From bf89fb7d86986de60e99a96104c2cc97b3d56230 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 19 Sep 2019 02:59:43 +0000 Subject: [CLANG][BPF] change __builtin_preserve_access_index() signature The clang intrinsic __builtin_preserve_access_index() currently has signature: const void * __builtin_preserve_access_index(const void * ptr) This may cause compiler warning when: - parameter type is "volatile void *" or "const volatile void *", or - the assign-to type of the intrinsic does not have "const" qualifier. Further, this signature does not allow dereference of the builtin result pointer as it is a "const void *" type, which adds extra step for the user to do type casting. Let us change the signature to: PointerT __builtin_preserve_access_index(PointerT ptr) such that the result and argument types are the same. With this, directly dereferencing the builtin return value becomes possible. Differential Revision: https://reviews.llvm.org/D67734 git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@372294 91177308-0d34-0410-b5e6-96231b3b80d8 --- docs/LanguageExtensions.rst | 4 +++- include/clang/Basic/Builtins.def | 2 +- include/clang/Basic/DiagnosticSemaKinds.td | 3 +++ lib/Sema/SemaChecking.cpp | 12 +++++++++++- test/Sema/builtin-preserve-access-index.c | 26 ++++++++++++++++++++++---- 5 files changed, 40 insertions(+), 7 deletions(-) diff --git a/docs/LanguageExtensions.rst b/docs/LanguageExtensions.rst index 80c960909f..9826c41c35 100644 --- a/docs/LanguageExtensions.rst +++ b/docs/LanguageExtensions.rst @@ -2353,12 +2353,14 @@ and other similar allocation libraries, and are only available in C++. array subscript access and structure/union member access are relocatable under bpf compile-once run-everywhere framework. Debuginfo (typically with ``-g``) is needed, otherwise, the compiler will exit with an error. +The return type for the intrinsic is the same as the type of the +argument, and must be a pointer type. **Syntax**: .. code-block:: c - const void * __builtin_preserve_access_index(const void * ptr) + PointerT __builtin_preserve_access_index(PointerT ptr) **Example of Use**: diff --git a/include/clang/Basic/Builtins.def b/include/clang/Basic/Builtins.def index 6dd0d3a731..ef5614a53f 100644 --- a/include/clang/Basic/Builtins.def +++ b/include/clang/Basic/Builtins.def @@ -1470,7 +1470,7 @@ BUILTIN(__builtin_operator_new, "v*z", "tc") BUILTIN(__builtin_operator_delete, "vv*", "tn") BUILTIN(__builtin_char_memchr, "c*cC*iz", "n") BUILTIN(__builtin_dump_struct, "ivC*v*", "tn") -BUILTIN(__builtin_preserve_access_index, "vC*vC*", "nU") +BUILTIN(__builtin_preserve_access_index, "v.", "t") // Safestack builtins BUILTIN(__builtin___get_unsafe_stack_start, "v*", "Fn") diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td index 8dd72d27e3..e72d1052dd 100644 --- a/include/clang/Basic/DiagnosticSemaKinds.td +++ b/include/clang/Basic/DiagnosticSemaKinds.td @@ -9925,4 +9925,7 @@ def err_bit_cast_non_trivially_copyable : Error< "__builtin_bit_cast %select{source|destination}0 type must be trivially copyable">; def err_bit_cast_type_size_mismatch : Error< "__builtin_bit_cast source size does not equal destination size (%0 vs %1)">; + +def err_builtin_preserve_access_index_invalid_arg : Error< + "__builtin_preserve_access_index argument must a pointer type instead of %0">; } // end of sema component. diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp index af69c231f1..4a3d26a5ab 100644 --- a/lib/Sema/SemaChecking.cpp +++ b/lib/Sema/SemaChecking.cpp @@ -191,12 +191,22 @@ static bool SemaBuiltinAddressof(Sema &S, CallExpr *TheCall) { return false; } -/// Check the number of arguments, and set the result type to +/// Check the number of arguments and arg type, and set the result type to /// the argument type. static bool SemaBuiltinPreserveAI(Sema &S, CallExpr *TheCall) { if (checkArgCount(S, TheCall, 1)) return true; + // The argument type must be a pointer + ExprResult Arg = TheCall->getArg(0); + QualType Ty = Arg.get()->getType(); + if (!Ty->isPointerType()) { + S.Diag(Arg.get()->getBeginLoc(), + diag::err_builtin_preserve_access_index_invalid_arg) + << Ty << Arg.get()->getSourceRange(); + return true; + } + TheCall->setType(TheCall->getArg(0)->getType()); return false; } diff --git a/test/Sema/builtin-preserve-access-index.c b/test/Sema/builtin-preserve-access-index.c index c10ceb5145..71da8457fa 100644 --- a/test/Sema/builtin-preserve-access-index.c +++ b/test/Sema/builtin-preserve-access-index.c @@ -4,10 +4,28 @@ const void *invalid1(const int *arg) { return __builtin_preserve_access_index(&arg[1], 1); // expected-error {{too many arguments to function call, expected 1, have 2}} } -void *invalid2(const int *arg) { - return __builtin_preserve_access_index(&arg[1]); // expected-warning {{returning 'const void *' from a function with result type 'void *' discards qualifiers}} +const void *invalid2(const int *arg) { + return __builtin_preserve_access_index(1); // expected-error {{__builtin_preserve_access_index argument must a pointer type instead of 'int'}} } -const void *invalid3(const int *arg) { - return __builtin_preserve_access_index(1); // expected-warning {{incompatible integer to pointer conversion passing 'int' to parameter of type 'const void *'}} +void *invalid3(const int *arg) { + return __builtin_preserve_access_index(&arg[1]); // expected-warning {{returning 'const int *' from a function with result type 'void *' discards qualifiers}} +} + +const void *invalid4(volatile const int *arg) { + return __builtin_preserve_access_index(arg); // expected-warning {{returning 'const volatile int *' from a function with result type 'const void *' discards qualifiers}} +} + +int *valid5(int *arg) { + return __builtin_preserve_access_index(arg); +} + +int valid6(const volatile int *arg) { + return *__builtin_preserve_access_index(arg); +} + +struct s { int a; int b; }; + +int valid7(struct s *arg) { + return *__builtin_preserve_access_index(&arg->b); } -- cgit v1.2.1