[Flang] Promote FortranEvaluateTesting library (#124417)

The non-GTest library will be shared by unittests of Flang and Flang-RT.
Promote it as a regular library for use by both projects.

In the long term, we may want to convert these to regular GTest checks
to avoid having multiple testing frameworks.

1 files changed, 124 insertions, 0 deletions

diff --git a/flang/lib/Testing/fp-testing.cpp b/flang/lib/Testing/fp-testing.cpp
new file mode 100644
index 000000000000..5e1728e8df5e
--- /dev/null
+++ b/flang/lib/Testing/fp-testing.cpp
@@ -0,0 +1,124 @@
+//===-- lib/Testing/fp-testing.cpp ------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "flang/Testing/fp-testing.h"
+#include "llvm/Support/Errno.h"
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#if __x86_64__
+#include <xmmintrin.h>
+#endif
+
+using Fortran::common::RealFlag;
+using Fortran::common::RoundingMode;
+
+ScopedHostFloatingPointEnvironment::ScopedHostFloatingPointEnvironment(
+#if __x86_64__
+    bool treatSubnormalOperandsAsZero, bool flushSubnormalResultsToZero
+#else
+    bool, bool
+#endif
+) {
+  errno = 0;
+  if (feholdexcept(&originalFenv_) != 0) {
+    std::fprintf(stderr, "feholdexcept() failed: %s\n",
+        llvm::sys::StrError(errno).c_str());
+    std::abort();
+  }
+  fenv_t currentFenv;
+  if (fegetenv(&currentFenv) != 0) {
+    std::fprintf(
+        stderr, "fegetenv() failed: %s\n", llvm::sys::StrError(errno).c_str());
+    std::abort();
+  }
+
+#if __x86_64__
+  originalMxcsr = _mm_getcsr();
+  unsigned int currentMxcsr{originalMxcsr};
+  if (treatSubnormalOperandsAsZero) {
+    currentMxcsr |= 0x0040;
+  } else {
+    currentMxcsr &= ~0x0040;
+  }
+  if (flushSubnormalResultsToZero) {
+    currentMxcsr |= 0x8000;
+  } else {
+    currentMxcsr &= ~0x8000;
+  }
+#else
+  // TODO others
+#endif
+  errno = 0;
+  if (fesetenv(&currentFenv) != 0) {
+    std::fprintf(
+        stderr, "fesetenv() failed: %s\n", llvm::sys::StrError(errno).c_str());
+    std::abort();
+  }
+#if __x86_64__
+  _mm_setcsr(currentMxcsr);
+#endif
+}
+
+ScopedHostFloatingPointEnvironment::~ScopedHostFloatingPointEnvironment() {
+  errno = 0;
+  if (fesetenv(&originalFenv_) != 0) {
+    std::fprintf(
+        stderr, "fesetenv() failed: %s\n", llvm::sys::StrError(errno).c_str());
+    std::abort();
+  }
+#if __x86_64__
+  _mm_setcsr(originalMxcsr);
+#endif
+}
+
+void ScopedHostFloatingPointEnvironment::ClearFlags() const {
+  feclearexcept(FE_ALL_EXCEPT);
+}
+
+RealFlags ScopedHostFloatingPointEnvironment::CurrentFlags() {
+  int exceptions = fetestexcept(FE_ALL_EXCEPT);
+  RealFlags flags;
+  if (exceptions & FE_INVALID) {
+    flags.set(RealFlag::InvalidArgument);
+  }
+  if (exceptions & FE_DIVBYZERO) {
+    flags.set(RealFlag::DivideByZero);
+  }
+  if (exceptions & FE_OVERFLOW) {
+    flags.set(RealFlag::Overflow);
+  }
+  if (exceptions & FE_UNDERFLOW) {
+    flags.set(RealFlag::Underflow);
+  }
+  if (exceptions & FE_INEXACT) {
+    flags.set(RealFlag::Inexact);
+  }
+  return flags;
+}
+
+void ScopedHostFloatingPointEnvironment::SetRounding(Rounding rounding) {
+  switch (rounding.mode) {
+  case RoundingMode::TiesToEven:
+    fesetround(FE_TONEAREST);
+    break;
+  case RoundingMode::ToZero:
+    fesetround(FE_TOWARDZERO);
+    break;
+  case RoundingMode::Up:
+    fesetround(FE_UPWARD);
+    break;
+  case RoundingMode::Down:
+    fesetround(FE_DOWNWARD);
+    break;
+  case RoundingMode::TiesAwayFromZero:
+    std::fprintf(stderr, "SetRounding: TiesAwayFromZero not available");
+    std::abort();
+    break;
+  }
+}