[mips][microMIPS] Fix issue with 16b instructions in jr instruction delay slot

[zoran.jovanovic]

Summary

16 bit instructions are not allowed in jr delay slot.
Same stands for PseudoIndirectBranch.

[zoran.jovanovic]

There is the same issue with PseudoReturn.

[sstankovic]

LGTM

lib/Target/Mips/MipsDelaySlotFiller.cpp

     template<typename IterTy>
     bool searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
                      RegDefsUses &RegDU, InspectMemInstr &IM,
-                     IterTy &Filler) const;
+                     IterTy &Filler, Iter Slot) const;
 
     /// This function searches in the backward direction for an instruction that
     /// can be moved to the delay slot. Returns true on success.

 template<typename IterTy>
 bool Filler::searchRange(MachineBasicBlock &MBB, IterTy Begin, IterTy End,
                          RegDefsUses &RegDU, InspectMemInstr& IM,
-                         IterTy &Filler) const {
+                         IterTy &Filler, Iter Slot) const {
   for (IterTy I = Begin; I != End; ++I) {
     // skip debug value
     if (I->isDebugValue())

         continue;
     }
 
+    bool InMicroMipsMode = TM.getSubtarget<MipsSubtarget>().inMicroMipsMode();
+    const MipsInstrInfo *TII = static_cast<const MipsInstrInfo *>(
+        TM.getSubtargetImpl()->getInstrInfo());
+    unsigned Opcode = (*Slot).getOpcode();
+    if (InMicroMipsMode && TII->GetInstSizeInBytes(&(*I)) == 2 &&
+        (Opcode == Mips::JR || Opcode == Mips::PseudoIndirectBranch))
+      continue;
+
     Filler = I;
     return true;
   }

 
   RegDU.init(*Slot);
 
-  if (!searchRange(MBB, ReverseIter(Slot), MBB.rend(), RegDU, MemDU, Filler))
+  if (!searchRange(MBB, ReverseIter(Slot), MBB.rend(), RegDU, MemDU, Filler,
+      Slot))
     return false;
 
   MBB.splice(std::next(Slot), &MBB, std::next(Filler).base());

 
   RegDU.setCallerSaved(*Slot);
 
-  if (!searchRange(MBB, std::next(Slot), MBB.end(), RegDU, NM, Filler))
+  if (!searchRange(MBB, std::next(Slot), MBB.end(), RegDU, NM, Filler, Slot))
     return false;
 
   MBB.splice(std::next(Slot), &MBB, Filler);

     IM.reset(new MemDefsUses(MFI));
   }
 
-  if (!searchRange(MBB, SuccBB->begin(), SuccBB->end(), RegDU, *IM, Filler))
+  if (!searchRange(MBB, SuccBB->begin(), SuccBB->end(), RegDU, *IM, Filler,
+      Slot))
     return false;
 
   insertDelayFiller(Filler, BrMap);

test/CodeGen/Mips/micromips-delay-slot-jr.ll

+; RUN: llc -march=mipsel -mcpu=mips32r2 -mattr=+micromips \
+; RUN:   -relocation-model=static -O2 < %s | FileCheck %s
+
+@main.L = internal unnamed_addr constant [3 x i8*] [i8* blockaddress(@main, %L1), i8* blockaddress(@main, %L2), i8* null], align 4
+@str = private unnamed_addr constant [2 x i8] c"A\00"
+@str2 = private unnamed_addr constant [2 x i8] c"B\00"
+
+define i32 @main() #0 {
+entry:
+  br label %L1
+
+L1:                                               ; preds = %entry, %L1
+  %i.0 = phi i32 [ 0, %entry ], [ %inc, %L1 ]
+  %puts = tail call i32 @puts(i8* getelementptr inbounds ([2 x i8]* @str, i32 0, i32 0))
+  %inc = add i32 %i.0, 1
+  %arrayidx = getelementptr inbounds [3 x i8*]* @main.L, i32 0, i32 %i.0
+  %0 = load i8** %arrayidx, align 4, !tbaa !1
+  indirectbr i8* %0, [label %L1, label %L2]
+
+L2:                                               ; preds = %L1
+  %puts2 = tail call i32 @puts(i8* getelementptr inbounds ([2 x i8]* @str2, i32 0, i32 0))
+  ret i32 0
+}
+
+declare i32 @puts(i8* nocapture readonly) #1
+
+!1 = !{!2, !2, i64 0}
+!2 = !{!"any pointer", !3, i64 0}
+!3 = !{!"omnipotent char", !4, i64 0}
+!4 = !{!"Simple C/C++ TBAA"}
+
+; CHECK:      jr
+; CHECK-NEXT: nop
+