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Stack coloring: remove lifetime intervals which contain escaped allocas.

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The input program may contain intructions which are not inside lifetime
markers. This can happen due to a bug in the compiler or due to a bug in
user code (for example, returning a reference to a local variable).
This commit adds checks that all of the instructions in the function and
invalidates lifetime ranges which do not contain all of the instructions.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@163678 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nadav Rotem
2012-09-12 04:57:37 +00:00
parent 2c57a334d7
commit 0a16da4457
2 changed files with 74 additions and 3 deletions
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lib/CodeGen/StackColoring.cpp
+47
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@@ -158,6 +158,14 @@ private:
/// slots to use the joint slots.
void remapInstructions(DenseMap<int, int> &SlotRemap);
/// The input program may contain intructions which are not inside lifetime
/// markers. This can happen due to a bug in the compiler or due to a bug in
/// user code (for example, returning a reference to a local variable).
/// This procedure checks all of the instructions in the function and
/// invalidates lifetime ranges which do not contain all of the instructions
/// which access that frame slot.
void removeInvalidSlotRanges();
/// Map entries which point to other entries to their destination.
/// A->B->C becomes A->C.
void expungeSlotMap(DenseMap<int, int> &SlotRemap, unsigned NumSlots);
@@ -543,6 +551,43 @@ void StackColoring::remapInstructions(DenseMap<int, int> &SlotRemap) {
DEBUG(dbgs()<<"Fixed "<<FixedInstr<<" machine instructions.\n");
}
void StackColoring::removeInvalidSlotRanges() {
MachineFunction::iterator BB, BBE;
MachineBasicBlock::iterator I, IE;
for (BB = MF->begin(), BBE = MF->end(); BB != BBE; ++BB)
for (I = BB->begin(), IE = BB->end(); I != IE; ++I) {
if (I->getOpcode() == TargetOpcode::LIFETIME_START ||
I->getOpcode() == TargetOpcode::LIFETIME_END || I->isDebugValue())
continue;
// Check all of the machine operands.
for (unsigned i = 0 ; i < I->getNumOperands(); ++i) {
MachineOperand &MO = I->getOperand(i);
if (!MO.isFI())
continue;
int Slot = MO.getIndex();
if (Slot<0)
continue;
if (Intervals[Slot]->empty())
continue;
// Check that the used slot is inside the calculated lifetime range.
// If it is not, warn about it and invalidate the range.
LiveInterval *Interval = Intervals[Slot];
SlotIndex Index = Indexes->getInstructionIndex(I);
if (Interval->find(Index) == Interval->end()) {
Intervals[Slot]->clear();
DEBUG(dbgs()<<"Invalidating range #"<<Slot<<"\n");
}
}
}
}
void StackColoring::expungeSlotMap(DenseMap<int, int> &SlotRemap,
unsigned NumSlots) {
// Expunge slot remap map.
@@ -617,6 +662,8 @@ bool StackColoring::runOnMachineFunction(MachineFunction &Func) {
// Propagate the liveness information.
calculateLiveIntervals(NumSlots);
removeInvalidSlotRanges();
// Maps old slots to new slots.
DenseMap<int, int> SlotRemap;
unsigned RemovedSlots = 0;