4 files changed, 21 insertions, 19 deletions

diff --git a/llvm/include/llvm/Transforms/Utils/GuardUtils.h b/llvm/include/llvm/Transforms/Utils/GuardUtils.h
index 43cd267f59b..7ab5d9ef4f2 100644
--- a/llvm/include/llvm/Transforms/Utils/GuardUtils.h
+++ b/llvm/include/llvm/Transforms/Utils/GuardUtils.h
@@ -23,8 +23,11 @@ class Value;
 /// by the condition of guard's first argument. The taken branch then goes to
 /// the block that contains  \p Guard's successors, and the non-taken branch
 /// goes to a newly-created deopt block that contains a sole call of the
-/// deoptimize function \p DeoptIntrinsic.
-void makeGuardControlFlowExplicit(Function *DeoptIntrinsic, CallInst *Guard);
+/// deoptimize function \p DeoptIntrinsic.  If 'UseWC' is set, preserve the
+/// widenable nature of the guard by lowering to equivelent form.  If not set,
+/// lower to a form without widenable semantics.
+void makeGuardControlFlowExplicit(Function *DeoptIntrinsic, CallInst *Guard,
+                                  bool UseWC);
 
 /// Given a branch we know is widenable (defined per Analysis/GuardUtils.h),
 /// widen it such that condition 'NewCond' is also known to hold on the taken
diff --git a/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp b/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
index f8aa2802cce..45f5929e3b9 100644
--- a/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
+++ b/llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp
@@ -61,7 +61,7 @@ static bool lowerGuardIntrinsic(Function &F) {
   DeoptIntrinsic->setCallingConv(GuardDecl->getCallingConv());
 
   for (auto *CI : ToLower) {
-    makeGuardControlFlowExplicit(DeoptIntrinsic, CI);
+    makeGuardControlFlowExplicit(DeoptIntrinsic, CI, false);
     CI->eraseFromParent();
   }
 
diff --git a/llvm/lib/Transforms/Scalar/MakeGuardsExplicit.cpp b/llvm/lib/Transforms/Scalar/MakeGuardsExplicit.cpp
index fd8a3643cff..0e3fcf0eb77 100644
--- a/llvm/lib/Transforms/Scalar/MakeGuardsExplicit.cpp
+++ b/llvm/lib/Transforms/Scalar/MakeGuardsExplicit.cpp
@@ -58,22 +58,9 @@ struct MakeGuardsExplicitLegacyPass : public FunctionPass {
 static void turnToExplicitForm(CallInst *Guard, Function *DeoptIntrinsic) {
   // Replace the guard with an explicit branch (just like in GuardWidening).
   BasicBlock *BB = Guard->getParent();
-  makeGuardControlFlowExplicit(DeoptIntrinsic, Guard);
-  BranchInst *ExplicitGuard = cast<BranchInst>(BB->getTerminator());
-  assert(ExplicitGuard->isConditional() && "Must be!");
+  makeGuardControlFlowExplicit(DeoptIntrinsic, Guard, true);
+  assert(isWidenableBranch(BB->getTerminator()) && "should hold");
 
-  // We want the guard to be expressed as explicit control flow, but still be
-  // widenable. For that, we add Widenable Condition intrinsic call to the
-  // guard's condition.
-  IRBuilder<> B(ExplicitGuard);
-  auto *WidenableCondition =
-      B.CreateIntrinsic(Intrinsic::experimental_widenable_condition,
-                        {}, {}, nullptr, "widenable_cond");
-  WidenableCondition->setCallingConv(Guard->getCallingConv());
-  auto *NewCond =
-      B.CreateAnd(ExplicitGuard->getCondition(), WidenableCondition);
-  NewCond->setName("exiplicit_guard_cond");
-  ExplicitGuard->setCondition(NewCond);
   Guard->eraseFromParent();
 }
 
diff --git a/llvm/lib/Transforms/Utils/GuardUtils.cpp b/llvm/lib/Transforms/Utils/GuardUtils.cpp
index 37fca0d129b..b8c4c764e74 100644
--- a/llvm/lib/Transforms/Utils/GuardUtils.cpp
+++ b/llvm/lib/Transforms/Utils/GuardUtils.cpp
@@ -26,7 +26,7 @@ static cl::opt<uint32_t> PredicatePassBranchWeight(
              "reciprocal of this value (default = 1 << 20)"));
 
 void llvm::makeGuardControlFlowExplicit(Function *DeoptIntrinsic,
-                                        CallInst *Guard) {
+                                        CallInst *Guard, bool UseWC) {
   OperandBundleDef DeoptOB(*Guard->getOperandBundle(LLVMContext::OB_deopt));
   SmallVector<Value *, 4> Args(std::next(Guard->arg_begin()), Guard->arg_end());
 
@@ -62,6 +62,18 @@ void llvm::makeGuardControlFlowExplicit(Function *DeoptIntrinsic,
 
   DeoptCall->setCallingConv(Guard->getCallingConv());
   DeoptBlockTerm->eraseFromParent();
+
+  if (UseWC) {
+    // We want the guard to be expressed as explicit control flow, but still be
+    // widenable. For that, we add Widenable Condition intrinsic call to the
+    // guard's condition.
+    IRBuilder<> B(CheckBI);
+    auto *WC = B.CreateIntrinsic(Intrinsic::experimental_widenable_condition,
+                                 {}, {}, nullptr, "widenable_cond");
+    CheckBI->setCondition(B.CreateAnd(CheckBI->getCondition(), WC,
+                                      "exiplicit_guard_cond"));
+    assert(isWidenableBranch(CheckBI) && "sanity check");
+  }
 }