[libc-commits] [libc] [libc][math] Implement double precision acos correctly rounded for all rounding modes. (PR #138308)

[via libc-commits]

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+//===-- Unittests for acos ------------------------------------------------===//
+//
+// 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 "src/math/acos.h"
+#include "test/UnitTest/FPMatcher.h"
+#include "test/UnitTest/Test.h"
+#include "utils/MPFRWrapper/MPFRUtils.h"
+
+using LlvmLibcAcosTest = LIBC_NAMESPACE::testing::FPTest<double>;
+
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+using LIBC_NAMESPACE::testing::tlog;
+
+TEST_F(LlvmLibcAcosTest, InDoubleRange) {
+  constexpr uint64_t COUNT = 123'451;
+  uint64_t START = FPBits(0x1.0p-60).uintval();
+  uint64_t STOP = FPBits(1.0).uintval();
+  uint64_t STEP = (STOP - START) / COUNT;
+
+  auto test = [&](mpfr::RoundingMode rounding_mode) {
+    mpfr::ForceRoundingMode __r(rounding_mode);
+    if (!__r.success)
+      return;
+
+    uint64_t fails = 0;
+    uint64_t count = 0;
+    uint64_t cc = 0;
+    double mx = 0.0, mr = 0.0;
+    double tol = 0.5;
+
+    for (uint64_t i = 0, v = START; i <= COUNT; ++i, v += STEP) {
+      double x = FPBits(v).get_val();
+      if (FPBits(v).is_nan() || FPBits(v).is_inf())
+        continue;
+      double result = LIBC_NAMESPACE::acos(x);
+      ++cc;
+      if (FPBits(result).is_nan() || FPBits(result).is_inf())
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lntue wrote:

Done.

https://github.com/llvm/llvm-project/pull/138308