1 files changed, 44 insertions, 31 deletions

diff --git a/contrib/llvm/lib/Target/Mips/MipsHazardSchedule.cpp b/contrib/llvm/lib/Target/Mips/MipsHazardSchedule.cpp
index 10022ba..31b8612 100644
--- a/contrib/llvm/lib/Target/Mips/MipsHazardSchedule.cpp
+++ b/contrib/llvm/lib/Target/Mips/MipsHazardSchedule.cpp
@@ -7,10 +7,10 @@
 //
 //===----------------------------------------------------------------------===//
 /// \file
-/// This pass is used to workaround certain pipeline hazards. For now, this covers
-/// compact branch hazards. In future this pass can be extended to other pipeline
-/// hazards, such as various MIPS1 hazards, processor errata that require
-/// instruction reorganization, etc.
+/// This pass is used to workaround certain pipeline hazards. For now, this
+/// covers compact branch hazards. In future this pass can be extended to other
+/// pipeline hazards, such as various MIPS1 hazards, processor errata that
+/// require instruction reorganization, etc.
 ///
 /// This pass has to run after the delay slot filler as that pass can introduce
 /// pipeline hazards, hence the existing hazard recognizer is not suitable.
@@ -18,8 +18,8 @@
 /// Hazards handled: forbidden slots for MIPSR6.
 ///
 /// A forbidden slot hazard occurs when a compact branch instruction is executed
-/// and the adjacent instruction in memory is a control transfer instruction such
-/// as a branch or jump, ERET, ERETNC, DERET, WAIT and PAUSE.
+/// and the adjacent instruction in memory is a control transfer instruction
+/// such as a branch or jump, ERET, ERETNC, DERET, WAIT and PAUSE.
 ///
 /// For example:
 ///
@@ -70,13 +70,13 @@ class MipsHazardSchedule : public MachineFunctionPass {
 public:
   MipsHazardSchedule() : MachineFunctionPass(ID) {}
 
-  const char *getPassName() const override { return "Mips Hazard Schedule"; }
+  StringRef getPassName() const override { return "Mips Hazard Schedule"; }
 
   bool runOnMachineFunction(MachineFunction &F) override;
 
   MachineFunctionProperties getRequiredProperties() const override {
     return MachineFunctionProperties().set(
-        MachineFunctionProperties::Property::AllVRegsAllocated);
+        MachineFunctionProperties::Property::NoVRegs);
   }
 
 private:
@@ -91,20 +91,43 @@ FunctionPass *llvm::createMipsHazardSchedule() {
   return new MipsHazardSchedule();
 }
 
-// Find the next real instruction from the current position.
-static Iter getNextMachineInstr(Iter Position) {
+// Find the next real instruction from the current position in current basic
+// block.
+static Iter getNextMachineInstrInBB(Iter Position) {
   Iter I = Position, E = Position->getParent()->end();
-  I = std::find_if_not(I, E, [](const Iter &Insn) { return Insn->isTransient(); });
-  assert(I != E);
+  I = std::find_if_not(I, E,
+                       [](const Iter &Insn) { return Insn->isTransient(); });
+
   return I;
 }
 
+// Find the next real instruction from the current position, looking through
+// basic block boundaries.
+static Iter getNextMachineInstr(Iter Position, MachineBasicBlock *Parent) {
+  if (Position == Parent->end()) {
+    MachineBasicBlock *Succ = Parent->getNextNode();
+    if (Succ != nullptr && Parent->isSuccessor(Succ)) {
+      Position = Succ->begin();
+      Parent = Succ;
+    } else {
+      llvm_unreachable(
+          "Should have identified the end of the function earlier!");
+    }
+  }
+
+  Iter Instr = getNextMachineInstrInBB(Position);
+  if (Instr == Parent->end()) {
+    return getNextMachineInstr(Instr, Parent);
+  }
+  return Instr;
+}
+
 bool MipsHazardSchedule::runOnMachineFunction(MachineFunction &MF) {
 
   const MipsSubtarget *STI =
       &static_cast<const MipsSubtarget &>(MF.getSubtarget());
 
-  // Forbidden slot hazards are only defined for MIPSR6.
+  // Forbidden slot hazards are only defined for MIPSR6 but not microMIPSR6.
   if (!STI->hasMips32r6() || STI->inMicroMipsMode())
     return false;
 
@@ -118,27 +141,17 @@ bool MipsHazardSchedule::runOnMachineFunction(MachineFunction &MF) {
       if (!TII->HasForbiddenSlot(*I))
         continue;
 
-      bool InsertNop = false;
-      // Next instruction in the basic block.
-      if (std::next(I) != FI->end() &&
-          !TII->SafeInForbiddenSlot(*getNextMachineInstr(std::next(I)))) {
-        InsertNop = true;
-      } else {
-        // Next instruction in the physical successor basic block.
-        for (auto *Succ : FI->successors()) {
-          if (FI->isLayoutSuccessor(Succ) &&
-              getNextMachineInstr(Succ->begin()) != Succ->end() &&
-              !TII->SafeInForbiddenSlot(*getNextMachineInstr(Succ->begin()))) {
-            InsertNop = true;
-            break;
-          }
-        }
+      Iter Inst;
+      bool LastInstInFunction =
+          std::next(I) == FI->end() && std::next(FI) == MF.end();
+      if (!LastInstInFunction) {
+        Inst = getNextMachineInstr(std::next(I), &*FI);
       }
 
-      if (InsertNop) {
+      if (LastInstInFunction || !TII->SafeInForbiddenSlot(*Inst)) {
         Changed = true;
-        MIBundleBuilder(&*I).append(
-            BuildMI(MF, I->getDebugLoc(), TII->get(Mips::NOP)));
+        MIBundleBuilder(&*I)
+            .append(BuildMI(MF, I->getDebugLoc(), TII->get(Mips::NOP)));
         NumInsertedNops++;
       }
     }