From: JF Bastien Date: Fri, 25 May 2018 00:07:09 +0000 (+0000) Subject: Make atomic non-member functions as nonnull X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=956d9d40ee4e56da887d6fbb92ccea1b9dc2cdf7;p=clang Make atomic non-member functions as nonnull Summary: As a companion to libc++ patch https://reviews.llvm.org/D47225, mark builtin atomic non-member functions which accept pointers as nonnull. The atomic non-member functions accept pointers to std::atomic / std::atomic_flag as well as to the non-atomic value. These are all dereferenced unconditionally when lowered, and therefore will fault if null. It's a tiny gotcha for new users, especially when they pass in NULL as expected value (instead of passing a pointer to a NULL value). Reviewers: arphaman Subscribers: aheejin, cfe-commits Differential Revision: https://reviews.llvm.org/D47229 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@333246 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp index bf95c22e99..6f956b42f0 100644 --- a/lib/Sema/SemaChecking.cpp +++ b/lib/Sema/SemaChecking.cpp @@ -3451,9 +3451,10 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, return ExprError(); } - // atomic_fetch_or takes a pointer to a volatile 'A'. We shouldn't let the - // volatile-ness of the pointee-type inject itself into the result or the - // other operands. Similarly atomic_load can take a pointer to a const 'A'. + // All atomic operations have an overload which takes a pointer to a volatile + // 'A'. We shouldn't let the volatile-ness of the pointee-type inject itself + // into the result or the other operands. Similarly atomic_load takes a + // pointer to a const 'A'. ValType.removeLocalVolatile(); ValType.removeLocalConst(); QualType ResultType = ValType; @@ -3466,16 +3467,27 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, // The type of a parameter passed 'by value'. In the GNU atomics, such // arguments are actually passed as pointers. QualType ByValType = ValType; // 'CP' - if (!IsC11 && !IsN) + bool IsPassedByAddress = false; + if (!IsC11 && !IsN) { ByValType = Ptr->getType(); + IsPassedByAddress = true; + } - // The first argument --- the pointer --- has a fixed type; we - // deduce the types of the rest of the arguments accordingly. Walk - // the remaining arguments, converting them to the deduced value type. - for (unsigned i = 1; i != TheCall->getNumArgs(); ++i) { + // The first argument's non-CV pointer type is used to deduce the type of + // subsequent arguments, except for: + // - weak flag (always converted to bool) + // - memory order (always converted to int) + // - scope (always converted to int) + for (unsigned i = 0; i != TheCall->getNumArgs(); ++i) { QualType Ty; if (i < NumVals[Form] + 1) { switch (i) { + case 0: + // The first argument is always a pointer. It has a fixed type. + // It is always dereferenced, a nullptr is undefined. + CheckNonNullArgument(*this, TheCall->getArg(i), DRE->getLocStart()); + // Nothing else to do: we already know all we want about this pointer. + continue; case 1: // The second argument is the non-atomic operand. For arithmetic, this // is always passed by value, and for a compare_exchange it is always @@ -3484,14 +3496,16 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, assert(Form != Load); if (Form == Init || (Form == Arithmetic && ValType->isIntegerType())) Ty = ValType; - else if (Form == Copy || Form == Xchg) + else if (Form == Copy || Form == Xchg) { + if (IsPassedByAddress) + // The value pointer is always dereferenced, a nullptr is undefined. + CheckNonNullArgument(*this, TheCall->getArg(i), DRE->getLocStart()); Ty = ByValType; - else if (Form == Arithmetic) + } else if (Form == Arithmetic) Ty = Context.getPointerDiffType(); else { Expr *ValArg = TheCall->getArg(i); - // Treat this argument as _Nonnull as we want to show a warning if - // NULL is passed into it. + // The value pointer is always dereferenced, a nullptr is undefined. CheckNonNullArgument(*this, ValArg, DRE->getLocStart()); LangAS AS = LangAS::Default; // Keep address space of non-atomic pointer type. @@ -3504,8 +3518,10 @@ ExprResult Sema::SemaAtomicOpsOverloaded(ExprResult TheCallResult, } break; case 2: - // The third argument to compare_exchange / GNU exchange is a - // (pointer to a) desired value. + // The third argument to compare_exchange / GNU exchange is the desired + // value, either by-value (for the *_n variant) or as a pointer. + if (!IsN) + CheckNonNullArgument(*this, TheCall->getArg(i), DRE->getLocStart()); Ty = ByValType; break; case 3: @@ -3887,7 +3903,7 @@ Sema::SemaBuiltinAtomicOverloaded(ExprResult TheCallResult) { ResultType = Context.BoolTy; break; - case Builtin::BI__sync_lock_test_and_set: + case Builtin::BI__sync_lock_test_and_set: case Builtin::BI__sync_lock_test_and_set_1: case Builtin::BI__sync_lock_test_and_set_2: case Builtin::BI__sync_lock_test_and_set_4: diff --git a/test/Sema/atomic-ops.c b/test/Sema/atomic-ops.c index 3b15c4f6c4..312a9fa846 100644 --- a/test/Sema/atomic-ops.c +++ b/test/Sema/atomic-ops.c @@ -531,8 +531,80 @@ void memory_checks(_Atomic(int) *Ap, int *p, int val) { } void nullPointerWarning(_Atomic(int) *Ap, int *p, int val) { - // The 'expected' pointer shouldn't be NULL. - (void)__c11_atomic_compare_exchange_strong(Ap, NULL, val, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} - (void)atomic_compare_exchange_weak(Ap, ((void*)0), val); // expected-warning {{null passed to a callee that requires a non-null argument}} - (void)__atomic_compare_exchange_n(p, NULL, val, 0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + volatile _Atomic(int) vai; + _Atomic(int) ai; + volatile int vi = 42; + int i = 42; + + __c11_atomic_init((volatile _Atomic(int)*)0, 42); // expected-warning {{null passed to a callee that requires a non-null argument}} + __c11_atomic_init((_Atomic(int)*)0, 42); // expected-warning {{null passed to a callee that requires a non-null argument}} + __c11_atomic_store((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __c11_atomic_store((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_load((volatile _Atomic(int)*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_load((_Atomic(int)*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_exchange((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_exchange((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_weak((volatile _Atomic(int)*)0, &i, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_weak((_Atomic(int)*)0, &i, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_weak(&vai, (int*)0, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_weak(&ai, (int*)0, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_strong((volatile _Atomic(int)*)0, &i, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_strong((_Atomic(int)*)0, &i, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_strong(&vai, (int*)0, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_compare_exchange_strong(&ai, (int*)0, 42, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_add((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_add((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_sub((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_sub((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_and((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_and((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_or((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_or((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_xor((volatile _Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__c11_atomic_fetch_xor((_Atomic(int)*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + + __atomic_store_n((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_store_n((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_store((volatile int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_store((int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_store(&vi, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_store(&i, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_load_n((volatile int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_load_n((int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_load((volatile int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_load((int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_load(&vi, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_load(&i, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_exchange_n((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_exchange_n((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange((volatile int*)0, &i, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange((int*)0, &i, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange(&vi, (int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange(&i, (int*)0, &i, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange(&vi, &i, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + __atomic_exchange(&i, &i, (int*)0, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange_n((volatile int*)0, &i, 42, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange_n((int*)0, &i, 42, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange_n(&vi, (int*)0, 42, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange_n(&i, (int*)0, 42, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange((volatile int*)0, &i, &i, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange((int*)0, &i, &i, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange(&vi, (int*)0, &i, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange(&i, (int*)0, &i, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange(&vi, &i, (int*)0, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_compare_exchange(&i, &i, (int*)0, /*weak=*/0, memory_order_relaxed, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_add((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_add((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_sub((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_sub((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_and((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_and((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_or((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_or((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_xor((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_xor((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_min((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_min((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_max((volatile int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} + (void)__atomic_fetch_max((int*)0, 42, memory_order_relaxed); // expected-warning {{null passed to a callee that requires a non-null argument}} }