[NFC] Factor out guard utility methods into a separate file

[mkazantsev]

Summary

This patch creates file GuardUtils which will contain logic for work with guards
that can be shared across different passes.

[fedor.sergeev]

LGTM, assuming that it is mostly the code movement.
I did not spend any effort to verify that code movement did not affect semantics :)

include/llvm/Transforms/Utils/GuardUtils.h

23

remove "previous" here, it does not add anything and is a bit confusing.

include/llvm/Transforms/Utils/GuardUtils.h

+//===-- GuardUtils.h - Utils for work with guards ---------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Utils that are used to perform transformations related to guards and their
+// conditions.
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TRANSFORMS_UTILS_GUARDUTILS_H
+#define LLVM_TRANSFORMS_UTILS_GUARDUTILS_H
+
+namespace llvm {
+
+class CallInst;
+class Function;
+
+/// Splits control flow at point of \p Guard, replacing it with explicit branch
+/// by the condition of guard's first argument. The taken branch then goes to
+/// the block that contains previous \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);
+
+} // llvm
+
+#endif // LLVM_TRANSFORMS_UTILS_GUARDUTILS_H

lib/Transforms/Scalar/LowerGuardIntrinsic.cpp

 // be widened.
 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Transforms/Scalar/LowerGuardIntrinsic.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/IR/BasicBlock.h"
 #include "llvm/IR/Function.h"
-#include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/InstIterator.h"
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/Intrinsics.h"
-#include "llvm/IR/MDBuilder.h"
 #include "llvm/IR/Module.h"
 #include "llvm/Pass.h"
 #include "llvm/Transforms/Scalar.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 
 using namespace llvm;
 
-static cl::opt<uint32_t> PredicatePassBranchWeight(
-    "guards-predicate-pass-branch-weight", cl::Hidden, cl::init(1 << 20),
-    cl::desc("The probability of a guard failing is assumed to be the "
-             "reciprocal of this value (default = 1 << 20)"));
-
 namespace {
 struct LowerGuardIntrinsicLegacyPass : public FunctionPass {
   static char ID;
   LowerGuardIntrinsicLegacyPass() : FunctionPass(ID) {
     initializeLowerGuardIntrinsicLegacyPassPass(
         *PassRegistry::getPassRegistry());
   }
 
   bool runOnFunction(Function &F) override;
 };
 }
 
-static void MakeGuardControlFlowExplicit(Function *DeoptIntrinsic,
-                                         CallInst *CI) {
-  OperandBundleDef DeoptOB(*CI->getOperandBundle(LLVMContext::OB_deopt));
-  SmallVector<Value *, 4> Args(std::next(CI->arg_begin()), CI->arg_end());
-
-  auto *CheckBB = CI->getParent();
-  auto *DeoptBlockTerm =
-      SplitBlockAndInsertIfThen(CI->getArgOperand(0), CI, true);
-
-  auto *CheckBI = cast<BranchInst>(CheckBB->getTerminator());
-
-  // SplitBlockAndInsertIfThen inserts control flow that branches to
-  // DeoptBlockTerm if the condition is true.  We want the opposite.
-  CheckBI->swapSuccessors();
-
-  CheckBI->getSuccessor(0)->setName("guarded");
-  CheckBI->getSuccessor(1)->setName("deopt");
-
-  if (auto *MD = CI->getMetadata(LLVMContext::MD_make_implicit))
-    CheckBI->setMetadata(LLVMContext::MD_make_implicit, MD);
-
-  MDBuilder MDB(CI->getContext());
-  CheckBI->setMetadata(LLVMContext::MD_prof,
-                       MDB.createBranchWeights(PredicatePassBranchWeight, 1));
-
-  IRBuilder<> B(DeoptBlockTerm);
-  auto *DeoptCall = B.CreateCall(DeoptIntrinsic, Args, {DeoptOB}, "");
-
-  if (DeoptIntrinsic->getReturnType()->isVoidTy()) {
-    B.CreateRetVoid();
-  } else {
-    DeoptCall->setName("deoptcall");
-    B.CreateRet(DeoptCall);
-  }
-
-  DeoptCall->setCallingConv(CI->getCallingConv());
-  DeoptBlockTerm->eraseFromParent();
-}
-
 static bool lowerGuardIntrinsic(Function &F) {
   // Check if we can cheaply rule out the possibility of not having any work to
   // do.
   auto *GuardDecl = F.getParent()->getFunction(
       Intrinsic::getName(Intrinsic::experimental_guard));
   if (!GuardDecl || GuardDecl->use_empty())
     return false;
 
   SmallVector<CallInst *, 8> ToLower;
   for (auto &I : instructions(F))
     if (auto *CI = dyn_cast<CallInst>(&I))
       if (auto *F = CI->getCalledFunction())
         if (F->getIntrinsicID() == Intrinsic::experimental_guard)
           ToLower.push_back(CI);
 
   if (ToLower.empty())
     return false;
 
   auto *DeoptIntrinsic = Intrinsic::getDeclaration(
       F.getParent(), Intrinsic::experimental_deoptimize, {F.getReturnType()});
   DeoptIntrinsic->setCallingConv(GuardDecl->getCallingConv());
 
   for (auto *CI : ToLower) {
-    MakeGuardControlFlowExplicit(DeoptIntrinsic, CI);
+    makeGuardControlFlowExplicit(DeoptIntrinsic, CI);
     CI->eraseFromParent();
   }
 
   return true;
 }
 
 bool LowerGuardIntrinsicLegacyPass::runOnFunction(Function &F) {
   return lowerGuardIntrinsic(F);

lib/Transforms/Utils/CMakeLists.txt

add_llvm_library(LLVMTransformUtils
   DemoteRegToStack.cpp
   EntryExitInstrumenter.cpp
   EscapeEnumerator.cpp
   Evaluator.cpp
   FlattenCFG.cpp
   FunctionComparator.cpp
   FunctionImportUtils.cpp
   GlobalStatus.cpp
+  GuardUtils.cpp
   ImplicitControlFlowTracking.cpp
   InlineFunction.cpp
   ImportedFunctionsInliningStatistics.cpp
   InstructionNamer.cpp
   IntegerDivision.cpp
   LCSSA.cpp
   LibCallsShrinkWrap.cpp
   Local.cpp

lib/Transforms/Utils/GuardUtils.cpp

+//===-- GuardUtils.cpp - Utils for work with guards -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// Utils that are used to perform transformations related to guards and their
+// conditions.
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Transforms/Utils/GuardUtils.h"
+#include "llvm/IR/Function.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/MDBuilder.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+
+using namespace llvm;
+
+static cl::opt<uint32_t> PredicatePassBranchWeight(
+    "guards-predicate-pass-branch-weight", cl::Hidden, cl::init(1 << 20),
+    cl::desc("The probability of a guard failing is assumed to be the "
+             "reciprocal of this value (default = 1 << 20)"));
+
+void llvm::makeGuardControlFlowExplicit(Function *DeoptIntrinsic,
+                                        CallInst *Guard) {
+  OperandBundleDef DeoptOB(*Guard->getOperandBundle(LLVMContext::OB_deopt));
+  SmallVector<Value *, 4> Args(std::next(Guard->arg_begin()), Guard->arg_end());
+
+  auto *CheckBB = Guard->getParent();
+  auto *DeoptBlockTerm =
+      SplitBlockAndInsertIfThen(Guard->getArgOperand(0), Guard, true);
+
+  auto *CheckBI = cast<BranchInst>(CheckBB->getTerminator());
+
+  // SplitBlockAndInsertIfThen inserts control flow that branches to
+  // DeoptBlockTerm if the condition is true.  We want the opposite.
+  CheckBI->swapSuccessors();
+
+  CheckBI->getSuccessor(0)->setName("guarded");
+  CheckBI->getSuccessor(1)->setName("deopt");
+
+  if (auto *MD = Guard->getMetadata(LLVMContext::MD_make_implicit))
+    CheckBI->setMetadata(LLVMContext::MD_make_implicit, MD);
+
+  MDBuilder MDB(Guard->getContext());
+  CheckBI->setMetadata(LLVMContext::MD_prof,
+                       MDB.createBranchWeights(PredicatePassBranchWeight, 1));
+
+  IRBuilder<> B(DeoptBlockTerm);
+  auto *DeoptCall = B.CreateCall(DeoptIntrinsic, Args, {DeoptOB}, "");
+
+  if (DeoptIntrinsic->getReturnType()->isVoidTy()) {
+    B.CreateRetVoid();
+  } else {
+    DeoptCall->setName("deoptcall");
+    B.CreateRet(DeoptCall);
+  }
+
+  DeoptCall->setCallingConv(Guard->getCallingConv());
+  DeoptBlockTerm->eraseFromParent();
+}