond.empty())
     return false;
+  // FIXME: This is overly conservative; it may be ok to relax this in the
+  // future under more specific conditions. If TailBB is an INLINEASM_BR
+  // indirect target, we need to see if the edge from PredBB to TailBB is from
+  // an INLINEASM_BR in PredBB, and then also if that edge was from the
+  // indirect target list, fallthrough/default target, or potentially both. If
+  // it's both, TailDuplicator::tailDuplicate will remove the edge, corrupting
+  // the successor list in PredBB and predecessor list in TailBB.
+  if (TailBB->isInlineAsmBrIndirectTarget())
+    return false;
   return true;
 }
 
@@ -826,7 +836,7 @@ bool TailDuplicator::tailDuplicate(bool IsSimple, MachineBasicBlock *TailBB,
   getRegsUsedByPHIs(*TailBB, &UsedByPhi);
 
   if (IsSimple)
-    return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi, Copies);
+    return duplicateSimpleBB(TailBB, TDBBs, UsedByPhi);
 
   // Iterate through all the unique predecessors and tail-duplicate this
   // block into them, if possible. Copying the list ahead of time also