Move isInTailCallPosition out of SelectionDAGBuilder, as it isn't

SelectionDAG-specific.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101801 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 86 deletions

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index fea8377a0b..9011610d74 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -4190,92 +4190,6 @@ SelectionDAGBuilder::visitIntrinsicCall(const CallInst &I, unsigned Intrinsic) {
   }
 }
 
-/// Test if the given instruction is in a position to be optimized
-/// with a tail-call. This roughly means that it's in a block with
-/// a return and there's nothing that needs to be scheduled
-/// between it and the return.
-///
-/// This function only tests target-independent requirements.
-static bool
-isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
-                     const TargetLowering &TLI) {
-  const Instruction *I = CS.getInstruction();
-  const BasicBlock *ExitBB = I->getParent();
-  const TerminatorInst *Term = ExitBB->getTerminator();
-  const ReturnInst *Ret = dyn_cast<ReturnInst>(Term);
-  const Function *F = ExitBB->getParent();
-
-  // The block must end in a return statement or unreachable.
-  //
-  // FIXME: Decline tailcall if it's not guaranteed and if the block ends in
-  // an unreachable, for now. The way tailcall optimization is currently
-  // implemented means it will add an epilogue followed by a jump. That is
-  // not profitable. Also, if the callee is a special function (e.g.
-  // longjmp on x86), it can end up causing miscompilation that has not
-  // been fully understood.
-  if (!Ret &&
-      (!GuaranteedTailCallOpt || !isa<UnreachableInst>(Term))) return false;
-
-  // If I will have a chain, make sure no other instruction that will have a
-  // chain interposes between I and the return.
-  if (I->mayHaveSideEffects() || I->mayReadFromMemory() ||
-      !I->isSafeToSpeculativelyExecute())
-    for (BasicBlock::const_iterator BBI = prior(prior(ExitBB->end())); ;
-         --BBI) {
-      if (&*BBI == I)
-        break;
-      // Debug info intrinsics do not get in the way of tail call optimization.
-      if (isa<DbgInfoIntrinsic>(BBI))
-        continue;
-      if (BBI->mayHaveSideEffects() || BBI->mayReadFromMemory() ||
-          !BBI->isSafeToSpeculativelyExecute())
-        return false;
-    }
-
-  // If the block ends with a void return or unreachable, it doesn't matter
-  // what the call's return type is.
-  if (!Ret || Ret->getNumOperands() == 0) return true;
-
-  // If the return value is undef, it doesn't matter what the call's
-  // return type is.
-  if (isa<UndefValue>(Ret->getOperand(0))) return true;
-
-  // Conservatively require the attributes of the call to match those of
-  // the return. Ignore noalias because it doesn't affect the call sequence.
-  unsigned CallerRetAttr = F->getAttributes().getRetAttributes();
-  if ((CalleeRetAttr ^ CallerRetAttr) & ~Attribute::NoAlias)
-    return false;
-
-  // It's not safe to eliminate the sign / zero extension of the return value.
-  if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
-    return false;
-
-  // Otherwise, make sure the unmodified return value of I is the return value.
-  for (const Instruction *U = dyn_cast<Instruction>(Ret->getOperand(0)); ;
-       U = dyn_cast<Instruction>(U->getOperand(0))) {
-    if (!U)
-      return false;
-    if (!U->hasOneUse())
-      return false;
-    if (U == I)
-      break;
-    // Check for a truly no-op truncate.
-    if (isa<TruncInst>(U) &&
-        TLI.isTruncateFree(U->getOperand(0)->getType(), U->getType()))
-      continue;
-    // Check for a truly no-op bitcast.
-    if (isa<BitCastInst>(U) &&
-        (U->getOperand(0)->getType() == U->getType() ||
-         (U->getOperand(0)->getType()->isPointerTy() &&
-          U->getType()->isPointerTy())))
-      continue;
-    // Otherwise it's not a true no-op.
-    return false;
-  }
-
-  return true;
-}
-
 void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,
                                       bool isTailCall,
                                       MachineBasicBlock *LandingPad) {