Author: Timm Bäder Date: 2024-04-16T13:58:52+02:00 New Revision: 75244a1043d2be5003dea6914d5edc940c437cd5
URL: https://github.com/llvm/llvm-project/commit/75244a1043d2be5003dea6914d5edc940c437cd5 DIFF: https://github.com/llvm/llvm-project/commit/75244a1043d2be5003dea6914d5edc940c437cd5.diff LOG: [clang][Interp] Implement align builtins __builtin_is_aligned __builtin_is_align_up __builtin_is_align_down Added: clang/test/AST/Interp/builtin-align-cxx.cpp Modified: clang/lib/AST/Interp/InterpBuiltin.cpp Removed: ################################################################################ diff --git a/clang/lib/AST/Interp/InterpBuiltin.cpp b/clang/lib/AST/Interp/InterpBuiltin.cpp index 984ba4f7f2689c..f562f9e1cb19fb 100644 --- a/clang/lib/AST/Interp/InterpBuiltin.cpp +++ b/clang/lib/AST/Interp/InterpBuiltin.cpp @@ -977,6 +977,117 @@ static bool interp__builtin_complex(InterpState &S, CodePtr OpPC, return true; } +/// __builtin_is_aligned() +/// __builtin_align_up() +/// __builtin_align_down() +/// The first parameter is either an integer or a pointer. +/// The second parameter is the requested alignment as an integer. +static bool interp__builtin_is_aligned_up_down(InterpState &S, CodePtr OpPC, + const InterpFrame *Frame, + const Function *Func, + const CallExpr *Call) { + unsigned BuiltinOp = Func->getBuiltinID(); + unsigned CallSize = callArgSize(S, Call); + + PrimType AlignmentT = *S.Ctx.classify(Call->getArg(1)); + const APSInt &Alignment = peekToAPSInt(S.Stk, AlignmentT); + + if (Alignment < 0 || !Alignment.isPowerOf2()) { + S.FFDiag(Call, diag::note_constexpr_invalid_alignment) << Alignment; + return false; + } + unsigned SrcWidth = S.getCtx().getIntWidth(Call->getArg(0)->getType()); + APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1)); + if (APSInt::compareValues(Alignment, MaxValue) > 0) { + S.FFDiag(Call, diag::note_constexpr_alignment_too_big) + << MaxValue << Call->getArg(0)->getType() << Alignment; + return false; + } + + // The first parameter is either an integer or a pointer (but not a function + // pointer). + PrimType FirstArgT = *S.Ctx.classify(Call->getArg(0)); + + if (isIntegralType(FirstArgT)) { + const APSInt &Src = peekToAPSInt(S.Stk, FirstArgT, CallSize); + APSInt Align = Alignment.extOrTrunc(Src.getBitWidth()); + if (BuiltinOp == Builtin::BI__builtin_align_up) { + APSInt AlignedVal = + APSInt((Src + (Align - 1)) & ~(Align - 1), Src.isUnsigned()); + pushInteger(S, AlignedVal, Call->getType()); + } else if (BuiltinOp == Builtin::BI__builtin_align_down) { + APSInt AlignedVal = APSInt(Src & ~(Align - 1), Src.isUnsigned()); + pushInteger(S, AlignedVal, Call->getType()); + } else { + assert(*S.Ctx.classify(Call->getType()) == PT_Bool); + S.Stk.push<Boolean>((Src & (Align - 1)) == 0); + } + return true; + } + + assert(FirstArgT == PT_Ptr); + const Pointer &Ptr = S.Stk.peek<Pointer>(CallSize); + + unsigned PtrOffset = Ptr.getByteOffset(); + PtrOffset = Ptr.getIndex(); + CharUnits BaseAlignment = + S.getCtx().getDeclAlign(Ptr.getDeclDesc()->asValueDecl()); + CharUnits PtrAlign = + BaseAlignment.alignmentAtOffset(CharUnits::fromQuantity(PtrOffset)); + + if (BuiltinOp == Builtin::BI__builtin_is_aligned) { + if (PtrAlign.getQuantity() >= Alignment) { + S.Stk.push<Boolean>(true); + return true; + } + // If the alignment is not known to be sufficient, some cases could still + // be aligned at run time. However, if the requested alignment is less or + // equal to the base alignment and the offset is not aligned, we know that + // the run-time value can never be aligned. + if (BaseAlignment.getQuantity() >= Alignment && + PtrAlign.getQuantity() < Alignment) { + S.Stk.push<Boolean>(false); + return true; + } + + S.FFDiag(Call->getArg(0), diag::note_constexpr_alignment_compute) + << Alignment; + return false; + } + + assert(BuiltinOp == Builtin::BI__builtin_align_down || + BuiltinOp == Builtin::BI__builtin_align_up); + + // For align_up/align_down, we can return the same value if the alignment + // is known to be greater or equal to the requested value. + if (PtrAlign.getQuantity() >= Alignment) { + S.Stk.push<Pointer>(Ptr); + return true; + } + + // The alignment could be greater than the minimum at run-time, so we cannot + // infer much about the resulting pointer value. One case is possible: + // For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we + // can infer the correct index if the requested alignment is smaller than + // the base alignment so we can perform the computation on the offset. + if (BaseAlignment.getQuantity() >= Alignment) { + assert(Alignment.getBitWidth() <= 64 && + "Cannot handle > 64-bit address-space"); + uint64_t Alignment64 = Alignment.getZExtValue(); + CharUnits NewOffset = + CharUnits::fromQuantity(BuiltinOp == Builtin::BI__builtin_align_down + ? llvm::alignDown(PtrOffset, Alignment64) + : llvm::alignTo(PtrOffset, Alignment64)); + + S.Stk.push<Pointer>(Ptr.atIndex(NewOffset.getQuantity())); + return true; + } + + // Otherwise, we cannot constant-evaluate the result. + S.FFDiag(Call->getArg(0), diag::note_constexpr_alignment_adjust) << Alignment; + return false; +} + bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F, const CallExpr *Call) { const InterpFrame *Frame = S.Current; @@ -1291,6 +1402,13 @@ bool InterpretBuiltin(InterpState &S, CodePtr OpPC, const Function *F, return false; break; + case Builtin::BI__builtin_is_aligned: + case Builtin::BI__builtin_align_up: + case Builtin::BI__builtin_align_down: + if (!interp__builtin_is_aligned_up_down(S, OpPC, Frame, F, Call)) + return false; + break; + default: S.FFDiag(S.Current->getLocation(OpPC), diag::note_invalid_subexpr_in_const_expr) diff --git a/clang/test/AST/Interp/builtin-align-cxx.cpp b/clang/test/AST/Interp/builtin-align-cxx.cpp new file mode 100644 index 00000000000000..62d73dba929b2c --- /dev/null +++ b/clang/test/AST/Interp/builtin-align-cxx.cpp @@ -0,0 +1,258 @@ +// C++-specific checks for the alignment builtins +// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -std=c++11 %s -fsyntax-only -verify=expected,both -fexperimental-new-constant-interpreter +// RUN: %clang_cc1 -triple=x86_64-unknown-unknown -std=c++11 %s -fsyntax-only -verify=ref,both + + +/// This is just a copy of the one from test/SemaCXX/ with some of the +/// diagnostic output adapted. +/// Also, align32array has an initializer now, which means it's not just +/// a dummy pointer for us and we do actually have type information for it. +/// In the future, we need to retain type information for dummy pointers as +/// well, so here is a test that will break once we do that: +namespace { + _Alignas(32) char heh[4]; + static_assert(!__builtin_is_aligned(&heh[1], 4), ""); // expected-error {{failed}} +} + + +// Check that we don't crash when using dependent types in __builtin_align: +template <typename a, a b> +void *c(void *d) { // both-note{{candidate template ignored}} + return __builtin_align_down(d, b); +} + +struct x {}; +x foo; +void test(void *value) { + c<int, 16>(value); + c<struct x, foo>(value); // both-error{{no matching function for call to 'c'}} +} + +template <typename T, long Alignment, long ArraySize = 16> +void test_templated_arguments() { + T array[ArraySize]; // both-error{{variable has incomplete type 'fwddecl'}} + static_assert(__is_same(decltype(__builtin_align_up(array, Alignment)), T *), // both-error{{requested alignment is not a power of 2}} + "return type should be the decayed array type"); + static_assert(__is_same(decltype(__builtin_align_down(array, Alignment)), T *), + "return type should be the decayed array type"); + static_assert(__is_same(decltype(__builtin_is_aligned(array, Alignment)), bool), + "return type should be bool"); + T *x1 = __builtin_align_up(array, Alignment); + T *x2 = __builtin_align_down(array, Alignment); + bool x3 = __builtin_align_up(array, Alignment); +} + +void test() { + test_templated_arguments<int, 32>(); // fine + test_templated_arguments<struct fwddecl, 16>(); + // both-note@-1{{in instantiation of function template specialization 'test_templated_arguments<fwddecl, 16L, 16L>'}} + // both-note@-2{{forward declaration of 'fwddecl'}} + test_templated_arguments<int, 7>(); // invalid alignment value + // both-note@-1{{in instantiation of function template specialization 'test_templated_arguments<int, 7L, 16L>'}} +} + +template <typename T, long ArraySize> +void test_incorrect_alignment_without_instatiation(T value) { + int array[32]; + static_assert(__is_same(decltype(__builtin_align_up(array, 31)), int *), // both-error{{requested alignment is not a power of 2}} + "return type should be the decayed array type"); + static_assert(__is_same(decltype(__builtin_align_down(array, 7)), int *), // both-error{{requested alignment is not a power of 2}} + "return type should be the decayed array type"); + static_assert(__is_same(decltype(__builtin_is_aligned(array, -1)), bool), // both-error{{requested alignment must be 1 or greater}} + "return type should be bool"); + __builtin_align_up(array); // both-error{{too few arguments to function call, expected 2, have 1}} + __builtin_align_up(array, 31); // both-error{{requested alignment is not a power of 2}} + __builtin_align_down(array, 31); // both-error{{requested alignment is not a power of 2}} + __builtin_align_up(array, 31); // both-error{{requested alignment is not a power of 2}} + __builtin_align_up(value, 31); // This shouldn't want since the type is dependent + __builtin_align_up(value); // Same here + + __builtin_align_up(array, sizeof(sizeof(value)) - 1); // both-error{{requested alignment is not a power of 2}} + __builtin_align_up(array, value); // no diagnostic as the alignment is value dependent. + (void)__builtin_align_up(array, ArraySize); // The same above here +} + +// The original fix for the issue above broke some legitimate code. +// Here is a regression test: +typedef __SIZE_TYPE__ size_t; +void *allocate_impl(size_t size); +template <typename T> +T *allocate() { + constexpr size_t allocation_size = + __builtin_align_up(sizeof(T), sizeof(void *)); + return static_cast<T *>( + __builtin_assume_aligned(allocate_impl(allocation_size), sizeof(void *))); +} +struct Foo { + int value; +}; +void *test2() { + return allocate<struct Foo>(); +} + +// Check that pointers-to-members cannot be used: +class MemPtr { +public: + int data; + void func(); + virtual void vfunc(); +}; +void test_member_ptr() { + __builtin_align_up(&MemPtr::data, 64); // both-error{{operand of type 'int MemPtr::*' where arithmetic or pointer type is required}} + __builtin_align_down(&MemPtr::func, 64); // both-error{{operand of type 'void (MemPtr::*)()' where arithmetic or pointer type is required}} + __builtin_is_aligned(&MemPtr::vfunc, 64); // both-error{{operand of type 'void (MemPtr::*)()' where arithmetic or pointer type is required}} +} + +void test_references(Foo &i) { + // Check that the builtins look at the referenced type rather than the reference itself. + (void)__builtin_align_up(i, 64); // both-error{{operand of type 'Foo' where arithmetic or pointer type is required}} + (void)__builtin_align_up(static_cast<Foo &>(i), 64); // both-error{{operand of type 'Foo' where arithmetic or pointer type is required}} + (void)__builtin_align_up(static_cast<const Foo &>(i), 64); // both-error{{operand of type 'const Foo' where arithmetic or pointer type is required}} + (void)__builtin_align_up(static_cast<Foo &&>(i), 64); // both-error{{operand of type 'Foo' where arithmetic or pointer type is required}} + (void)__builtin_align_up(static_cast<const Foo &&>(i), 64); // both-error{{operand of type 'const Foo' where arithmetic or pointer type is required}} + (void)__builtin_align_up(&i, 64); +} + +// Check that constexpr wrapper functions can be constant-evaluated. +template <typename T> +constexpr bool wrap_is_aligned(T ptr, long align) { + return __builtin_is_aligned(ptr, align); + // both-note@-1{{requested alignment -3 is not a positive power of two}} + // both-note@-2{{requested alignment 19 is not a positive power of two}} + // both-note@-3{{requested alignment must be 128 or less for type 'char'; 4194304 is invalid}} +} +template <typename T> +constexpr T wrap_align_up(T ptr, long align) { + return __builtin_align_up(ptr, align); + // both-note@-1{{requested alignment -2 is not a positive power of two}} + // both-note@-2{{requested alignment 18 is not a positive power of two}} + // both-note@-3{{requested alignment must be 2147483648 or less for type 'int'; 8589934592 is invalid}} + // both-error@-4{{operand of type 'bool' where arithmetic or pointer type is required}} +} + +template <typename T> +constexpr T wrap_align_down(T ptr, long align) { + return __builtin_align_down(ptr, align); + // both-note@-1{{requested alignment -1 is not a positive power of two}} + // both-note@-2{{requested alignment 17 is not a positive power of two}} + // both-note@-3{{requested alignment must be 32768 or less for type 'short'; 1048576 is invalid}} +} + +constexpr int a1 = wrap_align_up(22, 32); +static_assert(a1 == 32, ""); +constexpr int a2 = wrap_align_down(22, 16); +static_assert(a2 == 16, ""); +constexpr bool a3 = wrap_is_aligned(22, 32); +static_assert(!a3, ""); +static_assert(wrap_align_down(wrap_align_up(22, 16), 32) == 32, ""); +static_assert(wrap_is_aligned(wrap_align_down(wrap_align_up(22, 16), 32), 32), ""); +static_assert(!wrap_is_aligned(wrap_align_down(wrap_align_up(22, 16), 32), 64), ""); + +constexpr long const_value(long l) { return l; } +// Check some invalid values during constant-evaluation +static_assert(wrap_align_down(1, const_value(-1)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_align_up(1, const_value(-2)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_is_aligned(1, const_value(-3)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_align_down(1, const_value(17)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_align_up(1, const_value(18)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_is_aligned(1, const_value(19)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} + +// Check invalid values for smaller types: +static_assert(wrap_align_down(static_cast<short>(1), const_value(1 << 20)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to }} +// Check invalid boolean type +static_assert(wrap_align_up(static_cast<int>(1), const_value(1ull << 33)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} +static_assert(wrap_is_aligned(static_cast<char>(1), const_value(1 << 22)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in call to}} + +// Check invalid boolean type +static_assert(wrap_align_up(static_cast<bool>(1), const_value(1 << 21)), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{in instantiation of function template specialization 'wrap_align_up<bool>' requested here}} + +// Check constant evaluation for pointers: +_Alignas(32) char align32array[128] = {}; +static_assert(&align32array[0] == &align32array[0], ""); +// __builtin_align_up/down can be constant evaluated as a no-op for values +// that are known to have greater alignment: +static_assert(__builtin_align_up(&align32array[0], 32) == &align32array[0], ""); +static_assert(__builtin_align_up(&align32array[0], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[0], 4) == __builtin_align_up(&align32array[0], 8), ""); +// But it can not be evaluated if the alignment is greater than the minimum +// known alignment, since in that case the value might be the same if it happens +// to actually be aligned to 64 bytes at run time. +static_assert(&align32array[0] == __builtin_align_up(&align32array[0], 64), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}} +static_assert(__builtin_align_up(&align32array[0], 64) == __builtin_align_up(&align32array[0], 64), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}} + +// However, we can compute in case the requested alignment is less than the +// base alignment: +static_assert(__builtin_align_up(&align32array[0], 4) == &align32array[0], ""); +static_assert(__builtin_align_up(&align32array[1], 4) == &align32array[4], ""); +static_assert(__builtin_align_up(&align32array[2], 4) == &align32array[4], ""); +static_assert(__builtin_align_up(&align32array[3], 4) == &align32array[4], ""); +static_assert(__builtin_align_up(&align32array[4], 4) == &align32array[4], ""); +static_assert(__builtin_align_up(&align32array[5], 4) == &align32array[8], ""); +static_assert(__builtin_align_up(&align32array[6], 4) == &align32array[8], ""); +static_assert(__builtin_align_up(&align32array[7], 4) == &align32array[8], ""); +static_assert(__builtin_align_up(&align32array[8], 4) == &align32array[8], ""); + +static_assert(__builtin_align_down(&align32array[0], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[1], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[2], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[3], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[4], 4) == &align32array[4], ""); +static_assert(__builtin_align_down(&align32array[5], 4) == &align32array[4], ""); +static_assert(__builtin_align_down(&align32array[6], 4) == &align32array[4], ""); +static_assert(__builtin_align_down(&align32array[7], 4) == &align32array[4], ""); +static_assert(__builtin_align_down(&align32array[8], 4) == &align32array[8], ""); + +// Achieving the same thing using casts to uintptr_t is not allowed: +static_assert((char *)((__UINTPTR_TYPE__)&align32array[7] & ~3) == &align32array[4], ""); // both-error{{not an integral constant expression}} \ + // expected-note {{cast that performs the conversions of a reinterpret_cast is not allowed in a constant expression}} + +static_assert(__builtin_align_down(&align32array[1], 4) == &align32array[0], ""); +static_assert(__builtin_align_down(&align32array[1], 64) == &align32array[0], ""); // both-error{{not an integral constant expression}} +// both-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}} + +// Add some checks for __builtin_is_aligned: +static_assert(__builtin_is_aligned(&align32array[0], 32), ""); +static_assert(__builtin_is_aligned(&align32array[4], 4), ""); +// We cannot constant evaluate whether the array is aligned to > 32 since this +// may well be true at run time. +static_assert(!__builtin_is_aligned(&align32array[0], 64), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{cannot constant evaluate whether run-time alignment is at least 64}} + +// However, if the alignment being checked is less than the minimum alignment of +// the base object we can check the low bits of the alignment: +static_assert(__builtin_is_aligned(&align32array[0], 4), ""); +static_assert(!__builtin_is_aligned(&align32array[1], 4), ""); +static_assert(!__builtin_is_aligned(&align32array[2], 4), ""); +static_assert(!__builtin_is_aligned(&align32array[3], 4), ""); +static_assert(__builtin_is_aligned(&align32array[4], 4), ""); + +// TODO: this should evaluate to true even though we can't evaluate the result +// of __builtin_align_up() to a concrete value +static_assert(__builtin_is_aligned(__builtin_align_up(&align32array[0], 64), 64), ""); // both-error{{not an integral constant expression}} +// both-note@-1{{cannot constant evaluate the result of adjusting alignment to 64}} + +// Check diff erent source and alignment type widths are handled correctly. +static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<signed short>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<signed short>(7), static_cast<signed long>(4)), ""); +// Also check signed -- unsigned mismatch. +static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<signed long>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<unsigned long>(7), static_cast<unsigned long>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<unsigned long>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<unsigned long>(7), static_cast<signed long>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<signed long>(7), static_cast<unsigned short>(4)), ""); +static_assert(!__builtin_is_aligned(static_cast<unsigned short>(7), static_cast<signed long>(4)), ""); + +// Check the diagnostic message +_Alignas(void) char align_void_array[1]; // both-error {{invalid application of '_Alignas' to an incomplete type 'void'}} _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits