Revert "Codegen: Tail-duplicate during placement."
This reverts commit ff234efbe23528e4f4c80c78057b920a51f434b2.
Causing crashes on aarch64 build.
llvm-svn: 283172
diff --git a/llvm/lib/CodeGen/TailDuplicator.cpp b/llvm/lib/CodeGen/TailDuplicator.cpp
index 5b93b88..26b9b07 100644
--- a/llvm/lib/CodeGen/TailDuplicator.cpp
+++ b/llvm/lib/CodeGen/TailDuplicator.cpp
@@ -20,7 +20,6 @@
#include "llvm/CodeGen/MachineBranchProbabilityInfo.h"
#include "llvm/CodeGen/MachineFunctionPass.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
@@ -65,7 +64,7 @@
void TailDuplicator::initMF(MachineFunction &MFin,
const MachineBranchProbabilityInfo *MBPIin,
- bool LayoutModeIn, unsigned TailDupSizeIn) {
+ unsigned TailDupSizeIn) {
MF = &MFin;
TII = MF->getSubtarget().getInstrInfo();
TRI = MF->getSubtarget().getRegisterInfo();
@@ -76,7 +75,6 @@
assert(MBPI != nullptr && "Machine Branch Probability Info required");
- LayoutMode = LayoutModeIn;
PreRegAlloc = MRI->isSSA();
}
@@ -129,23 +127,18 @@
/// Tail duplicate the block and cleanup.
/// \p IsSimple - return value of isSimpleBB
/// \p MBB - block to be duplicated
-/// \p ForcedLayoutPred - If non-null, treat this block as the layout
-/// predecessor, instead of using the ordering in MF
/// \p DuplicatedPreds - if non-null, \p DuplicatedPreds will contain a list of
/// all Preds that received a copy of \p MBB.
-/// \p RemovalCallback - if non-null, called just before MBB is deleted.
bool TailDuplicator::tailDuplicateAndUpdate(
bool IsSimple, MachineBasicBlock *MBB,
- MachineBasicBlock *ForcedLayoutPred,
- SmallVectorImpl<MachineBasicBlock*> *DuplicatedPreds,
- llvm::function_ref<void(MachineBasicBlock *)> *RemovalCallback) {
+ SmallVectorImpl<MachineBasicBlock*> *DuplicatedPreds) {
// Save the successors list.
SmallSetVector<MachineBasicBlock *, 8> Succs(MBB->succ_begin(),
MBB->succ_end());
SmallVector<MachineBasicBlock *, 8> TDBBs;
SmallVector<MachineInstr *, 16> Copies;
- if (!tailDuplicate(IsSimple, MBB, ForcedLayoutPred, TDBBs, Copies))
+ if (!tailDuplicate(IsSimple, MBB, TDBBs, Copies))
return false;
++NumTails;
@@ -163,7 +156,7 @@
// If it is dead, remove it.
if (isDead) {
NumTailDupRemoved += MBB->size();
- removeDeadBlock(MBB, RemovalCallback);
+ removeDeadBlock(MBB);
++NumDeadBlocks;
}
@@ -262,7 +255,7 @@
if (!shouldTailDuplicate(IsSimple, *MBB))
continue;
- MadeChange |= tailDuplicateAndUpdate(IsSimple, MBB, nullptr);
+ MadeChange |= tailDuplicateAndUpdate(IsSimple, MBB);
}
if (PreRegAlloc && TailDupVerify)
@@ -521,10 +514,8 @@
/// Determine if it is profitable to duplicate this block.
bool TailDuplicator::shouldTailDuplicate(bool IsSimple,
MachineBasicBlock &TailBB) {
- // When doing tail-duplication during layout, the block ordering is in flux,
- // so canFallThrough returns a result based on incorrect information and
- // should just be ignored.
- if (!LayoutMode && TailBB.canFallThrough())
+ // Only duplicate blocks that end with unconditional branches.
+ if (TailBB.canFallThrough())
return false;
// Don't try to tail-duplicate single-block loops.
@@ -744,7 +735,7 @@
bool TailDuplicator::canTailDuplicate(MachineBasicBlock *TailBB,
MachineBasicBlock *PredBB) {
- // EH edges are ignored by analyzeBranch.
+ // EH edges are ignored by AnalyzeBranch.
if (PredBB->succ_size() > 1)
return false;
@@ -759,16 +750,7 @@
/// If it is profitable, duplicate TailBB's contents in each
/// of its predecessors.
-/// \p IsSimple result of isSimpleBB
-/// \p TailBB Block to be duplicated.
-/// \p ForcedLayoutPred When non-null, use this block as the layout predecessor
-/// instead of the previous block in MF's order.
-/// \p TDBBs A vector to keep track of all blocks tail-duplicated
-/// into.
-/// \p Copies A vector of copy instructions inserted. Used later to
-/// walk all the inserted copies and remove redundant ones.
bool TailDuplicator::tailDuplicate(bool IsSimple, MachineBasicBlock *TailBB,
- MachineBasicBlock *ForcedLayoutPred,
SmallVectorImpl<MachineBasicBlock *> &TDBBs,
SmallVectorImpl<MachineInstr *> &Copies) {
DEBUG(dbgs() << "\n*** Tail-duplicating BB#" << TailBB->getNumber() << '\n');
@@ -793,12 +775,7 @@
continue;
// Don't duplicate into a fall-through predecessor (at least for now).
- bool IsLayoutSuccessor = false;
- if (ForcedLayoutPred)
- IsLayoutSuccessor = (ForcedLayoutPred == PredBB);
- else if (PredBB->isLayoutSuccessor(TailBB) && PredBB->canFallThrough())
- IsLayoutSuccessor = true;
- if (IsLayoutSuccessor)
+ if (PredBB->isLayoutSuccessor(TailBB) && PredBB->canFallThrough())
continue;
DEBUG(dbgs() << "\nTail-duplicating into PredBB: " << *PredBB
@@ -851,20 +828,16 @@
// If TailBB was duplicated into all its predecessors except for the prior
// block, which falls through unconditionally, move the contents of this
// block into the prior block.
- MachineBasicBlock *PrevBB = ForcedLayoutPred;
- if (!PrevBB)
- PrevBB = &*std::prev(TailBB->getIterator());
+ MachineBasicBlock *PrevBB = &*std::prev(TailBB->getIterator());
MachineBasicBlock *PriorTBB = nullptr, *PriorFBB = nullptr;
SmallVector<MachineOperand, 4> PriorCond;
// This has to check PrevBB->succ_size() because EH edges are ignored by
- // analyzeBranch.
+ // AnalyzeBranch.
if (PrevBB->succ_size() == 1 &&
// Layout preds are not always CFG preds. Check.
*PrevBB->succ_begin() == TailBB &&
!TII->analyzeBranch(*PrevBB, PriorTBB, PriorFBB, PriorCond, true) &&
- PriorCond.empty() &&
- (!PriorTBB || PriorTBB == TailBB) &&
- TailBB->pred_size() == 1 &&
+ PriorCond.empty() && !PriorTBB && TailBB->pred_size() == 1 &&
!TailBB->hasAddressTaken()) {
DEBUG(dbgs() << "\nMerging into block: " << *PrevBB
<< "From MBB: " << *TailBB);
@@ -891,7 +864,6 @@
}
appendCopies(PrevBB, CopyInfos, Copies);
} else {
- TII->removeBranch(*PrevBB);
// No PHIs to worry about, just splice the instructions over.
PrevBB->splice(PrevBB->end(), TailBB, TailBB->begin(), TailBB->end());
}
@@ -964,15 +936,10 @@
/// Remove the specified dead machine basic block from the function, updating
/// the CFG.
-void TailDuplicator::removeDeadBlock(
- MachineBasicBlock *MBB,
- llvm::function_ref<void(MachineBasicBlock *)> *RemovalCallback) {
+void TailDuplicator::removeDeadBlock(MachineBasicBlock *MBB) {
assert(MBB->pred_empty() && "MBB must be dead!");
DEBUG(dbgs() << "\nRemoving MBB: " << *MBB);
- if (RemovalCallback)
- (*RemovalCallback)(MBB);
-
// Remove all successors.
while (!MBB->succ_empty())
MBB->removeSuccessor(MBB->succ_end() - 1);