#include "llvm/IR/CFG.h"
#include "llvm/IR/CallSite.h"
#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
namespace {
struct TailCallElim : public FunctionPass {
const TargetTransformInfo *TTI;
+ const DataLayout *DL;
static char ID; // Pass identification, replacement for typeid
TailCallElim() : FunctionPass(ID) {
if (skipOptnoneFunction(F))
return false;
+ DL = F.getParent()->getDataLayout();
+
bool AllCallsAreTailCalls = false;
bool Modified = markTails(F, AllCallsAreTailCalls);
if (AllCallsAreTailCalls)
auto AddUsesToWorklist = [&](Value *V) {
for (auto &U : V->uses()) {
- if (!Visited.insert(&U))
+ if (!Visited.insert(&U).second)
continue;
Worklist.push_back(&U);
}
}
void callUsesLocalStack(CallSite CS, bool IsNocapture) {
- // Add it to the list of alloca users. If it's already there, skip further
- // processing.
- if (!AllocaUsers.insert(CS.getInstruction()))
- return;
+ // Add it to the list of alloca users.
+ AllocaUsers.insert(CS.getInstruction());
- // If it's nocapture then it can't capture the alloca.
+ // If it's nocapture then it can't capture this alloca.
if (IsNocapture)
return;
break;
}
if (SafeToTail) {
- F.getContext().emitOptimizationRemark(
- "tailcallelim", F, CI->getDebugLoc(),
+ emitOptimizationRemark(
+ F.getContext(), "tailcallelim", F, CI->getDebugLoc(),
"marked this readnone call a tail call candidate");
CI->setTailCall();
Modified = true;
if (Visited[CI->getParent()] != ESCAPED) {
// If the escape point was part way through the block, calls after the
// escape point wouldn't have been put into DeferredTails.
- F.getContext().emitOptimizationRemark(
- "tailcallelim", F, CI->getDebugLoc(),
- "marked this call a tail call candidate");
+ emitOptimizationRemark(F.getContext(), "tailcallelim", F,
+ CI->getDebugLoc(),
+ "marked this call a tail call candidate");
CI->setTailCall();
Modified = true;
} else {
// alloca' is changed from being a static alloca to being a dynamic alloca.
// Until this is resolved, disable this transformation if that would ever
// happen. This bug is PR962.
+ SmallVector<BasicBlock*, 8> BBToErase;
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
if (ReturnInst *Ret = dyn_cast<ReturnInst>(BB->getTerminator())) {
bool Change = ProcessReturningBlock(Ret, OldEntry, TailCallsAreMarkedTail,
ArgumentPHIs, !CanTRETailMarkedCall);
- if (!Change && BB->getFirstNonPHIOrDbg() == Ret)
+ if (!Change && BB->getFirstNonPHIOrDbg() == Ret) {
Change = FoldReturnAndProcessPred(BB, Ret, OldEntry,
TailCallsAreMarkedTail, ArgumentPHIs,
!CanTRETailMarkedCall);
+ // FoldReturnAndProcessPred may have emptied some BB. Remember to
+ // erase them.
+ if (Change && BB->empty())
+ BBToErase.push_back(BB);
+
+ }
MadeChange |= Change;
}
}
+ for (auto BB: BBToErase)
+ BB->eraseFromParent();
+
// If we eliminated any tail recursions, it's possible that we inserted some
// silly PHI nodes which just merge an initial value (the incoming operand)
// with themselves. Check to see if we did and clean up our mess if so. This
// being loaded from.
if (CI->mayWriteToMemory() ||
!isSafeToLoadUnconditionally(L->getPointerOperand(), L,
- L->getAlignment()))
+ L->getAlignment(), DL))
return false;
}
}
BasicBlock *BB = Ret->getParent();
Function *F = BB->getParent();
- F->getContext().emitOptimizationRemark(
- "tailcallelim", *F, CI->getDebugLoc(),
- "transforming tail recursion to loop");
+ emitOptimizationRemark(F->getContext(), "tailcallelim", *F, CI->getDebugLoc(),
+ "transforming tail recursion to loop");
// OK! We can transform this tail call. If this is the first one found,
// create the new entry block, allowing us to branch back to the old entry.
if (CallInst *CI = FindTRECandidate(BI, CannotTailCallElimCallsMarkedTail)){
DEBUG(dbgs() << "FOLDING: " << *BB
<< "INTO UNCOND BRANCH PRED: " << *Pred);
- EliminateRecursiveTailCall(CI, FoldReturnIntoUncondBranch(Ret, BB, Pred),
- OldEntry, TailCallsAreMarkedTail, ArgumentPHIs,
+ ReturnInst *RI = FoldReturnIntoUncondBranch(Ret, BB, Pred);
+
+ // Cleanup: if all predecessors of BB have been eliminated by
+ // FoldReturnIntoUncondBranch, we would like to delete it, but we
+ // can not just nuke it as it is being used as an iterator by our caller.
+ // Just empty it, and the caller will erase it when it is safe to do so.
+ // It is important to empty it, because the ret instruction in there is
+ // still using a value which EliminateRecursiveTailCall will attempt
+ // to remove.
+ if (!BB->hasAddressTaken() && pred_begin(BB) == pred_end(BB))
+ BB->getInstList().clear();
+
+ EliminateRecursiveTailCall(CI, RI, OldEntry, TailCallsAreMarkedTail,
+ ArgumentPHIs,
CannotTailCallElimCallsMarkedTail);
++NumRetDuped;
Change = true;