[libc-commits] [libc] [libc][NFC] Remove dead code (PR #81005)

[via libc-commits]

llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-libc

Author: Guillaume Chatelet (gchatelet)

<details>
<summary>Changes</summary>



---
Full diff: https://github.com/llvm/llvm-project/pull/81005.diff


2 Files Affected:

- (modified) libc/src/__support/FPUtil/CMakeLists.txt (-10) 
- (removed) libc/src/__support/FPUtil/XFloat.h (-180) 


``````````diff
diff --git a/libc/src/__support/FPUtil/CMakeLists.txt b/libc/src/__support/FPUtil/CMakeLists.txt
index 47c102a47426c..3307d33434f0b 100644
--- a/libc/src/__support/FPUtil/CMakeLists.txt
+++ b/libc/src/__support/FPUtil/CMakeLists.txt
@@ -143,16 +143,6 @@ add_header_library(
     libc.src.__support.uint128
 )
 
-add_header_library(
-  xfloat
-  HDRS
-    XFloat.h
-  DEPENDS
-    .fp_bits
-    .normal_float
-    libc.src.__support.uint
-)
-
 add_header_library(
   sqrt
   HDRS
diff --git a/libc/src/__support/FPUtil/XFloat.h b/libc/src/__support/FPUtil/XFloat.h
deleted file mode 100644
index fe334f8a33011..0000000000000
--- a/libc/src/__support/FPUtil/XFloat.h
+++ /dev/null
@@ -1,180 +0,0 @@
-//===-- Utility class to manipulate wide floats. ----------------*- 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
-//
-//===----------------------------------------------------------------------===//
-
-#include "FPBits.h"
-#include "NormalFloat.h"
-#include "src/__support/UInt.h"
-
-#include <stdint.h>
-
-namespace LIBC_NAMESPACE {
-namespace fputil {
-
-// Store and manipulate positive double precision numbers at |Precision| bits.
-template <size_t Precision> class XFloat {
-  static constexpr uint64_t OneMask = (uint64_t(1) << 63);
-  UInt<Precision> man;
-  static constexpr uint64_t WORDCOUNT = Precision / 64;
-  int exp;
-
-  size_t bit_width(uint64_t x) {
-    if (x == 0)
-      return 0;
-    size_t shift = 0;
-    while ((OneMask & x) == 0) {
-      ++shift;
-      x <<= 1;
-    }
-    return 64 - shift;
-  }
-
-public:
-  XFloat() : exp(0) {
-    for (int i = 0; i < WORDCOUNT; ++i)
-      man[i] = 0;
-  }
-
-  XFloat(const XFloat &other) : exp(other.exp) {
-    for (int i = 0; i < WORDCOUNT; ++i)
-      man[i] = other.man[i];
-  }
-
-  explicit XFloat(double x) {
-    auto xn = NormalFloat<double>(x);
-    exp = xn.exponent;
-    man[WORDCOUNT - 1] = xn.mantissa << 11;
-    for (int i = 0; i < WORDCOUNT - 1; ++i)
-      man[i] = 0;
-  }
-
-  XFloat(int e, const UInt<Precision> &bits) : exp(e) {
-    for (size_t i = 0; i < WORDCOUNT; ++i)
-      man[i] = bits[i];
-  }
-
-  // Multiply this number with x and store the result in this number.
-  void mul(double x) {
-    auto xn = NormalFloat<double>(x);
-    exp += xn.exponent;
-    uint64_t carry = man.mul(xn.mantissa << 11);
-    size_t carry_width = bit_width(carry);
-    carry_width = (carry_width == 64 ? 64 : 63);
-    man.shift_right(carry_width);
-    man[WORDCOUNT - 1] = man[WORDCOUNT - 1] + (carry << (64 - carry_width));
-    exp += carry_width == 64 ? 1 : 0;
-    normalize();
-  }
-
-  void drop_int() {
-    if (exp < 0)
-      return;
-    if (exp > int(Precision - 1)) {
-      for (size_t i = 0; i < WORDCOUNT; ++i)
-        man[i] = 0;
-      return;
-    }
-
-    man.shift_left(exp + 1);
-    man.shift_right(exp + 1);
-
-    normalize();
-  }
-
-  double mul(const XFloat<Precision> &other) {
-    constexpr size_t row_words = 2 * WORDCOUNT + 1;
-    constexpr size_t row_precision = row_words * 64;
-    constexpr size_t result_bits = 2 * Precision;
-    UInt<row_precision> rows[WORDCOUNT];
-
-    for (size_t r = 0; r < WORDCOUNT; ++r) {
-      for (size_t i = 0; i < row_words; ++i) {
-        if (i < WORDCOUNT)
-          rows[r][i] = man[i];
-        else
-          rows[r][i] = 0;
-      }
-      rows[r].mul(other.man[r]);
-      rows[r].shift_left(r * 64);
-    }
-
-    for (size_t r = 1; r < WORDCOUNT; ++r) {
-      rows[0].add(rows[r]);
-    }
-    int result_exp = exp + other.exp;
-    uint64_t carry = rows[0][row_words - 1];
-    if (carry) {
-      size_t carry_width = bit_width(carry);
-      rows[0].shift_right(carry_width);
-      rows[0][row_words - 2] =
-          rows[0][row_words - 2] + (carry << (64 - carry_width));
-      result_exp += carry_width;
-    }
-
-    if (rows[0][row_words - 2] & OneMask) {
-      ++result_exp;
-    } else {
-      rows[0].shift_left(1);
-    }
-
-    UInt<result_bits> result_man;
-    for (size_t i = 0; i < result_bits / 64; ++i)
-      result_man[i] = rows[0][i];
-    XFloat<result_bits> result(result_exp, result_man);
-    result.normalize();
-    return double(result);
-  }
-
-  explicit operator double() {
-    normalize();
-
-    constexpr uint64_t one = uint64_t(1) << 10;
-    constexpr uint64_t excess_mask = (one << 1) - 1;
-    uint64_t excess = man[WORDCOUNT - 1] & excess_mask;
-    uint64_t new_man = man[WORDCOUNT - 1] >> 11;
-    if (excess > one) {
-      // We have to round up.
-      ++new_man;
-    } else if (excess == one) {
-      bool greater_than_one = false;
-      for (size_t i = 0; i < WORDCOUNT - 1; ++i) {
-        greater_than_one = (man[i] != 0);
-        if (greater_than_one)
-          break;
-      }
-      if (greater_than_one || (new_man & 1) != 0) {
-        ++new_man;
-      }
-    }
-
-    if (new_man == (uint64_t(1) << 53))
-      ++exp;
-
-    // We use NormalFloat as it can produce subnormal numbers or underflow to 0
-    // if necessary.
-    NormalFloat<double> d(exp, new_man, 0);
-    return double(d);
-  }
-
-  // Normalizes this number.
-  void normalize() {
-    uint64_t man_bits = 0;
-    for (size_t i = 0; i < WORDCOUNT; ++i)
-      man_bits |= man[i];
-
-    if (man_bits == 0)
-      return;
-
-    while ((man[WORDCOUNT - 1] & OneMask) == 0) {
-      man.shift_left(1);
-      --exp;
-    }
-  }
-};
-
-} // namespace fputil
-} // namespace LIBC_NAMESPACE

``````````

</details>


https://github.com/llvm/llvm-project/pull/81005