[PATCH 07/38] [noalias] D9378: Add IRBuilder support

[jeroen.dobbelaere]

Summary

This is part of the series started by D68484.

Rebase of D9378.

[lebedev.ri]

llvm/lib/IR/IRBuilder.cpp

475–484

I'd suggest to return Value* from CreateNoAliasPointer() and to cleanup this to

if (Ret->getType() == Ptr->getType())
  return Ret;
return CreateBitCast(Ret, Ptr->getType());

[jeroen.dobbelaere]

Rebased

[jeroen.dobbelaere]

For review convenience, all changes related to the original local restrict patches have now been incorporated in the full restrict patch series.

llvm/include/llvm/IR/IRBuilder.h

public:
   /// Create a call to Masked Scatter intrinsic
   CallInst *CreateMaskedScatter(Value *Val, Value *Ptrs, unsigned Align,
                                 Value *Mask = nullptr);
 
   /// Create an assume intrinsic call that allows the optimizer to
   /// assume that the provided condition will be true.
   CallInst *CreateAssumption(Value *Cond);
 
+  /// \brief Create an noalias intrinsic.
+  Instruction *CreateNoAliasPointer(Value *Ptr, MDNode *ScopeTag);
+
   /// Create a call to the experimental.gc.statepoint intrinsic to
   /// start a new statepoint sequence.
   CallInst *CreateGCStatepointCall(uint64_t ID, uint32_t NumPatchBytes,
                                    Value *ActualCallee,
                                    ArrayRef<Value *> CallArgs,
                                    ArrayRef<Value *> DeoptArgs,
                                    ArrayRef<Value *> GCArgs,
                                    const Twine &Name = "");

llvm/lib/IR/IRBuilder.cpp

 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/IntrinsicInst.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Metadata.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/IR/Statepoint.h"
 #include "llvm/IR/Type.h"
 #include "llvm/IR/Value.h"
 #include "llvm/Support/Casting.h"
 #include "llvm/Support/MathExtras.h"
 #include <cassert>
 #include <cstdint>
assert(Cond->getType() == getInt1Ty() &&
          "an assumption condition must be of type i1");
 
   Value *Ops[] = { Cond };
   Module *M = BB->getParent()->getParent();
   Function *FnAssume = Intrinsic::getDeclaration(M, Intrinsic::assume);
   return createCallHelper(FnAssume, Ops, this);
 }
 
+Instruction *IRBuilderBase::CreateNoAliasPointer(Value *Ptr, MDNode *ScopeTag) {
+  // FIXME: We can currently mangle just about everything, but not literal
+  // structs (for those, bitcast to i8*).
+  Value *CPtr = Ptr;
+  if (auto *STyp =
+        dyn_cast<StructType>(CPtr->getType()->getPointerElementType())) {
+    if (STyp->isLiteral())
+      CPtr = getCastedInt8PtrValue(CPtr);
+  }
+
+  Type *Types[] = { CPtr->getType() };
+  Value *Ops[] = { CPtr, MetadataAsValue::get(Context, ScopeTag) };
+  Module *M = BB->getModule();
+  Function *FnNoAlias = Intrinsic::getDeclaration(M, Intrinsic::noalias, Types);
+  Instruction *Ret = createCallHelper(FnNoAlias, Ops, this);
+
+  if (Ret->getType() != Ptr->getType()) {
+    BitCastInst *BCI = new BitCastInst(Ret, Ptr->getType(), "");
+    BB->getInstList().insert(InsertPt, BCI);
+    SetInstDebugLocation(BCI);
+    Ret = BCI;
+  }
+
+  return Ret;
+}
+
 /// Create a call to a Masked Load intrinsic.
 /// \p Ptr      - base pointer for the load
 /// \p Align    - alignment of the source location
 /// \p Mask     - vector of booleans which indicates what vector lanes should
 ///               be accessed in memory
 /// \p PassThru - pass-through value that is used to fill the masked-off lanes
 ///               of the result
 /// \p Name     - name of the result variable

llvm/unittests/IR/IRBuilderTest.cpp

TEST_F(IRBuilderTest, ConstrainedFP) {
   EXPECT_EQ(CII->getIntrinsicID(), Intrinsic::experimental_constrained_fadd);
   ASSERT_TRUE(CII->getExceptionBehavior() == ConstrainedFPIntrinsic::ebMayTrap);
   ASSERT_TRUE(CII->getRoundingMode() == ConstrainedFPIntrinsic::rmDownward);
 
   Builder.CreateRetVoid();
   EXPECT_FALSE(verifyModule(*M));
 }
 
+TEST_F(IRBuilderTest, NoAlias) {
+  IRBuilder<> Builder(BB);
+  AllocaInst *Var1 = Builder.CreateAlloca(Builder.getInt8Ty());
+
+  MDBuilder MDB(BB->getContext());
+  MDNode *NewDomain =
+    MDB.createAnonymousAliasScopeDomain("Test Domain");
+  MDNode *AScope =
+    MDB.createAnonymousAliasScope(NewDomain, "Test Scope");
+
+  CallInst *NAP = cast<CallInst>(Builder.CreateNoAliasPointer(Var1, AScope));
+
+  EXPECT_EQ(NAP->getArgOperand(0), Var1);
+  EXPECT_EQ(cast<MetadataAsValue>(NAP->getArgOperand(1))->getMetadata(),
+            AScope);
+
+  IntrinsicInst *II_NAP = dyn_cast<IntrinsicInst>(NAP);
+  ASSERT_TRUE(II_NAP != nullptr);
+  EXPECT_EQ(II_NAP->getIntrinsicID(), Intrinsic::noalias);
+
+  EXPECT_TRUE(NAP->onlyAccessesArgMemory());
+  EXPECT_TRUE(NAP->doesNotThrow());
+}
+
 TEST_F(IRBuilderTest, SideChannel) {
   IRBuilder<> Builder(BB);
 
   auto *L = Builder.CreateLoad(GV->getValueType(), GV);
   EXPECT_TRUE(!L->hasNoaliasSideChannelOperand());
 
   auto *S = Builder.CreateStore(L, GV);
   EXPECT_TRUE(!S->hasNoaliasSideChannelOperand());