[libc] sqrt and log functions fuzz tests (#148006)

added fuzz tests for sqrt and log functions

---------

Co-authored-by: Sriya Pratipati <sriyap@google.com>

1 files changed, 50 insertions, 0 deletions

diff --git a/libc/fuzzing/math/sqrt_fuzz.cpp b/libc/fuzzing/math/sqrt_fuzz.cpp
new file mode 100644
index 0000000..e81cf1a
--- /dev/null
+++ b/libc/fuzzing/math/sqrt_fuzz.cpp
@@ -0,0 +1,50 @@
+//===-- sqrt_fuzz.cpp -----------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// Fuzzing test for llvm-libc sqrt implementation.
+///
+//===----------------------------------------------------------------------===//
+
+#include "src/__support/FPUtil/generic/sqrt.h"
+#include "utils/MPFRWrapper/mpfr_inc.h"
+#include <cstdint>
+#include <cstring>
+#include <iostream>
+#include <math.h>
+
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
+  mpfr_t input;
+  mpfr_init2(input, 53);
+  for (size_t i = 0; i < size / sizeof(double); ++i) {
+    double x;
+    std::memcpy(&x, data, sizeof(double));
+    data += sizeof(double);
+    // remove NaN and inf and values outside accepted range
+    if (isnan(x) || isinf(x) || x < 0)
+      return 0;
+    // signed zeros already tested in unit tests
+    if (signbit(x) && x == 0.0)
+      return 0;
+
+    mpfr_set_d(input, x, MPFR_RNDN);
+    int output = mpfr_sqrt(input, input, MPFR_RNDN);
+    mpfr_subnormalize(input, output, MPFR_RNDN);
+    double to_compare = mpfr_get_d(input, MPFR_RNDN);
+
+    double result = LIBC_NAMESPACE::fputil::sqrt<double>(x);
+
+    if (result != to_compare) {
+      std::cout << std::hexfloat << "Failing input: " << x << std::endl;
+      std::cout << std::hexfloat << "Failing output: " << result << std::endl;
+      std::cout << std::hexfloat << "Expected: " << to_compare << std::endl;
+      __builtin_trap();
+    }
+  }
+  mpfr_clear(input);
+  return 0;
+}