[libc-commits] [libc] [llvm] [libc][math] Refactor hypotf16 to header-only shared math (PR #175438)

[Muhammad Bassiouni via libc-commits]

================
@@ -7,85 +7,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "src/math/hypotf16.h"
-#include "src/__support/FPUtil/FEnvImpl.h"
-#include "src/__support/FPUtil/FPBits.h"
-#include "src/__support/FPUtil/cast.h"
-#include "src/__support/FPUtil/multiply_add.h"
-#include "src/__support/FPUtil/sqrt.h"
-#include "src/__support/common.h"
-#include "src/__support/macros/optimization.h"
-#include "src/__support/macros/properties/types.h"
+#include "src/__support/math/hypotf16.h"
 
 namespace LIBC_NAMESPACE_DECL {
 
-// For targets where conversion from float to float16 has to be
-// emulated, fputil::hypot<float16> is faster
 LLVM_LIBC_FUNCTION(float16, hypotf16, (float16 x, float16 y)) {
-  using FloatBits = fputil::FPBits<float>;
-  using FPBits = fputil::FPBits<float16>;
-
-  FPBits x_abs = FPBits(x).abs();
-  FPBits y_abs = FPBits(y).abs();
-
-  bool x_abs_larger = x_abs.uintval() >= y_abs.uintval();
-
-  FPBits a_bits = x_abs_larger ? x_abs : y_abs;
-  FPBits b_bits = x_abs_larger ? y_abs : x_abs;
-
-  uint16_t a_u = a_bits.uintval();
-  uint16_t b_u = b_bits.uintval();
-
-  // Note: replacing `a_u >= FPBits::EXP_MASK` with `a_bits.is_inf_or_nan()`
-  // generates extra exponent bit masking instructions on x86-64.
-  if (LIBC_UNLIKELY(a_u >= FPBits::EXP_MASK)) {
-    // x or y is inf or nan
-    if (a_bits.is_signaling_nan() || b_bits.is_signaling_nan()) {
-      fputil::raise_except_if_required(FE_INVALID);
-      return FPBits::quiet_nan().get_val();
-    }
-    if (a_bits.is_inf() || b_bits.is_inf())
-      return FPBits::inf().get_val();
-    return a_bits.get_val();
-  }
-
-  float af = fputil::cast<float>(a_bits.get_val());
-  float bf = fputil::cast<float>(b_bits.get_val());
-
-  // Compiler runtime basic operations for float16 might not be correctly
-  // rounded for all rounding modes.
-  if (LIBC_UNLIKELY(a_u - b_u >=
-                    static_cast<uint16_t>((FPBits::FRACTION_LEN + 2)
-                                          << FPBits::FRACTION_LEN)))
-    return fputil::cast<float16>(af + bf);
-
-  // These squares are exact.
-  float a_sq = af * af;
-  float sum_sq = fputil::multiply_add(bf, bf, a_sq);
-
-  FloatBits result(fputil::sqrt<float>(sum_sq));
-  uint32_t r_u = result.uintval();
-
-  // If any of the sticky bits of the result are non-zero, except the LSB, then
-  // the rounded result is correct.
-  if (LIBC_UNLIKELY(((r_u + 1) & 0x0000'0FFE) == 0)) {
-    float r_d = result.get_val();
-
-    // Perform rounding correction.
-    float sum_sq_lo = fputil::multiply_add(bf, bf, a_sq - sum_sq);
-    float err = sum_sq_lo - fputil::multiply_add(r_d, r_d, -sum_sq);
-
-    if (err > 0) {
-      r_u |= 1;
-    } else if ((err < 0) && (r_u & 1) == 0) {
-      r_u -= 1;
-    } else if ((r_u & 0x0000'1FFF) == 0) {
-      // The rounded result is exact.
-      fputil::clear_except_if_required(FE_INEXACT);
-    }
-    return fputil::cast<float16>(FloatBits(r_u).get_val());
-  }
-
-  return fputil::cast<float16>(result.get_val());
+  return math::hypotf16(x, y);
 }
 
-} // namespace LIBC_NAMESPACE_DECL
+} // namespace LIBC_NAMESPACE_DECL
----------------
bassiounix wrote:

Don't remove the last line separator
```suggestion
} // namespace LIBC_NAMESPACE_DECL

```

https://github.com/llvm/llvm-project/pull/175438