- clang-formatted the files

- added missing header

Author: amemov

libc/src/__support/math/rsqrtf.h

@@ -0,0 +1,81 @@
+//===-- Implementation header for rsqrtf ----------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
+#define LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H
+
+#include "src/__support/FPUtil/FEnvImpl.h"
+#include "src/__support/FPUtil/FPBits.h"
+#include "src/__support/FPUtil/ManipulationFunctions.h"
+#include "src/__support/FPUtil/cast.h"
+#include "src/__support/FPUtil/multiply_add.h"
+#include "src/__support/FPUtil/sqrt.h"
+#include "src/__support/macros/optimization.h"
+
+namespace LIBC_NAMESPACE_DECL {
+namespace math {
+
+LIBC_INLINE static constexpr float rsqrtf(float x) {
+  using FPBits = fputil::FPBits<float>;
+  FPBits xbits(x);
+
+  uint32_t x_u = xbits.uintval();
+  uint32_t x_abs = x_u & 0x7fff'ffffU;
+
+  constexpr uint32_t INF_BIT = FPBits::inf().uintval();
+
+  // x is 0, inf/nan, or negative.
+  if (LIBC_UNLIKELY(x_u == 0 || x_u >= INF_BIT)) {
+    // x is NaN
+    if (x_abs > INF_BIT) {
+      if (xbits.is_signaling_nan()) {
+        fputil::raise_except_if_required(FE_INVALID);
+        return FPBits::quiet_nan().get_val();
+      }
+      return x;
+    }
+
+    // |x| = 0
+    if (x_abs == 0) {
+      fputil::raise_except_if_required(FE_DIVBYZERO);
+      fputil::set_errno_if_required(ERANGE);
+      return FPBits::inf(xbits.sign()).get_val();
+    }
+
+    // -inf <= x < 0
+    if (x_u > 0x7fff'ffffU) {
+      fputil::raise_except_if_required(FE_INVALID);
+      fputil::set_errno_if_required(EDOM);
+      return FPBits::quiet_nan().get_val();
+    }
+
+    // x = +inf => rsqrt(x) = 0
+    return FPBits::zero().get_val();
+  }
+
+  // TODO: add integer based implementation when LIBC_TARGET_CPU_HAS_FPU_FLOAT
+  // is not defined
+  double result = 1.0f / fputil::sqrt<double>(fputil::cast<double>(x));
+
+  // Targeted post-corrections to ensure correct rounding in half for specific
+  // mantissa patterns
+  /*
+  const uint32_t half_mantissa = x_abs & 0x3ff;
+  if (LIBC_UNLIKELY(half_mantissa == 0x011F)) {
+    result = fputil::multiply_add(result, 0x1.0p-21f, result);
+  } else if (LIBC_UNLIKELY(half_mantissa == 0x0313)) {
+    result = fputil::multiply_add(result, -0x1.0p-21f, result);
+  }*/
+
+  return fputil::cast<float>(result);
+}
+
+} // namespace math
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_MATH_RSQRTF_H

libc/test/src/math/rsqrtf_test.cpp

@@ -16,7 +16,7 @@ using LlvmLibcRsqrtfTest = LIBC_NAMESPACE::testing::FPTest<float>;
 namespace mpfr = LIBC_NAMESPACE::testing::mpfr;
 
 // Range: [0, Inf]
-static constexpr uint32_t POS_START = 0x00000000u; 
+static constexpr uint32_t POS_START = 0x00000000u;
 static constexpr uint32_t POS_STOP = 0x7F800000u;
 
 // Range: [-Inf, 0)

libc/test/src/math/smoke/rsqrtf_test.cpp

@@ -26,9 +26,7 @@ TEST_F(LlvmLibcRsqrtfTest, SpecialNumbers) {
   EXPECT_FP_EQ(neg_inf, LIBC_NAMESPACE::rsqrtf(neg_zero));
   EXPECT_MATH_ERRNO(ERANGE);
 
-  EXPECT_FP_EQ(
-      1.0f,
-      LIBC_NAMESPACE::rsqrtf(1.0f));
+  EXPECT_FP_EQ(1.0f, LIBC_NAMESPACE::rsqrtf(1.0f));
   EXPECT_MATH_ERRNO(0);
 
   EXPECT_FP_EQ(zero, LIBC_NAMESPACE::rsqrtf(inf));