RPCSX/llvm
1
0
Fork 0
mirror of https://github.com/RPCSX/llvm.git synced 2024-11-30 15:10:33 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

[StatepointLowering] Clean up allocateStackSlot

Browse Source 
This removes the unusual loop structure in allocateStackSlot in favor of
something more straightforward.  I've also removed the cautionary
comment in the function, which I suspect is historical cruft now, and
confuses more than it enlightens.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@261335 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjoy Das 2016-02-19 17:15:17 +00:00
parent ffe13b0d29
commit f08995153b
1 changed files with 20 additions and 33 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
lib/CodeGen/SelectionDAG/StatepointLowering.cpp
View File

@ -72,49 +72,36 @@ void StatepointLoweringState::clear() {
SDValue
StatepointLoweringState::allocateStackSlot(EVT ValueType,
SelectionDAGBuilder &Builder) {
NumSlotsAllocatedForStatepoints++;
// The basic scheme here is to first look for a previously created stack slot
// which is not in use (accounting for the fact arbitrary slots may already
// be reserved), or to create a new stack slot and use it.
// First look for a previously created stack slot which is not in
// use (accounting for the fact arbitrary slots may already be
// reserved), or to create a new stack slot and use it.
// If this doesn't succeed in 40000 iterations, something is seriously wrong
for (int i = 0; i < 40000; i++) {
assert(Builder.FuncInfo.StatepointStackSlots.size() ==
AllocatedStackSlots.size() &&
"broken invariant");
const size_t NumSlots = AllocatedStackSlots.size();
assert(NextSlotToAllocate <= NumSlots && "broken invariant");
const size_t NumSlots = AllocatedStackSlots.size();
assert(NextSlotToAllocate <= NumSlots && "Broken invariant");
if (NextSlotToAllocate >= NumSlots) {
assert(NextSlotToAllocate == NumSlots);
// record stats
if (NumSlots + 1 > StatepointMaxSlotsRequired) {
StatepointMaxSlotsRequired = NumSlots + 1;
}
SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
auto *MFI = Builder.DAG.getMachineFunction().getFrameInfo();
MFI->markAsStatepointSpillSlotObjectIndex(FI);
Builder.FuncInfo.StatepointStackSlots.push_back(FI);
AllocatedStackSlots.push_back(true);
return SpillSlot;
}
for (; NextSlotToAllocate < NumSlots; NextSlotToAllocate++) {
if (!AllocatedStackSlots[NextSlotToAllocate]) {
const int FI = Builder.FuncInfo.StatepointStackSlots[NextSlotToAllocate];
AllocatedStackSlots[NextSlotToAllocate] = true;
return Builder.DAG.getFrameIndex(FI, ValueType);
}
// Note: We deliberately choose to advance this only on the failing path.
// Doing so on the succeeding path involves a bit of complexity that caused
// a minor bug previously. Unless performance shows this matters, please
// keep this code as simple as possible.
NextSlotToAllocate++;
}
llvm_unreachable("infinite loop?");
// Couldn't find a free slot, so create a new one:
StatepointMaxSlotsRequired =
std::max<unsigned long>(StatepointMaxSlotsRequired, NumSlots + 1);
SDValue SpillSlot = Builder.DAG.CreateStackTemporary(ValueType);
const unsigned FI = cast<FrameIndexSDNode>(SpillSlot)->getIndex();
auto *MFI = Builder.DAG.getMachineFunction().getFrameInfo();
MFI->markAsStatepointSpillSlotObjectIndex(FI);
Builder.FuncInfo.StatepointStackSlots.push_back(FI);
AllocatedStackSlots.push_back(true);
return SpillSlot;
}
/// Utility function for reservePreviousStackSlotForValue. Tries to find