1 files changed, 48 insertions, 28 deletions

diff --git a/contrib/llvm-project/llvm/lib/CodeGen/MachineCopyPropagation.cpp b/contrib/llvm-project/llvm/lib/CodeGen/MachineCopyPropagation.cpp
index 10b74f5f47f5..7c83bacd80d9 100644
--- a/contrib/llvm-project/llvm/lib/CodeGen/MachineCopyPropagation.cpp
+++ b/contrib/llvm-project/llvm/lib/CodeGen/MachineCopyPropagation.cpp
@@ -414,6 +414,31 @@ bool MachineCopyPropagation::isForwardableRegClassCopy(const MachineInstr &Copy,
   if (!UseI.isCopy())
     return false;
 
+  const TargetRegisterClass *CopySrcRC =
+      TRI->getMinimalPhysRegClass(CopySrcReg);
+  const TargetRegisterClass *UseDstRC =
+      TRI->getMinimalPhysRegClass(UseI.getOperand(0).getReg());
+  const TargetRegisterClass *CrossCopyRC = TRI->getCrossCopyRegClass(CopySrcRC);
+
+  // If cross copy register class is not the same as copy source register class
+  // then it is not possible to copy the register directly and requires a cross
+  // register class copy. Fowarding this copy without checking register class of
+  // UseDst may create additional cross register copies when expanding the copy
+  // instruction in later passes.
+  if (CopySrcRC != CrossCopyRC) {
+    const TargetRegisterClass *CopyDstRC =
+        TRI->getMinimalPhysRegClass(Copy.getOperand(0).getReg());
+
+    // Check if UseDstRC matches the necessary register class to copy from
+    // CopySrc's register class. If so then forwarding the copy will not
+    // introduce any cross-class copys. Else if CopyDstRC matches then keep the
+    // copy and do not forward. If neither UseDstRC or CopyDstRC matches then
+    // we may need a cross register copy later but we do not worry about it
+    // here.
+    if (UseDstRC != CrossCopyRC && CopyDstRC == CrossCopyRC)
+      return false;
+  }
+
   /// COPYs don't have register class constraints, so if the user instruction
   /// is a COPY, we just try to avoid introducing additional cross-class
   /// COPYs.  For example:
@@ -430,9 +455,6 @@ bool MachineCopyPropagation::isForwardableRegClassCopy(const MachineInstr &Copy,
   ///
   /// so we have reduced the number of cross-class COPYs and potentially
   /// introduced a nop COPY that can be removed.
-  const TargetRegisterClass *UseDstRC =
-      TRI->getMinimalPhysRegClass(UseI.getOperand(0).getReg());
-
   const TargetRegisterClass *SuperRC = UseDstRC;
   for (TargetRegisterClass::sc_iterator SuperRCI = UseDstRC->getSuperClasses();
        SuperRC; SuperRC = *SuperRCI++)
@@ -554,6 +576,7 @@ void MachineCopyPropagation::forwardUses(MachineInstr &MI) {
     MOUse.setReg(CopySrcReg);
     if (!CopySrc.isRenamable())
       MOUse.setIsRenamable(false);
+    MOUse.setIsUndef(CopySrc.isUndef());
 
     LLVM_DEBUG(dbgs() << "MCP: After replacement: " << MI << "\n");
 
@@ -571,19 +594,16 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
   LLVM_DEBUG(dbgs() << "MCP: ForwardCopyPropagateBlock " << MBB.getName()
                     << "\n");
 
-  for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ) {
-    MachineInstr *MI = &*I;
-    ++I;
-
+  for (MachineInstr &MI : llvm::make_early_inc_range(MBB)) {
     // Analyze copies (which don't overlap themselves).
-    if (MI->isCopy() && !TRI->regsOverlap(MI->getOperand(0).getReg(),
-                                          MI->getOperand(1).getReg())) {
-      assert(MI->getOperand(0).getReg().isPhysical() &&
-             MI->getOperand(1).getReg().isPhysical() &&
+    if (MI.isCopy() && !TRI->regsOverlap(MI.getOperand(0).getReg(),
+                                         MI.getOperand(1).getReg())) {
+      assert(MI.getOperand(0).getReg().isPhysical() &&
+             MI.getOperand(1).getReg().isPhysical() &&
              "MachineCopyPropagation should be run after register allocation!");
 
-      MCRegister Def = MI->getOperand(0).getReg().asMCReg();
-      MCRegister Src = MI->getOperand(1).getReg().asMCReg();
+      MCRegister Def = MI.getOperand(0).getReg().asMCReg();
+      MCRegister Src = MI.getOperand(1).getReg().asMCReg();
 
       // The two copies cancel out and the source of the first copy
       // hasn't been overridden, eliminate the second one. e.g.
@@ -600,31 +620,31 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
       //  %ecx = COPY %eax
       // =>
       //  %ecx = COPY %eax
-      if (eraseIfRedundant(*MI, Def, Src) || eraseIfRedundant(*MI, Src, Def))
+      if (eraseIfRedundant(MI, Def, Src) || eraseIfRedundant(MI, Src, Def))
         continue;
 
-      forwardUses(*MI);
+      forwardUses(MI);
 
       // Src may have been changed by forwardUses()
-      Src = MI->getOperand(1).getReg().asMCReg();
+      Src = MI.getOperand(1).getReg().asMCReg();
 
       // If Src is defined by a previous copy, the previous copy cannot be
       // eliminated.
-      ReadRegister(Src, *MI, RegularUse);
-      for (const MachineOperand &MO : MI->implicit_operands()) {
+      ReadRegister(Src, MI, RegularUse);
+      for (const MachineOperand &MO : MI.implicit_operands()) {
         if (!MO.isReg() || !MO.readsReg())
           continue;
         MCRegister Reg = MO.getReg().asMCReg();
         if (!Reg)
           continue;
-        ReadRegister(Reg, *MI, RegularUse);
+        ReadRegister(Reg, MI, RegularUse);
       }
 
-      LLVM_DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI->dump());
+      LLVM_DEBUG(dbgs() << "MCP: Copy is a deletion candidate: "; MI.dump());
 
       // Copy is now a candidate for deletion.
       if (!MRI->isReserved(Def))
-        MaybeDeadCopies.insert(MI);
+        MaybeDeadCopies.insert(&MI);
 
       // If 'Def' is previously source of another copy, then this earlier copy's
       // source is no longer available. e.g.
@@ -634,7 +654,7 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
       // ...
       // %xmm2 = copy %xmm9
       Tracker.clobberRegister(Def, *TRI);
-      for (const MachineOperand &MO : MI->implicit_operands()) {
+      for (const MachineOperand &MO : MI.implicit_operands()) {
         if (!MO.isReg() || !MO.isDef())
           continue;
         MCRegister Reg = MO.getReg().asMCReg();
@@ -643,29 +663,29 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
         Tracker.clobberRegister(Reg, *TRI);
       }
 
-      Tracker.trackCopy(MI, *TRI);
+      Tracker.trackCopy(&MI, *TRI);
 
       continue;
     }
 
     // Clobber any earlyclobber regs first.
-    for (const MachineOperand &MO : MI->operands())
+    for (const MachineOperand &MO : MI.operands())
       if (MO.isReg() && MO.isEarlyClobber()) {
         MCRegister Reg = MO.getReg().asMCReg();
         // If we have a tied earlyclobber, that means it is also read by this
         // instruction, so we need to make sure we don't remove it as dead
         // later.
         if (MO.isTied())
-          ReadRegister(Reg, *MI, RegularUse);
+          ReadRegister(Reg, MI, RegularUse);
         Tracker.clobberRegister(Reg, *TRI);
       }
 
-    forwardUses(*MI);
+    forwardUses(MI);
 
     // Not a copy.
     SmallVector<Register, 2> Defs;
     const MachineOperand *RegMask = nullptr;
-    for (const MachineOperand &MO : MI->operands()) {
+    for (const MachineOperand &MO : MI.operands()) {
       if (MO.isRegMask())
         RegMask = &MO;
       if (!MO.isReg())
@@ -681,7 +701,7 @@ void MachineCopyPropagation::ForwardCopyPropagateBlock(MachineBasicBlock &MBB) {
         Defs.push_back(Reg.asMCReg());
         continue;
       } else if (MO.readsReg())
-        ReadRegister(Reg.asMCReg(), *MI, MO.isDebug() ? DebugUse : RegularUse);
+        ReadRegister(Reg.asMCReg(), MI, MO.isDebug() ? DebugUse : RegularUse);
     }
 
     // The instruction has a register mask operand which means that it clobbers