1 files changed, 65 insertions, 2 deletions
diff --git a/llvm/lib/Transforms/Utils/GuardUtils.cpp b/llvm/lib/Transforms/Utils/GuardUtils.cpp
index 34c32d9c0c98..4cfc9358499a 100644
--- a/llvm/lib/Transforms/Utils/GuardUtils.cpp
+++ b/llvm/lib/Transforms/Utils/GuardUtils.cpp
@@ -10,13 +10,17 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Utils/GuardUtils.h"
+#include "llvm/Analysis/GuardUtils.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/Instructions.h"
 #include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
 #include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/PatternMatch.h"
+#include "llvm/Support/CommandLine.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
 using namespace llvm;
+using namespace llvm::PatternMatch;
 
 static cl::opt<uint32_t> PredicatePassBranchWeight(
     "guards-predicate-pass-branch-weight", cl::Hidden, cl::init(1 << 20),
@@ -24,7 +28,7 @@ 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());
 
@@ -60,4 +64,63 @@ 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");
+  }
+}
+
+
+void llvm::widenWidenableBranch(BranchInst *WidenableBR, Value *NewCond) {
+  assert(isWidenableBranch(WidenableBR) && "precondition");
+
+  // The tempting trivially option is to produce something like this:
+  // br (and oldcond, newcond) where oldcond is assumed to contain a widenable
+  // condition, but that doesn't match the pattern parseWidenableBranch expects
+  // so we have to be more sophisticated.
+
+  Use *C, *WC;
+  BasicBlock *IfTrueBB, *IfFalseBB;
+  parseWidenableBranch(WidenableBR, C, WC, IfTrueBB, IfFalseBB);
+  if (!C) {
+    // br (wc()), ... form
+    IRBuilder<> B(WidenableBR);
+    WidenableBR->setCondition(B.CreateAnd(NewCond, WC->get()));
+  } else {
+    // br (wc & C), ... form
+    IRBuilder<> B(WidenableBR);
+    C->set(B.CreateAnd(NewCond, C->get()));
+    Instruction *WCAnd = cast<Instruction>(WidenableBR->getCondition());
+    // Condition is only guaranteed to dominate branch
+    WCAnd->moveBefore(WidenableBR);    
+  }
+  assert(isWidenableBranch(WidenableBR) && "preserve widenabiliy");
+}
+
+void llvm::setWidenableBranchCond(BranchInst *WidenableBR, Value *NewCond) {
+  assert(isWidenableBranch(WidenableBR) && "precondition");
+
+  Use *C, *WC;
+  BasicBlock *IfTrueBB, *IfFalseBB;
+  parseWidenableBranch(WidenableBR, C, WC, IfTrueBB, IfFalseBB);
+  if (!C) {
+    // br (wc()), ... form
+    IRBuilder<> B(WidenableBR);
+    WidenableBR->setCondition(B.CreateAnd(NewCond, WC->get()));
+  } else {
+    // br (wc & C), ... form
+    Instruction *WCAnd = cast<Instruction>(WidenableBR->getCondition());
+    // Condition is only guaranteed to dominate branch
+    WCAnd->moveBefore(WidenableBR);
+    C->set(NewCond);
+  }
+  assert(isWidenableBranch(WidenableBR) && "preserve widenabiliy");
 }