!fixup address latest comments, thanks!

Author: fhahn

clang/include/clang/Basic/Builtins.td

@@ -841,7 +841,7 @@ def BuiltinAssumeAligned : Builtin {
 
 def BuiltinAssumeDereferenceable : Builtin {
   let Spellings = ["__builtin_assume_dereferenceable"];
-  let Attributes = [NoThrow, Const, Constexpr];
+  let Attributes = [NoThrow, Const];
   let Prototype = "void(void const*, _Constant size_t)";
 }
 

clang/lib/CodeGen/CGBuiltin.cpp

@@ -3841,12 +3841,14 @@ RValue CodeGenFunction::EmitBuiltinExpr(const GlobalDecl GD, unsigned BuiltinID,
   }
   case Builtin::BI__builtin_assume_dereferenceable: {
     const Expr *Ptr = E->getArg(0);
+    const Expr *Size= E->getArg(1);
     Value *PtrValue = EmitScalarExpr(Ptr);
-    Value *SizeValue = EmitScalarExpr(E->getArg(1));
+    Value *SizeValue = EmitScalarExpr(Size);
     if (SizeValue->getType() != IntPtrTy)
       SizeValue =
           Builder.CreateIntCast(SizeValue, IntPtrTy, false, "casted.size");
     Builder.CreateDereferenceableAssumption(PtrValue, SizeValue);
+    Builder.CreateNonNullAssumption(PtrValue);
     return RValue::get(nullptr);
   }
   case Builtin::BI__assume:

clang/test/CodeGen/builtin-assume-dereferenceable.c

@@ -7,6 +7,7 @@
 // CHECK-NEXT:    store ptr [[A:%.*]], ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    call void @llvm.assume(i1 true) [ "dereferenceable"(ptr [[TMP0]], i64 10) ]
+// CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[TMP0]]) ]
 // CHECK-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i64 0
 // CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr [[ARRAYIDX]], align 4
@@ -23,6 +24,7 @@ int test1(int *a) {
 // CHECK-NEXT:    store ptr [[A:%.*]], ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    [[TMP0:%.*]] = load ptr, ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    call void @llvm.assume(i1 true) [ "dereferenceable"(ptr [[TMP0]], i64 32) ]
+// CHECK-NEXT:    call void @llvm.assume(i1 true) [ "nonnull"(ptr [[TMP0]]) ]
 // CHECK-NEXT:    [[TMP1:%.*]] = load ptr, ptr [[A_ADDR]], align 8
 // CHECK-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, ptr [[TMP1]], i64 0
 // CHECK-NEXT:    [[TMP2:%.*]] = load i32, ptr [[ARRAYIDX]], align 4

clang/test/Sema/builtin-assume-dereferenceable.c renamed to clang/test/SemaCXX/builtin-assume-dereferenceable.cpp

@@ -1,4 +1,6 @@
-// RUN: %clang_cc1 -DSIZE_T_64 -fsyntax-only -Wno-strict-prototypes -triple x86_64-linux -verify %s
+// RUN: %clang_cc1 -DSIZE_T_64 -fsyntax-only -verify -std=c++11 -triple x86_64-linux-gnu %s
+// RUN: %clang_cc1 -DSIZE_T_64 -fsyntax-only -verify -std=c++11 -triple x86_64-linux-gnu %s -fexperimental-new-constant-interpreter
+
 
 int test1(int *a) {
   __builtin_assume_dereferenceable(a, 32);
@@ -26,7 +28,7 @@ int test5(int *a, unsigned long long size) {
 }
 
 int test6(float a) {
-  __builtin_assume_dereferenceable(a, 2); // expected-error {{passing 'float' to parameter of incompatible type 'const void *'}}
+  __builtin_assume_dereferenceable(a, 2); // expected-error {{cannot initialize a parameter of type 'const void *' with an lvalue of type 'float'}}
   return 0;;
 }
 
@@ -39,3 +41,15 @@ int test8(int *a) {
   __builtin_assume_dereferenceable(a); // expected-error {{too few arguments to function call, expected 2, have 1}}
   return a[0];
 }
+
+int test9(int *a) {
+  a[0] = __builtin_assume_dereferenceable(a, 32); // expected-error {{assigning to 'int' from incompatible type 'void'}}
+  return a[0];
+}
+
+constexpr int *p = 0;
+constexpr void *l = __builtin_assume_dereferenceable(p, 4); // expected-error {{cannot initialize a variable of type 'void *const' with an rvalue of type 'void'}}
+
+void *foo() {
+  return l;
+}

llvm/include/llvm/IR/IRBuilder.h

@@ -2687,8 +2687,11 @@ class IRBuilderBase {
 
   /// Create an assume intrinsic call that represents an dereferencable
   /// assumption on the provided pointer.
-  ///
   CallInst *CreateDereferenceableAssumption(Value *PtrValue, Value *SizeValue);
+
+  /// Create an assume intrinsic call that represents a nonnull assumption
+  /// on the provided pointer.
+  CallInst *CreateNonNullAssumption(Value *PtrValue);
 };
 
 /// This provides a uniform API for creating instructions and inserting

llvm/lib/IR/IRBuilder.cpp

@@ -1294,6 +1294,14 @@ CallInst *IRBuilderBase::CreateDereferenceableAssumption(Value *PtrValue,
                           {DereferenceableOpB});
 }
 
+CallInst *IRBuilderBase::CreateNonNullAssumption(Value *PtrValue) {
+  assert(isa<PointerType>(PtrValue->getType()) &&
+         "trying to create an nonnull assumption on a non-pointer?");
+  SmallVector<Value *, 4> Vals({PtrValue});
+  OperandBundleDefT<Value *> NonNullOpB("nonnull", Vals);
+  return CreateAssumption(ConstantInt::getTrue(getContext()), {NonNullOpB});
+}
+
 IRBuilderDefaultInserter::~IRBuilderDefaultInserter() = default;
 IRBuilderCallbackInserter::~IRBuilderCallbackInserter() = default;
 IRBuilderFolder::~IRBuilderFolder() = default;