Export of internal Abseil changes

--
dab5caab05d89d03066ef92584660688595a3aaf by Mark Barolak <mbar@google.com>:

Add absl::Status and absl::StatusOr to absl/README.md

Import of https://github.com/abseil/abseil-cpp/pull/863

PiperOrigin-RevId: 347857368

--
1ca3c7a96417cd6e6d62f4dc36fd5ddaa61cfa20 by Chris Kennelly <ckennelly@google.com>:

Leverage integer power-of-2 functions and bit counting library in Abseil.

PiperOrigin-RevId: 347816486

--
e5cbe05879fd65dce7875e2e0105331a1615d89b by Chris Kennelly <ckennelly@google.com>:

Mitigate narrowing warning on MSVC.

If sizeof(x) <= sizeof(uint32_t), no truncation occurs when casting to
uint32_t, but the compiler cannot always determine this.

PiperOrigin-RevId: 347696526

--
079dff64cb175d282d9e22dfb4a522199ffdae2e by Benjamin Barenblat <bbaren@google.com>:

Avoid libgcc -NaN narrowing bug

When testing -NaN parsing, avoid narrowing -NaN from double to float.
This avoids a bug in libgcc
(https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98251).

PiperOrigin-RevId: 347654751

--
2e78a7634865aeef6765e1f447e96cf8d9985059 by Chris Kennelly <ckennelly@google.com>:

Mark popcount helpers as inline.

These are conditionally constexpr, so we need to add inline to cover the
non-constexpr builds to avoid ODR violations.

PiperOrigin-RevId: 347620138

--
437fbb363aea1654179f102dcdd607ec33c1af1e by Chris Kennelly <ckennelly@google.com>:

Use explicit narrowing cast.

This is never invoked in practice, but compilers with -Wimplicit-int-conversion
may trigger when sizeof(T) > sizeof(uint16_t) prior to determining this never
runs.

PiperOrigin-RevId: 347609857
GitOrigin-RevId: dab5caab05d89d03066ef92584660688595a3aaf
Change-Id: I6296ddffe7ec646f8ce121138f21e1e85a2cff4b

4 files changed, 14 insertions, 11 deletions

diff --git a/absl/numeric/BUILD.bazel b/absl/numeric/BUILD.bazel
index fb782ef3..5d7b1857 100644
--- a/absl/numeric/BUILD.bazel
+++ b/absl/numeric/BUILD.bazel
@@ -64,7 +64,7 @@ cc_library(
     copts = ABSL_DEFAULT_COPTS,
     linkopts = ABSL_DEFAULT_LINKOPTS,
     deps = [
-        "//absl/base:bits",
+        ":bits",
         "//absl/base:config",
         "//absl/base:core_headers",
     ],
diff --git a/absl/numeric/CMakeLists.txt b/absl/numeric/CMakeLists.txt
index 77e3f5ee..be94352a 100644
--- a/absl/numeric/CMakeLists.txt
+++ b/absl/numeric/CMakeLists.txt
@@ -55,7 +55,7 @@ absl_cc_library(
   DEPS
     absl::config
     absl::core_headers
-    absl::internal_bits
+    absl::bits
   PUBLIC
 )
 
diff --git a/absl/numeric/int128.cc b/absl/numeric/int128.cc
index e21e5e9a..5160df79 100644
--- a/absl/numeric/int128.cc
+++ b/absl/numeric/int128.cc
@@ -23,8 +23,8 @@
 #include <string>
 #include <type_traits>
 
-#include "absl/base/internal/bits.h"
 #include "absl/base/optimization.h"
+#include "absl/numeric/bits.h"
 
 namespace absl {
 ABSL_NAMESPACE_BEGIN
@@ -43,11 +43,11 @@ namespace {
 inline ABSL_ATTRIBUTE_ALWAYS_INLINE int Fls128(uint128 n) {
   if (uint64_t hi = Uint128High64(n)) {
     ABSL_INTERNAL_ASSUME(hi != 0);
-    return 127 - base_internal::CountLeadingZeros64(hi);
+    return 127 - countl_zero(hi);
   }
   const uint64_t low = Uint128Low64(n);
   ABSL_INTERNAL_ASSUME(low != 0);
-  return 63 - base_internal::CountLeadingZeros64(low);
+  return 63 - countl_zero(low);
 }
 
 // Long division/modulo for uint128 implemented using the shift-subtract
diff --git a/absl/numeric/internal/bits.h b/absl/numeric/internal/bits.h
index 60478f52..50828156 100644
--- a/absl/numeric/internal/bits.h
+++ b/absl/numeric/internal/bits.h
@@ -89,7 +89,8 @@ ABSL_MUST_USE_RESULT ABSL_ATTRIBUTE_ALWAYS_INLINE constexpr T RotateLeft(
          static_cast<T>(x >> ((-s) & (std::numeric_limits<T>::digits - 1)));
 }
 
-ABSL_INTERNAL_CONSTEXPR_POPCOUNT int Popcount32(uint32_t x) noexcept {
+ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
+Popcount32(uint32_t x) noexcept {
 #if ABSL_HAVE_BUILTIN(__builtin_popcount)
   static_assert(sizeof(unsigned int) == sizeof(x),
                 "__builtin_popcount does not take 32-bit arg");
@@ -101,7 +102,8 @@ ABSL_INTERNAL_CONSTEXPR_POPCOUNT int Popcount32(uint32_t x) noexcept {
 #endif
 }
 
-ABSL_INTERNAL_CONSTEXPR_POPCOUNT int Popcount64(uint64_t x) noexcept {
+ABSL_ATTRIBUTE_ALWAYS_INLINE ABSL_INTERNAL_CONSTEXPR_POPCOUNT inline int
+Popcount64(uint64_t x) noexcept {
 #if ABSL_HAVE_BUILTIN(__builtin_popcountll)
   static_assert(sizeof(unsigned long long) == sizeof(x),  // NOLINT(runtime/int)
                 "__builtin_popcount does not take 64-bit arg");
@@ -231,11 +233,11 @@ CountLeadingZeroes(T x) {
                 "T must have a power-of-2 size");
   static_assert(sizeof(T) <= sizeof(uint64_t), "T too large");
   return sizeof(T) <= sizeof(uint16_t)
-             ? CountLeadingZeroes16(x) -
+             ? CountLeadingZeroes16(static_cast<uint16_t>(x)) -
                    (std::numeric_limits<uint16_t>::digits -
                     std::numeric_limits<T>::digits)
              : (sizeof(T) <= sizeof(uint32_t)
-                    ? CountLeadingZeroes32(x) -
+                    ? CountLeadingZeroes32(static_cast<uint32_t>(x)) -
                           (std::numeric_limits<uint32_t>::digits -
                            std::numeric_limits<T>::digits)
                     : CountLeadingZeroes64(x));
@@ -314,9 +316,10 @@ CountTrailingZeroes(T x) noexcept {
   static_assert(sizeof(T) <= sizeof(uint64_t), "T too large");
   return x == 0 ? std::numeric_limits<T>::digits
                 : (sizeof(T) <= sizeof(uint16_t)
-                       ? CountTrailingZeroesNonzero16(x)
+                       ? CountTrailingZeroesNonzero16(static_cast<uint16_t>(x))
                        : (sizeof(T) <= sizeof(uint32_t)
-                              ? CountTrailingZeroesNonzero32(x)
+                              ? CountTrailingZeroesNonzero32(
+                                    static_cast<uint32_t>(x))
                               : CountTrailingZeroesNonzero64(x)));
 }