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-rw-r--r--lib/CodeGen/LiveInterval.cpp5
-rw-r--r--lib/CodeGen/RegisterCoalescer.cpp79
2 files changed, 63 insertions, 21 deletions
diff --git a/lib/CodeGen/LiveInterval.cpp b/lib/CodeGen/LiveInterval.cpp
index aa44d3738e..010ef48f5c 100644
--- a/lib/CodeGen/LiveInterval.cpp
+++ b/lib/CodeGen/LiveInterval.cpp
@@ -681,7 +681,10 @@ void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[],
SlotIndex Idx = LIS.getInstructionIndex(MI);
Idx = Idx.getRegSlot(MO.isUse());
const VNInfo *VNI = LI.getVNInfoAt(Idx);
- assert(VNI && "Interval not live at use.");
+ // FIXME: We should be able to assert(VNI) here, but the coalescer leaves
+ // dangling defs around.
+ if (!VNI)
+ continue;
MO.setReg(LIV[getEqClass(VNI)]->reg);
}
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 8f4a10c808..84fd590f26 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -21,29 +21,30 @@
#include "llvm/Pass.h"
#include "llvm/Value.h"
+#include "llvm/ADT/OwningPtr.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/ADT/SmallSet.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/CodeGen/MachineInstr.h"
-#include "llvm/CodeGen/MachineRegisterInfo.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/CodeGen/LiveIntervalAnalysis.h"
-#include "llvm/Analysis/AliasAnalysis.h"
+#include "llvm/CodeGen/LiveRangeEdit.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstr.h"
#include "llvm/CodeGen/MachineLoopInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/Passes.h"
-#include "llvm/Target/TargetInstrInfo.h"
-#include "llvm/Target/TargetMachine.h"
-#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
-#include "llvm/ADT/OwningPtr.h"
-#include "llvm/ADT/SmallSet.h"
-#include "llvm/ADT/Statistic.h"
-#include "llvm/ADT/STLExtras.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetOptions.h"
+#include "llvm/Target/TargetRegisterInfo.h"
#include <algorithm>
#include <cmath>
using namespace llvm;
@@ -67,7 +68,8 @@ VerifyCoalescing("verify-coalescing",
cl::Hidden);
namespace {
- class RegisterCoalescer : public MachineFunctionPass {
+ class RegisterCoalescer : public MachineFunctionPass,
+ private LiveRangeEdit::Delegate {
MachineFunction* MF;
MachineRegisterInfo* MRI;
const TargetMachine* TM;
@@ -83,10 +85,6 @@ namespace {
///
SmallPtrSet<MachineInstr*, 32> JoinedCopies;
- /// ReMatCopies - Keep track of copies eliminated due to remat.
- ///
- SmallPtrSet<MachineInstr*, 32> ReMatCopies;
-
/// ReMatDefs - Keep track of definition instructions which have
/// been remat'ed.
SmallPtrSet<MachineInstr*, 8> ReMatDefs;
@@ -94,6 +92,19 @@ namespace {
/// WorkList - Copy instructions yet to be coalesced.
SmallVector<MachineInstr*, 8> WorkList;
+ /// ErasedInstrs - Set of instruction pointers that have been erased, and
+ /// that may be present in WorkList.
+ SmallPtrSet<MachineInstr*, 8> ErasedInstrs;
+
+ /// Dead instructions that are about to be deleted.
+ SmallVector<MachineInstr*, 8> DeadDefs;
+
+ /// Recursively eliminate dead defs in DeadDefs.
+ void eliminateDeadDefs();
+
+ /// LiveRangeEdit callback.
+ void LRE_WillEraseInstruction(MachineInstr *MI);
+
/// joinAllIntervals - join compatible live intervals
void joinAllIntervals();
@@ -383,6 +394,17 @@ void RegisterCoalescer::markAsJoined(MachineInstr *CopyMI) {
I->setIsUndef(true);
}
+void RegisterCoalescer::eliminateDeadDefs() {
+ SmallVector<LiveInterval*, 8> NewRegs;
+ LiveRangeEdit(0, NewRegs, *MF, *LIS, 0, this).eliminateDeadDefs(DeadDefs);
+}
+
+// Callback from eliminateDeadDefs().
+void RegisterCoalescer::LRE_WillEraseInstruction(MachineInstr *MI) {
+ // MI may be in WorkList. Make sure we don't visit it.
+ ErasedInstrs.insert(MI);
+}
+
/// adjustCopiesBackFrom - We found a non-trivially-coalescable copy with IntA
/// being the source and IntB being the dest, thus this defines a value number
/// in IntB. If the source value number (in IntA) is defined by a copy from B,
@@ -844,7 +866,7 @@ bool RegisterCoalescer::reMaterializeTrivialDef(LiveInterval &SrcInt,
}
CopyMI->eraseFromParent();
- ReMatCopies.insert(CopyMI);
+ ErasedInstrs.insert(CopyMI);
ReMatDefs.insert(DefMI);
DEBUG(dbgs() << "Remat: " << *NewMI);
++NumReMats;
@@ -1025,7 +1047,7 @@ bool RegisterCoalescer::canJoinPhys(CoalescerPair &CP) {
bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
Again = false;
- if (JoinedCopies.count(CopyMI) || ReMatCopies.count(CopyMI))
+ if (JoinedCopies.count(CopyMI))
return false; // Already done.
DEBUG(dbgs() << LIS->getInstructionIndex(CopyMI) << '\t' << *CopyMI);
@@ -1036,6 +1058,16 @@ bool RegisterCoalescer::joinCopy(MachineInstr *CopyMI, bool &Again) {
return false;
}
+ // Dead code elimination. This really should be handled by MachineDCE, but
+ // sometimes dead copies slip through, and we can't generate invalid live
+ // ranges.
+ if (!CP.isPhys() && CopyMI->allDefsAreDead()) {
+ DEBUG(dbgs() << "\tCopy is dead.\n");
+ DeadDefs.push_back(CopyMI);
+ eliminateDeadDefs();
+ return true;
+ }
+
// If they are already joined we continue.
if (CP.getSrcReg() == CP.getDstReg()) {
markAsJoined(CopyMI);
@@ -1542,6 +1574,12 @@ bool RegisterCoalescer::copyCoalesceWorkList(unsigned From) {
for (unsigned i = From, e = WorkList.size(); i != e; ++i) {
if (!WorkList[i])
continue;
+ // Skip instruction pointers that have already been erased, for example by
+ // dead code elimination.
+ if (ErasedInstrs.erase(WorkList[i])) {
+ WorkList[i] = 0;
+ continue;
+ }
bool Again = false;
bool Success = joinCopy(WorkList[i], Again);
Progress |= Success;
@@ -1609,9 +1647,10 @@ void RegisterCoalescer::joinAllIntervals() {
void RegisterCoalescer::releaseMemory() {
JoinedCopies.clear();
- ReMatCopies.clear();
+ ErasedInstrs.clear();
ReMatDefs.clear();
WorkList.clear();
+ DeadDefs.clear();
}
bool RegisterCoalescer::runOnMachineFunction(MachineFunction &fn) {
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-12 13:17:45 +0000