[NFC] Unify guards detection

We have multiple places in code where we try to identify whether or not
some instruction is a guard. This patch factors out this logic into a separate
utility function which works uniformly in all places.

Differential Revision: https://reviews.llvm.org/D51152
Reviewed By: fedor.sergeev

llvm-svn: 340921

llvm/include/llvm/Transforms/Utils/GuardUtils.h

@@ -17,6 +17,10 @@ namespace llvm {
 
 class CallInst;
 class Function;
+class User;
+
+/// Returns true iff \p U has semantics of a guard.
+bool isGuard(const User *U);
 
 /// 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

llvm/lib/Analysis/AliasSetTracker.cpp

@@ -34,6 +34,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include <cassert>
 #include <cstdint>
 #include <vector>
@@ -172,8 +173,7 @@ void AliasSet::addUnknownInst(Instruction *I, AliasAnalysis &AA) {
   // Guards are marked as modifying memory for control flow modelling purposes,
   // but don't actually modify any specific memory location.
   using namespace PatternMatch;
-  bool MayWriteMemory = I->mayWriteToMemory() &&
-    !match(I, m_Intrinsic<Intrinsic::experimental_guard>()) &&
+  bool MayWriteMemory = I->mayWriteToMemory() && !isGuard(I) &&
     !(I->use_empty() && match(I, m_Intrinsic<Intrinsic::invariant_start>()));
   if (!MayWriteMemory) {
     Alias = SetMayAlias;

llvm/lib/Analysis/ValueTracking.cpp

@@ -66,6 +66,7 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/KnownBits.h"
 #include "llvm/Support/MathExtras.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include <algorithm>
 #include <array>
 #include <cassert>
@@ -1902,8 +1903,7 @@ static bool isKnownNonNullFromDominatingCondition(const Value *V,
           BasicBlockEdge Edge(BI->getParent(), NonNullSuccessor);
           if (Edge.isSingleEdge() && DT->dominates(Edge, CtxI->getParent()))
             return true;
-        } else if (Pred == ICmpInst::ICMP_NE &&
-                   match(Curr, m_Intrinsic<Intrinsic::experimental_guard>()) &&
+        } else if (Pred == ICmpInst::ICMP_NE && isGuard(Curr) &&
                    DT->dominates(cast<Instruction>(Curr), CtxI)) {
           return true;
         }

llvm/lib/Transforms/Scalar/EarlyCSE.cpp

@@ -54,6 +54,7 @@
 #include "llvm/Support/RecyclingAllocator.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include <cassert>
 #include <deque>
 #include <memory>
@@ -863,7 +864,7 @@ bool EarlyCSE::processNode(DomTreeNode *Node) {
       continue;
     }
 
-    if (match(Inst, m_Intrinsic<Intrinsic::experimental_guard>())) {
+    if (isGuard(Inst)) {
       if (auto *CondI =
               dyn_cast<Instruction>(cast<CallInst>(Inst)->getArgOperand(0))) {
         if (SimpleValue::canHandle(CondI)) {

llvm/lib/Transforms/Scalar/GuardWidening.cpp

@@ -57,6 +57,7 @@
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/KnownBits.h"
 #include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 
 using namespace llvm;
@@ -107,12 +108,6 @@ static void setCondition(Instruction *I, Value *NewCond) {
   cast<BranchInst>(I)->setCondition(NewCond);
 }
 
-// Whether or not the particular instruction \p I is a guard.
-static bool isGuard(const Instruction *I) {
-  using namespace llvm::PatternMatch;
-  return match(I, m_Intrinsic<Intrinsic::experimental_guard>());
-}
-
 // Eliminates the guard instruction properly.
 static void eliminateGuard(Instruction *GuardInst) {
   GuardInst->eraseFromParent();

llvm/lib/Transforms/Scalar/JumpThreading.cpp

@@ -65,6 +65,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Cloning.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
@@ -2607,9 +2608,8 @@ bool JumpThreadingPass::ProcessGuards(BasicBlock *BB) {
 
   if (auto *BI = dyn_cast<BranchInst>(Parent->getTerminator()))
     for (auto &I : *BB)
-      if (match(&I, m_Intrinsic<Intrinsic::experimental_guard>()))
-        if (ThreadGuard(BB, cast<IntrinsicInst>(&I), BI))
-          return true;
+      if (isGuard(&I) && ThreadGuard(BB, cast<IntrinsicInst>(&I), BI))
+        return true;
 
   return false;
 }

llvm/lib/Transforms/Scalar/LICM.cpp

@@ -66,6 +66,7 @@
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/LoopPassManager.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/GuardUtils.h"
 #include "llvm/Transforms/Utils/LoopUtils.h"
 #include "llvm/Transforms/Utils/SSAUpdater.h"
 #include <algorithm>
@@ -527,7 +528,7 @@ bool llvm::hoistRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
       using namespace PatternMatch;
       if (((I.use_empty() &&
             match(&I, m_Intrinsic<Intrinsic::invariant_start>())) ||
-           match(&I, m_Intrinsic<Intrinsic::experimental_guard>())) &&
+           isGuard(&I)) &&
           IsMustExecute && IsMemoryNotModified &&
           CurLoop->hasLoopInvariantOperands(&I)) {
         hoist(I, DT, CurLoop, SafetyInfo, ORE);

llvm/lib/Transforms/Scalar/LowerGuardIntrinsic.cpp

@@ -49,10 +49,8 @@ static bool lowerGuardIntrinsic(Function &F) {
 
   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 (isGuard(&I))
+      ToLower.push_back(cast<CallInst>(&I));
 
   if (ToLower.empty())
     return false;

llvm/lib/Transforms/Utils/GuardUtils.cpp

@@ -15,6 +15,7 @@
 #include "llvm/IR/Instructions.h"
 #include "llvm/IR/IRBuilder.h"
 #include "llvm/IR/MDBuilder.h"
+#include "llvm/IR/PatternMatch.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 
 using namespace llvm;
@@ -24,6 +25,11 @@ static cl::opt<uint32_t> PredicatePassBranchWeight(
     cl::desc("The probability of a guard failing is assumed to be the "
              "reciprocal of this value (default = 1 << 20)"));
 
+bool llvm::isGuard(const User *U) {
+  using namespace llvm::PatternMatch;
+  return match(U, m_Intrinsic<Intrinsic::experimental_guard>());
+}
+
 void llvm::makeGuardControlFlowExplicit(Function *DeoptIntrinsic,
                                         CallInst *Guard) {
   OperandBundleDef DeoptOB(*Guard->getOperandBundle(LLVMContext::OB_deopt));