Keep track of register masks in LiveIntervalAnalysis.
Build an ordered vector of register mask operands (i.e., calls) when
computing live intervals. Provide a checkRegMaskInterference() function
that computes a bit mask of usable registers for a live range.
This is a quick way of determining of a live range crosses any calls,
and restricting it to the callee saved registers if it does.
Previously, we had to discover call clobbers for each candidate register
independently.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@150077 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/LiveIntervalAnalysis.cpp b/lib/CodeGen/LiveIntervalAnalysis.cpp
index 4da4997..7d24732 100644
--- a/lib/CodeGen/LiveIntervalAnalysis.cpp
+++ b/lib/CodeGen/LiveIntervalAnalysis.cpp
@@ -88,6 +88,8 @@
delete I->second;
r2iMap_.clear();
+ RegMaskSlots.clear();
+ RegMaskBits.clear();
// Release VNInfo memory regions, VNInfo objects don't need to be dtor'd.
VNInfoAllocator.Reset();
@@ -558,10 +560,20 @@
DEBUG(dbgs() << MIIndex << "\t" << *MI);
if (MI->isDebugValue())
continue;
+ assert(indexes_->getInstructionFromIndex(MIIndex) == MI &&
+ "Lost SlotIndex synchronization");
// Handle defs.
for (int i = MI->getNumOperands() - 1; i >= 0; --i) {
MachineOperand &MO = MI->getOperand(i);
+
+ // Collect register masks.
+ if (MO.isRegMask()) {
+ RegMaskSlots.push_back(MIIndex.getRegSlot());
+ RegMaskBits.push_back(MO.getRegMask());
+ continue;
+ }
+
if (!MO.isReg() || !MO.getReg())
continue;
@@ -1111,3 +1123,53 @@
return LR;
}
+
+
+//===----------------------------------------------------------------------===//
+// Register mask functions
+//===----------------------------------------------------------------------===//
+
+bool LiveIntervals::checkRegMaskInterference(LiveInterval &LI,
+ BitVector &UsableRegs) {
+ if (LI.empty())
+ return false;
+
+ // We are going to enumerate all the register mask slots contained in LI.
+ // Start with a binary search of RegMaskSlots to find a starting point.
+ LiveInterval::iterator LiveI = LI.begin(), LiveE = LI.end();
+ ArrayRef<SlotIndex> Slots = getRegMaskSlots();
+ ArrayRef<SlotIndex>::iterator SlotI =
+ std::lower_bound(Slots.begin(), Slots.end(), LiveI->start);
+ ArrayRef<SlotIndex>::iterator SlotE = Slots.end();
+
+ // No slots in range, LI begins after the last call.
+ if (SlotI == SlotE)
+ return false;
+
+ bool Found = false;
+ for (;;) {
+ assert(*SlotI >= LiveI->start);
+ // Loop over all slots overlapping this segment.
+ while (*SlotI < LiveI->end) {
+ // *SlotI overlaps LI. Collect mask bits.
+ if (!Found) {
+ // This is the first overlap. Initialize UsableRegs to all ones.
+ UsableRegs.clear();
+ UsableRegs.resize(tri_->getNumRegs(), true);
+ Found = true;
+ }
+ // Remove usable registers clobbered by this mask.
+ UsableRegs.clearBitsNotInMask(RegMaskBits[SlotI-Slots.begin()]);
+ if (++SlotI == SlotE)
+ return Found;
+ }
+ // *SlotI is beyond the current LI segment.
+ LiveI = LI.advanceTo(LiveI, *SlotI);
+ if (LiveI == LiveE)
+ return Found;
+ // Advance SlotI until it overlaps.
+ while (*SlotI < LiveI->start)
+ if (++SlotI == SlotE)
+ return Found;
+ }
+}