[libc-commits] [libc] [libc][math][C23] add software float16 support (PR #184283)

[via libc-commits]

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+//===-- Exhaustive tests for float -> float16 conversion ------------------===//
+//
+// 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 "exhaustive_test.h"
+#include "src/__support/FPUtil/cast.h"
+#include "utils/MPFRWrapper/MPCommon.h"
+
+using namespace LIBC_NAMESPACE::fputil;
+namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
+
+template <typename InType>
+struct Float16ConversionChecker : public virtual LIBC_NAMESPACE::testing::Test {
+  using FloatType = InType;
+  using FPBits = LIBC_NAMESPACE::fputil::FPBits<FloatType>;
+  using StorageType = typename FPBits::StorageType;
+
+  // Check in a range, return the number of failures.
+  uint64_t check(StorageType start, StorageType stop,
+                 mpfr::RoundingMode rounding) {
+    mpfr::ForceRoundingMode r(rounding);
+    if (!r.success)
+      return (stop > start);
+    StorageType bits = start;
+    uint64_t failed = 0;
+    do {
+      FPBits x_bits(bits);
+      FloatType x = x_bits.get_val();
+
+      const float16 libc_result = cast<float16>(x);
+      const float16 mpfr_result = mpfr::MPFRNumber(x).as<float16>();
+
+      const bool correct =
+          LIBC_NAMESPACE::testing::getMatcher<
+              LIBC_NAMESPACE::testing::TestCond::EQ>(mpfr_result)
+              .match(libc_result);
+
+      failed += (!correct);
+    } while (bits++ < stop);
+    return failed;
+  }
+};
+
+template <typename FloatType>
+using LlvmLibcFloat16ExhaustiveTest =
+    LlvmLibcExhaustiveMathTest<Float16ConversionChecker<FloatType>>;
+using LlvmLibcFloat16FromFloatTest = LlvmLibcFloat16ExhaustiveTest<float>;
+
+// Positive Range: [0, Inf];
+constexpr uint32_t POS_START = 0x0000'0000U;
+constexpr uint32_t POS_STOP = 0x7f80'0000U;
+
+// Negative Range: [-Inf, 0];
+constexpr uint32_t NEG_START = 0xb000'0000U;
+constexpr uint32_t NEG_STOP = 0xff80'0000U;
+
+TEST_F(LlvmLibcFloat16FromFloatTest, PostiveRange) {
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Sukumarsawant wrote:

nit: `positive`

https://github.com/llvm/llvm-project/pull/184283