[ARM] Disallow zexts in ARMCodeGenPrepare

[samparker]

Summary

Enabling ARMCodeGenPrepare by default caused a whole load of failures. This is due to zexts and truncs not being handled properly. ZExts are messy so it's just easier to disable for now and truncs are allowed only as 'sinks'. I still need to figure out why allowing them as 'sources' causes so many failures. The other main change is that we are explicit in the types that we converting to, it's now always 'TypeSize'. Type support is also now performed while checking for valid opcodes as it unnecessarily complicated having the checks are different stages.

I've moved the tests around too, so we have the zext and truncs in their own file as well as the overflowing opcode tests.

[rnk]

I'm not familiar enough with the code to stamp it, but thanks for fixing this!

lib/Target/ARM/ARMCodeGenPrepare.cpp

517–518

Commented out code not intended for commit?

test/CodeGen/ARM/arm-cgp-zext-truncs.ll

267–270

I take it this is a reduction of the test case I sent?

[samparker]

lib/Target/ARM/ARMCodeGenPrepare.cpp

517–518

ah yep.

test/CodeGen/ARM/arm-cgp-zext-truncs.ll

267–270

yes, its the exact IR just with the function renamed to something half readable.

[SjoerdMeijer]

lib/Target/ARM/ARMCodeGenPrepare.cpp

146

This is a nit, but I would appreciate if you can elaborate a little on the definition of "sources" and "sinks". Thus, more in general, elaborate a bit on the terminology, and also the rationale behind it. I mean, for example, I appreciate I can read in the implementation that an argument, load, call, can be a source. But could there be more, and if so, why are you only interested in these? Perhaps a bit of an algorithmic description is nice too and how these sources and sinks fit in to the bigger picture? I appreciate most information is there already, but could be made a bit more explicit, which is why this is a nit.

[samparker]

• Removed commented out code
• Added some TODOs
• Expanded the description of what a source and sink are

[SjoerdMeijer]

These changes look reasonable to me.

The pass is still disabled by default, so this is a good opportunity (before we start thinking about flipping the switch again) to do more testing and get more experience with the pass without annoying others.

lib/Target/ARM/ARMCodeGenPrepare.cpp

495

Some inconsistent terminology here (sources vs. roots), but this can be addressed in follow up patches.

lib/Target/ARM/ARMCodeGenPrepare.cpp

void Mutate(Type *OrigTy,
               SmallPtrSetImpl<Value*> &Leaves,
               SmallPtrSetImpl<Instruction*> &Roots);
 };
 
 class ARMCodeGenPrepare : public FunctionPass {
   const ARMSubtarget *ST = nullptr;
   IRPromoter *Promoter = nullptr;
   std::set<Value*> AllVisited;
-  Type *OrigTy = nullptr;
-  unsigned TypeSize = 0;
 
   bool isNarrowInstSupported(Instruction *I);
   bool isSupportedValue(Value *V);
   bool isLegalToPromote(Value *V);
   bool TryToPromote(Value *V);
 
 public:
   static char ID;
+  static unsigned TypeSize;
+  Type *OrigTy = nullptr;
 
   ARMCodeGenPrepare() : FunctionPass(ID) {}
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.addRequired<TargetPassConfig>();
   }
 
   StringRef getPassName() const override { return "ARM IR optimizations"; }
return Opc == Instruction::AShr || Opc == Instruction::SDiv ||
          Opc == Instruction::SRem;
 }
 
 /// Some instructions can use 8- and 16-bit operands, and we don't need to
 /// promote anything larger. We disallow booleans to make life easier when
 /// dealing with icmps but allow any other integer that is <= 16 bits. Void
 /// types are accepted so we can handle switches.
 static bool isSupportedType(Value *V) {
-  if (V->getType()->isVoidTy())
+  LLVM_DEBUG(dbgs() << "ARM CGP: isSupportedType: " << *V << "\n");
+  Type *Ty = V->getType();
+  if (Ty->isVoidTy())
     return true;
 
-  const IntegerType *IntTy = dyn_cast<IntegerType>(V->getType());
-  if (!IntTy)
-    return false;
+  if (auto *Ld = dyn_cast<LoadInst>(V))
+    Ty = cast<PointerType>(Ld->getPointerOperandType())->getElementType();
 
-  // Don't try to promote boolean values.
-  if (IntTy->getBitWidth() == 1)
+  const IntegerType *IntTy = dyn_cast<IntegerType>(Ty);
+  if (!IntTy) {
+    LLVM_DEBUG(dbgs() << "ARM CGP: No, not an integer.\n");
     return false;
+  }
 
-  if (auto *ZExt = dyn_cast<ZExtInst>(V))
-    return isSupportedType(ZExt->getOperand(0));
+  return IntTy->getBitWidth() == ARMCodeGenPrepare::TypeSize;
+}
 
-  return IntTy->getBitWidth() <= 16;
+/// Return true if the given value is a leaf that will need to be zext'd.
+static bool isSource(Value *V) {
+  if (isa<Argument>(V))
+    return true;
+  else if (isa<LoadInst>(V))
+    return true;
+  else if (auto *Call = dyn_cast<CallInst>(V))
+    return Call->hasRetAttr(Attribute::AttrKind::ZExt);
+  return false;
 }
 
 /// Return true if V will require any promoted values to be truncated for the
 /// use to be valid.
 static bool isSink(Value *V) {
   auto UsesNarrowValue = [](Value *V) {
-    return V->getType()->getScalarSizeInBits() <= 32;
+    return V->getType()->getScalarSizeInBits() == ARMCodeGenPrepare::TypeSize;
   };
 
   if (auto *Store = dyn_cast<StoreInst>(V))
     return UsesNarrowValue(Store->getValueOperand());
   if (auto *Return = dyn_cast<ReturnInst>(V))
     return UsesNarrowValue(Return->getReturnValue());
+  if (auto *Trunc = dyn_cast<TruncInst>(V))
+    return UsesNarrowValue(Trunc->getOperand(0));
 
   return isa<CallInst>(V);
 }
 
-/// Return true if the given value is a leaf that will need to be zext'd.
-static bool isSource(Value *V) {
-  if (isa<Argument>(V) && isSupportedType(V))
-    return true;
-  else if (isa<TruncInst>(V))
-    return true;
-  else if (auto *ZExt = dyn_cast<ZExtInst>(V))
-    // ZExt can be a leaf if its the only user of a load.
-    return isa<LoadInst>(ZExt->getOperand(0)) &&
-                         ZExt->getOperand(0)->hasOneUse();
-  else if (auto *Call = dyn_cast<CallInst>(V))
-    return Call->hasRetAttr(Attribute::AttrKind::ZExt);
-  else if (auto *Load = dyn_cast<LoadInst>(V)) {
-    if (!isa<IntegerType>(Load->getType()))
-      return false;
-    // A load is a leaf, unless its already just being zext'd.
-    if (Load->hasOneUse() && isa<ZExtInst>(*Load->use_begin()))
-      return false;
-
-    return true;
-  }
-  return false;
-}
-
 /// Return whether the instruction can be promoted within any modifications to
 /// it's operands or result.
 static bool isSafeOverflow(Instruction *I) {
-  if (isa<OverflowingBinaryOperator>(I) && I->hasNoUnsignedWrap())
+  if (isa<OverflowingBinaryOperator>(I) && I->hasNoUnsignedWrap())// && I->hasNoSignedWrap())
     return true;
 
   unsigned Opc = I->getOpcode();
   if (Opc == Instruction::Add || Opc == Instruction::Sub) {
     // We don't care if the add or sub could wrap if the value is decreasing
     // and is only being used by an unsigned compare.
     if (!I->hasOneUse() ||
         !isa<ICmpInst>(*I->user_begin()) ||
for (auto &Op : I->operands()) {
     if (auto *Const = dyn_cast<ConstantInt>(Op))
       if (Const->isNegative())
         return false;
   }
   return false;
 }
 
 static bool shouldPromote(Value *V) {
-  auto *I = dyn_cast<Instruction>(V);
-  if (!I)
+  if (!isa<IntegerType>(V->getType()) || isSink(V))
     return false;
 
-  if (!isa<IntegerType>(V->getType()))
-    return false;
+  if (isSource(V))
+    return true;
 
-  if (isa<StoreInst>(I) || isa<TerminatorInst>(I) || isa<TruncInst>(I) ||
-      isa<ICmpInst>(I))
+  auto *I = dyn_cast<Instruction>(V);
+  if (!I)
     return false;
 
-  if (auto *ZExt = dyn_cast<ZExtInst>(I))
-    return !ZExt->getDestTy()->isIntegerTy(32);
+  if (isa<ICmpInst>(I))
+    return false;
 
   return true;
 }
 
 /// Return whether we can safely mutate V's type to ExtTy without having to be
 /// concerned with zero extending or truncation.
 static bool isPromotedResultSafe(Value *V) {
   if (!isa<Instruction>(V))
static bool isPromotedResultSafe(Value *V) {
   if (isa<OverflowingBinaryOperator>(I))
     return isSafeOverflow(I);
   return true;
 }
 
 /// Return the intrinsic for the instruction that can perform the same
 /// operation but on a narrow type. This is using the parallel dsp intrinsics
 /// on scalar values.
-static Intrinsic::ID getNarrowIntrinsic(Instruction *I, unsigned TypeSize) {
+static Intrinsic::ID getNarrowIntrinsic(Instruction *I) {
   // Whether we use the signed or unsigned versions of these intrinsics
   // doesn't matter because we're not using the GE bits that they set in
   // the APSR.
   switch(I->getOpcode()) {
   default:
     break;
   case Instruction::Add:
-    return TypeSize == 16 ? Intrinsic::arm_uadd16 :
+    return ARMCodeGenPrepare::TypeSize == 16 ? Intrinsic::arm_uadd16 :
       Intrinsic::arm_uadd8;
   case Instruction::Sub:
-    return TypeSize == 16 ? Intrinsic::arm_usub16 :
+    return ARMCodeGenPrepare::TypeSize == 16 ? Intrinsic::arm_usub16 :
       Intrinsic::arm_usub8;
   }
   llvm_unreachable("unhandled opcode for narrow intrinsic");
 }
 
 void IRPromoter::Mutate(Type *OrigTy,
                         SmallPtrSetImpl<Value*> &Visited,
                         SmallPtrSetImpl<Value*> &Leaves,
                         SmallPtrSetImpl<Instruction*> &Roots) {
   IRBuilder<> Builder{Ctx};
   Type *ExtTy = Type::getInt32Ty(M->getContext());
-  unsigned TypeSize = OrigTy->getPrimitiveSizeInBits();
   SmallPtrSet<Value*, 8> Promoted;
-  LLVM_DEBUG(dbgs() << "ARM CGP: Promoting use-def chains to from " << TypeSize
-        << " to 32-bits\n");
+  LLVM_DEBUG(dbgs() << "ARM CGP: Promoting use-def chains to from "
+             << ARMCodeGenPrepare::TypeSize << " to 32-bits\n");
 
   auto ReplaceAllUsersOfWith = [&](Value *From, Value *To) {
     SmallVector<Instruction*, 4> Users;
     Instruction *InstTo = dyn_cast<Instruction>(To);
     for (Use &U : From->uses()) {
       auto *User = cast<Instruction>(U.getUser());
       if (InstTo && User->isIdenticalTo(InstTo))
         continue;
auto FixConst = [&](ConstantInt *Const, Instruction *I) {
     }
     I->replaceUsesOfWith(Const, NewConst);
   };
 
   auto InsertDSPIntrinsic = [&](Instruction *I) {
     LLVM_DEBUG(dbgs() << "ARM CGP: Inserting DSP intrinsic for "
                << *I << "\n");
     Function *DSPInst =
-      Intrinsic::getDeclaration(M, getNarrowIntrinsic(I, TypeSize));
+      Intrinsic::getDeclaration(M, getNarrowIntrinsic(I));
     Builder.SetInsertPoint(I);
     Builder.SetCurrentDebugLocation(I->getDebugLoc());
     Value *Args[] = { I->getOperand(0), I->getOperand(1) };
     CallInst *Call = Builder.CreateCall(DSPInst, Args);
     ReplaceAllUsersOfWith(I, Call);
     InstsToRemove.push_back(I);
     NewInsts.insert(Call);
   };
auto InsertZExt = [&](Value *V, Instruction *InsertPt) {
     ReplaceAllUsersOfWith(V, ZExt);
     NewInsts.insert(ZExt);
   };
 
   // First, insert extending instructions between the leaves and their users.
   LLVM_DEBUG(dbgs() << "ARM CGP: Promoting leaves:\n");
   for (auto V : Leaves) {
     LLVM_DEBUG(dbgs() << " - " << *V << "\n");
-    if (auto *ZExt = dyn_cast<ZExtInst>(V))
-      ZExt->mutateType(ExtTy);
-    else if (auto *I = dyn_cast<Instruction>(V))
+    if (auto *I = dyn_cast<Instruction>(V))
       InsertZExt(I, I);
     else if (auto *Arg = dyn_cast<Argument>(V)) {
       BasicBlock &BB = Arg->getParent()->front();
       InsertZExt(Arg, &*BB.getFirstInsertionPt());
     } else {
       llvm_unreachable("unhandled leaf that needs extending");
     }
     Promoted.insert(V);
for (auto *V : Visited) {
     }
   }
 
   // Now we need to remove any zexts that have become unnecessary, as well
   // as insert any intrinsics.
   for (auto *V : Visited) {
     if (Leaves.count(V))
       continue;
-    if (auto *ZExt = dyn_cast<ZExtInst>(V)) {
-      if (ZExt->getDestTy() != ExtTy) {
-        ZExt->mutateType(ExtTy);
-        Promoted.insert(ZExt);
-      }
-      else if (ZExt->getSrcTy() == ExtTy) {
-        ReplaceAllUsersOfWith(V, ZExt->getOperand(0));
-        InstsToRemove.push_back(ZExt);
-      }
+
+    if (!isa<Instruction>(V))
       continue;
-    }
 
     if (!shouldPromote(V) || isPromotedResultSafe(V))
       continue;
 
     // Replace unsafe instructions with appropriate intrinsic calls.
     InsertDSPIntrinsic(cast<Instruction>(V));
   }
 

 
 /// We accept most instructions, as well as Arguments and ConstantInsts. We
 /// Disallow casts other than zext and truncs and only allow calls if their
 /// return value is zeroext. We don't allow opcodes that can introduce sign
 /// bits.
 bool ARMCodeGenPrepare::isSupportedValue(Value *V) {
   LLVM_DEBUG(dbgs() << "ARM CGP: Is " << *V << " supported?\n");
 
-  // Non-instruction values that we can handle.
-  if (isa<ConstantInt>(V) || isa<Argument>(V))
-    return true;
+  if (auto *ICmp = dyn_cast<ICmpInst>(V))
+    return ICmp->isEquality() || !ICmp->isSigned();
 
   // Memory instructions
-  if (isa<StoreInst>(V) || isa<LoadInst>(V) || isa<GetElementPtrInst>(V))
+  if (isa<StoreInst>(V) || isa<GetElementPtrInst>(V))
     return true;
 
   // Branches and targets.
-  if (auto *ICmp = dyn_cast<ICmpInst>(V))
-    return ICmp->isEquality() || !ICmp->isSigned();
-
   if( isa<BranchInst>(V) || isa<SwitchInst>(V) || isa<BasicBlock>(V))
     return true;
 
-  if (isa<PHINode>(V) || isa<SelectInst>(V) || isa<ReturnInst>(V))
-    return true;
+  // Non-instruction values that we can handle.
+  if (isa<ConstantInt>(V) || isa<Argument>(V))
+    return isSupportedType(V);
+
+  if (isa<PHINode>(V) || isa<SelectInst>(V) || isa<ReturnInst>(V) ||
+      isa<LoadInst>(V))
+    return isSupportedType(V);
+
+  // Currently, Trunc is the only cast we support.
+  if (auto *Trunc = dyn_cast<TruncInst>(V))
+    return isSupportedType(Trunc->getOperand(0));
 
   // Special cases for calls as we need to check for zeroext
   // TODO We should accept calls even if they don't have zeroext, as they can
   // still be roots.
   if (auto *Call = dyn_cast<CallInst>(V))
-    return Call->hasRetAttr(Attribute::AttrKind::ZExt);
-  else if (auto *Cast = dyn_cast<CastInst>(V)) {
-    if (isa<ZExtInst>(Cast))
-      return Cast->getDestTy()->getScalarSizeInBits() <= 32;
-    else if (auto *Trunc = dyn_cast<TruncInst>(V))
-      return Trunc->getDestTy()->getScalarSizeInBits() <= TypeSize;
-    else {
-      LLVM_DEBUG(dbgs() << "ARM CGP: No, unsupported cast.\n");
-      return false;
-    }
-  } else if (!isa<BinaryOperator>(V)) {
+    return isSupportedType(Call) &&
+           Call->hasRetAttr(Attribute::AttrKind::ZExt);
+
+  if (!isa<BinaryOperator>(V)) {
     LLVM_DEBUG(dbgs() << "ARM CGP: No, not a binary operator.\n");
     return false;
   }
+  if (!isSupportedType(V))
+    return false;
 
   bool res = !isSigned(V);
   if (!res)
     LLVM_DEBUG(dbgs() << "ARM CGP: No, it's a signed instruction.\n");
   return res;
 }
 
 /// Check that the type of V would be promoted and that the original type is
 /// smaller than the targeted promoted type. Check that we're not trying to
 /// promote something larger than our base 'TypeSize' type.
 bool ARMCodeGenPrepare::isLegalToPromote(Value *V) {
-  if (!isSupportedType(V))
-    return false;
-
-  unsigned VSize = 0;
-  if (auto *Ld = dyn_cast<LoadInst>(V)) {
-    auto *PtrTy = cast<PointerType>(Ld->getPointerOperandType());
-    VSize = PtrTy->getElementType()->getPrimitiveSizeInBits();
-  } else if (auto *ZExt = dyn_cast<ZExtInst>(V)) {
-    VSize = ZExt->getOperand(0)->getType()->getPrimitiveSizeInBits();
-  } else {
-    VSize = V->getType()->getPrimitiveSizeInBits();
-  }
-
-  if (VSize > TypeSize)
-    return false;
+  //if (!isSupportedType(V))
+    //return false;
 
   if (isPromotedResultSafe(V))
     return true;
 
   if (auto *I = dyn_cast<Instruction>(V))
     return isNarrowInstSupported(I);
 
   return false;
 }
 
 bool ARMCodeGenPrepare::TryToPromote(Value *V) {
   OrigTy = V->getType();
   TypeSize = OrigTy->getPrimitiveSizeInBits();
+  if (TypeSize > 16)
+    return false;
 
   if (!isSupportedValue(V) || !shouldPromote(V) || !isLegalToPromote(V))
     return false;
 
-  LLVM_DEBUG(dbgs() << "ARM CGP: TryToPromote: " << *V << "\n");
+  LLVM_DEBUG(dbgs() << "ARM CGP: TryToPromote: " << *V << ", TypeSize = "
+             << TypeSize << "\n");
 
   SetVector<Value*> WorkList;
   SmallPtrSet<Value*, 8> Leaves;
   SmallPtrSet<Instruction*, 4> Roots;
   WorkList.insert(V);
   SmallPtrSet<Value*, 16> CurrentVisited;
   CurrentVisited.clear();
 
   // Return true if the given value can, or has been, visited. Add V to the
   // worklist if needed.
   auto AddLegalInst = [&](Value *V) {
     if (CurrentVisited.count(V))
       return true;
 
+    // Ignore pointer value that aren't instructions.
+    if (!isa<Instruction>(V) && isa<PointerType>(V->getType()))
+      return true;
+
     if (!isSupportedValue(V) || (shouldPromote(V) && !isLegalToPromote(V))) {
       LLVM_DEBUG(dbgs() << "ARM CGP: Can't handle: " << *V << "\n");
       return false;
     }
 
     WorkList.insert(V);
     return true;
   };
while (!WorkList.empty()) {
     if (isSource(V) || shouldPromote(V)) {
       for (Use &U : V->uses()) {
         if (!AddLegalInst(U.getUser()))
           return false;
       }
     }
   }
 
-  unsigned NumToPromote = 0;
-  unsigned Cost = 0;
-  for (auto *V : CurrentVisited) {
-    // Truncs will cause a uxt and no zeroext arguments will often require
-    // a uxt somewhere.
-    if (isa<TruncInst>(V))
-      ++Cost;
-    else if (auto *Arg = dyn_cast<Argument>(V)) {
-      if (!Arg->hasZExtAttr())
-        ++Cost;
-    }
-
-    // Mem ops can automatically be extended/truncated and non-instructions
-    // don't need anything done.
-    if (Leaves.count(V) || isa<StoreInst>(V) || !isa<Instruction>(V))
-      continue;
-
-    // Will need to truncate calls args and returns.
-    if (Roots.count(cast<Instruction>(V))) {
-      ++Cost;
-      continue;
-    }
-
-    if (shouldPromote(V))
-      ++NumToPromote;
-  }
-
   LLVM_DEBUG(dbgs() << "ARM CGP: Visited nodes:\n";
              for (auto *I : CurrentVisited)
                I->dump();
              );
-  LLVM_DEBUG(dbgs() << "ARM CGP: Cost of promoting " << NumToPromote
-             << " instructions = " << Cost << "\n");
-  if (Cost > NumToPromote || (NumToPromote == 0))
-    return false;
 
   Promoter->Mutate(OrigTy, CurrentVisited, Leaves, Roots);
   return true;
 }
 
 bool ARMCodeGenPrepare::doInitialization(Module &M) {
   Promoter = new IRPromoter(&M);
   return false;
for (auto &I : Insts) {
         auto &CI = cast<ICmpInst>(I);
 
         // Skip signed or pointer compares
         if (CI.isSigned() || !isa<IntegerType>(CI.getOperand(0)->getType()))
           continue;
 
         LLVM_DEBUG(dbgs() << "ARM CGP: Searching from: " << CI << "\n");
         for (auto &Op : CI.operands()) {
-          if (auto *I = dyn_cast<Instruction>(Op)) {
-            if (isa<ZExtInst>(I))
-              MadeChange |= TryToPromote(I->getOperand(0));
-            else
-              MadeChange |= TryToPromote(I);
-          }
-        }
-      }
-    }
+          if (auto *I = dyn_cast<Instruction>(Op))
     Promoter->Cleanup();
     LLVM_DEBUG(if (verifyFunction(F, &dbgs())) {
                 dbgs();
                 report_fatal_error("Broken function after type promotion");
                });
   }
   if (MadeChange)
     LLVM_DEBUG(dbgs() << "After ARMCodeGenPrepare: " << F << "\n");
 
   return MadeChange;
 }
 
 bool ARMCodeGenPrepare::doFinalization(Module &M) {
   delete Promoter;
   return false;
 }
 
 INITIALIZE_PASS_BEGIN(ARMCodeGenPrepare, DEBUG_TYPE,
                       "ARM IR optimizations", false, false)
 INITIALIZE_PASS_END(ARMCodeGenPrepare, DEBUG_TYPE, "ARM IR optimizations",
                     false, false)
 
 char ARMCodeGenPrepare::ID = 0;
+unsigned ARMCodeGenPrepare::TypeSize = 0;
 
 FunctionPass *llvm::createARMCodeGenPreparePass() {
   return new ARMCodeGenPrepare();
 }

test/CodeGen/ARM/arm-cgp-icmps.ll

   %and = and i8 %x, 7
   %sub = sub i8 %and, %xor
   %add = add i8 %sub, 1
   %cmp = icmp ult i8 %add, 254
   %res = select i1 %cmp, i32 35, i32 47
   ret i32 %res
 }
 
-; CHECK-COMMON-LABEL: dsp_imm2
-; CHECK-COMMON:   add   r0, r1
-; CHECK-DSP-NEXT: ldrh  r1, [r3]
-; CHECK-DSP-NEXT: ldrh  r2, [r2]
-; CHECK-DSP-NEXT: subs  r1, r1, r0
-; CHECK-DSP-NEXT: add   r0, r2
-; CHECK-DSP-NEXT: uxth  r3, r1
-; CHECK-DSP-NEXT: uxth  r2, r0
-; CHECK-DSP-NEXT: cmp   r2, r3
-
-; CHECK-DSP-IMM:      movs  r1, #0
-; CHECK-DSP-IMM-NEXT: uxth  r0, r0
-; CHECK-DSP-IMM-NEXT: usub16  r1, r1, r0
-; CHECK-DSP-IMM-NEXT: ldrh  r0, [r2]
-; CHECK-DSP-IMM-NEXT: ldrh  r3, [r3]
-; CHECK-DSP-IMM-NEXT: usub16  r0, r0, r1
-; CHECK-DSP-IMM-NEXT: uadd16  r1, r3, r1
-; CHECK-DSP-IMM-NEXT: cmp r0, r1
-
-define i16 @dsp_imm2(i32 %arg0, i32 %arg1, i16* %gep0, i16* %gep1) {
-entry:
-  %add0 = add i32 %arg0, %arg1
-  %conv0 = trunc i32 %add0 to i16
-  %sub0 = sub i16 0, %conv0
-  %load0 = load i16, i16* %gep0, align 2
-  %load1 = load i16, i16* %gep1, align 2
-  %sub1 = sub i16 %load0, %sub0
-  %add1 = add i16 %load1, %sub0
-  %cmp = icmp ult i16 %sub1, %add1
-  %res = select i1 %cmp, i16 %add1, i16 %sub1
-  ret i16 %res
-}
-
 ; CHECK-COMMON-LABEL: dsp_var:
 ; CHECK-COMMON:   eors    r1, r0
 ; CHECK-COMMON:   and     r2, r0, #7
 ; CHECK-NODSP:    subs    r1, r2, r1
 ; CHECK-NODSP:    add.w   r0, r1, r0, lsl #1
 ; CHECK-NODSP:    uxtb    r1, r0
 ; CHECK-DSP:      usub8   r1, r2, r1
 ; CHECK-DSP:      lsls    r0, r0, #1

 define i32 @ugt_1_dec_var(i8 zeroext %x, i8 zeroext %y) {
 entry:
   %sub = sub i8 %x, %y
   %cmp = icmp ugt i8 %sub, 1
   %res = select i1 %cmp, i32 35, i32 47
   ret i32 %res
 }
 
-; CHECK-COMMON-LABEL: icmp_i32_zext:
-; CHECK-COMMON:     ldrb [[LD:r[^ ]+]], [r0]
-; CHECK-COMMON:     subs [[SUB:r[^ ]+]], [[LD]], #1
-; CHECK-COMMON-NOT: uxt
-; CHECK-COMMON:     cmp [[LD]], [[SUB]]
-; CHECK-COMMON-NOT: uxt
-define i8 @icmp_i32_zext(i8* %ptr) {
-entry:
-  %gep = getelementptr inbounds i8, i8* %ptr, i32 0
-  %0 = load i8, i8* %gep, align 1
-  %1 = sub nuw nsw i8 %0, 1
-  %conv44 = zext i8 %0 to i32
-  br label %preheader
-
-preheader:
-  br label %body
-
-body:
-  %2 = phi i8 [ %1, %preheader ], [ %3, %if.end ]
-  %si.0274 = phi i32 [ %conv44, %preheader ], [ %inc, %if.end ]
-  %conv51266 = zext i8 %2 to i32
-  %cmp52267 = icmp eq i32 %si.0274, %conv51266
-  br i1 %cmp52267, label %if.end, label %exit
-
-if.end:
-  %inc = add i32 %si.0274, 1
-  %gep1 = getelementptr inbounds i8, i8* %ptr, i32 %inc
-  %3 = load i8, i8* %gep1, align 1
-  br label %body
-
-exit:
-  ret i8 %2
-}
-
-@d_uch = hidden local_unnamed_addr global [16 x i8] zeroinitializer, align 1
-@sh1 = hidden local_unnamed_addr global i16 0, align 2
-@d_sh = hidden local_unnamed_addr global [16 x i16] zeroinitializer, align 2
-
-; CHECK-COMMON-LABEL: icmp_sext_zext_store_i8_i16
-; CHECK-NODSP: ldrb [[BYTE:r[^ ]+]],
-; CHECK-NODSP: strh [[BYTE]],
-; CHECK-NODSP: ldrsh.w
-define i32 @icmp_sext_zext_store_i8_i16() {
-entry:
-  %0 = load i8, i8* getelementptr inbounds ([16 x i8], [16 x i8]* @d_uch, i32 0, i32 2), align 1
-  %conv = zext i8 %0 to i16
-  store i16 %conv, i16* @sh1, align 2
-  %conv1 = zext i8 %0 to i32
-  %1 = load i16, i16* getelementptr inbounds ([16 x i16], [16 x i16]* @d_sh, i32 0, i32 2), align 2
-  %conv2 = sext i16 %1 to i32
-  %cmp = icmp eq i32 %conv1, %conv2
-  %conv3 = zext i1 %cmp to i32
-  ret i32 %conv3
-}
-
-; CHECK-COMMON-LABEL: or_icmp_ugt:
-; CHECK-COMMON:     ldrb [[LD:r[^ ]+]], [r1]
-; CHECK-COMMON:     subs [[SUB:r[^ ]+]], #1
-; CHECK-COMMON-NOT: uxtb
-; CHECK-COMMON:     cmp [[SUB]], #3
-define i1 @or_icmp_ugt(i32 %arg, i8* %ptr) {
-entry:
-  %0 = load i8, i8* %ptr
-  %1 = zext i8 %0 to i32
-  %mul = shl nuw nsw i32 %1, 1
-  %add0 = add nuw nsw i32 %mul, 6
-  %cmp0 = icmp ne i32 %arg, %add0
-  %add1 = add i8 %0, -1
-  %cmp1 = icmp ugt i8 %add1, 3
-  %or = or i1 %cmp0, %cmp1
-  ret i1 %or
-}
-
-; CHECK-COMMON-LABEL: icmp_switch_trunc:
-; CHECK-COMMON-NOT: uxt
-define i16 @icmp_switch_trunc(i16 zeroext %arg) {
-entry:
-  %conv = add nuw i16 %arg, 15
-  %mul = mul nuw nsw i16 %conv, 3
-  %trunc = trunc i16 %arg to i3
-  switch i3 %trunc, label %default [
-    i3 0, label %sw.bb
-    i3 1, label %sw.bb.i
-  ]
-
-sw.bb:
-  %cmp0 = icmp ult i16 %mul, 127
-  %select = select i1 %cmp0, i16 %mul, i16 127
-  br label %exit
-
-sw.bb.i:
-  %cmp1 = icmp ugt i16 %mul, 34
-  %select.i = select i1 %cmp1, i16 %mul, i16 34
-  br label %exit
-
-default:
-  br label %exit
-
-exit:
-  %res = phi i16 [ %select, %sw.bb ], [ %select.i, %sw.bb.i ], [ %mul, %default ]
-  ret i16 %res
-}
-
 ; CHECK-COMMON-LABEL: icmp_eq_minus_one
 ; CHECK-COMMON: cmp r0, #255
 define i32 @icmp_eq_minus_one(i8* %ptr) {
   %load = load i8, i8* %ptr, align 1
   %conv = zext i8 %load to i32
   %cmp = icmp eq i8 %load, -1
   %ret = select i1 %cmp, i32 %conv, i32 -1
   ret i32 %ret
 }
 
 ; CHECK-COMMON-LABEL: icmp_not
 ; CHECK-COMMON: movw r2, #65535
 ; CHECK-COMMON: eors r2, r0
 ; CHECK-COMMON: movs r0, #32
 ; CHECK-COMMON: cmp r2, r1
 define i32 @icmp_not(i16 zeroext %arg0, i16 zeroext %arg1) {
   %not = xor i16 %arg0, -1
   %cmp = icmp eq i16 %not, %arg1
   %res = select i1 %cmp, i32 16, i32 32
   ret i32 %res
 }
 
-; CHECK-COMMON-LABEL: mul_wrap
-; CHECK-COMMON: mul
-; CHECK-COMMON: uxth
-; CHECK-COMMON: cmp
-define i16 @mul_wrap(i16 %arg0, i16 %arg1) {
-  %mul = mul i16 %arg0, %arg1
-  %cmp = icmp eq i16 %mul, 1
-  %res = select i1 %cmp, i16 %arg0, i16 47
-  ret i16 %res
-}
-
-; CHECK-COMMON-LABEL: shl_wrap
-; CHECK-COMMON: lsl
-; CHECK-COMMON: uxth
-; CHECK-COMMON: cmp
-define i16 @shl_wrap(i16 %arg0) {
-  %mul = shl i16 %arg0, 4
-  %cmp = icmp eq i16 %mul, 1
-  %res = select i1 %cmp, i16 %arg0, i16 47
-  ret i16 %res
-}
-
-; CHECK-COMMON-LABEL: add_wrap
-; CHECK-COMMON: add
-; CHECK-COMMON: uxth
-; CHECK-COMMON: cmp
-define i16 @add_wrap(i16 %arg0, i16 %arg1) {
-  %add = add i16 %arg0, 128
-  %cmp = icmp eq i16 %add, %arg1
-  %res = select i1 %cmp, i16 %arg0, i16 1
-  ret i16 %res
-}
-
-; CHECK-COMMON-LABEL: sub_wrap
-; CHECK-COMMON: sub
-; CHECK-COMMON: uxth
-; CHECK-COMMON: cmp
-define i16 @sub_wrap(i16 %arg0, i16 %arg1, i16 %arg2) {
-  %sub = sub i16 %arg0, %arg2
-  %cmp = icmp eq i16 %sub, %arg1
-  %res = select i1 %cmp, i16 %arg0, i16 1
-  ret i16 %res
-}
-
-; CHECK-COMMON-LABEL: urem_trunc_icmps
-; CHECK-COMMON-NOT: uxt
-define void @urem_trunc_icmps(i16** %in, i32* %g, i32* %k) {
-entry:
-  %ptr = load i16*, i16** %in, align 4
-  %ld = load i16, i16* %ptr, align 2
-  %cmp.i = icmp eq i16 %ld, 0
-  br i1 %cmp.i, label %exit, label %cond.false.i
-
-cond.false.i:
-  %rem = urem i16 5, %ld
-  %extract.t = trunc i16 %rem to i8
-  br label %body
-
-body:
-  %cond.in.i.off0 = phi i8 [ %extract.t, %cond.false.i ], [ %add, %for.inc ]
-  %cmp = icmp ugt i8 %cond.in.i.off0, 7
-  %conv5 = zext i1 %cmp to i32
-  store i32 %conv5, i32* %g, align 4
-  %.pr = load i32, i32* %k, align 4
-  %tobool13150 = icmp eq i32 %.pr, 0
-  br i1 %tobool13150, label %for.inc, label %exit
-
-for.inc:
-  %add = add nuw i8 %cond.in.i.off0, 1
-  br label %body
-
-exit:
-  ret void
-}

test/CodeGen/ARM/arm-cgp-overflow.ll

+; RUN: llc -mtriple=thumbv8.main -mcpu=cortex-m33 %s -arm-disable-cgp=false -o - | FileCheck %s
+
+; CHECK: overflow_add
+; CHECK: add
+; CHECK: uxth
+; CHECK: cmp
+define zeroext i16 @overflow_add(i16 zeroext %a, i16 zeroext %b) {
+  %add = add i16 %a, %b
+  %or = or i16 %add, 1
+  %cmp = icmp ugt i16 %or, 1024
+  %res = select i1 %cmp, i16 2, i16 5
+  ret i16 %res
+}
+
+; CHECK-LABEL: overflow_sub
+; CHECK: sub
+; CHECK: uxth
+; CHECK: cmp
+define zeroext i16 @overflow_sub(i16 zeroext %a, i16 zeroext %b) {
+  %add = sub i16 %a, %b
+  %or = or i16 %add, 1
+  %cmp = icmp ugt i16 %or, 1024
+  %res = select i1 %cmp, i16 2, i16 5
+  ret i16 %res
+}
+
+; CHECK-LABEL: overflow_mul
+; CHECK: mul
+; CHECK: uxth
+; CHECK: cmp
+define zeroext i16 @overflow_mul(i16 zeroext %a, i16 zeroext %b) {
+  %add = mul i16 %a, %b
+  %or = or i16 %add, 1
+  %cmp = icmp ugt i16 %or, 1024
+  %res = select i1 %cmp, i16 2, i16 5
+  ret i16 %res
+}
+
+; CHECK-LABEL: overflow_shl
+; CHECK-COMMON: lsl
+; CHECK-COMMON: uxth
+; CHECK-COMMON: cmp
+define zeroext i16 @overflow_shl(i16 zeroext %a, i16 zeroext %b) {
+  %add = shl i16 %a, %b
+  %or = or i16 %add, 1
+  %cmp = icmp ugt i16 %or, 1024
+  %res = select i1 %cmp, i16 2, i16 5
+  ret i16 %res
+}

test/CodeGen/ARM/arm-cgp-phis-calls-ret.ll

   %inc2 = phi i16 [ %inc, %if.then], [ %inc1, %if.else ]
   %cmp1 = icmp ult i16 %inc2, 253
   br i1 %cmp1, label %loop, label %exit
 
 exit:
   ret void
 }
 
-; CHECK-COMMON-LABEL: phi_feeding_switch
-; CHECK-COMMON: ldrb
-; CHECK-COMMON: uxtb
-; CHECK-COMMON-NOT: uxt
-define void @phi_feeding_switch(i8* %memblock, i8* %store, i16 %arg) {
-entry:
-  %pre = load i8, i8* %memblock, align 1
-  %conv = trunc i16 %arg to i8
-  br label %header
-
-header:
-  %phi.0 = phi i8 [ %pre, %entry ], [ %count, %latch ]
-  %phi.1 = phi i8 [ %conv, %entry ], [ %phi.3, %latch ]
-  %phi.2 = phi i8 [ 0, %entry], [ %count, %latch ]
-  switch i8 %phi.0, label %default [
-    i8 43, label %for.inc.i
-    i8 45, label %for.inc.i.i
-  ]
-
-for.inc.i:
-  %xor = xor i8 %phi.1, 1
-  br label %latch
-
-for.inc.i.i:
-  %and = and i8 %phi.1, 3
-  br label %latch
-
-default:
-  %sub = sub i8 %phi.0, 1
-  %cmp2 = icmp ugt i8 %sub, 4
-  br i1 %cmp2, label %latch, label %exit
-
-latch:
-  %phi.3 = phi i8 [ %xor, %for.inc.i ], [ %and, %for.inc.i.i ], [ %phi.2, %default ]
-  %count = add nuw i8 %phi.2, 1
-  store i8 %count, i8* %store, align 1
-  br label %header
-
-exit:
-  ret void
-}
-
 ; CHECK-COMMON-LABEL: ret_i8
 ; CHECK-COMMON-NOT:   uxt
 define i8 @ret_i8() {
 entry:
   br label %loop
 
 loop:
   %val = phi i8 [ 0, %entry ], [ %inc2, %if.end ]

   %inc2 = phi i8 [ %inc, %if.then], [ %inc1, %if.else ]
   %cmp1 = icmp ult i8 %inc2, 253
   br i1 %cmp1, label %exit, label %loop
 
 exit:
   ret i8 %inc2
 }
 
-; Check that %exp requires uxth in all cases, and will also be required to
-; promote %1 for the call - unless we can generate a uadd16.
-; CHECK-COMMON-LABEL: zext_load_sink_call:
-; CHECK-COMMON:       uxt
-; CHECK-DSP-IMM:      uadd16
-; CHECK-COMMON:       cmp
-; CHECK-DSP:          uxt
-; CHECK-DSP-IMM-NOT:  uxt
-define i32 @zext_load_sink_call(i16* %ptr, i16 %exp) {
-entry:
-  %0 = load i16, i16* %ptr, align 4
-  %1 = add i16 %exp, 3
-  %cmp = icmp eq i16 %0, %exp
-  br i1 %cmp, label %exit, label %if.then
-
-if.then:
-  %conv0 = zext i16 %0 to i32
-  %conv1 = zext i16 %1 to i32
-  %call = tail call arm_aapcs_vfpcc i32 @dummy(i32 %conv0, i32 %conv1)
-  br label %exit
-
-exit:
-  %exitval = phi i32 [ %call, %if.then ], [ 0, %entry  ]
-  ret i32 %exitval
-}
-
-
 ; Check that the pass doesn't try to promote the immediate parameters.
 ; CHECK-COMMON-LABEL: call_with_imms
 ; CHECK-COMMON-NOT:   uxt
 define i8 @call_with_imms(i8* %arg) {
   %call = tail call arm_aapcs_vfpcc zeroext i8 @dummy2(i8* nonnull %arg, i8 zeroext 0, i8 zeroext 0)
   %cmp = icmp eq i8 %call, 0
   %res = select i1 %cmp, i8 %call, i8 1
   ret i8 %res

   %or = or i16 %1, ptrtoint (i32* @b to i16)
   store i16 %or, i16* %0, align 2
   %cmp = icmp ne i16 %or, 4
   %conv3 = zext i1 %cmp to i32
   %call = tail call i32 bitcast (i32 (...)* @e to i32 (i32)*)(i32 %conv3) #2
   ret i32 undef
 }
 
+; Transform will bail because of the zext
 ; Check that d.sroa.0.0.be is promoted passed directly into the tail call.
 ; CHECK-COMMON-LABEL: check_zext_phi_call_arg
-; CHECK-COMMON-NOT: uxt
+; CHECK-COMMON: uxt
 define i32 @check_zext_phi_call_arg() {
 entry:
   br label %for.cond
 
 for.cond:                                         ; preds = %for.cond.backedge, %entry
   %d.sroa.0.0 = phi i16 [ 30, %entry ], [ %d.sroa.0.0.be, %for.cond.backedge ]
   %tobool = icmp eq i16 %d.sroa.0.0, 0
   br i1 %tobool, label %for.cond.backedge, label %if.then

 declare fastcc signext i16 @safe_sub_func_int16_t_s_s(i16 signext %si2)
 declare dso_local fastcc i64 @safe_sub_func_int64_t_s_s(i64, i64)
 declare dso_local fastcc zeroext i8 @safe_lshift_func(i8 zeroext, i32)
 declare dso_local fastcc zeroext i8 @safe_mul_func_uint8_t_u_u(i8 returned zeroext)
 
 declare dso_local i32 @e(...) local_unnamed_addr #1
 declare dso_local zeroext i16 @f(...) local_unnamed_addr #1
 
-declare i32 @dummy(i32, i32)
 declare i8 @dummy_i8(i8)
 declare i8 @dummy2(i8*, i8, i8)
 declare i16 @dummy3(i16)
 declare i32 @assert(...)

test/CodeGen/ARM/arm-cgp-zext-truncs.ll

+; RUN: llc -mtriple=thumbv8.main -mcpu=cortex-m33 %s -arm-disable-cgp=false -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
+; RUN: llc -mtriple=thumbv7-linux-android %s -arm-disable-cgp=false -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-NODSP
+; RUN: llc -mtriple=thumbv7em %s -arm-disable-cgp=false -arm-enable-scalar-dsp=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP
+; RUN: llc -mtriple=thumbv8 %s -arm-disable-cgp=false -arm-enable-scalar-dsp=true -arm-enable-scalar-dsp-imms=true -o - | FileCheck %s --check-prefix=CHECK-COMMON --check-prefix=CHECK-DSP-IMM
+
+; Transform will fail because the trunc is not a sink.
+; CHECK-COMMON-LABEL: dsp_trunc
+; CHECK-COMMON:   add   [[ADD:[^ ]+]],
+; CHECK-DSP-NEXT: ldrh  r1, [r3]
+; CHECK-DSP-NEXT: ldrh  r2, [r2]
+; CHECK-DSP-NEXT: subs  r1, r1, [[ADD]]
+; CHECK-DSP-NEXT: add   r0, r2
+; CHECK-DSP-NEXT: uxth  r3, r1
+; CHECK-DSP-NEXT: uxth  r2, r0
+; CHECK-DSP-NEXT: cmp   r2, r3
+
+; With DSP-IMM, we could have:
+; movs  r1, #0
+; uxth  r0, r0
+; usub16  r1, r1, r0
+; ldrh  r0, [r2]
+; ldrh  r3, [r3]
+; usub16  r0, r0, r1
+; uadd16  r1, r3, r1
+; cmp r0, r1
+define i16 @dsp_trunc(i32 %arg0, i32 %arg1, i16* %gep0, i16* %gep1) {
+entry:
+  %add0 = add i32 %arg0, %arg1
+  %conv0 = trunc i32 %add0 to i16
+  %sub0 = sub i16 0, %conv0
+  %load0 = load i16, i16* %gep0, align 2
+  %load1 = load i16, i16* %gep1, align 2
+  %sub1 = sub i16 %load0, %sub0
+  %add1 = add i16 %load1, %sub0
+  %cmp = icmp ult i16 %sub1, %add1
+  %res = select i1 %cmp, i16 %add1, i16 %sub1
+  ret i16 %res
+}
+
+; CHECK-COMMON-LABEL: trunc_i16_i8
+; CHECK-COMMON: ldrh
+; CHECK-COMMON: uxtb
+; CHECK-COMMON: cmp
+define i8 @trunc_i16_i8(i16* %ptr, i16 zeroext %arg0, i8 zeroext %arg1) {
+entry:
+  %0 = load i16, i16* %ptr
+  %1 = add i16 %0, %arg0
+  %2 = trunc i16 %1 to i8
+  %3 = icmp ugt i8 %2, %arg1
+  %4 = select i1 %3, i8 %2, i8 %arg1
+  ret i8 %4
+}
+
+; The pass will bail because of the zext, otherwise we'd want something like:
+; ldrb [[LD:r[^ ]+]], [r0]
+; subs [[SUB:r[^ ]+]], [[LD]], #1
+; cmp [[LD]], [[SUB]]
+; CHECK-COMMON-LABEL: icmp_i32_zext:
+; CHECK-COMMON: uxtb
+define i8 @icmp_i32_zext(i8* %ptr) {
+entry:
+  %gep = getelementptr inbounds i8, i8* %ptr, i32 0
+  %0 = load i8, i8* %gep, align 1
+  %1 = sub nuw nsw i8 %0, 1
+  %conv44 = zext i8 %0 to i32
+  br label %preheader
+
+preheader:
+  br label %body
+
+body:
+  %2 = phi i8 [ %1, %preheader ], [ %3, %if.end ]
+  %si.0274 = phi i32 [ %conv44, %preheader ], [ %inc, %if.end ]
+  %conv51266 = zext i8 %2 to i32
+  %cmp52267 = icmp eq i32 %si.0274, %conv51266
+  br i1 %cmp52267, label %if.end, label %exit
+
+if.end:
+  %inc = add i32 %si.0274, 1
+  %gep1 = getelementptr inbounds i8, i8* %ptr, i32 %inc
+  %3 = load i8, i8* %gep1, align 1
+  br label %body
+
+exit:
+  ret i8 %2
+}
+
+; Won't handle zext or sext
+; CHECK-COMMON-LABEL: icmp_sext_zext_store_i8_i16
+define i32 @icmp_sext_zext_store_i8_i16() {
+entry:
+  %0 = load i8, i8* getelementptr inbounds ([16 x i8], [16 x i8]* @d_uch, i32 0, i32 2), align 1
+  %conv = zext i8 %0 to i16
+  store i16 %conv, i16* @sh1, align 2
+  %conv1 = zext i8 %0 to i32
+  %1 = load i16, i16* getelementptr inbounds ([16 x i16], [16 x i16]* @d_sh, i32 0, i32 2), align 2
+  %conv2 = sext i16 %1 to i32
+  %cmp = icmp eq i32 %conv1, %conv2
+  %conv3 = zext i1 %cmp to i32
+  ret i32 %conv3
+}
+
+; Pass will bail because of the zext, otherwise:
+; ldrb [[LD:r[^ ]+]], [r1]
+; subs [[SUB:r[^ ]+]], #1
+; cmp [[SUB]], #3
+; CHECK-COMMON-LABEL: or_icmp_ugt:
+; CHECK-COMMON: uxt
+define i1 @or_icmp_ugt(i32 %arg, i8* %ptr) {
+entry:
+  %0 = load i8, i8* %ptr
+  %1 = zext i8 %0 to i32
+  %mul = shl nuw nsw i32 %1, 1
+  %add0 = add nuw nsw i32 %mul, 6
+  %cmp0 = icmp ne i32 %arg, %add0
+  %add1 = add i8 %0, -1
+  %cmp1 = icmp ugt i8 %add1, 3
+  %or = or i1 %cmp0, %cmp1
+  ret i1 %or
+}
+
+; CHECK-COMMON-LABEL: icmp_switch_trunc:
+; CHECK-COMMON-NOT: uxt
+define i16 @icmp_switch_trunc(i16 zeroext %arg) {
+entry:
+  %conv = add nuw i16 %arg, 15
+  %mul = mul nuw nsw i16 %conv, 3
+  %trunc = trunc i16 %arg to i3
+  switch i3 %trunc, label %default [
+    i3 0, label %sw.bb
+    i3 1, label %sw.bb.i
+  ]
+
+sw.bb:
+  %cmp0 = icmp ult i16 %mul, 127
+  %select = select i1 %cmp0, i16 %mul, i16 127
+  br label %exit
+
+sw.bb.i:
+  %cmp1 = icmp ugt i16 %mul, 34
+  %select.i = select i1 %cmp1, i16 %mul, i16 34
+  br label %exit
+
+default:
+  br label %exit
+
+exit:
+  %res = phi i16 [ %select, %sw.bb ], [ %select.i, %sw.bb.i ], [ %mul, %default ]
+  ret i16 %res
+}
+
+; Pass will bail because of the zext
+; CHECK-COMMON-LABEL: urem_trunc_icmps
+; CHECK-COMMON: uxt
+define void @urem_trunc_icmps(i16** %in, i32* %g, i32* %k) {
+entry:
+  %ptr = load i16*, i16** %in, align 4
+  %ld = load i16, i16* %ptr, align 2
+  %cmp.i = icmp eq i16 %ld, 0
+  br i1 %cmp.i, label %exit, label %cond.false.i
+
+cond.false.i:
+  %rem = urem i16 5, %ld
+  %extract.t = trunc i16 %rem to i8
+  br label %body
+
+body:
+  %cond.in.i.off0 = phi i8 [ %extract.t, %cond.false.i ], [ %add, %for.inc ]
+  %cmp = icmp ugt i8 %cond.in.i.off0, 7
+  %conv5 = zext i1 %cmp to i32
+  store i32 %conv5, i32* %g, align 4
+  %.pr = load i32, i32* %k, align 4
+  %tobool13150 = icmp eq i32 %.pr, 0
+  br i1 %tobool13150, label %for.inc, label %exit
+
+for.inc:
+  %add = add nuw i8 %cond.in.i.off0, 1
+  br label %body
+
+exit:
+  ret void
+}
+
+; CHECK-COMMON-LABEL: phi_feeding_switch
+; CHECK-COMMON: ldrb
+; CHECK-COMMON: uxtb
+; CHECK-COMMON: uxtb
+define void @phi_feeding_switch(i8* %memblock, i8* %store, i16 %arg) {
+entry:
+  %pre = load i8, i8* %memblock, align 1
+  %conv = trunc i16 %arg to i8
+  br label %header
+
+header:
+  %phi.0 = phi i8 [ %pre, %entry ], [ %count, %latch ]
+  %phi.1 = phi i8 [ %conv, %entry ], [ %phi.3, %latch ]
+  %phi.2 = phi i8 [ 0, %entry], [ %count, %latch ]
+  switch i8 %phi.0, label %default [
+    i8 43, label %for.inc.i
+    i8 45, label %for.inc.i.i
+  ]
+
+for.inc.i:
+  %xor = xor i8 %phi.1, 1
+  br label %latch
+
+for.inc.i.i:
+  %and = and i8 %phi.1, 3
+  br label %latch
+
+default:
+  %sub = sub i8 %phi.0, 1
+  %cmp2 = icmp ugt i8 %sub, 4
+  br i1 %cmp2, label %latch, label %exit
+
+latch:
+  %phi.3 = phi i8 [ %xor, %for.inc.i ], [ %and, %for.inc.i.i ], [ %phi.2, %default ]
+  %count = add nuw i8 %phi.2, 1
+  store i8 %count, i8* %store, align 1
+  br label %header
+
+exit:
+  ret void
+}
+
+; Again, zexts will prevent the transform.
+; Check that %exp requires uxth in all cases, and will also be required to
+; promote %1 for the call - unless we can generate a uadd16.
+; CHECK-COMMON-LABEL: zext_load_sink_call:
+; CHECK-COMMON: uxt
+; uadd16
+; cmp
+; CHECK-COMMON: uxt
+define i32 @zext_load_sink_call(i16* %ptr, i16 %exp) {
+entry:
+  %0 = load i16, i16* %ptr, align 4
+  %1 = add i16 %exp, 3
+  %cmp = icmp eq i16 %0, %exp
+  br i1 %cmp, label %exit, label %if.then
+
+if.then:
+  %conv0 = zext i16 %0 to i32
+  %conv1 = zext i16 %1 to i32
+  %call = tail call arm_aapcs_vfpcc i32 @dummy(i32 %conv0, i32 %conv1)
+  br label %exit
+
+exit:
+  %exitval = phi i32 [ %call, %if.then ], [ 0, %entry  ]
+  ret i32 %exitval
+}
+
+%class.ae = type { i8 }
+%class.x = type { i8 }
+%class.v = type { %class.q }
+%class.q = type { i16 }
+
+; CHECK-COMMON-LABEL: trunc_i16_i9_switch
+; CHECK-COMMON-NOT: uxt
+define i32 @trunc_i16_i9_switch(%class.ae* %this) {
+entry:
+  %call = tail call %class.x* @_ZNK2ae2afEv(%class.ae* %this)
+  %call2 = tail call %class.v* @_ZN1x2acEv(%class.x* %call)
+  %0 = getelementptr inbounds %class.v, %class.v* %call2, i32 0, i32 0, i32 0
+  %1 = load i16, i16* %0, align 2
+  %2 = trunc i16 %1 to i9
+  %trunc = and i9 %2, -64
+  switch i9 %trunc, label %cleanup.fold.split [
+    i9 0, label %cleanup
+    i9 -256, label %if.then7
+  ]
+
+if.then7:
+  %3 = and i16 %1, 7
+  %tobool = icmp eq i16 %3, 0
+  %cond = select i1 %tobool, i32 2, i32 1
+  br label %cleanup
+
+cleanup.fold.split:
+  br label %cleanup
+
+cleanup:
+  %retval.0 = phi i32 [ %cond, %if.then7 ], [ 0, %entry ], [ 2, %cleanup.fold.split ]
+  ret i32 %retval.0
+}
+
+declare %class.x* @_ZNK2ae2afEv(%class.ae*) local_unnamed_addr
+declare %class.v* @_ZN1x2acEv(%class.x*) local_unnamed_addr
+declare i32 @dummy(i32, i32)
+
+@d_uch = hidden local_unnamed_addr global [16 x i8] zeroinitializer, align 1
+@sh1 = hidden local_unnamed_addr global i16 0, align 2
+@d_sh = hidden local_unnamed_addr global [16 x i16] zeroinitializer, align 2