[GuardWidening] Support widening of explicitly expressed guards

[mkazantsev]

Summary

This patch adds support of guards expressed in explicit form via widenable_condition
in Guard Widening pass.

[mkazantsev]

test/Transforms/GuardWidening/basic_explicit_guards.ll

670

Actually I don't understand why we think that widening here is profitable in intrinsic case. Not sure if we should do it.

[mkazantsev]

test/Transforms/GuardWidening/basic_explicit_guards.ll

886

I've re-read the test carefully. We don't do it in intrinsic case and shouldn't. TODO is to be removed.

[mkazantsev]

lib/Transforms/Scalar/GuardWidening.cpp

495

Actually the problem is in PDT with infinite loops. This comment needs removed.

[mkazantsev]

Updated tests.

[reames]

lib/Transforms/Scalar/GuardWidening.cpp

87

As noted elsewhere, I dislike the explicit terminology. I'd suggest calling this guard-widening-include-widenable-conditions.

That naming does imply something slightly more general though, see further comments.

101

I really don't like the coupling between the single and matcher and the caller. What if we later extend the matcher to (v1 and (v2 and WC))?

402

Not sure this check is needed?

484

Having this adjust only one of the two variables looks awfully suspicious?

584

No, just no. You've screwed up your abstraction here. WideanbleCondition had better be either Cond1 or Cond2 for this function to have reasonable semantics.

[mkazantsev]

lib/Transforms/Scalar/GuardWidening.cpp

101

What is the benefit of that? When a guard looks like br((A & B) & WC()), it is possible to strip the widenable condition from it, getting (A & B). When we have something like br((A & WC) & B)`, stripping WC would need to create instructions that don't currently exist. I would better stick to one canonical form, the more that it is easy to sustain.

402

The logic here is a bit messy, I'll try to find a way to refactor the code around to go without it if possible.

484

We can widen *any* condition (in theory even not a condition from guard) into a dominating guard. Here we require that the dominating guard is what we are trying to support, and the dominated instruction can be anything with condition. Maybe the renaming in underlying code would make sense.

[mkazantsev]

Refactored underlying code to get rid of non-obvious things in logic. Rebased.

[reames]

A few minor tweaks left, but rapidly approaching ready to land.

lib/Transforms/Scalar/GuardWidening.cpp

402

See my response to one of your NFC cleanups on how this can be removed entirely.

544

This bit of code would make a lot more sense in the caller widenGuard - it's only needed by one of two callers - and would require a lot less code as well.

test/Transforms/GuardWidening/basic_explicit_guards.ll

6

This declaration is unused. Can you fix that by adding at least two tests mixing guards and widenable conditions? (i.e. one each widening from the other)

[mkazantsev]

test/Transforms/GuardWidening/basic_explicit_guards.ll

6

These tests have already be derived from test/Transforms/GuardWidening/basic.ll Does it make sense to duplicate?

[mkazantsev]

Housted logic from widenCondCommon to widenGuard.

[mkazantsev]

Removed redundant code by an NFC, rebased.

[mkazantsev]

test/Transforms/GuardWidening/basic_explicit_guards.ll

6

i.e. these tests are directly derived from tests from basic.ll using MakeGuardsExplicit pass. I'm not sure that it makes sense to have them in two files at the same time.

[reames]

LGTM w/two required follow ups. Can be before or after landing.

lib/Transforms/Scalar/GuardWidening.cpp

279

minor: We're not changing toWiden, so this can be done as a single check below the call to widenCondCommon

test/Transforms/GuardWidening/basic_explicit_guards.ll

6

Max, I can't follow your response to my comment here. I'm asking for a test mixing guards and wideable conditions. That is not tested elsewhere. I don't care which file you put the tests in provided you add them.

[mkazantsev]

Added test with mixed guards (both intrinsic and widenable conditions).

lib/Transforms/Scalar/GuardWidening.cpp

static cl::opt<unsigned> FrequentBranchThreshold(
     "guard-widening-frequent-branch-threshold", cl::Hidden,
     cl::desc("When WidenFrequentBranches is set to true, this option is used "
              "to determine which branches are frequently taken. The criteria "
              "that a branch is taken more often than "
              "((FrequentBranchThreshold - 1) / FrequentBranchThreshold), then "
              "it is considered frequently taken"),
     cl::init(1000));
 
+static cl::opt<bool>
+    WidenExplicitGuards("guard-widening-widen-explicit-guards", cl::Hidden,
+                        cl::desc("Whether or not we should widen guards "
+                                 "expressed in explicit control flow form "),
+                        cl::init(true));
 
 namespace {
 
 // Get the condition of \p I. It can either be a guard or a conditional branch.
 static Value *getCondition(Instruction *I) {
   if (IntrinsicInst *GI = dyn_cast<IntrinsicInst>(I)) {
     assert(GI->getIntrinsicID() == Intrinsic::experimental_guard &&
            "Bad guard intrinsic?");
     return GI->getArgOperand(0);
   }
+  if (isExplicitGuard(I)) {
+    auto *Cond = cast<BranchInst>(I)->getCondition();
+    return cast<BinaryOperator>(Cond)->getOperand(0);
+  }
   return cast<BranchInst>(I)->getCondition();
 }
 
 // Set the condition for \p I to \p NewCond. \p I can either be a guard or a
 // conditional branch.
 static void setCondition(Instruction *I, Value *NewCond) {
   if (IntrinsicInst *GI = dyn_cast<IntrinsicInst>(I)) {
     assert(GI->getIntrinsicID() == Intrinsic::experimental_guard &&
class GuardWideningImpl {
   }
 
   /// If \p InvertCondition is false, Widen \p ToWiden to fail if
   /// \p NewCondition is false, otherwise make it fail if \p NewCondition is
   /// true (in addition to whatever it is already checking).
   void widenGuard(Instruction *ToWiden, Value *NewCondition,
                   bool InvertCondition) {
     Value *Result;
-    widenCondCommon(ToWiden->getOperand(0), NewCondition, ToWiden, Result,
+    widenCondCommon(getCondition(ToWiden), NewCondition, ToWiden, Result,
                     InvertCondition);
     setCondition(ToWiden, Result);
   }
 
 public:
 
   explicit GuardWideningImpl(DominatorTree &DT, PostDominatorTree *PDT,
                              LoopInfo &LI, BranchProbabilityInfo *BPI,
                              DomTreeNode *Root,
                              std::function<bool(BasicBlock*)> BlockFilter)
     : DT(DT), PDT(PDT), LI(LI), BPI(BPI), Root(Root), BlockFilter(BlockFilter)
         {}
 
   /// The entry point for this pass.
   bool run();
 };
 }
 
+static bool isSupportedGuardInstruction(const Instruction *Insn) {
+  if (isGuard(Insn))
+    return true;
+  if (WidenExplicitGuards && isExplicitGuard(Insn))
+    return true;
+  return false;
+}
+
 bool GuardWideningImpl::run() {
   DenseMap<BasicBlock *, SmallVector<Instruction *, 8>> GuardsInBlock;
   bool Changed = false;
   Optional<BranchProbability> LikelyTaken = None;
   if (WidenFrequentBranches && BPI) {
     unsigned Threshold = FrequentBranchThreshold;
     assert(Threshold > 0 && "Zero threshold makes no sense!");
     LikelyTaken = BranchProbability(Threshold - 1, Threshold);
   }
 
   for (auto DFI = df_begin(Root), DFE = df_end(Root);
        DFI != DFE; ++DFI) {
     auto *BB = (*DFI)->getBlock();
     if (!BlockFilter(BB))
       continue;
 
     auto &CurrentList = GuardsInBlock[BB];
 
     for (auto &I : *BB)
-      if (isGuard(&I))
+      if (isSupportedGuardInstruction(&I))
         CurrentList.push_back(cast<Instruction>(&I));
 
     for (auto *II : CurrentList)
       Changed |= eliminateGuardViaWidening(II, DFI, GuardsInBlock);
     if (WidenFrequentBranches && BPI)
       if (auto *BI = dyn_cast<BranchInst>(BB->getTerminator()))
         if (BI->isConditional()) {
           // If one of branches of a conditional is likely taken, try to
           // eliminate it.
           if (BPI->getEdgeProbability(BB, 0U) >= *LikelyTaken)
             Changed |= eliminateGuardViaWidening(BI, DFI, GuardsInBlock);
           else if (BPI->getEdgeProbability(BB, 1U) >= *LikelyTaken)
             Changed |= eliminateGuardViaWidening(BI, DFI, GuardsInBlock,
                                                  /*InvertCondition*/true);
         }
   }
 
   assert(EliminatedGuardsAndBranches.empty() || Changed);
   for (auto *I : EliminatedGuardsAndBranches)
     if (!WidenedGuards.count(I)) {
       assert(isa<ConstantInt>(getCondition(I)) && "Should be!");
-      if (isGuard(I))
+      if (isSupportedGuardInstruction(I))
         eliminateGuard(I);
       else {
         assert(isa<BranchInst>(I) &&
                "Eliminated something other than guard or branch?");
         ++CondBranchEliminated;
       }
     }
 
#ifndef NDEBUG
       }
       assert(Index == GuardsInCurBB.size() &&
              "Guards expected to be in order!");
     }
 #endif
 
     assert((i == (e - 1)) == (GuardInst->getParent() == CurBB) && "Bad DFS?");
 
-    if (i == (e - 1) && CurBB->getTerminator() != GuardInst) {
+    if (i == (e - 1) && (CurBB->getTerminator() != GuardInst ||
+                         isExplicitGuard(CurBB->getTerminator()))) {
       // Corner case: make sure we're only looking at guards strictly dominating
       // GuardInst when visiting GuardInst->getParent().
       auto NewEnd = std::find(I, E, GuardInst);
       assert(NewEnd != E && "GuardInst not in its own block?");
       E = NewEnd;
     }
 
     for (auto *Candidate : make_range(I, E)) {
if (HoistingOutOfLoop)
     return WS_Positive;
 
   // Returns true if we might be hoisting above explicit control flow.  Note
   // that this completely ignores implicit control flow (guards, calls which
   // throw, etc...).  That choice appears arbitrary.
   auto MaybeHoistingOutOfIf = [&]() {
     auto *DominatingBlock = DominatingGuard->getParent();
     auto *DominatedBlock = DominatedGuard->getParent();
+    if (isExplicitGuard(DominatingGuard))
+      DominatingBlock = cast<BranchInst>(DominatingGuard)->getSuccessor(0);
 
     // Same Block?
     if (DominatedBlock == DominatingBlock)
       return false;
     // Obvious successor (common loop header/preheader case)
     if (DominatedBlock == DominatingBlock->getUniqueSuccessor())
       return false;
     // TODO: diamond, triangle cases
     if (!PDT) return true;
+    // TODO: This is not working well with explicit guards, see examples at
+    // test/Transforms/GuardWidening/basic_explicit_guards.ll, tests f_11 and
+    // f_14. We should make something smarter here.
     return !PDT->dominates(DominatedBlock, DominatingBlock);
   };
 
   return MaybeHoistingOutOfIf() ? WS_IllegalOrNegative : WS_Neutral;
 }
 
 bool GuardWideningImpl::isAvailableAt(Value *V, Instruction *Loc,
                                       SmallPtrSetImpl<Instruction *> &Visited) {
void GuardWideningImpl::makeAvailableAt(Value *V, Instruction *Loc) {
   Inst->moveBefore(Loc);
 }
 
 bool GuardWideningImpl::widenCondCommon(Value *Cond0, Value *Cond1,
                                         Instruction *InsertPt, Value *&Result,
                                         bool InvertCondition) {
   using namespace llvm::PatternMatch;
 
+  Value *WidenableCondition = nullptr;
+  if (InsertPt && isExplicitGuard(InsertPt)) {
+    auto *Cond = cast<BranchInst>(InsertPt)->getCondition();
+    WidenableCondition = cast<BinaryOperator>(Cond)->getOperand(1);
+  }
+
   {
     // L >u C0 && L >u C1  ->  L >u max(C0, C1)
     ConstantInt *RHS0, *RHS1;
     Value *LHS;
     ICmpInst::Predicate Pred0, Pred1;
     if (match(Cond0, m_ICmp(Pred0, m_Value(LHS), m_ConstantInt(RHS0))) &&
         match(Cond1, m_ICmp(Pred1, m_Specific(LHS), m_ConstantInt(RHS1)))) {
       if (InvertCondition)
if (match(Cond0, m_ICmp(Pred0, m_Value(LHS), m_ConstantInt(RHS0))) &&
 
       APInt NewRHSAP;
       CmpInst::Predicate Pred;
       if (SubsetIntersect == SupersetIntersect &&
           SubsetIntersect.getEquivalentICmp(Pred, NewRHSAP)) {
         if (InsertPt) {
           ConstantInt *NewRHS = ConstantInt::get(Cond0->getContext(), NewRHSAP);
           Result = new ICmpInst(InsertPt, Pred, LHS, NewRHS, "wide.chk");
+          if (WidenableCondition)
+            Result = BinaryOperator::CreateAnd(Result, WidenableCondition,
+                                               "guard.chk", InsertPt);
         }
         return true;
       }
     }
   }
 
   {
     SmallVector<GuardWideningImpl::RangeCheck, 4> Checks, CombinedChecks;
     // TODO: Support InvertCondition case?
     if (!InvertCondition &&
         parseRangeChecks(Cond0, Checks) && parseRangeChecks(Cond1, Checks) &&
         combineRangeChecks(Checks, CombinedChecks)) {
       if (InsertPt) {
         Result = nullptr;
         for (auto &RC : CombinedChecks) {
           makeAvailableAt(RC.getCheckInst(), InsertPt);
           if (Result)
             Result = BinaryOperator::CreateAnd(RC.getCheckInst(), Result, "",
                                                InsertPt);
           else
             Result = RC.getCheckInst();
         }
 
         Result->setName("wide.chk");
+        if (WidenableCondition)
+          Result = BinaryOperator::CreateAnd(Result, WidenableCondition,
+                                             "guard.chk", InsertPt);
       }
       return true;
     }
   }
 
   // Base case -- just logical-and the two conditions together.
 
   if (InsertPt) {
     makeAvailableAt(Cond0, InsertPt);
     makeAvailableAt(Cond1, InsertPt);
     if (InvertCondition)
       Cond1 = BinaryOperator::CreateNot(Cond1, "inverted", InsertPt);
     Result = BinaryOperator::CreateAnd(Cond0, Cond1, "wide.chk", InsertPt);
+    if (WidenableCondition)
+      Result = BinaryOperator::CreateAnd(Result, WidenableCondition,
+                                         "guard.chk", InsertPt);
   }
 
   // We were not able to compute Cond0 AND Cond1 for the price of one.
   return false;
 }
 
 bool GuardWideningImpl::parseRangeChecks(
     Value *CheckCond, SmallVectorImpl<GuardWideningImpl::RangeCheck> &Checks,

test/Transforms/GuardWidening/basic_explicit_guards.ll

+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -guard-widening-widen-explicit-guards=true -guard-widening < %s        | FileCheck %s
+; RUN: opt -S -guard-widening-widen-explicit-guards=true -passes=guard-widening < %s | FileCheck %s
+
+declare void @llvm.experimental.guard(i1, ...)
+
+; Basic test case: we wide the first check to check both the
+; conditions.
+define void @f_0(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_0(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_0]], [[COND_1:%.*]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  ret void
+}
+
+; Same as @f_0, but with using a more general notion of postdominance.
+define void @f_1(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_0]], [[COND_1:%.*]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       right:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  br label %merge
+
+right:                                            ; preds = %guarded
+  br label %merge
+
+merge:                                            ; preds = %right, %left
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %merge
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %merge
+  ret void
+}
+
+; Like @f_1, but we have some code we need to hoist before we can
+; widen a dominanting check.
+define void @f_2(i32 %a, i32 %b) {
+; CHECK-LABEL: @f_2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[A:%.*]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp ult i32 [[B:%.*]], 10
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_0]], [[COND_1]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    br label [[MERGE:%.*]]
+; CHECK:       right:
+; CHECK-NEXT:    br label [[MERGE]]
+; CHECK:       merge:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ult i32 %a, 10
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  br label %merge
+
+right:                                            ; preds = %guarded
+  br label %merge
+
+merge:                                            ; preds = %right, %left
+  %cond_1 = icmp ult i32 %b, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %merge
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %merge
+  ret void
+}
+
+; Negative test: don't hoist stuff out of control flow
+; indiscriminately, since that can make us do more work than needed.
+define void @f_3(i32 %a, i32 %b) {
+; CHECK-LABEL: @f_3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[A:%.*]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp ult i32 [[B:%.*]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+; CHECK:       right:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ult i32 %a, 10
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  %cond_1 = icmp ult i32 %b, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %left
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %left
+  ret void
+
+right:                                            ; preds = %guarded
+  ret void
+}
+
+; But hoisting out of control flow is fine if it makes a loop computed
+; condition loop invariant.  This behavior may require some tuning in
+; the future.
+define void @f_4(i32 %a, i32 %b) {
+; CHECK-LABEL: @f_4(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[A:%.*]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp ult i32 [[B:%.*]], 10
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_0]], [[COND_1]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LOOP:%.*]], label [[LEAVE:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    br i1 undef, label [[LOOP]], label [[LEAVE]]
+; CHECK:       leave:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ult i32 %a, 10
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %loop, label %leave
+
+loop:                                             ; preds = %guarded1, %guarded
+  %cond_1 = icmp ult i32 %b, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %loop
+  br i1 undef, label %loop, label %leave
+
+leave:                                            ; preds = %guarded1, %guarded
+  ret void
+}
+
+; Hoisting out of control flow is also fine if we can widen the
+; dominating check without doing any extra work.
+define void @f_5(i32 %a) {
+; CHECK-LABEL: @f_5(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ugt i32 [[A:%.*]], 7
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = icmp uge i32 [[A]], 11
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp ugt i32 [[A]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+; CHECK:       right:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ugt i32 %a, 7
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  %cond_1 = icmp ugt i32 %a, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %left
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %left
+  ret void
+
+right:                                            ; preds = %guarded
+  ret void
+}
+
+; Negative test: the load from %a can be safely speculated to before
+; the first guard, but there is no guarantee that it will produce the
+; same value.
+define void @f_6(i1* dereferenceable(32) %a, i1* %b, i1 %unknown) {
+; CHECK-LABEL: @f_6(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = load i1, i1* [[A:%.*]]
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    store i1 [[UNKNOWN:%.*]], i1* [[B:%.*]]
+; CHECK-NEXT:    [[COND_1:%.*]] = load i1, i1* [[A]]
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = load i1, i1* %a
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  store i1 %unknown, i1* %b
+  %cond_1 = load i1, i1* %a
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  ret void
+}
+
+; All else equal, we try to widen the earliest guard we can.  This
+; heuristic can use some tuning.
+define void @f_7(i32 %a, i1* %cond_buf) {
+; CHECK-LABEL: @f_7(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_1:%.*]] = load volatile i1, i1* [[COND_BUF:%.*]]
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[COND_3:%.*]] = icmp ult i32 [[A:%.*]], 7
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_1]], [[COND_3]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    [[COND_2:%.*]] = load volatile i1, i1* [[COND_BUF]]
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_2]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    [[WIDENABLE_COND7:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND8:%.*]] = and i1 [[COND_3]], [[WIDENABLE_COND7]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED5:%.*]], label [[DEOPT6:%.*]], !prof !0
+; CHECK:       deopt6:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded5:
+; CHECK-NEXT:    br label [[LEFT]]
+; CHECK:       right:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_1 = load volatile i1, i1* %cond_buf
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_1, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  %cond_2 = load volatile i1, i1* %cond_buf
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_2, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded5, %guarded1
+  %cond_3 = icmp ult i32 %a, 7
+  %widenable_cond7 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond8 = and i1 %cond_3, %widenable_cond7
+  br i1 %exiplicit_guard_cond8, label %guarded5, label %deopt6, !prof !0
+
+deopt6:                                           ; preds = %left
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded5:                                         ; preds = %left
+  br label %left
+
+right:                                            ; preds = %guarded1
+  ret void
+}
+
+; In this case the earliest dominating guard is in a loop, and we
+; don't want to put extra work in there.  This heuristic can use some
+; tuning.
+define void @f_8(i32 %a, i1 %cond_1, i1 %cond_2) {
+; CHECK-LABEL: @f_8(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_1:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LOOP]], label [[LEAVE:%.*]]
+; CHECK:       leave:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_2:%.*]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    [[COND_3:%.*]] = icmp ult i32 [[A:%.*]], 7
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 [[COND_2]], [[COND_3]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    br i1 undef, label [[LOOP2:%.*]], label [[LEAVE2:%.*]]
+; CHECK:       loop2:
+; CHECK-NEXT:    [[WIDENABLE_COND7:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND8:%.*]] = and i1 [[COND_3]], [[WIDENABLE_COND7]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED5:%.*]], label [[DEOPT6:%.*]], !prof !0
+; CHECK:       deopt6:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded5:
+; CHECK-NEXT:    br label [[LOOP2]]
+; CHECK:       leave2:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:                                             ; preds = %guarded, %entry
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_1, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %loop
+  br i1 undef, label %loop, label %leave
+
+leave:                                            ; preds = %guarded
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_2, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %leave
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %leave
+  br i1 undef, label %loop2, label %leave2
+
+loop2:                                            ; preds = %guarded5, %guarded1
+  %cond_3 = icmp ult i32 %a, 7
+  %widenable_cond7 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond8 = and i1 %cond_3, %widenable_cond7
+  br i1 %exiplicit_guard_cond8, label %guarded5, label %deopt6, !prof !0
+
+deopt6:                                           ; preds = %loop2
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded5:                                         ; preds = %loop2
+  br label %loop2
+
+leave2:                                           ; preds = %guarded1
+  ret void
+}
+
+; In cases like these where there isn't any "obviously profitable"
+; widening sites, we refuse to do anything.
+define void @f_9(i32 %a, i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_9(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[FIRST_LOOP:%.*]]
+; CHECK:       first_loop:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[FIRST_LOOP]], label [[SECOND_LOOP:%.*]]
+; CHECK:       second_loop:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1:%.*]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    br label [[SECOND_LOOP]]
+;
+entry:
+  br label %first_loop
+
+first_loop:                                       ; preds = %guarded, %entry
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %first_loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %first_loop
+  br i1 undef, label %first_loop, label %second_loop
+
+second_loop:                                      ; preds = %guarded1, %guarded
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %second_loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %second_loop
+  br label %second_loop
+}
+
+; Same situation as in @f_9: no "obviously profitable" widening sites,
+; so we refuse to do anything.
+define void @f_10(i32 %a, i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_10(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LOOP]], label [[NO_LOOP:%.*]]
+; CHECK:       no_loop:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1:%.*]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  br label %loop
+
+loop:                                             ; preds = %guarded, %entry
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %loop
+  br i1 undef, label %loop, label %no_loop
+
+no_loop:                                          ; preds = %guarded
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %no_loop
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %no_loop
+  ret void
+}
+
+; With guards in loops, we're okay hoisting out the guard into the
+; containing loop.
+; TODO: Support widening for this case. We do it for intrinsic guards.
+define void @f_11(i32 %a, i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_11(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[INNER:%.*]]
+; CHECK:       inner:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[INNER]], label [[OUTER:%.*]]
+; CHECK:       outer:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1:%.*]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    br label [[INNER]]
+;
+entry:
+  br label %inner
+
+inner:                                            ; preds = %guarded1, %guarded, %entry
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %inner
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %inner
+  br i1 undef, label %inner, label %outer
+
+outer:                                            ; preds = %guarded
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %outer
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %outer
+  br label %inner
+}
+
+; Checks that we are adequately guarded against exponential-time
+; behavior when hoisting code.
+define void @f_12(i32 %a0) {
+; CHECK-LABEL: @f_12(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 true, [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[A1:%.*]] = mul i32 [[A0:%.*]], [[A0]]
+; CHECK-NEXT:    [[A2:%.*]] = mul i32 [[A1]], [[A1]]
+; CHECK-NEXT:    [[A3:%.*]] = mul i32 [[A2]], [[A2]]
+; CHECK-NEXT:    [[A4:%.*]] = mul i32 [[A3]], [[A3]]
+; CHECK-NEXT:    [[A5:%.*]] = mul i32 [[A4]], [[A4]]
+; CHECK-NEXT:    [[A6:%.*]] = mul i32 [[A5]], [[A5]]
+; CHECK-NEXT:    [[A7:%.*]] = mul i32 [[A6]], [[A6]]
+; CHECK-NEXT:    [[A8:%.*]] = mul i32 [[A7]], [[A7]]
+; CHECK-NEXT:    [[A9:%.*]] = mul i32 [[A8]], [[A8]]
+; CHECK-NEXT:    [[A10:%.*]] = mul i32 [[A9]], [[A9]]
+; CHECK-NEXT:    [[A11:%.*]] = mul i32 [[A10]], [[A10]]
+; CHECK-NEXT:    [[A12:%.*]] = mul i32 [[A11]], [[A11]]
+; CHECK-NEXT:    [[A13:%.*]] = mul i32 [[A12]], [[A12]]
+; CHECK-NEXT:    [[A14:%.*]] = mul i32 [[A13]], [[A13]]
+; CHECK-NEXT:    [[A15:%.*]] = mul i32 [[A14]], [[A14]]
+; CHECK-NEXT:    [[A16:%.*]] = mul i32 [[A15]], [[A15]]
+; CHECK-NEXT:    [[A17:%.*]] = mul i32 [[A16]], [[A16]]
+; CHECK-NEXT:    [[A18:%.*]] = mul i32 [[A17]], [[A17]]
+; CHECK-NEXT:    [[A19:%.*]] = mul i32 [[A18]], [[A18]]
+; CHECK-NEXT:    [[A20:%.*]] = mul i32 [[A19]], [[A19]]
+; CHECK-NEXT:    [[A21:%.*]] = mul i32 [[A20]], [[A20]]
+; CHECK-NEXT:    [[A22:%.*]] = mul i32 [[A21]], [[A21]]
+; CHECK-NEXT:    [[A23:%.*]] = mul i32 [[A22]], [[A22]]
+; CHECK-NEXT:    [[A24:%.*]] = mul i32 [[A23]], [[A23]]
+; CHECK-NEXT:    [[A25:%.*]] = mul i32 [[A24]], [[A24]]
+; CHECK-NEXT:    [[A26:%.*]] = mul i32 [[A25]], [[A25]]
+; CHECK-NEXT:    [[A27:%.*]] = mul i32 [[A26]], [[A26]]
+; CHECK-NEXT:    [[A28:%.*]] = mul i32 [[A27]], [[A27]]
+; CHECK-NEXT:    [[A29:%.*]] = mul i32 [[A28]], [[A28]]
+; CHECK-NEXT:    [[A30:%.*]] = mul i32 [[A29]], [[A29]]
+; CHECK-NEXT:    [[COND:%.*]] = trunc i32 [[A30]] to i1
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = and i1 true, [[COND]]
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 true, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  %a1 = mul i32 %a0, %a0
+  %a2 = mul i32 %a1, %a1
+  %a3 = mul i32 %a2, %a2
+  %a4 = mul i32 %a3, %a3
+  %a5 = mul i32 %a4, %a4
+  %a6 = mul i32 %a5, %a5
+  %a7 = mul i32 %a6, %a6
+  %a8 = mul i32 %a7, %a7
+  %a9 = mul i32 %a8, %a8
+  %a10 = mul i32 %a9, %a9
+  %a11 = mul i32 %a10, %a10
+  %a12 = mul i32 %a11, %a11
+  %a13 = mul i32 %a12, %a12
+  %a14 = mul i32 %a13, %a13
+  %a15 = mul i32 %a14, %a14
+  %a16 = mul i32 %a15, %a15
+  %a17 = mul i32 %a16, %a16
+  %a18 = mul i32 %a17, %a17
+  %a19 = mul i32 %a18, %a18
+  %a20 = mul i32 %a19, %a19
+  %a21 = mul i32 %a20, %a20
+  %a22 = mul i32 %a21, %a21
+  %a23 = mul i32 %a22, %a22
+  %a24 = mul i32 %a23, %a23
+  %a25 = mul i32 %a24, %a24
+  %a26 = mul i32 %a25, %a25
+  %a27 = mul i32 %a26, %a26
+  %a28 = mul i32 %a27, %a27
+  %a29 = mul i32 %a28, %a28
+  %a30 = mul i32 %a29, %a29
+  %cond = trunc i32 %a30 to i1
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  ret void
+}
+
+define void @f_13(i32 %a) {
+; CHECK-LABEL: @f_13(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[A:%.*]], 14
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    [[WIDE_CHK:%.*]] = icmp ult i32 [[A]], 10
+; CHECK-NEXT:    [[GUARD_CHK:%.*]] = and i1 [[WIDE_CHK]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[GUARD_CHK]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp slt i32 [[A]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 true, label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+; CHECK:       right:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ult i32 %a, 14
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  %cond_1 = icmp slt i32 %a, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %left
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %left
+  ret void
+
+right:                                            ; preds = %guarded
+  ret void
+}
+
+; TODO: Support widening here. We do it for intrinsic guards.
+define void @f_14(i32 %a) {
+; CHECK-LABEL: @f_14(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[A:%.*]], 14
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    br i1 undef, label [[LEFT:%.*]], label [[RIGHT:%.*]]
+; CHECK:       left:
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp sgt i32 [[A]], 10
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 [[COND_1]], [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+; CHECK:       right:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %cond_0 = icmp ult i32 %a, 14
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  br i1 undef, label %left, label %right
+
+left:                                             ; preds = %guarded
+  %cond_1 = icmp sgt i32 %a, 10
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 %cond_1, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %left
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %left
+  ret void
+
+right:                                            ; preds = %guarded
+  ret void
+}
+
+; Make sure we do not widen guard by trivial true conditions into something.
+define void @f_15(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_15(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 true, [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 true, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  ret void
+}
+
+; Make sure we do not widen guard by trivial false conditions into something.
+define void @f_16(i1 %cond_0, i1 %cond_1) {
+; CHECK-LABEL: @f_16(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[WIDENABLE_COND:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND:%.*]] = and i1 [[COND_0:%.*]], [[WIDENABLE_COND]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND]], label [[GUARDED:%.*]], label [[DEOPT:%.*]], !prof !0
+; CHECK:       deopt:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded:
+; CHECK-NEXT:    [[WIDENABLE_COND3:%.*]] = call i1 @llvm.experimental.widenable.condition()
+; CHECK-NEXT:    [[EXIPLICIT_GUARD_COND4:%.*]] = and i1 false, [[WIDENABLE_COND3]]
+; CHECK-NEXT:    br i1 [[EXIPLICIT_GUARD_COND4]], label [[GUARDED1:%.*]], label [[DEOPT2:%.*]], !prof !0
+; CHECK:       deopt2:
+; CHECK-NEXT:    call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+; CHECK-NEXT:    ret void
+; CHECK:       guarded1:
+; CHECK-NEXT:    ret void
+;
+entry:
+  %widenable_cond = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond = and i1 %cond_0, %widenable_cond
+  br i1 %exiplicit_guard_cond, label %guarded, label %deopt, !prof !0
+
+deopt:                                            ; preds = %entry
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded:                                          ; preds = %entry
+  %widenable_cond3 = call i1 @llvm.experimental.widenable.condition()
+  %exiplicit_guard_cond4 = and i1 false, %widenable_cond3
+  br i1 %exiplicit_guard_cond4, label %guarded1, label %deopt2, !prof !0
+
+deopt2:                                           ; preds = %guarded
+  call void (...) @llvm.experimental.deoptimize.isVoid() [ "deopt"() ]
+  ret void
+
+guarded1:                                         ; preds = %guarded
+  ret void
+}
+
+declare void @llvm.experimental.deoptimize.isVoid(...)
+
+; Function Attrs: inaccessiblememonly nounwind
+declare i1 @llvm.experimental.widenable.condition() #0
+
+attributes #0 = { inaccessiblememonly nounwind }
+
+!0 = !{!"branch_weights", i32 1048576, i32 1}