cutlass/test/unit/cute/core/constant_arithmetic.cpp
2023-08-25 23:05:46 -04:00

107 lines
5.6 KiB
C++

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#include "cutlass_unit_test.h"
#include <cutlass/trace.h>
#include <cute/swizzle.hpp>
TEST(CuTe_core, ConstantArithmetic) {
using namespace cute;
constexpr cute::integral_constant<uint32_t, 0> uzero{};
// This extra test exists historically as part of the diagnosis
// of a possible Clang 14 bug. However, it's a nice test for
// cute::integral_constant's arithmetic operators, so it's saved here.
// It also demonstrates how to work with cute::integral_constant
// and lambda captures. Microsoft Visual Studio ("MSVC") tends to
// disagree with other compilers about the meaning of decltype
// for variables captured by reference. MSVC and GCC 8.3.0
// also tend to disagree with other compilers (and other GCC versions)
// about whether expressions involving such variables
// are constant expressions.
//
// A typical CuTe idiom is to do lambda captures by reference [&].
// This test changes them to capture by value, except for
// the innermost lambda's capture of S1, which is by reference.
// The point is to show that MSVC and GCC 8 have issues with this
// that other compilers do not. For example,
//
// 1. MSVC needs remove_cvref_t around decltype(S1)
// in order to access decltype(S1)::value, and
// 2. MSVC and GCC 8.3.0 both report a build error with S1()
// (that is, calling operator() on S1, which returns the
// same thing as S1.value).
//
// The reason for (2) is that neither compiler thinks
// that S1() is a constant expression.
//
// This leaves S1.value as the most concise portable expression
// for the "value" member of a cute::integral_constant.
for_each(make_integer_sequence<uint32_t, 8>{}, [uzero](auto S0) {
for_each(make_integer_sequence<uint32_t, 8>{}, [uzero,S0](auto F0) {
for_each(make_integer_sequence<uint32_t, 8>{}, [uzero,S0,F0](auto S1) {
for_each(make_integer_sequence<uint32_t, 8>{}, [uzero,S0,F0,&S1](auto F1) {
static_assert((decltype(S0)::value & decltype(F0)::value) == decltype(S0 & F0)::value);
// Using S1.value means you don't have to use remove_cvref_t
// with a captured-by-reference variable.
static_assert((cute::remove_cvref_t<decltype(S1)>::value & decltype(F1)::value) == decltype(S1 & F1)::value);
static_assert((S1.value & decltype(F1)::value) == decltype(S1 & F1)::value);
// S1() _should_ work, but does not with Visual Studio 2022,
// which emits C2131 ("expression did not evaluate to a constant").
// It also does not with GCC 8.3.0, which emits an error with messages
// "non-constant condition for static assertion" and
// "'this' is not a constant expression."
//
//static_assert((S1() & decltype(F1)::value) == decltype(S1 & F1)::value);
static_assert(decltype((S0 & F0) != uzero)::value == ((decltype(S0)::value & decltype(F0)::value) != 0));
static_assert(decltype((S1 & F1) != uzero)::value == ((cute::remove_cvref_t<decltype(S1)>::value & decltype(F1)::value) != 0));
static_assert(decltype((S1 & F1) != uzero)::value == ((S1.value & decltype(F1)::value) != 0));
constexpr bool left = decltype((S0 & F0) != uzero || (S1 & F1) != uzero)::value;
constexpr bool right =
((decltype(S0)::value & decltype(F0)::value) != 0) ||
((cute::remove_cvref_t<decltype(S1)>::value & decltype(F1)::value) != 0);
constexpr bool right2 =
((decltype(S0)::value & decltype(F0)::value) != 0) ||
((S1.value & decltype(F1)::value) != 0);
static_assert(right == right2);
static_assert(left == right);
constexpr bool left2 = decltype((S0 & F0) != uzero)::value || decltype((S1 & F1) != uzero)::value;
static_assert(left == left2);
});
});
});
});
}