[llvm-commits] [llvm] r134053 - in /llvm/trunk/lib/CodeGen: RegAllocGreedy.cpp SplitKit.cpp SplitKit.h
Jakob Stoklund Olesen
stoklund at 2pi.dk
Tue Jun 28 19:03:37 PDT 2011
Author: stoklund
Date: Tue Jun 28 21:03:36 2011
New Revision: 134053
URL: http://llvm.org/viewvc/llvm-project?rev=134053&view=rev
Log:
Revert r134047 while investigating a llvm-gcc-i386-linux-selfhost
miscompile.
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=134053&r1=134052&r2=134053&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
+++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Tue Jun 28 21:03:36 2011
@@ -763,46 +763,32 @@
// Create the main cross-block interval.
const unsigned MainIntv = SE->openIntv();
- // First handle all the blocks with uses.
+ // First add all defs that are live out of a block.
ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
for (unsigned i = 0; i != UseBlocks.size(); ++i) {
const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
- bool RegIn = BI.LiveIn &&
- LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
- bool RegOut = BI.LiveOut &&
- LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
+ bool RegIn = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
+ bool RegOut = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
// Create separate intervals for isolated blocks with multiple uses.
- //
- // |---o---o---| Enter and leave on the stack.
- // ____-----____ Create local interval for uses.
- //
- // | o---o---| Defined in block, leave on stack.
- // -----____ Create local interval for uses.
- //
- // |---o---x | Enter on stack, killed in block.
- // ____----- Create local interval for uses.
- //
- if (!RegIn && !RegOut) {
+ if (!RegIn && !RegOut && BI.FirstUse != BI.LastUse) {
DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " isolated.\n");
- if (!BI.isOneInstr()) {
- SE->splitSingleBlock(BI);
- SE->selectIntv(MainIntv);
- }
+ SE->splitSingleBlock(BI);
+ SE->selectIntv(MainIntv);
continue;
}
+ // Should the register be live out?
+ if (!BI.LiveOut || !RegOut)
+ continue;
+
SlotIndex Start, Stop;
tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
Intf.moveToBlock(BI.MBB->getNumber());
- DEBUG(dbgs() << "EB#" << Bundles->getBundle(BI.MBB->getNumber(), 0)
- << (RegIn ? " => " : " -- ")
- << "BB#" << BI.MBB->getNumber()
- << (RegOut ? " => " : " -- ")
- << " EB#" << Bundles->getBundle(BI.MBB->getNumber(), 1)
+ DEBUG(dbgs() << "BB#" << BI.MBB->getNumber() << " -> EB#"
+ << Bundles->getBundle(BI.MBB->getNumber(), 1)
<< " [" << Start << ';'
<< SA->getLastSplitPoint(BI.MBB->getNumber()) << '-' << Stop
- << ") uses [" << BI.FirstUse << ';' << BI.LastUse
<< ") intf [" << Intf.first() << ';' << Intf.last() << ')');
// The interference interval should either be invalid or overlap MBB.
@@ -811,266 +797,150 @@
assert((!Intf.hasInterference() || Intf.last() > Start)
&& "Bad interference");
- // We are now ready to decide where to split in the current block. There
- // are many variables guiding the decision:
- //
- // - RegIn / RegOut: The global splitting algorithm's decisions for our
- // ingoing and outgoing bundles.
- //
- // - BI.BlockIn / BI.BlockOut: Is the live range live-in and/or live-out
- // from this block.
- //
- // - Intf.hasInterference(): Is there interference in this block.
- //
- // - Intf.first() / Inft.last(): The range of interference.
- //
- // The live range should be split such that MainIntv is live-in when RegIn
- // is set, and live-out when RegOut is set. MainIntv should never overlap
- // the interference, and the stack interval should never have more than one
- // use per block.
-
- // No splits can be inserted after LastSplitPoint, overlap instead.
- SlotIndex LastSplitPoint = Stop;
- if (BI.LiveOut)
- LastSplitPoint = SA->getLastSplitPoint(BI.MBB->getNumber());
-
- // At this point, we know that either RegIn or RegOut is set. We dealt with
- // the all-stack case above.
-
- // Blocks without interference are relatively easy.
+ // Check interference leaving the block.
if (!Intf.hasInterference()) {
- DEBUG(dbgs() << ", no interference.\n");
- SE->selectIntv(MainIntv);
- // The easiest case has MainIntv live through.
- //
- // |---o---o---| Live-in, live-out.
- // ============= Use MainIntv everywhere.
- //
- SlotIndex From = Start, To = Stop;
-
- // Block entry. Reload before the first use if MainIntv is not live-in.
- //
- // |---o-- Enter on stack.
- // ____=== Reload before first use.
- //
- // | o-- Defined in block.
- // === Use MainIntv from def.
- //
- if (!RegIn)
- From = SE->enterIntvBefore(BI.FirstUse);
-
- // Block exit. Handle cases where MainIntv is not live-out.
- if (!BI.LiveOut)
- //
- // --x | Killed in block.
- // === Use MainIntv up to kill.
- //
- To = SE->leaveIntvAfter(BI.LastUse);
- else if (!RegOut) {
- //
- // --o---| Live-out on stack.
- // ===____ Use MainIntv up to last use, switch to stack.
- //
- // -----o| Live-out on stack, last use after last split point.
- // ====== Extend MainIntv to last use, overlapping.
- // \____ Copy to stack interval before last split point.
- //
- if (BI.LastUse < LastSplitPoint)
- To = SE->leaveIntvAfter(BI.LastUse);
- else {
- // The last use is after the last split point, it is probably an
- // indirect branch.
- To = SE->leaveIntvBefore(LastSplitPoint);
- // Run a double interval from the split to the last use. This makes
- // it possible to spill the complement without affecting the indirect
- // branch.
- SE->overlapIntv(To, BI.LastUse);
- }
+ // Block is interference-free.
+ DEBUG(dbgs() << ", no interference");
+ if (!BI.LiveThrough) {
+ DEBUG(dbgs() << ", not live-through.\n");
+ SE->useIntv(SE->enterIntvBefore(BI.FirstUse), Stop);
+ continue;
}
-
- // Paint in MainIntv liveness for this block.
- SE->useIntv(From, To);
+ if (!RegIn) {
+ // Block is live-through, but entry bundle is on the stack.
+ // Reload just before the first use.
+ DEBUG(dbgs() << ", not live-in, enter before first use.\n");
+ SE->useIntv(SE->enterIntvBefore(BI.FirstUse), Stop);
+ continue;
+ }
+ DEBUG(dbgs() << ", live-through.\n");
continue;
}
- // We are now looking at a block with interference, and we know that either
- // RegIn or RegOut is set.
- assert(Intf.hasInterference() && (RegIn || RegOut) && "Bad invariant");
+ // Block has interference.
+ DEBUG(dbgs() << ", interference to " << Intf.last());
- // If the live range is not live through the block, it is possible that the
- // interference doesn't even overlap. Deal with those cases first. Since
- // no copy instructions are required, we can tolerate interference starting
- // or ending at the same instruction that kills or defines our live range.
-
- // Live-in, killed before interference.
- //
- // ~~~ Interference after kill.
- // |---o---x | Killed in block.
- // ========= Use MainIntv everywhere.
- //
- if (RegIn && !BI.LiveOut && BI.LastUse <= Intf.first()) {
- DEBUG(dbgs() << ", live-in, killed before interference.\n");
- SE->selectIntv(MainIntv);
- SlotIndex To = SE->leaveIntvAfter(BI.LastUse);
- SE->useIntv(Start, To);
+ if (!BI.LiveThrough && Intf.last() <= BI.FirstUse) {
+ // The interference doesn't reach the outgoing segment.
+ DEBUG(dbgs() << " doesn't affect def from " << BI.FirstUse << '\n');
+ SE->useIntv(BI.FirstUse, Stop);
continue;
}
- // Live-out, defined after interference.
- //
- // ~~~ Interference before def.
- // | o---o---| Defined in block.
- // ========= Use MainIntv everywhere.
- //
- if (RegOut && !BI.LiveIn && BI.FirstUse >= Intf.last()) {
- DEBUG(dbgs() << ", live-out, defined after interference.\n");
- SE->selectIntv(MainIntv);
- SlotIndex From = SE->enterIntvBefore(BI.FirstUse);
- SE->useIntv(From, Stop);
- continue;
+ SlotIndex LastSplitPoint = SA->getLastSplitPoint(BI.MBB->getNumber());
+ if (Intf.last().getBoundaryIndex() < BI.LastUse) {
+ // There are interference-free uses at the end of the block.
+ // Find the first use that can get the live-out register.
+ SmallVectorImpl<SlotIndex>::const_iterator UI =
+ std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
+ Intf.last().getBoundaryIndex());
+ assert(UI != SA->UseSlots.end() && "Couldn't find last use");
+ SlotIndex Use = *UI;
+ assert(Use <= BI.LastUse && "Couldn't find last use");
+ // Only attempt a split befroe the last split point.
+ if (Use.getBaseIndex() <= LastSplitPoint) {
+ DEBUG(dbgs() << ", free use at " << Use << ".\n");
+ SlotIndex SegStart = SE->enterIntvBefore(Use);
+ assert(SegStart >= Intf.last() && "Couldn't avoid interference");
+ assert(SegStart < LastSplitPoint && "Impossible split point");
+ SE->useIntv(SegStart, Stop);
+ continue;
+ }
}
- // The interference is now known to overlap the live range, but it may
- // still be easy to avoid if all the interference is on one side of the
- // uses, and we enter or leave on the stack.
+ // Interference is after the last use.
+ DEBUG(dbgs() << " after last use.\n");
+ SlotIndex SegStart = SE->enterIntvAtEnd(*BI.MBB);
+ assert(SegStart >= Intf.last() && "Couldn't avoid interference");
+ }
- // Live-out on stack, interference after last use.
- //
- // ~~~ Interference after last use.
- // |---o---o---| Live-out on stack.
- // =========____ Leave MainIntv after last use.
- //
- // ~ Interference after last use.
- // |---o---o--o| Live-out on stack, late last use.
- // =========____ Copy to stack after LSP, overlap MainIntv.
- //
- if (!RegOut && Intf.first() > BI.LastUse.getBoundaryIndex()) {
- assert(RegIn && "Stack-in, stack-out should already be handled");
- if (BI.LastUse < LastSplitPoint) {
- DEBUG(dbgs() << ", live-in, stack-out, interference after last use.\n");
- SE->selectIntv(MainIntv);
- SlotIndex To = SE->leaveIntvAfter(BI.LastUse);
- assert(To <= Intf.first() && "Expected to avoid interference");
- SE->useIntv(Start, To);
- } else {
- DEBUG(dbgs() << ", live-in, stack-out, avoid last split point\n");
- SE->selectIntv(MainIntv);
- SlotIndex To = SE->leaveIntvBefore(LastSplitPoint);
- assert(To <= Intf.first() && "Expected to avoid interference");
- SE->overlapIntv(To, BI.LastUse);
- SE->useIntv(Start, To);
+ // Now all defs leading to live bundles are handled, do everything else.
+ for (unsigned i = 0; i != UseBlocks.size(); ++i) {
+ const SplitAnalysis::BlockInfo &BI = UseBlocks[i];
+ bool RegIn = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 0)];
+ bool RegOut = LiveBundles[Bundles->getBundle(BI.MBB->getNumber(), 1)];
+
+ // Is the register live-in?
+ if (!BI.LiveIn || !RegIn)
+ continue;
+
+ // We have an incoming register. Check for interference.
+ SlotIndex Start, Stop;
+ tie(Start, Stop) = Indexes->getMBBRange(BI.MBB);
+ Intf.moveToBlock(BI.MBB->getNumber());
+ DEBUG(dbgs() << "EB#" << Bundles->getBundle(BI.MBB->getNumber(), 0)
+ << " -> BB#" << BI.MBB->getNumber() << " [" << Start << ';'
+ << SA->getLastSplitPoint(BI.MBB->getNumber()) << '-' << Stop
+ << ')');
+
+ // Check interference entering the block.
+ if (!Intf.hasInterference()) {
+ // Block is interference-free.
+ DEBUG(dbgs() << ", no interference");
+ if (!BI.LiveThrough) {
+ DEBUG(dbgs() << ", killed in block.\n");
+ SE->useIntv(Start, SE->leaveIntvAfter(BI.LastUse));
+ continue;
}
+ if (!RegOut) {
+ SlotIndex LastSplitPoint = SA->getLastSplitPoint(BI.MBB->getNumber());
+ // Block is live-through, but exit bundle is on the stack.
+ // Spill immediately after the last use.
+ if (BI.LastUse < LastSplitPoint) {
+ DEBUG(dbgs() << ", uses, stack-out.\n");
+ SE->useIntv(Start, SE->leaveIntvAfter(BI.LastUse));
+ continue;
+ }
+ // The last use is after the last split point, it is probably an
+ // indirect jump.
+ DEBUG(dbgs() << ", uses at " << BI.LastUse << " after split point "
+ << LastSplitPoint << ", stack-out.\n");
+ SlotIndex SegEnd = SE->leaveIntvBefore(LastSplitPoint);
+ SE->useIntv(Start, SegEnd);
+ // Run a double interval from the split to the last use.
+ // This makes it possible to spill the complement without affecting the
+ // indirect branch.
+ SE->overlapIntv(SegEnd, BI.LastUse);
+ continue;
+ }
+ // Register is live-through.
+ DEBUG(dbgs() << ", uses, live-through.\n");
+ SE->useIntv(Start, Stop);
continue;
}
- // Live-in on stack, interference before first use.
- //
- // ~~~ Interference before first use.
- // |---o---o---| Live-in on stack.
- // ____========= Enter MainIntv before first use.
- //
- if (!RegIn && Intf.last() < BI.FirstUse.getBaseIndex()) {
- assert(RegOut && "Stack-in, stack-out should already be handled");
- DEBUG(dbgs() << ", stack-in, interference before first use.\n");
- SE->selectIntv(MainIntv);
- SlotIndex From = SE->enterIntvBefore(BI.FirstUse);
- assert(From >= Intf.last() && "Expected to avoid interference");
- SE->useIntv(From, Stop);
+ // Block has interference.
+ DEBUG(dbgs() << ", interference from " << Intf.first());
+
+ if (!BI.LiveThrough && Intf.first() >= BI.LastUse) {
+ // The interference doesn't reach the outgoing segment.
+ DEBUG(dbgs() << " doesn't affect kill at " << BI.LastUse << '\n');
+ SE->useIntv(Start, BI.LastUse);
continue;
}
- // The interference is overlapping somewhere we wanted to use MainIntv. That
- // means we need to create a local interval that can be allocated a
- // different register.
- DEBUG(dbgs() << ", creating local interval.\n");
- unsigned LocalIntv = SE->openIntv();
-
- // We may be creating copies directly between MainIntv and LocalIntv,
- // bypassing the stack interval. When we do that, we should never use the
- // leaveIntv* methods as they define values in the stack interval. By
- // starting from the end of the block and working our way backwards, we can
- // get by with only enterIntv* methods.
- //
- // When selecting split points, we generally try to maximize the stack
- // interval as long at it contains no uses, maximize the main interval as
- // long as it doesn't overlap interference, and minimize the local interval
- // that we don't know how to allocate yet.
-
- // Handle the block exit, set Pos to the first handled slot.
- SlotIndex Pos = BI.LastUse;
- if (RegOut) {
- assert(Intf.last() < LastSplitPoint && "Cannot be live-out in register");
- // Create a snippet of MainIntv that is live-out.
- //
- // ~~~ Interference overlapping uses.
- // --o---| Live-out in MainIntv.
- // ----=== Switch from LocalIntv to MainIntv after interference.
- //
- SE->selectIntv(MainIntv);
- Pos = SE->enterIntvAfter(Intf.last());
- assert(Pos >= Intf.last() && "Expected to avoid interference");
- SE->useIntv(Pos, Stop);
- SE->selectIntv(LocalIntv);
- } else if (BI.LiveOut) {
- if (BI.LastUse < LastSplitPoint) {
- // Live-out on the stack.
- //
- // ~~~ Interference overlapping uses.
- // --o---| Live-out on stack.
- // ---____ Switch from LocalIntv to stack after last use.
- //
- Pos = SE->leaveIntvAfter(BI.LastUse);
- } else {
- // Live-out on the stack, last use after last split point.
- //
- // ~~~ Interference overlapping uses.
- // --o--o| Live-out on stack, late use.
- // ------ Copy to stack before LSP, overlap LocalIntv.
- // \__
- //
- Pos = SE->leaveIntvBefore(LastSplitPoint);
- // We need to overlap LocalIntv so it can reach LastUse.
- SE->overlapIntv(Pos, BI.LastUse);
- }
+ if (Intf.first().getBaseIndex() > BI.FirstUse) {
+ // There are interference-free uses at the beginning of the block.
+ // Find the last use that can get the register.
+ SmallVectorImpl<SlotIndex>::const_iterator UI =
+ std::lower_bound(SA->UseSlots.begin(), SA->UseSlots.end(),
+ Intf.first().getBaseIndex());
+ assert(UI != SA->UseSlots.begin() && "Couldn't find first use");
+ SlotIndex Use = (--UI)->getBoundaryIndex();
+ DEBUG(dbgs() << ", free use at " << *UI << ".\n");
+ SlotIndex SegEnd = SE->leaveIntvAfter(Use);
+ assert(SegEnd <= Intf.first() && "Couldn't avoid interference");
+ SE->useIntv(Start, SegEnd);
+ continue;
}
- // When not live-out, leave Pos at LastUse. We have handled everything from
- // Pos to Stop. Find the starting point for LocalIntv.
- assert(SE->currentIntv() == LocalIntv && "Expecting local interval");
-
- if (RegIn) {
- assert(Start < Intf.first() && "Cannot be live-in with interference");
- // Live-in in MainIntv, only use LocalIntv for interference.
- //
- // ~~~ Interference overlapping uses.
- // |---o-- Live-in in MainIntv.
- // ====--- Switch to LocalIntv before interference.
- //
- SlotIndex Switch = SE->enterIntvBefore(Intf.first());
- assert(Switch <= Intf.first() && "Expected to avoid interference");
- SE->useIntv(Switch, Pos);
- SE->selectIntv(MainIntv);
- SE->useIntv(Start, Switch);
- } else {
- // Live-in on stack, enter LocalIntv before first use.
- //
- // ~~~ Interference overlapping uses.
- // |---o-- Live-in in MainIntv.
- // ____--- Reload to LocalIntv before interference.
- //
- // Defined in block.
- //
- // ~~~ Interference overlapping uses.
- // | o-- Defined in block.
- // --- Begin LocalIntv at first use.
- //
- SlotIndex Switch = SE->enterIntvBefore(BI.FirstUse);
- SE->useIntv(Switch, Pos);
- }
+ // Interference is before the first use.
+ DEBUG(dbgs() << " before first use.\n");
+ SlotIndex SegEnd = SE->leaveIntvAtTop(*BI.MBB);
+ assert(SegEnd <= Intf.first() && "Couldn't avoid interference");
}
// Handle live-through blocks.
- SE->selectIntv(MainIntv);
for (unsigned i = 0, e = Cand.ActiveBlocks.size(); i != e; ++i) {
unsigned Number = Cand.ActiveBlocks[i];
bool RegIn = LiveBundles[Bundles->getBundle(Number, 0)];
Modified: llvm/trunk/lib/CodeGen/SplitKit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.cpp?rev=134053&r1=134052&r2=134053&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.cpp (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.cpp Tue Jun 28 21:03:36 2011
@@ -636,7 +636,6 @@
void SplitEditor::selectIntv(unsigned Idx) {
assert(Idx != 0 && "Cannot select the complement interval");
assert(Idx < Edit->size() && "Can only select previously opened interval");
- DEBUG(dbgs() << " selectIntv " << OpenIdx << " -> " << Idx << '\n');
OpenIdx = Idx;
}
@@ -657,24 +656,6 @@
return VNI->def;
}
-SlotIndex SplitEditor::enterIntvAfter(SlotIndex Idx) {
- assert(OpenIdx && "openIntv not called before enterIntvAfter");
- DEBUG(dbgs() << " enterIntvAfter " << Idx);
- Idx = Idx.getBoundaryIndex();
- VNInfo *ParentVNI = Edit->getParent().getVNInfoAt(Idx);
- if (!ParentVNI) {
- DEBUG(dbgs() << ": not live\n");
- return Idx;
- }
- DEBUG(dbgs() << ": valno " << ParentVNI->id << '\n');
- MachineInstr *MI = LIS.getInstructionFromIndex(Idx);
- assert(MI && "enterIntvAfter called with invalid index");
-
- VNInfo *VNI = defFromParent(OpenIdx, ParentVNI, Idx, *MI->getParent(),
- llvm::next(MachineBasicBlock::iterator(MI)));
- return VNI->def;
-}
-
SlotIndex SplitEditor::enterIntvAtEnd(MachineBasicBlock &MBB) {
assert(OpenIdx && "openIntv not called before enterIntvAtEnd");
SlotIndex End = LIS.getMBBEndIdx(&MBB);
@@ -1026,6 +1007,12 @@
markComplexMapped(i, ParentVNI);
}
+#ifndef NDEBUG
+ // Every new interval must have a def by now, otherwise the split is bogus.
+ for (LiveRangeEdit::iterator I = Edit->begin(), E = Edit->end(); I != E; ++I)
+ assert((*I)->hasAtLeastOneValue() && "Split interval has no value");
+#endif
+
// Transfer the simply mapped values, check if any are skipped.
bool Skipped = transferValues();
if (Skipped)
Modified: llvm/trunk/lib/CodeGen/SplitKit.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SplitKit.h?rev=134053&r1=134052&r2=134053&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SplitKit.h (original)
+++ llvm/trunk/lib/CodeGen/SplitKit.h Tue Jun 28 21:03:36 2011
@@ -81,12 +81,6 @@
bool LiveThrough; ///< Live in whole block (Templ 5. above).
bool LiveIn; ///< Current reg is live in.
bool LiveOut; ///< Current reg is live out.
-
- /// isOneInstr - Returns true when this BlockInfo describes a single
- /// instruction.
- bool isOneInstr() const {
- return SlotIndex::isSameInstr(FirstUse, LastUse);
- }
};
private:
@@ -366,10 +360,6 @@
/// Return the beginning of the new live range.
SlotIndex enterIntvBefore(SlotIndex Idx);
- /// enterIntvAfter - Enter the open interval after the instruction at Idx.
- /// Return the beginning of the new live range.
- SlotIndex enterIntvAfter(SlotIndex Idx);
-
/// enterIntvAtEnd - Enter the open interval at the end of MBB.
/// Use the open interval from he inserted copy to the MBB end.
/// Return the beginning of the new live range.
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