[InstCombine] Improve foldOpIntoPhi() to use isImpliedCondition

[kitaisreal]

Summary

Example https://godbolt.org/z/acq4rqdqK.
Depends on D156619.

[nikic]

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

1393

There is an isImpliedByCondition() overload that accepts unpacked icmp operands. We should use that instead of cloning the instruction.

[kitaisreal]

Updated implementation.

[nikic]

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

1388

Please extract the code above here into a separate function (which does simplifyInstructionWithOperands plus the special icmp case).

1394

I don't think the RHSOp0, RHSOp1 variables really add value over Ops[0], Ops[1] here.

1395

I think your tests currently only cover one of the LHSIsTrue cases. You also need one with successors swapped.

1402

You can use ConstantInt::getBool() here.

[goldstein.w.n]

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

1400

can rename variable from 'Constant'. Its a big confusing to have variable name ==type.

[kitaisreal]

Updated implementation.

[nikic]

Looks basically fine to me.

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

1338

I think this should check that getSuccessor(0) != getSuccessor(1). This will get canonicalized away, but is not guaranteed due to worklist order.

1345

I'd personally move this block to the end, because simplifyInstructionWithOperands() is the normal case, and this is a special case.

1355

Omit braces

[kitaisreal]

Updated implementation.

[nikic]

LGTM

llvm/lib/Transforms/InstCombine/InstructionCombining.cpp

Instruction *InstCombinerImpl::FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
   // Create an instruction for the arm that did not fold.
   if (!NewTV)
     NewTV = foldOperationIntoSelectOperand(Op, SI, TV, *this);
   if (!NewFV)
     NewFV = foldOperationIntoSelectOperand(Op, SI, FV, *this);
   return SelectInst::Create(SI->getCondition(), NewTV, NewFV, "", nullptr, SI);
 }
 
+static Value *simplifyInstructionWithPHI(Instruction &I, PHINode *PN,
+                                         Value *InValue, BasicBlock *InBB,
+                                         const DataLayout &DL,
+                                         const SimplifyQuery SQ) {
+  // NB: It is a precondition of this transform that the operands be
+  // phi translatable! This is usually trivially satisfied by limiting it
+  // to constant ops, and for selects we do a more sophisticated check.
+  SmallVector<Value *> Ops;
+  for (Value *Op : I.operands()) {
+    if (Op == PN)
+      Ops.push_back(InValue);
+    else
+      Ops.push_back(Op->DoPHITranslation(PN->getParent(), InBB));
+  }
+
+  // Check if incoming PHI value can be replaced with constant
+  // based on implied condition.
+  BranchInst *TerminatorBI = dyn_cast<BranchInst>(InBB->getTerminator());
+  const ICmpInst *ICmp = dyn_cast<ICmpInst>(&I);
+  if (TerminatorBI && TerminatorBI->isConditional() && ICmp) {
+    bool LHSIsTrue = TerminatorBI->getSuccessor(0) == PN->getParent();
+    std::optional<bool> ImpliedCond =
+        isImpliedCondition(TerminatorBI->getCondition(), ICmp->getPredicate(),
+                           Ops[0], Ops[1], DL, LHSIsTrue);
+    if (ImpliedCond)
+      return ConstantInt::getBool(I.getType(), ImpliedCond.value());
+  }
+
+  // Don't consider the simplification successful if we get back a constant
+  // expression. That's just an instruction in hiding.
+  // Also reject the case where we simplify back to the phi node. We wouldn't
+  // be able to remove it in that case.
+  Value *NewVal = simplifyInstructionWithOperands(
+      &I, Ops, SQ.getWithInstruction(InBB->getTerminator()));
+  if (NewVal && NewVal != PN && !match(NewVal, m_ConstantExpr())) {
+    return NewVal;
+  }
+
+  return nullptr;
+}
+
 Instruction *InstCombinerImpl::foldOpIntoPhi(Instruction &I, PHINode *PN) {
   unsigned NumPHIValues = PN->getNumIncomingValues();
   if (NumPHIValues == 0)
     return nullptr;
 
   // We normally only transform phis with a single use.  However, if a PHI has
   // multiple uses and they are all the same operation, we can fold *all* of the
   // uses into the PHI.
Instruction *InstCombinerImpl::foldOpIntoPhi(Instruction &I, PHINode *PN) {
   // If there is more than one or if *it* is a PHI, bail out.
   SmallVector<Value *> NewPhiValues;
   BasicBlock *NonSimplifiedBB = nullptr;
   Value *NonSimplifiedInVal = nullptr;
   for (unsigned i = 0; i != NumPHIValues; ++i) {
     Value *InVal = PN->getIncomingValue(i);
     BasicBlock *InBB = PN->getIncomingBlock(i);
 
-    // NB: It is a precondition of this transform that the operands be
-    // phi translatable! This is usually trivially satisfied by limiting it
-    // to constant ops, and for selects we do a more sophisticated check.
-    SmallVector<Value *> Ops;
-    for (Value *Op : I.operands()) {
-      if (Op == PN)
-        Ops.push_back(InVal);
-      else
-        Ops.push_back(Op->DoPHITranslation(PN->getParent(), InBB));
-    }
-
-    // Don't consider the simplification successful if we get back a constant
-    // expression. That's just an instruction in hiding.
-    // Also reject the case where we simplify back to the phi node. We wouldn't
-    // be able to remove it in that case.
-    Value *NewVal = simplifyInstructionWithOperands(
-        &I, Ops, SQ.getWithInstruction(InBB->getTerminator()));
-    if (NewVal && NewVal != PN && !match(NewVal, m_ConstantExpr())) {
+    if (auto *NewVal = simplifyInstructionWithPHI(I, PN, InVal, InBB, DL, SQ)) {
       NewPhiValues.push_back(NewVal);
       continue;
     }
 
     if (isa<PHINode>(InVal)) return nullptr;  // Itself a phi.
     if (NonSimplifiedBB) return nullptr;  // More than one non-simplified value.
 
     NonSimplifiedBB = InBB;
     NonSimplifiedInVal = InVal;
     NewPhiValues.push_back(nullptr);
 
     // If the InVal is an invoke at the end of the pred block, then we can't
     // insert a computation after it without breaking the edge.
     if (isa<InvokeInst>(InVal))
       if (cast<Instruction>(InVal)->getParent() == NonSimplifiedBB)
         return nullptr;
 
     // If the incoming non-constant value is reachable from the phis block,
     // we'll push the operation across a loop backedge. This could result in
     // an infinite combine loop, and is generally non-profitable (especially
     // if the operation was originally outside the loop).
     if (isPotentiallyReachable(PN->getParent(), NonSimplifiedBB, nullptr, &DT,

llvm/test/Transforms/InstCombine/phi.ll

if.end:
   %y = phi i32 [ %i, %if.then ], [ 0, %entry ]
   %add = sub i32 %y, %x
   ret i32 %add
 }
 
 define i1 @cmp_eq_phi_node_can_fold_1(ptr %C) {
 ; CHECK-LABEL: @cmp_eq_phi_node_can_fold_1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP8:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP7]], [[SUB_IS_ZERO]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP8]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ [[TMP5]], [[SUB_IS_ZERO]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %sub_is_zero, label %join
 
 sub_is_zero:
   %5 = getelementptr inbounds i8, ptr %C, i64 1
   %6 = load i8, ptr %5, align 1
   %7 = zext i8 %6 to i32
   br label %join
 
 join:
   %8 = phi i32 [ %3, %0 ], [ %7, %sub_is_zero ]
   %cmp = icmp eq i32 %8, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_eq_phi_node_can_fold_2(ptr %C) {
 ; CHECK-LABEL: @cmp_eq_phi_node_can_fold_2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
-; CHECK-NEXT:    [[TMP8:%.*]] = add nsw i32 [[TMP7]], -49
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
-; CHECK-NEXT:    br i1 [[TMP9]], label [[SUB_IS_ZERO1:%.*]], label [[JOIN]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 49
+; CHECK-NEXT:    br i1 [[TMP5]], label [[SUB_IS_ZERO1:%.*]], label [[JOIN]]
 ; CHECK:       sub_is_zero1:
-; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
-; CHECK-NEXT:    [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
-; CHECK-NEXT:    [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
+; CHECK-NEXT:    [[TMP7:%.*]] = load i8, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i8 [[TMP7]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP13:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP8]], [[SUB_IS_ZERO]] ], [ [[TMP12]], [[SUB_IS_ZERO1]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP13]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ false, [[SUB_IS_ZERO]] ], [ [[TMP8]], [[SUB_IS_ZERO1]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %sub_is_zero, label %join
 
join:
   %13 = phi i32 [ %3, %0 ], [ %8, %sub_is_zero ], [ %12, %sub_is_zero1 ]
   %cmp = icmp eq i32 %13, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_eq_phi_node_can_fold_3(ptr %C) {
 ; CHECK-LABEL: @cmp_eq_phi_node_can_fold_3(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP8:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP7]], [[SUB_IS_ZERO]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP8]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ true, [[TMP0:%.*]] ], [ [[TMP5]], [[SUB_IS_ZERO]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero
 
 sub_is_zero:
   %5 = getelementptr inbounds i8, ptr %C, i64 1
   %6 = load i8, ptr %5, align 1
   %7 = zext i8 %6 to i32
   br label %join
 
 join:
   %8 = phi i32 [ %3, %0 ], [ %7, %sub_is_zero ]
   %cmp = icmp eq i32 %8, 0
   ret i1 %cmp
 }
 
 
 define i1 @cmp_eq_phi_node_can_fold_4(ptr %C) {
 ; CHECK-LABEL: @cmp_eq_phi_node_can_fold_4(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
-; CHECK-NEXT:    [[TMP8:%.*]] = add nsw i32 [[TMP7]], -49
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
-; CHECK-NEXT:    br i1 [[TMP9]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 49
+; CHECK-NEXT:    br i1 [[TMP5]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
 ; CHECK:       sub_is_zero1:
-; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
-; CHECK-NEXT:    [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
-; CHECK-NEXT:    [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
+; CHECK-NEXT:    [[TMP7:%.*]] = load i8, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp eq i8 [[TMP7]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP13:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP8]], [[SUB_IS_ZERO]] ], [ [[TMP12]], [[SUB_IS_ZERO1]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp eq i32 [[TMP13]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ true, [[TMP0:%.*]] ], [ true, [[SUB_IS_ZERO]] ], [ [[TMP8]], [[SUB_IS_ZERO1]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero
 
join:
   %13 = phi i32 [ %3, %0 ], [ %8, %sub_is_zero ], [ %12, %sub_is_zero1 ]
   %cmp = icmp eq i32 %13, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_ne_phi_node_can_fold_1(ptr %C) {
 ; CHECK-LABEL: @cmp_ne_phi_node_can_fold_1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp ne i8 [[TMP4]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP8:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP7]], [[SUB_IS_ZERO]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP8]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ true, [[TMP0:%.*]] ], [ [[TMP5]], [[SUB_IS_ZERO]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %sub_is_zero, label %join
 
 sub_is_zero:
   %5 = getelementptr inbounds i8, ptr %C, i64 1
   %6 = load i8, ptr %5, align 1
   %7 = zext i8 %6 to i32
   br label %join
 
 join:
   %8 = phi i32 [ %3, %0 ], [ %7, %sub_is_zero ]
   %cmp = icmp ne i32 %8, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_ne_phi_node_can_fold_2(ptr %C) {
 ; CHECK-LABEL: @cmp_ne_phi_node_can_fold_2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[SUB_IS_ZERO:%.*]], label [[JOIN:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
-; CHECK-NEXT:    [[TMP8:%.*]] = add nsw i32 [[TMP7]], -49
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
-; CHECK-NEXT:    br i1 [[TMP9]], label [[SUB_IS_ZERO1:%.*]], label [[JOIN]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 49
+; CHECK-NEXT:    br i1 [[TMP5]], label [[SUB_IS_ZERO1:%.*]], label [[JOIN]]
 ; CHECK:       sub_is_zero1:
-; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
-; CHECK-NEXT:    [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
-; CHECK-NEXT:    [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
+; CHECK-NEXT:    [[TMP7:%.*]] = load i8, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ne i8 [[TMP7]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP13:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP8]], [[SUB_IS_ZERO]] ], [ [[TMP12]], [[SUB_IS_ZERO1]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP13]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ true, [[TMP0:%.*]] ], [ true, [[SUB_IS_ZERO]] ], [ [[TMP8]], [[SUB_IS_ZERO1]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %sub_is_zero, label %join
 
join:
   %13 = phi i32 [ %3, %0 ], [ %8, %sub_is_zero ], [ %12, %sub_is_zero1 ]
   %cmp = icmp ne i32 %13, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_ne_phi_node_can_fold_3(ptr %C) {
 ; CHECK-LABEL: @cmp_ne_phi_node_can_fold_3(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp ne i8 [[TMP4]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP8:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP7]], [[SUB_IS_ZERO]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP8]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ [[TMP5]], [[SUB_IS_ZERO]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero
 
 sub_is_zero:
   %5 = getelementptr inbounds i8, ptr %C, i64 1
   %6 = load i8, ptr %5, align 1
   %7 = zext i8 %6 to i32
   br label %join
 
 join:
   %8 = phi i32 [ %3, %0 ], [ %7, %sub_is_zero ]
   %cmp = icmp ne i32 %8, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_ne_phi_node_can_fold_4(ptr %C) {
 ; CHECK-LABEL: @cmp_ne_phi_node_can_fold_4(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
-; CHECK-NEXT:    [[TMP8:%.*]] = add nsw i32 [[TMP7]], -49
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
-; CHECK-NEXT:    br i1 [[TMP9]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 49
+; CHECK-NEXT:    br i1 [[TMP5]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
 ; CHECK:       sub_is_zero1:
-; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
-; CHECK-NEXT:    [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
-; CHECK-NEXT:    [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
+; CHECK-NEXT:    [[TMP7:%.*]] = load i8, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ne i8 [[TMP7]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP13:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP8]], [[SUB_IS_ZERO]] ], [ [[TMP12]], [[SUB_IS_ZERO1]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP13]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ false, [[SUB_IS_ZERO]] ], [ [[TMP8]], [[SUB_IS_ZERO1]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero
 
join:
   %13 = phi i32 [ %3, %0 ], [ %8, %sub_is_zero ], [ %12, %sub_is_zero1 ]
   %cmp = icmp ne i32 %13, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_sgt_phi_node_can_fold_1(ptr %C) {
 ; CHECK-LABEL: @cmp_sgt_phi_node_can_fold_1(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp ne i8 [[TMP4]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP8:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP7]], [[SUB_IS_ZERO]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP8]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ [[TMP5]], [[SUB_IS_ZERO]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero
 
 sub_is_zero:
   %5 = getelementptr inbounds i8, ptr %C, i64 1
   %6 = load i8, ptr %5, align 1
   %7 = zext i8 %6 to i32
   br label %join
 
 join:
   %8 = phi i32 [ %3, %0 ], [ %7, %sub_is_zero ]
   %cmp = icmp sgt i32 %8, 0
   ret i1 %cmp
 }
 
 define i1 @cmp_sgt_phi_node_can_fold_2(ptr %C) {
 ; CHECK-LABEL: @cmp_sgt_phi_node_can_fold_2(
 ; CHECK-NEXT:    [[TMP1:%.*]] = load i8, ptr [[C:%.*]], align 1
-; CHECK-NEXT:    [[TMP2:%.*]] = zext i8 [[TMP1]] to i32
-; CHECK-NEXT:    [[TMP3:%.*]] = add nsw i32 [[TMP2]], -48
-; CHECK-NEXT:    [[TMP4:%.*]] = icmp eq i32 [[TMP3]], 0
-; CHECK-NEXT:    br i1 [[TMP4]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
+; CHECK-NEXT:    [[TMP2:%.*]] = icmp eq i8 [[TMP1]], 48
+; CHECK-NEXT:    br i1 [[TMP2]], label [[JOIN:%.*]], label [[SUB_IS_ZERO:%.*]]
 ; CHECK:       sub_is_zero:
-; CHECK-NEXT:    [[TMP5:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
-; CHECK-NEXT:    [[TMP6:%.*]] = load i8, ptr [[TMP5]], align 1
-; CHECK-NEXT:    [[TMP7:%.*]] = zext i8 [[TMP6]] to i32
-; CHECK-NEXT:    [[TMP8:%.*]] = add nsw i32 [[TMP7]], -49
-; CHECK-NEXT:    [[TMP9:%.*]] = icmp eq i32 [[TMP8]], 0
-; CHECK-NEXT:    br i1 [[TMP9]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
+; CHECK-NEXT:    [[TMP3:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 1
+; CHECK-NEXT:    [[TMP4:%.*]] = load i8, ptr [[TMP3]], align 1
+; CHECK-NEXT:    [[TMP5:%.*]] = icmp eq i8 [[TMP4]], 49
+; CHECK-NEXT:    br i1 [[TMP5]], label [[JOIN]], label [[SUB_IS_ZERO1:%.*]]
 ; CHECK:       sub_is_zero1:
-; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
-; CHECK-NEXT:    [[TMP11:%.*]] = load i8, ptr [[TMP10]], align 1
-; CHECK-NEXT:    [[TMP12:%.*]] = zext i8 [[TMP11]] to i32
+; CHECK-NEXT:    [[TMP6:%.*]] = getelementptr inbounds i8, ptr [[C]], i64 2
+; CHECK-NEXT:    [[TMP7:%.*]] = load i8, ptr [[TMP6]], align 1
+; CHECK-NEXT:    [[TMP8:%.*]] = icmp ne i8 [[TMP7]], 0
 ; CHECK-NEXT:    br label [[JOIN]]
 ; CHECK:       join:
-; CHECK-NEXT:    [[TMP13:%.*]] = phi i32 [ [[TMP3]], [[TMP0:%.*]] ], [ [[TMP8]], [[SUB_IS_ZERO]] ], [ [[TMP12]], [[SUB_IS_ZERO1]] ]
-; CHECK-NEXT:    [[CMP:%.*]] = icmp ne i32 [[TMP13]], 0
+; CHECK-NEXT:    [[CMP:%.*]] = phi i1 [ false, [[TMP0:%.*]] ], [ false, [[SUB_IS_ZERO]] ], [ [[TMP8]], [[SUB_IS_ZERO1]] ]
 ; CHECK-NEXT:    ret i1 [[CMP]]
 ;
   %1 = load i8, ptr %C, align 1
   %2 = zext i8 %1 to i32
   %3 = sub nsw i32 %2, 48
   %4 = icmp eq i32 %3, 0
   br i1 %4, label %join, label %sub_is_zero