Rewrite MachineInstr::addOperand() to avoid NumImplicitOps.

The function needs to scan the implicit operands anyway, so no
performance is won by caching the number of implicit operands added to
an instruction.

This also fixes a bug when adding operands after an implicit operand has
been added manually.  The NumImplicitOps count wasn't kept up to date.

MachineInstr::addOperand() will now consistently place all explicit
operands before all the implicit operands, regardless of the order they
are added.  It is possible to change an MI opcode and add additional
explicit operands.  They will be inserted before any existing implicit
operands.

The only exception is inline asm instructions where operands are never
reordered.  This is because of a hack that marks explicit clobber regs
on inline asm as <implicit-def> to please the fast register allocator.
This hack can go away when InstrEmitter and FastIsel can add exact
<dead> flags to physreg defs.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@140744 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/MachineInstr.cpp b/lib/CodeGen/MachineInstr.cpp
index dd8cbe4e216eac60d28420f0b88a0ae0642d8c68..70e3609a830f1376957ae438f5d54e64d50f6ee9 100644 (file)
--- a/lib/CodeGen/MachineInstr.cpp
+++ b/lib/CodeGen/MachineInstr.cpp
@@ -607,100 +607,72 @@ void MachineInstr::AddRegOperandsToUseLists(MachineRegisterInfo &RegInfo) {
 /// an explicit operand it is added at the end of the explicit operand list
 /// (before the first implicit operand).
 void MachineInstr::addOperand(const MachineOperand &Op) {
+  assert(MCID && "Cannot add operands before providing an instr descriptor");
   bool isImpReg = Op.isReg() && Op.isImplicit();
-  assert((isImpReg || !OperandsComplete()) &&
-         "Trying to add an operand to a machine instr that is already done!");
-
   MachineRegisterInfo *RegInfo = getRegInfo();
 
-  // If we are adding the operand to the end of the list, our job is simpler.
-  // This is true most of the time, so this is a reasonable optimization.
-  if (isImpReg || NumImplicitOps == 0) {
-    // We can only do this optimization if we know that the operand list won't
-    // reallocate.
-    if (Operands.empty() || Operands.size()+1 <= Operands.capacity()) {
-      Operands.push_back(Op);
-
-      // Set the parent of the operand.
-      Operands.back().ParentMI = this;
-
-      // If the operand is a register, update the operand's use list.
-      if (Op.isReg()) {
-        Operands.back().AddRegOperandToRegInfo(RegInfo);
-        // If the register operand is flagged as early, mark the operand as such
-        unsigned OpNo = Operands.size() - 1;
-        if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
-          Operands[OpNo].setIsEarlyClobber(true);
-      }
-      return;
+  // If the Operands backing store is reallocated, all register operands must
+  // be removed and re-added to RegInfo.  It is storing pointers to operands.
+  bool Reallocate = RegInfo &&
+    !Operands.empty() && Operands.size() == Operands.capacity();
+
+  // Find the insert location for the new operand.  Implicit registers go at
+  // the end, everything goes before the implicit regs.
+  unsigned OpNo = Operands.size();
+
+  // Remove all the implicit operands from RegInfo if they need to be shifted.
+  // FIXME: Allow mixed explicit and implicit operands on inline asm.
+  // InstrEmitter::EmitSpecialNode() is marking inline asm clobbers as
+  // implicit-defs, but they must not be moved around.  See the FIXME in
+  // InstrEmitter.cpp.
+  if (!isImpReg && !isInlineAsm()) {
+    while (OpNo && Operands[OpNo-1].isReg() && Operands[OpNo-1].isImplicit()) {
+      --OpNo;
+      if (RegInfo)
+        Operands[OpNo].RemoveRegOperandFromRegInfo();
     }
   }
 
-  // Otherwise, we have to insert a real operand before any implicit ones.
-  unsigned OpNo = Operands.size()-NumImplicitOps;
-
-  // If this instruction isn't embedded into a function, then we don't need to
-  // update any operand lists.
-  if (RegInfo == 0) {
-    // Simple insertion, no reginfo update needed for other register operands.
-    Operands.insert(Operands.begin()+OpNo, Op);
-    Operands[OpNo].ParentMI = this;
-
-    // Do explicitly set the reginfo for this operand though, to ensure the
-    // next/prev fields are properly nulled out.
-    if (Operands[OpNo].isReg()) {
-      Operands[OpNo].AddRegOperandToRegInfo(0);
-      // If the register operand is flagged as early, mark the operand as such
-      if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
-        Operands[OpNo].setIsEarlyClobber(true);
-    }
+  // OpNo now points as the desired insertion point.  Unless this is a variadic
+  // instruction, only implicit regs are allowed beyond MCID->getNumOperands().
+  assert((isImpReg || MCID->isVariadic() || OpNo < MCID->getNumOperands()) &&
+         "Trying to add an operand to a machine instr that is already done!");
 
-  } else if (Operands.size()+1 <= Operands.capacity()) {
-    // Otherwise, we have to remove register operands from their register use
-    // list, add the operand, then add the register operands back to their use
-    // list.  This also must handle the case when the operand list reallocates
-    // to somewhere else.
+  // All operands from OpNo have been removed from RegInfo.  If the Operands
+  // backing store needs to be reallocated, we also need to remove any other
+  // register operands.
+  if (Reallocate)
+    for (unsigned i = 0; i != OpNo; ++i)
+      if (Operands[i].isReg())
+        Operands[i].RemoveRegOperandFromRegInfo();
 
-    // If insertion of this operand won't cause reallocation of the operand
-    // list, just remove the implicit operands, add the operand, then re-add all
-    // the rest of the operands.
-    for (unsigned i = OpNo, e = Operands.size(); i != e; ++i) {
-      assert(Operands[i].isReg() && "Should only be an implicit reg!");
-      Operands[i].RemoveRegOperandFromRegInfo();
-    }
+  // Insert the new operand at OpNo.
+  Operands.insert(Operands.begin() + OpNo, Op);
+  Operands[OpNo].ParentMI = this;
 
-    // Add the operand.  If it is a register, add it to the reg list.
-    Operands.insert(Operands.begin()+OpNo, Op);
-    Operands[OpNo].ParentMI = this;
+  // The Operands backing store has now been reallocated, so we can re-add the
+  // operands before OpNo.
+  if (Reallocate)
+    for (unsigned i = 0; i != OpNo; ++i)
+      if (Operands[i].isReg())
+        Operands[i].AddRegOperandToRegInfo(RegInfo);
 
-    if (Operands[OpNo].isReg()) {
-      Operands[OpNo].AddRegOperandToRegInfo(RegInfo);
-      // If the register operand is flagged as early, mark the operand as such
-      if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
-        Operands[OpNo].setIsEarlyClobber(true);
-    }
+  // When adding a register operand, tell RegInfo about it.
+  if (Operands[OpNo].isReg()) {
+    // Add the new operand to RegInfo, even when RegInfo is NULL.
+    // This will initialize the linked list pointers.
+    Operands[OpNo].AddRegOperandToRegInfo(RegInfo);
+    // If the register operand is flagged as early, mark the operand as such.
+    if (MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
+      Operands[OpNo].setIsEarlyClobber(true);
+  }
 
-    // Re-add all the implicit ops.
-    for (unsigned i = OpNo+1, e = Operands.size(); i != e; ++i) {
+  // Re-add all the implicit ops.
+  if (RegInfo) {
+    for (unsigned i = OpNo + 1, e = Operands.size(); i != e; ++i) {
       assert(Operands[i].isReg() && "Should only be an implicit reg!");
       Operands[i].AddRegOperandToRegInfo(RegInfo);
     }
-  } else {
-    // Otherwise, we will be reallocating the operand list.  Remove all reg
-    // operands from their list, then readd them after the operand list is
-    // reallocated.
-    RemoveRegOperandsFromUseLists();
-
-    Operands.insert(Operands.begin()+OpNo, Op);
-    Operands[OpNo].ParentMI = this;
-
-    // Re-add all the operands.
-    AddRegOperandsToUseLists(*RegInfo);
-
-      // If the register operand is flagged as early, mark the operand as such
-    if (Operands[OpNo].isReg()
-        && MCID->getOperandConstraint(OpNo, MCOI::EARLY_CLOBBER) != -1)
-      Operands[OpNo].setIsEarlyClobber(true);
   }
 }
 
@@ -1385,7 +1357,7 @@ void MachineInstr::print(raw_ostream &OS, const TargetMachine *TM) const {
   unsigned AsmDescOp = ~0u;
   unsigned AsmOpCount = 0;
 
-  if (isInlineAsm()) {
+  if (isInlineAsm() && e >= InlineAsm::MIOp_FirstOperand) {
     // Print asm string.
     OS << " ";
     getOperand(InlineAsm::MIOp_AsmString).print(OS, TM);