Teach taildup to update livein set. rdar://11538365
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157663 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/TailDuplication.cpp b/lib/CodeGen/TailDuplication.cpp
index 3e20385..d077b09 100644
--- a/lib/CodeGen/TailDuplication.cpp
+++ b/lib/CodeGen/TailDuplication.cpp
@@ -20,7 +20,9 @@
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/MachineSSAUpdater.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
@@ -57,8 +59,10 @@
/// TailDuplicatePass - Perform tail duplication.
class TailDuplicatePass : public MachineFunctionPass {
const TargetInstrInfo *TII;
+ const TargetRegisterInfo *TRI;
MachineModuleInfo *MMI;
MachineRegisterInfo *MRI;
+ RegScavenger *RS;
bool PreRegAlloc;
// SSAUpdateVRs - A list of virtual registers for which to update SSA form.
@@ -124,9 +128,13 @@
bool TailDuplicatePass::runOnMachineFunction(MachineFunction &MF) {
TII = MF.getTarget().getInstrInfo();
+ TRI = MF.getTarget().getRegisterInfo();
MRI = &MF.getRegInfo();
MMI = getAnalysisIfAvailable<MachineModuleInfo>();
PreRegAlloc = MRI->isSSA();
+ RS = NULL;
+ if (MRI->tracksLiveness() && TRI->trackLivenessAfterRegAlloc(MF))
+ RS = new RegScavenger();
bool MadeChange = false;
while (TailDuplicateBlocks(MF))
@@ -777,6 +785,23 @@
// Remove PredBB's unconditional branch.
TII->RemoveBranch(*PredBB);
+ if (RS && !TailBB->livein_empty()) {
+ // Update PredBB livein.
+ RS->enterBasicBlock(PredBB);
+ if (!PredBB->empty())
+ RS->forward(prior(PredBB->end()));
+ BitVector RegsLiveAtExit(TRI->getNumRegs());
+ RS->getRegsUsed(RegsLiveAtExit, false);
+ for (MachineBasicBlock::livein_iterator I = TailBB->livein_begin(),
+ E = TailBB->livein_end(); I != E; ++I) {
+ if (!RegsLiveAtExit[*I])
+ // If a register is previously livein to the tail but it's not live
+ // at the end of predecessor BB, then it should be added to its
+ // livein list.
+ PredBB->addLiveIn(*I);
+ }
+ }
+
// Clone the contents of TailBB into PredBB.
DenseMap<unsigned, unsigned> LocalVRMap;
SmallVector<std::pair<unsigned,unsigned>, 4> CopyInfos;