[foldMemoryOperand()] Pass LiveIntervals to enable liveness check.

SystemZ (and probably other targets as well) can fold a memory operand
by changing the opcode into a new instruction that as a side-effect
also clobbers the CC-reg.

In order to do this, liveness of that reg must first be checked. When
LIS is passed, getRegUnit() can be called on it and the right
LiveRange is computed on demand.

Reviewed by Matthias Braun.
http://reviews.llvm.org/D19861

llvm-svn: 269026

llvm/include/llvm/Target/TargetInstrInfo.h

@@ -21,6 +21,7 @@
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/Support/BranchProbability.h"
 #include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
 
 namespace llvm {
 
@@ -799,13 +800,15 @@ public:
   /// The new instruction is inserted before MI, and the client is responsible
   /// for removing the old instruction.
   MachineInstr *foldMemoryOperand(MachineBasicBlock::iterator MI,
-                                  ArrayRef<unsigned> Ops, int FrameIndex) const;
+                                  ArrayRef<unsigned> Ops, int FrameIndex,
+                                  LiveIntervals *LIS = nullptr) const;
 
   /// Same as the previous version except it allows folding of any load and
   /// store from / to any address, not just from a specific stack slot.
   MachineInstr *foldMemoryOperand(MachineBasicBlock::iterator MI,
                                   ArrayRef<unsigned> Ops,
-                                  MachineInstr *LoadMI) const;
+                                  MachineInstr *LoadMI,
+                                  LiveIntervals *LIS = nullptr) const;
 
   /// Return true when there is potentially a faster code sequence
   /// for an instruction chain ending in \p Root. All potential patterns are
@@ -884,7 +887,8 @@ protected:
   /// at InsertPt.
   virtual MachineInstr *foldMemoryOperandImpl(
       MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-      MachineBasicBlock::iterator InsertPt, int FrameIndex) const {
+      MachineBasicBlock::iterator InsertPt, int FrameIndex,
+      LiveIntervals *LIS = nullptr) const {
     return nullptr;
   }
 
@@ -895,7 +899,8 @@ protected:
   /// at InsertPt.
   virtual MachineInstr *foldMemoryOperandImpl(
       MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-      MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI) const {
+      MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI,
+      LiveIntervals *LIS = nullptr) const {
     return nullptr;
   }
 

llvm/lib/CodeGen/InlineSpiller.cpp

@@ -761,8 +761,8 @@ foldMemoryOperand(ArrayRef<std::pair<MachineInstr*, unsigned> > Ops,
   MachineInstrSpan MIS(MI);
 
   MachineInstr *FoldMI =
-                LoadMI ? TII.foldMemoryOperand(MI, FoldOps, LoadMI)
+                LoadMI ? TII.foldMemoryOperand(MI, FoldOps, LoadMI, &LIS)
-                       : TII.foldMemoryOperand(MI, FoldOps, StackSlot);
+                       : TII.foldMemoryOperand(MI, FoldOps, StackSlot, &LIS);
   if (!FoldMI)
     return false;
 

llvm/lib/CodeGen/LiveRangeEdit.cpp

@@ -205,7 +205,7 @@ bool LiveRangeEdit::foldAsLoad(LiveInterval *LI,
   if (UseMI->readsWritesVirtualRegister(LI->reg, &Ops).second)
     return false;
 
-  MachineInstr *FoldMI = TII.foldMemoryOperand(UseMI, Ops, DefMI);
+  MachineInstr *FoldMI = TII.foldMemoryOperand(UseMI, Ops, DefMI, &LIS);
   if (!FoldMI)
     return false;
   DEBUG(dbgs() << "                folded: " << *FoldMI);

llvm/lib/CodeGen/TargetInstrInfo.cpp

@@ -497,7 +497,8 @@ static MachineInstr *foldPatchpoint(MachineFunction &MF, MachineInstr *MI,
 /// stream.
 MachineInstr *TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
                                                  ArrayRef<unsigned> Ops,
-                                                 int FI) const {
+                                                 int FI,
+                                                 LiveIntervals *LIS) const {
   unsigned Flags = 0;
   for (unsigned i = 0, e = Ops.size(); i != e; ++i)
     if (MI->getOperand(Ops[i]).isDef())
@@ -519,7 +520,7 @@ MachineInstr *TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
       MBB->insert(MI, NewMI);
   } else {
     // Ask the target to do the actual folding.
-    NewMI = foldMemoryOperandImpl(MF, MI, Ops, MI, FI);
+    NewMI = foldMemoryOperandImpl(MF, MI, Ops, MI, FI, LIS);
   }
 
   if (NewMI) {
@@ -778,7 +779,8 @@ void TargetInstrInfo::genAlternativeCodeSequence(
 /// stack slot.
 MachineInstr *TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
                                                  ArrayRef<unsigned> Ops,
-                                                 MachineInstr *LoadMI) const {
+                                                 MachineInstr *LoadMI,
+                                                 LiveIntervals *LIS) const {
   assert(LoadMI->canFoldAsLoad() && "LoadMI isn't foldable!");
 #ifndef NDEBUG
   for (unsigned i = 0, e = Ops.size(); i != e; ++i)
@@ -800,7 +802,7 @@ MachineInstr *TargetInstrInfo::foldMemoryOperand(MachineBasicBlock::iterator MI,
       NewMI = MBB.insert(MI, NewMI);
   } else {
     // Ask the target to do the actual folding.
-    NewMI = foldMemoryOperandImpl(MF, MI, Ops, MI, LoadMI);
+    NewMI = foldMemoryOperandImpl(MF, MI, Ops, MI, LoadMI, LIS);
   }
 
   if (!NewMI) return nullptr;

llvm/lib/Target/AArch64/AArch64InstrInfo.cpp

@@ -2448,7 +2448,8 @@ void llvm::emitFrameOffset(MachineBasicBlock &MBB,
 
 MachineInstr *AArch64InstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, int FrameIndex) const {
+    MachineBasicBlock::iterator InsertPt, int FrameIndex,
+    LiveIntervals *LIS) const {
   // This is a bit of a hack. Consider this instruction:
   //
   //   %vreg0<def> = COPY %SP; GPR64all:%vreg0

llvm/lib/Target/AArch64/AArch64InstrInfo.h

@@ -143,7 +143,8 @@ public:
   MachineInstr *foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                                       ArrayRef<unsigned> Ops,
                                       MachineBasicBlock::iterator InsertPt,
-                                      int FrameIndex) const override;
+                                      int FrameIndex,
+                                      LiveIntervals *LIS = nullptr) const override;
 
   bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                      MachineBasicBlock *&FBB,

llvm/lib/Target/SystemZ/SystemZInstrInfo.cpp

@@ -15,6 +15,7 @@
 #include "SystemZInstrBuilder.h"
 #include "SystemZTargetMachine.h"
 #include "llvm/CodeGen/LiveVariables.h"
+#include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 
 using namespace llvm;
@@ -846,31 +847,42 @@ SystemZInstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
 
 MachineInstr *SystemZInstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, int FrameIndex) const {
+    MachineBasicBlock::iterator InsertPt, int FrameIndex,
+    LiveIntervals *LIS) const {
+  const TargetRegisterInfo *TRI = MF.getSubtarget().getRegisterInfo();
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   unsigned Size = MFI->getObjectSize(FrameIndex);
   unsigned Opcode = MI->getOpcode();
 
-// XXX This is an introduction of a CC def and is illegal! Reactivate
-// with a check of liveness of CC reg.
-#if 0
   if (Ops.size() == 2 && Ops[0] == 0 && Ops[1] == 1) {
-    if ((Opcode == SystemZ::LA || Opcode == SystemZ::LAY) &&
+    if (LIS != nullptr &&
+        (Opcode == SystemZ::LA || Opcode == SystemZ::LAY) &&
         isInt<8>(MI->getOperand(2).getImm()) &&
         !MI->getOperand(3).getReg()) {
-      // LA(Y) %reg, CONST(%reg) -> AGSI %mem, CONST
+
-      MachineInstr *BuiltMI =
+      // Check CC liveness, since new instruction introduces a dead
-        BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
+      // def of CC.
-                     get(SystemZ::AGSI))
+      MCRegUnitIterator CCUnit(SystemZ::CC, TRI);
+      LiveRange &CCLiveRange = LIS->getRegUnit(*CCUnit);
+      ++CCUnit;
+      assert (!CCUnit.isValid() && "CC only has one reg unit.");
+      SlotIndex MISlot =
+        LIS->getSlotIndexes()->getInstructionIndex(*MI).getRegSlot();
+      if (!CCLiveRange.liveAt(MISlot)) {
+        // LA(Y) %reg, CONST(%reg) -> AGSI %mem, CONST
+        MachineInstr *BuiltMI =
+          BuildMI(*InsertPt->getParent(), InsertPt, MI->getDebugLoc(),
+                  get(SystemZ::AGSI))
           .addFrameIndex(FrameIndex)
           .addImm(0)
           .addImm(MI->getOperand(2).getImm());
-      BuiltMI->findRegisterDefOperand(SystemZ::CC)->setIsDead(true);
+        BuiltMI->findRegisterDefOperand(SystemZ::CC)->setIsDead(true);
-      return BuiltMI;
+        CCLiveRange.createDeadDef(MISlot, LIS->getVNInfoAllocator());
+        return BuiltMI;
+      }
     }
     return nullptr;
   }
-#endif
 
   // All other cases require a single operand.
   if (Ops.size() != 1)
@@ -992,7 +1004,8 @@ MachineInstr *SystemZInstrInfo::foldMemoryOperandImpl(
 
 MachineInstr *SystemZInstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI) const {
+    MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI,
+    LiveIntervals *LIS) const {
   return nullptr;
 }
 

llvm/lib/Target/SystemZ/SystemZInstrInfo.h

@@ -202,11 +202,13 @@ public:
   MachineInstr *foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                                       ArrayRef<unsigned> Ops,
                                       MachineBasicBlock::iterator InsertPt,
-                                      int FrameIndex) const override;
+                                      int FrameIndex,
+                                      LiveIntervals *LIS = nullptr) const override;
   MachineInstr *foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                                       ArrayRef<unsigned> Ops,
                                       MachineBasicBlock::iterator InsertPt,
-                                      MachineInstr *LoadMI) const override;
+                                      MachineInstr *LoadMI,
+                                      LiveIntervals *LIS = nullptr) const override;
   bool expandPostRAPseudo(MachineBasicBlock::iterator MBBI) const override;
   bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const
     override;

llvm/lib/Target/X86/X86InstrInfo.cpp

@@ -6081,7 +6081,8 @@ breakPartialRegDependency(MachineBasicBlock::iterator MI, unsigned OpNum,
 
 MachineInstr *X86InstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, int FrameIndex) const {
+    MachineBasicBlock::iterator InsertPt, int FrameIndex,
+    LiveIntervals *LIS) const {
   // Check switch flag
   if (NoFusing)
     return nullptr;
@@ -6193,14 +6194,15 @@ static bool isNonFoldablePartialRegisterLoad(const MachineInstr &LoadMI,
 
 MachineInstr *X86InstrInfo::foldMemoryOperandImpl(
     MachineFunction &MF, MachineInstr *MI, ArrayRef<unsigned> Ops,
-    MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI) const {
+    MachineBasicBlock::iterator InsertPt, MachineInstr *LoadMI,
+    LiveIntervals *LIS) const {
   // If loading from a FrameIndex, fold directly from the FrameIndex.
   unsigned NumOps = LoadMI->getDesc().getNumOperands();
   int FrameIndex;
   if (isLoadFromStackSlot(LoadMI, FrameIndex)) {
     if (isNonFoldablePartialRegisterLoad(*LoadMI, *MI, MF))
       return nullptr;
-    return foldMemoryOperandImpl(MF, MI, Ops, InsertPt, FrameIndex);
+    return foldMemoryOperandImpl(MF, MI, Ops, InsertPt, FrameIndex, LIS);
   }
 
   // Check switch flag

llvm/lib/Target/X86/X86InstrInfo.h

@@ -370,7 +370,8 @@ public:
   MachineInstr *foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                                       ArrayRef<unsigned> Ops,
                                       MachineBasicBlock::iterator InsertPt,
-                                      int FrameIndex) const override;
+                                      int FrameIndex,
+                                      LiveIntervals *LIS = nullptr) const override;
 
   /// foldMemoryOperand - Same as the previous version except it allows folding
   /// of any load and store from / to any address, not just from a specific
@@ -378,7 +379,8 @@ public:
   MachineInstr *foldMemoryOperandImpl(MachineFunction &MF, MachineInstr *MI,
                                       ArrayRef<unsigned> Ops,
                                       MachineBasicBlock::iterator InsertPt,
-                                      MachineInstr *LoadMI) const override;
+                                      MachineInstr *LoadMI,
+                                      LiveIntervals *LIS = nullptr) const override;
 
   /// unfoldMemoryOperand - Separate a single instruction which folded a load or
   /// a store or a load and a store into two or more instruction. If this is

llvm/test/CodeGen/SystemZ/int-add-12.ll

@@ -130,7 +130,7 @@ define void @f10(i64 %base, i64 %index) {
 ; Check that adding 127 to a spilled value can use AGSI.
 define void @f11(i64 *%ptr, i32 %sel) {
 ; CHECK-LABEL: f11:
-; _CHECK: agsi {{[0-9]+}}(%r15), 127
+; CHECK: agsi {{[0-9]+}}(%r15), 127
 ; CHECK: br %r14
 entry:
   %val0 = load volatile i64 , i64 *%ptr