1 //===-- FEnvSafeTest.h -----------------------------------------*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===---------------------------------------------------------------------===// 8 9 #ifndef LLVM_LIBC_TEST_UNITTEST_FPENVSAFE_H 10 #define LLVM_LIBC_TEST_UNITTEST_FPENVSAFE_H 11 12 #include "hdr/types/fenv_t.h" 13 #include "src/__support/CPP/utility.h" 14 #include "test/UnitTest/Test.h" 15 16 namespace LIBC_NAMESPACE::testing { 17 18 // This provides a test fixture (or base class for other test fixtures) that 19 // asserts that each test does not leave the FPU state represented by `fenv_t` 20 // (aka `FPState`) perturbed from its initial state. 21 class FEnvSafeTest : public Test { 22 public: 23 void TearDown() override; 24 25 protected: 26 // This is an RAII type where `PreserveFEnv preserve{this};` will sample the 27 // `fenv_t` state and restore it when `preserve` goes out of scope. 28 class PreserveFEnv { 29 fenv_t before; 30 FEnvSafeTest &test; 31 32 public: PreserveFEnv(FEnvSafeTest * self)33 explicit PreserveFEnv(FEnvSafeTest *self) : test{*self} { 34 test.get_fenv(before); 35 } 36 37 // Cause test expectation failures if the current state doesn't match what 38 // was captured in the constructor. 39 void check(); 40 41 // Restore the state captured in the constructor. restore()42 void restore() { test.set_fenv(before); } 43 ~PreserveFEnv()44 ~PreserveFEnv() { restore(); } 45 }; 46 47 // This is an RAII type where `CheckFEnv check{this};` will sample the 48 // `fenv_t` state and require it be the same when `check` goes out of scope. 49 struct CheckFEnv : public PreserveFEnv { 50 using PreserveFEnv::PreserveFEnv; 51 ~CheckFEnvCheckFEnv52 ~CheckFEnv() { check(); } 53 }; 54 55 // This calls callable() and returns its value, but has EXPECT_* failures if 56 // the `fenv_t` state is not preserved by the call. decltype(auto)57 template <typename T> decltype(auto) check_fenv_preserved(T &&callable) { 58 CheckFEnv check{this}; 59 return cpp::forward<T>(callable)(); 60 } 61 62 // This calls callable() and returns its value, but saves and restores the 63 // `fenv_t` state around the call. 64 template <typename T> 65 auto with_fenv_preserved(T &&callable) 66 -> decltype(cpp::forward<decltype(callable)>(callable)()) { 67 PreserveFEnv preserve{this}; 68 return cpp::forward<T>(callable)(); 69 } 70 71 // A test can call these to indicate it will or won't change `fenv_t` state. will_change_fenv()72 void will_change_fenv() { should_be_unchanged = false; } will_not_change_fenv()73 void will_not_change_fenv() { should_be_unchanged = true; } 74 75 // This explicitly resets back to the "before" state captured in SetUp(). 76 // TearDown() always does this, but should_be_unchanged controls whether 77 // it also causes test failures if a test fails to restore it. restore_fenv()78 void restore_fenv() { check.restore(); } 79 80 private: 81 void get_fenv(fenv_t &fenv); 82 void set_fenv(const fenv_t &fenv); 83 void expect_fenv_eq(const fenv_t &before_fenv, const fenv_t &after_fenv); 84 85 CheckFEnv check{this}; 86 87 // TODO: Many tests fail if this is true. It needs to be figured out whether 88 // the state should be preserved by each library function under test, and 89 // separately whether each test itself should preserve the state. It 90 // probably isn't important that tests be explicitly written to preserve the 91 // state, as the fixture can (and does) reset it--the next test can rely on 92 // getting "normal" ambient state initially. For library functions that 93 // should preserve the state, that should be checked after each call, not 94 // just after the whole test. So they can use check_fenv_preserved or 95 // with_fenv_preserved as appropriate. 96 bool should_be_unchanged = false; 97 }; 98 99 } // namespace LIBC_NAMESPACE::testing 100 101 #endif // LLVM_LIBC_TEST_UNITTEST_FPENVSAFE_H 102