Thanks! Can you update cxx_status.html to mark P0595R2 as done?
On Tue, 23 Apr 2019 at 19:21, Eric Fiselier via cfe-commits <cfe-commits@lists.llvm.org> wrote: > > Author: ericwf > Date: Tue Apr 23 19:23:30 2019 > New Revision: 359067 > > URL: http://llvm.org/viewvc/llvm-project?rev=359067&view=rev > Log: > [Builtins] Implement __builtin_is_constant_evaluated for use in C++2a > > Summary: > This patch implements `__builtin_is_constant_evaluated` as specifier by > [P0595R2](https://wg21.link/p0595r2). It is built on the back of Bill > Wendling's work for `__builtin_constant_p()`. > > More tests to come, but early feedback is appreciated. > > I plan to implement warnings for common mis-usages like those belowe in a > following patch: > ``` > void foo(int x) { > if constexpr (std::is_constant_evaluated())) { // condition is always > `true`. Should use plain `if` instead. > foo_constexpr(x); > } else { > foo_runtime(x); > } > } > ``` > > > > Reviewers: rsmith, MaskRay, bruno, void > > Reviewed By: rsmith > > Subscribers: dexonsmith, zoecarver, fdeazeve, kristina, cfe-commits > > Differential Revision: https://reviews.llvm.org/D55500 > > Added: > cfe/trunk/test/CodeGenCXX/builtin-is-constant-evaluated.cpp > cfe/trunk/test/SemaCXX/builtin-is-constant-evaluated.cpp > Modified: > cfe/trunk/include/clang/Basic/Builtins.def > cfe/trunk/lib/AST/ExprConstant.cpp > cfe/trunk/lib/Basic/Builtins.cpp > cfe/trunk/lib/CodeGen/CGDecl.cpp > cfe/trunk/test/Sema/builtins.c > > Modified: cfe/trunk/include/clang/Basic/Builtins.def > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Basic/Builtins.def?rev=359067&r1=359066&r2=359067&view=diff > ============================================================================== > --- cfe/trunk/include/clang/Basic/Builtins.def (original) > +++ cfe/trunk/include/clang/Basic/Builtins.def Tue Apr 23 19:23:30 2019 > @@ -500,6 +500,7 @@ BUILTIN(__builtin_vsprintf, "ic*cC*a", " > BUILTIN(__builtin_vsnprintf, "ic*zcC*a", "nFP:2:") > BUILTIN(__builtin_thread_pointer, "v*", "nc") > BUILTIN(__builtin_launder, "v*v*", "nt") > +LANGBUILTIN(__builtin_is_constant_evaluated, "b", "n", CXX_LANG) > > // GCC exception builtins > BUILTIN(__builtin_eh_return, "vzv*", "r") // FIXME: Takes intptr_t, not > size_t! > > Modified: cfe/trunk/lib/AST/ExprConstant.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/AST/ExprConstant.cpp?rev=359067&r1=359066&r2=359067&view=diff > ============================================================================== > --- cfe/trunk/lib/AST/ExprConstant.cpp (original) > +++ cfe/trunk/lib/AST/ExprConstant.cpp Tue Apr 23 19:23:30 2019 > @@ -8279,6 +8279,9 @@ bool IntExprEvaluator::VisitBuiltinCallE > return Success(false, E); > } > > + case Builtin::BI__builtin_is_constant_evaluated: > + return Success(Info.InConstantContext, E); > + > case Builtin::BI__builtin_ctz: > case Builtin::BI__builtin_ctzl: > case Builtin::BI__builtin_ctzll: > @@ -11139,6 +11142,7 @@ bool Expr::EvaluateAsConstantExpr(EvalRe > EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression; > EvalInfo Info(Ctx, Result, EM); > Info.InConstantContext = true; > + > if (!::Evaluate(Result.Val, Info, this)) > return false; > > > Modified: cfe/trunk/lib/Basic/Builtins.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Basic/Builtins.cpp?rev=359067&r1=359066&r2=359067&view=diff > ============================================================================== > --- cfe/trunk/lib/Basic/Builtins.cpp (original) > +++ cfe/trunk/lib/Basic/Builtins.cpp Tue Apr 23 19:23:30 2019 > @@ -75,9 +75,12 @@ bool Builtin::Context::builtinIsSupporte > bool OclCUnsupported = !LangOpts.OpenCL && > (BuiltinInfo.Langs & ALL_OCLC_LANGUAGES); > bool OpenMPUnsupported = !LangOpts.OpenMP && BuiltinInfo.Langs == OMP_LANG; > + bool CPlusPlusUnsupported = > + !LangOpts.CPlusPlus && BuiltinInfo.Langs == CXX_LANG; > return !BuiltinsUnsupported && !MathBuiltinsUnsupported && > !OclCUnsupported && > !OclC1Unsupported && !OclC2Unsupported && !OpenMPUnsupported && > - !GnuModeUnsupported && !MSModeUnsupported && !ObjCUnsupported; > + !GnuModeUnsupported && !MSModeUnsupported && !ObjCUnsupported && > + !CPlusPlusUnsupported; > } > > /// initializeBuiltins - Mark the identifiers for all the builtins with their > > Modified: cfe/trunk/lib/CodeGen/CGDecl.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGDecl.cpp?rev=359067&r1=359066&r2=359067&view=diff > ============================================================================== > --- cfe/trunk/lib/CodeGen/CGDecl.cpp (original) > +++ cfe/trunk/lib/CodeGen/CGDecl.cpp Tue Apr 23 19:23:30 2019 > @@ -1783,7 +1783,8 @@ void CodeGenFunction::EmitAutoVarInit(co > } > > llvm::Constant *constant = nullptr; > - if (emission.IsConstantAggregate || D.isConstexpr()) { > + if (emission.IsConstantAggregate || D.isConstexpr() || > + D.isUsableInConstantExpressions(getContext())) { > assert(!capturedByInit && "constant init contains a capturing block?"); > constant = ConstantEmitter(*this).tryEmitAbstractForInitializer(D); > if (constant && trivialAutoVarInit != > > Added: cfe/trunk/test/CodeGenCXX/builtin-is-constant-evaluated.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/builtin-is-constant-evaluated.cpp?rev=359067&view=auto > ============================================================================== > --- cfe/trunk/test/CodeGenCXX/builtin-is-constant-evaluated.cpp (added) > +++ cfe/trunk/test/CodeGenCXX/builtin-is-constant-evaluated.cpp Tue Apr 23 > 19:23:30 2019 > @@ -0,0 +1,133 @@ > +// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm %s -std=c++2a > -o %t.ll > +// RUN: FileCheck -check-prefix=CHECK-FN-CG -input-file=%t.ll %s > +// RUN: FileCheck -check-prefix=CHECK-STATIC -input-file=%t.ll %s > +// RUN: FileCheck -check-prefix=CHECK-DYN -input-file=%t.ll %s > +// RUN: FileCheck -check-prefix=CHECK-ARR -input-file=%t.ll %s > +// RUN: FileCheck -check-prefix=CHECK-FOLD -input-file=%t.ll %s > + > +using size_t = decltype(sizeof(int)); > + > +#define CONSTINIT __attribute__((require_constant_initialization)) > + > +extern "C" [[noreturn]] void BOOM(); > +extern "C" void OK(); > +extern "C" size_t RANDU(); > + > +namespace std { > +inline constexpr bool is_constant_evaluated() noexcept { > + return __builtin_is_constant_evaluated(); > +} > +} // namespace std > + > +// CHECK-FN-CG-LABEL: define zeroext i1 @_Z3foov() > +// CHECK-FN-CG: ret i1 false > +bool foo() { > + return __builtin_is_constant_evaluated(); > +} > + > +// CHECK-FN-CG-LABEL: define linkonce_odr i32 @_Z1fv() > +constexpr int f() { > + // CHECK-FN-CG: store i32 13, i32* %n, align 4 > + // CHECK-FN-CG: store i32 17, i32* %m, align 4 > + // CHECK-FN-CG: %1 = load i32, i32* %m, align 4 > + // CHECK-FN-CG: %add = add nsw i32 %1, 13 > + // CHECK-FN-CG: ret i32 %add > + const int n = __builtin_is_constant_evaluated() && > std::is_constant_evaluated() ? 13 : 17; // n == 13 > + int m = __builtin_is_constant_evaluated() ? 13 : 17; // m might be > 13 or 17 (see below) > + char arr[n] = {}; // char[13] > + return m + int(sizeof(arr)); > +} > + > +// CHECK-STATIC-DAG: @p = global i32 26, > +CONSTINIT int p = f(); // f().m == 13; initialized to 26 > +// CHECK-STATIC-DAG: @p2 = global i32 26, > +int p2 = f(); // same result without CONSTINIT > + > +// CHECK-DYN-LABEL: define internal void @__cxx_global_var_init() > +// CHECK-DYN: %0 = load i32, i32* @p, align 4 > +// CHECK-DYN-NEXT: %call = call i32 @_Z1fv() > +// CHECK-DYN-NEXT: %add = add nsw i32 %0, %call > +// CHECK-DYN-NEXT: store i32 %add, i32* @q, align 4 > +// CHECK-DYN-NEXT: ret void > +int q = p + f(); // m == 17 for this call; initialized to 56 > + > +int y; > + > +// CHECK-STATIC-DAG: @b = global i32 2, > +CONSTINIT int b = __builtin_is_constant_evaluated() ? 2 : y; // static > initialization to 2 > + > +// CHECK-DYN-LABEL: define internal void @__cxx_global_var_init.1() > +// CHECK-DYN: %0 = load i32, i32* @y, align 4 > +// CHECK-DYN: %1 = load i32, i32* @y, align 4 > +// CHECK-DYN-NEXT: %add = add > +// CHECK-DYN-NEXT: store i32 %add, i32* @c, > +int c = y + (__builtin_is_constant_evaluated() ? 2 : y); // dynamic > initialization to y+y > + > +// CHECK-DYN-LABEL: define internal void @__cxx_global_var_init.2() > +// CHECK-DYN: store i32 1, i32* @_ZL1a, align 4 > +// CHECK-DYN-NEXT: ret void > +const int a = __builtin_is_constant_evaluated() ? y : 1; // dynamic > initialization to 1 > +const int *a_sink = &a; > + > +// CHECK-ARR-LABEL: define void @_Z13test_arr_exprv > +void test_arr_expr() { > + // CHECK-ARR: %x1 = alloca [101 x i8], > + char x1[std::is_constant_evaluated() && __builtin_is_constant_evaluated() > ? 101 : 1]; > + > + // CHECK-ARR: %x2 = alloca [42 x i8], > + char x2[std::is_constant_evaluated() && __builtin_is_constant_evaluated() > ? 42 : RANDU()]; > + > + // CHECK-ARR: call i8* @llvm.stacksave() > + // CHECK-ARR: %vla = alloca i8, i64 13, > + char x3[std::is_constant_evaluated() || __builtin_is_constant_evaluated() > ? RANDU() : 13]; > +} > + > +// CHECK-ARR-LABEL: define void @_Z17test_new_arr_exprv > +void test_new_arr_expr() { > + // CHECK-ARR: call i8* @_Znam(i64 17) > + new char[std::is_constant_evaluated() || __builtin_is_constant_evaluated() > ? 1 : 17]; > +} > + > +// CHECK-FOLD-LABEL: @_Z31test_constant_initialized_locali( > +bool test_constant_initialized_local(int k) { > + // CHECK-FOLD: store i8 1, i8* %n, > + // CHECK-FOLD: store volatile i8* %n, i8** %p, > + const bool n = __builtin_is_constant_evaluated() && > std::is_constant_evaluated(); > + const bool *volatile p = &n; > + return *p; > +} > + > +// CHECK-FOLD-LABEL: define void @_Z21test_ir_constant_foldv() > +void test_ir_constant_fold() { > + // CHECK-FOLD-NEXT: entry: > + // CHECK-FOLD-NEXT: call void @OK() > + // CHECK-FOLD-NEXT: call void @OK() > + // CHECK-FOLD-NEXT: ret void > + if (std::is_constant_evaluated()) { > + BOOM(); > + } else { > + OK(); > + } > + std::is_constant_evaluated() ? BOOM() : OK(); > +} > + > +// CHECK-STATIC-DAG: @ir = constant i32* @i_constant, > +int i_constant; > +int i_not_constant; > +int &ir = __builtin_is_constant_evaluated() ? i_constant : i_not_constant; > + > +// CHECK-FOLD-LABEL: @_Z35test_ref_initialization_local_scopev() > +void test_ref_initialization_local_scope() { > + const int i_constant = 42; > + const int i_non_constant = 101; > + // CHECK-FOLD: store i32* %i_non_constant, i32** %r, > + const int &r = __builtin_is_constant_evaluated() ? i_constant : > i_non_constant; > +} > + > +// CHECK-FOLD-LABEL: @_Z22test_ref_to_static_varv() > +void test_ref_to_static_var() { > + static int i_constant = 42; > + static int i_non_constant = 101; > + // CHECK-FOLD: store i32* @_ZZ22test_ref_to_static_varvE10i_constant, > i32** %r, > + int &r = __builtin_is_constant_evaluated() ? i_constant : i_non_constant; > +} > \ No newline at end of file > > Modified: cfe/trunk/test/Sema/builtins.c > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/Sema/builtins.c?rev=359067&r1=359066&r2=359067&view=diff > ============================================================================== > --- cfe/trunk/test/Sema/builtins.c (original) > +++ cfe/trunk/test/Sema/builtins.c Tue Apr 23 19:23:30 2019 > @@ -314,3 +314,9 @@ void test23() { > memcpy(buf, src, 11); // expected-warning{{'memcpy' will always overflow; > destination buffer has size 10, but size argument is 11}} > my_memcpy(buf, src, 11); // expected-warning{{'memcpy' will always > overflow; destination buffer has size 10, but size argument is 11}} > } > + > +// Test that __builtin_is_constant_evaluated() is not allowed in C > +int test_cxx_builtin() { > + // expected-error@+1 {{use of unknown builtin > '__builtin_is_constant_evaluated'}} > + return __builtin_is_constant_evaluated(); > +} > > Added: cfe/trunk/test/SemaCXX/builtin-is-constant-evaluated.cpp > URL: > http://llvm.org/viewvc/llvm-project/cfe/trunk/test/SemaCXX/builtin-is-constant-evaluated.cpp?rev=359067&view=auto > ============================================================================== > --- cfe/trunk/test/SemaCXX/builtin-is-constant-evaluated.cpp (added) > +++ cfe/trunk/test/SemaCXX/builtin-is-constant-evaluated.cpp Tue Apr 23 > 19:23:30 2019 > @@ -0,0 +1,121 @@ > +// RUN: %clang_cc1 -std=c++2a -verify %s -fcxx-exceptions > -triple=x86_64-linux-gnu > + > +using size_t = decltype(sizeof(int)); > + > +namespace std { > +inline constexpr bool is_constant_evaluated() noexcept { > + return __builtin_is_constant_evaluated(); > +} > +} // namespace std > + > +extern int dummy; // expected-note 1+ {{declared here}} > + > +static_assert(__builtin_is_constant_evaluated()); > +static_assert(noexcept(__builtin_is_constant_evaluated())); > + > +constexpr bool b = __builtin_is_constant_evaluated(); > +static_assert(b); > + > +const int n = __builtin_is_constant_evaluated() ? 4 : dummy; > +static_assert(n == 4); > +constexpr int cn = __builtin_is_constant_evaluated() ? 11 : dummy; > +static_assert(cn == 11); > +// expected-error@+1 {{'bn' must be initialized by a constant expression}} > +constexpr int bn = __builtin_is_constant_evaluated() ? dummy : 42; // > expected-note {{non-const variable 'dummy' is not allowed}} > + > +const int n2 = __builtin_is_constant_evaluated() ? dummy : 42; // > expected-note {{declared here}} > +static_assert(n2 == 42); // > expected-error {{static_assert expression is not an integral constant}} > +// expected-note@-1 {{initializer of 'n2' is not a constant expression}} > + > +template <bool V, bool Default = std::is_constant_evaluated()> > +struct Templ { static_assert(V); static_assert(Default); }; > +Templ<__builtin_is_constant_evaluated()> x; // type X<true> > + > +template <class T> > +void test_if_constexpr() { > + if constexpr (__builtin_is_constant_evaluated()) { > + static_assert(__is_same(T, int)); > + } else { > + using Test = typename T::DOES_NOT_EXIST; > + } > +} > +template void test_if_constexpr<int>(); > + > +void test_array_decl() { > + char x[__builtin_is_constant_evaluated() + std::is_constant_evaluated()]; > + static_assert(sizeof(x) == 2, ""); > +} > + > +void test_case_stmt(int x) { > + switch (x) { > + case 0: // > OK > + case __builtin_is_constant_evaluated(): // > expected-note {{previous case}} > + case std::is_constant_evaluated() + __builtin_is_constant_evaluated(): // > expected-note {{previous case}} > + case 1: // > expected-error {{duplicate case value '1'}} > + case 2: // > expected-error {{duplicate case value '2'}} > + break; > + } > +} > + > +constexpr size_t good_array_size() { > + return std::is_constant_evaluated() ? 42 : static_cast<size_t>(-1); > +} > + > +constexpr size_t bad_array_size() { > + return std::is_constant_evaluated() ? static_cast<size_t>(-1) : 13; > +} > + > +template <class T> > +constexpr T require_constexpr(T v) { > + if (!std::is_constant_evaluated()) > + throw "BOOM"; > + return v; > +} > + > +void test_new_expr() { > + constexpr size_t TooLarge = -1; > + auto *x = new int[std::is_constant_evaluated() ? 1 : TooLarge]; // > expected-error {{array is too large}} > + auto *x2 = new int[std::is_constant_evaluated() ? TooLarge : 1]; // OK > + auto *y = new int[1][std::is_constant_evaluated() ? TooLarge : 1]{}; // > expected-error {{array is too large}} > + auto *y2 = new int[1][require_constexpr(42)]; > +} > + > +void test_alignas_operand() { > + alignas(std::is_constant_evaluated() ? 8 : 2) char dummy; > + static_assert(__alignof(dummy) == 8); > +} > + > +void test_static_assert_operand() { > + static_assert(std::is_constant_evaluated(), ""); > +} > + > +void test_enumerator() { > + enum MyEnum { > + ZERO = 0, > + ONE = std::is_constant_evaluated() > + }; > + static_assert(ONE == 1, ""); > +} > + > +struct TestBitfieldWidth { > + unsigned Bits : std::is_constant_evaluated(); > +}; > + > +void test_operand_of_noexcept_fn() noexcept(std::is_constant_evaluated()); > +static_assert(noexcept(test_operand_of_noexcept_fn()), ""); > + > + > +namespace test_ref_initialization { > +int x; > +int y; > +int &r = __builtin_is_constant_evaluated() ? x : y; > +static_assert(&r == &x); > + > +} // namespace test_ref_initialization > + > +#if defined(__cpp_conditional_explicit) > +struct TestConditionalExplicit { > + explicit(__builtin_is_constant_evaluated()) TestConditionalExplicit(int) {} > +}; > +TestConditionalExplicit e = 42; > +#endif > > > _______________________________________________ > cfe-commits mailing list > cfe-commits@lists.llvm.org > https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
