Implement single block splitting.
Before spilling a live range, we split it into a separate range for each basic
block where it is used. That way we only get one reload per basic block if the
new smaller ranges can allocate to a register.
This type of splitting is already present in the standard spiller.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@110934 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index d125a45..663626e 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -37,10 +37,6 @@
const MachineLoopInfo &loops_;
const TargetInstrInfo &tii_;
-private:
- // Current live interval.
- const LiveInterval *curli_;
-
// Instructions using the the current register.
typedef SmallPtrSet<const MachineInstr*, 16> InstrPtrSet;
InstrPtrSet usingInstrs_;
@@ -53,6 +49,10 @@
typedef SmallPtrSet<const MachineLoop*, 16> LoopPtrSet;
LoopPtrSet usingLoops_;
+private:
+ // Current live interval.
+ const LiveInterval *curli_;
+
// Sumarize statistics by counting instructions using curli_.
void analyzeUses();
@@ -118,6 +118,11 @@
/// getBestSplitLoop - Return the loop where curli may best be split to a
/// separate register, or NULL.
const MachineLoop *getBestSplitLoop();
+
+ /// getMultiUseBlocks - Add basic blocks to Blocks that may benefit from
+ /// having curli split to a new live interval. Return true if Blocks can be
+ /// passed to SplitEditor::splitSingleBlocks.
+ bool getMultiUseBlocks(BlockPtrSet &Blocks);
};
/// SplitEditor - Edit machine code and LiveIntervals for live range
@@ -156,7 +161,7 @@
/// getDupLI - Ensure dupli is created and return it.
LiveInterval *getDupLI();
- /// valueMap_ - Map values in dupli to values in openIntv. These are direct 1-1
+ /// valueMap_ - Map values in cupli to values in openli. These are direct 1-1
/// mappings, and do not include values created by inserted copies.
DenseMap<const VNInfo*, VNInfo*> valueMap_;
@@ -192,6 +197,10 @@
/// Create a new virtual register and live interval.
void openIntv();
+ /// enterIntvBefore - Enter openli before the instruction at Idx. If curli is
+ /// not live before Idx, a COPY is not inserted.
+ void enterIntvBefore(SlotIndex Idx);
+
/// enterIntvAtEnd - Enter openli at the end of MBB.
/// PhiMBB is a successor inside openli where a PHI value is created.
/// Currently, all entries must share the same PhiMBB.
@@ -203,6 +212,9 @@
/// useIntv - indicate that all instructions in range should use openli.
void useIntv(SlotIndex Start, SlotIndex End);
+ /// leaveIntvAfter - Leave openli after the instruction at Idx.
+ void leaveIntvAfter(SlotIndex Idx);
+
/// leaveIntvAtTop - Leave the interval at the top of MBB.
/// Currently, only one value can leave the interval.
void leaveIntvAtTop(MachineBasicBlock &MBB);
@@ -222,6 +234,10 @@
/// curli is still intact, and needs to be spilled or split further.
bool splitAroundLoop(const MachineLoop*);
+ /// splitSingleBlocks - Split curli into a separate live interval inside each
+ /// basic block in Blocks. Return true if curli has been completely replaced,
+ /// false if curli is still intact, and needs to be spilled or split further.
+ bool splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks);
};