[llvm-commits] [llvm] r132245 - in /llvm/trunk/lib/CodeGen: RegAllocGreedy.cpp SplitKit.cpp SplitKit.h
Jakob Stoklund Olesen
stoklund at 2pi.dk
Fri May 27 19:33:00 PDT 2011
Author: stoklund
Date: Fri May 27 21:33:00 2011
New Revision: 132245
URL: http://llvm.org/viewvc/llvm-project?rev=132245&view=rev
Log:
Create two BlockInfo entries when a live range is discontinuous through a block.
Delete the Kill and Def markers in BlockInfo. They are no longer
necessary when BlockInfo describes a continuous live range.
This only affects the relatively rare kind of basic block where a live
range looks like this:
|---x o---|
Now live range splitting can pretend that it is looking at two blocks:
|---x
o---|
This allows the code to be simplified a bit.
Modified:
llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
llvm/trunk/lib/CodeGen/SplitKit.cpp
llvm/trunk/lib/CodeGen/SplitKit.h
Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=132245&r1=132244&r2=132245&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Fri May 27 21:33:00 2011
@@ -552,7 +552,7 @@
BC.Entry = SpillPlacement::MustSpill, ++Ins;
else if (Intf.first() < BI.FirstUse)
BC.Entry = SpillPlacement::PrefSpill, ++Ins;
- else if (Intf.first() < (BI.LiveThrough ? BI.LastUse : BI.Kill))
+ else if (Intf.first() < BI.LastUse)
++Ins;
}
@@ -562,7 +562,7 @@
BC.Exit = SpillPlacement::MustSpill, ++Ins;
else if (Intf.last() > BI.LastUse)
BC.Exit = SpillPlacement::PrefSpill, ++Ins;
- else if (Intf.last() > (BI.LiveThrough ? BI.FirstUse : BI.Def))
+ else if (Intf.last() > BI.FirstUse)
++Ins;
}
@@ -811,7 +811,7 @@
DEBUG(dbgs() << ", no interference");
if (!BI.LiveThrough) {
DEBUG(dbgs() << ", not live-through.\n");
- SE->useIntv(SE->enterIntvBefore(BI.Def), Stop);
+ SE->useIntv(SE->enterIntvBefore(BI.FirstUse), Stop);
continue;
}
if (!RegIn) {
@@ -828,10 +828,10 @@
// Block has interference.
DEBUG(dbgs() << ", interference to " << Intf.last());
- if (!BI.LiveThrough && Intf.last() <= BI.Def) {
+ if (!BI.LiveThrough && Intf.last() <= BI.FirstUse) {
// The interference doesn't reach the outgoing segment.
- DEBUG(dbgs() << " doesn't affect def from " << BI.Def << '\n');
- SE->useIntv(BI.Def, Stop);
+ DEBUG(dbgs() << " doesn't affect def from " << BI.FirstUse << '\n');
+ SE->useIntv(BI.FirstUse, Stop);
continue;
}
@@ -887,7 +887,7 @@
DEBUG(dbgs() << ", no interference");
if (!BI.LiveThrough) {
DEBUG(dbgs() << ", killed in block.\n");
- SE->useIntv(Start, SE->leaveIntvAfter(BI.Kill));
+ SE->useIntv(Start, SE->leaveIntvAfter(BI.LastUse));
continue;
}
if (!RegOut) {
@@ -920,10 +920,10 @@
// Block has interference.
DEBUG(dbgs() << ", interference from " << Intf.first());
- if (!BI.LiveThrough && Intf.first() >= BI.Kill) {
+ if (!BI.LiveThrough && Intf.first() >= BI.LastUse) {
// The interference doesn't reach the outgoing segment.
- DEBUG(dbgs() << " doesn't affect kill at " << BI.Kill << '\n');
- SE->useIntv(Start, BI.Kill);
+ DEBUG(dbgs() << " doesn't affect kill at " << BI.LastUse << '\n');
+ SE->useIntv(Start, BI.LastUse);
continue;
}
Modified: llvm/trunk/lib/CodeGen/SplitKit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.cpp?rev=132245&r1=132244&r2=132245&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.cpp (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.cpp Fri May 27 21:33:00 2011
@@ -145,7 +145,7 @@
/// where CurLI is live.
bool SplitAnalysis::calcLiveBlockInfo() {
ThroughBlocks.resize(MF.getNumBlockIDs());
- NumThroughBlocks = 0;
+ NumThroughBlocks = NumGapBlocks = 0;
if (CurLI->empty())
return true;
@@ -164,55 +164,62 @@
SlotIndex Start, Stop;
tie(Start, Stop) = LIS.getSlotIndexes()->getMBBRange(BI.MBB);
- // LVI is the first live segment overlapping MBB.
- BI.LiveIn = LVI->start <= Start;
- if (!BI.LiveIn)
- BI.Def = LVI->start;
-
- // Find the first and last uses in the block.
- bool Uses = UseI != UseE && *UseI < Stop;
- if (Uses) {
+ // If the block contains no uses, the range must be live through. At one
+ // point, SimpleRegisterCoalescing could create dangling ranges that ended
+ // mid-block.
+ if (UseI == UseE || *UseI >= Stop) {
+ ++NumThroughBlocks;
+ ThroughBlocks.set(BI.MBB->getNumber());
+ // The range shouldn't end mid-block if there are no uses. This shouldn't
+ // happen.
+ if (LVI->end < Stop)
+ return false;
+ } else {
+ // This block has uses. Find the first and last uses in the block.
BI.FirstUse = *UseI;
assert(BI.FirstUse >= Start);
do ++UseI;
while (UseI != UseE && *UseI < Stop);
BI.LastUse = UseI[-1];
assert(BI.LastUse < Stop);
- }
- // Look for gaps in the live range.
- bool hasGap = false;
- BI.LiveOut = true;
- while (LVI->end < Stop) {
- SlotIndex LastStop = LVI->end;
- if (++LVI == LVE || LVI->start >= Stop) {
- BI.Kill = LastStop;
- BI.LiveOut = false;
- break;
- }
- if (LastStop < LVI->start) {
- hasGap = true;
- BI.Kill = LastStop;
- BI.Def = LVI->start;
+ // LVI is the first live segment overlapping MBB.
+ BI.LiveIn = LVI->start <= Start;
+
+ // Look for gaps in the live range.
+ BI.LiveOut = true;
+ while (LVI->end < Stop) {
+ SlotIndex LastStop = LVI->end;
+ if (++LVI == LVE || LVI->start >= Stop) {
+ BI.LiveOut = false;
+ break;
+ }
+ if (LastStop < LVI->start) {
+ // There is a gap in the live range. Create duplicate entries for the
+ // live-in snippet and the live-out snippet.
+ ++NumGapBlocks;
+
+ // Push the Live-in part.
+ BI.LiveThrough = false;
+ BI.LiveOut = false;
+ UseBlocks.push_back(BI);
+ UseBlocks.back().LastUse = LastStop;
+
+ // Set up BI for the live-out part.
+ BI.LiveIn = false;
+ BI.LiveOut = true;
+ BI.FirstUse = LVI->start;
+ }
}
- }
- // Don't set LiveThrough when the block has a gap.
- BI.LiveThrough = !hasGap && BI.LiveIn && BI.LiveOut;
- if (Uses)
+ // Don't set LiveThrough when the block has a gap.
+ BI.LiveThrough = BI.LiveIn && BI.LiveOut;
UseBlocks.push_back(BI);
- else {
- ++NumThroughBlocks;
- ThroughBlocks.set(BI.MBB->getNumber());
- }
- // FIXME: This should never happen. The live range stops or starts without a
- // corresponding use. An earlier pass did something wrong.
- if (!BI.LiveThrough && !Uses)
- return false;
- // LVI is now at LVE or LVI->end >= Stop.
- if (LVI == LVE)
- break;
+ // LVI is now at LVE or LVI->end >= Stop.
+ if (LVI == LVE)
+ break;
+ }
// Live segment ends exactly at Stop. Move to the next segment.
if (LVI->end == Stop && ++LVI == LVE)
Modified: llvm/trunk/lib/CodeGen/SplitKit.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.h?rev=132245&r1=132244&r2=132245&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.h (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.h Fri May 27 21:33:00 2011
@@ -63,17 +63,22 @@
/// 1. | o---x | Internal to block. Variable is only live in this block.
/// 2. |---x | Live-in, kill.
/// 3. | o---| Def, live-out.
- /// 4. |---x o---| Live-in, kill, def, live-out.
+ /// 4. |---x o---| Live-in, kill, def, live-out. Counted by NumGapBlocks.
/// 5. |---o---o---| Live-through with uses or defs.
- /// 6. |-----------| Live-through without uses. Transparent.
+ /// 6. |-----------| Live-through without uses. Counted by NumThroughBlocks.
+ ///
+ /// Two BlockInfo entries are created for template 4. One for the live-in
+ /// segment, and one for the live-out segment. These entries look as if the
+ /// block were split in the middle where the live range isn't live.
+ ///
+ /// Live-through blocks without any uses don't get BlockInfo entries. They
+ /// are simply listed in ThroughBlocks instead.
///
struct BlockInfo {
MachineBasicBlock *MBB;
SlotIndex FirstUse; ///< First instr using current reg.
SlotIndex LastUse; ///< Last instr using current reg.
- SlotIndex Kill; ///< Interval end point inside block.
- SlotIndex Def; ///< Interval start point inside block.
- bool LiveThrough; ///< Live in whole block (Templ 5. or 6. above).
+ bool LiveThrough; ///< Live in whole block (Templ 5. above).
bool LiveIn; ///< Current reg is live in.
bool LiveOut; ///< Current reg is live out.
};
@@ -91,6 +96,10 @@
/// UseBlocks - Blocks where CurLI has uses.
SmallVector<BlockInfo, 8> UseBlocks;
+ /// NumGapBlocks - Number of duplicate entries in UseBlocks for blocks where
+ /// the live range has a gap.
+ unsigned NumGapBlocks;
+
/// ThroughBlocks - Block numbers where CurLI is live through without uses.
BitVector ThroughBlocks;
@@ -160,7 +169,7 @@
/// getNumLiveBlocks - Return the number of blocks where CurLI is live.
unsigned getNumLiveBlocks() const {
- return getUseBlocks().size() + getNumThroughBlocks();
+ return getUseBlocks().size() - NumGapBlocks + getNumThroughBlocks();
}
/// countLiveBlocks - Return the number of blocks where li is live. This is
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