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[ExecutionDepsFix] Don't recurse over the CFG 

Summary:
Use an explicit work queue instead, to avoid accidentally
causing stack overflows for input with very large CFGs.

Reviewed By: mehdi_amini
Differential Revision: https://reviews.llvm.org/D31681

llvm-svn: 299569
This commit is contained in:
Keno Fischer 2017-04-05 17:42:56 +00:00
parent 519a87a468
commit 4ecee77c9a
2 changed files with 23 additions and 23 deletions
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1
llvm/include/llvm/CodeGen/ExecutionDepsFix.h
View File

@ -205,7 +205,6 @@ private:
void leaveBasicBlock(MachineBasicBlock*);
bool isBlockDone(MachineBasicBlock *);
void processBasicBlock(MachineBasicBlock *MBB, bool PrimaryPass);
void updateSuccessors(MachineBasicBlock *MBB, bool PrimaryPass);
bool visitInstr(MachineInstr *);
void processDefs(MachineInstr *, bool breakDependency, bool Kill);
void visitSoftInstr(MachineInstr*, unsigned mask);

45
llvm/lib/CodeGen/ExecutionDepsFix.cpp
View File

@ -616,26 +616,6 @@ bool ExecutionDepsFix::isBlockDone(MachineBasicBlock *MBB) {
MBBInfos[MBB].IncomingProcessed == MBB->pred_size();
}
void ExecutionDepsFix::updateSuccessors(MachineBasicBlock *MBB, bool Primary) {
bool Done = isBlockDone(MBB);
for (auto *Succ : MBB->successors()) {
if (!isBlockDone(Succ)) {
if (Primary) {
MBBInfos[Succ].IncomingProcessed++;
}
if (Done) {
MBBInfos[Succ].IncomingCompleted++;
}
if (isBlockDone(Succ)) {
// Perform secondary processing for this successor. See the big comment
// in runOnMachineFunction, for an explanation of the iteration order.
processBasicBlock(Succ, false);
updateSuccessors(Succ, false);
}
}
}
}
bool ExecutionDepsFix::runOnMachineFunction(MachineFunction &mf) {
if (skipFunction(*mf.getFunction()))
return false;
@ -708,6 +688,7 @@ bool ExecutionDepsFix::runOnMachineFunction(MachineFunction &mf) {
MachineBasicBlock *Entry = &*MF->begin();
ReversePostOrderTraversal<MachineBasicBlock*> RPOT(Entry);
SmallVector<MachineBasicBlock *, 4> Workqueue;
for (ReversePostOrderTraversal<MachineBasicBlock*>::rpo_iterator
MBBI = RPOT.begin(), MBBE = RPOT.end(); MBBI != MBBE; ++MBBI) {
MachineBasicBlock *MBB = *MBBI;
@ -715,8 +696,28 @@ bool ExecutionDepsFix::runOnMachineFunction(MachineFunction &mf) {
// processing this block's predecessors.
MBBInfos[MBB].PrimaryCompleted = true;
MBBInfos[MBB].PrimaryIncoming = MBBInfos[MBB].IncomingProcessed;
processBasicBlock(MBB, true);
updateSuccessors(MBB, true);
bool Primary = true;
Workqueue.push_back(MBB);
while (!Workqueue.empty()) {
MachineBasicBlock *ActiveMBB = &*Workqueue.back();
Workqueue.pop_back();
processBasicBlock(ActiveMBB, Primary);
bool Done = isBlockDone(ActiveMBB);
for (auto *Succ : ActiveMBB->successors()) {
if (!isBlockDone(Succ)) {
if (Primary) {
MBBInfos[Succ].IncomingProcessed++;
}
if (Done) {
MBBInfos[Succ].IncomingCompleted++;
}
if (isBlockDone(Succ)) {
Workqueue.push_back(Succ);
}
}
}
Primary = false;
}
}
// We need to go through again and finalize any blocks that are not done yet.