Make fbstring libgcc-safe

[folly.git] / folly / Bits.h

diff --git a/folly/Bits.h b/folly/Bits.h
index d9bf1ad09119ac287d3d6a5758cec706d795205e..78160533959ab4b7b43b84e8917ef9a20da907d7 100644 (file)
--- a/folly/Bits.h
+++ b/folly/Bits.h
@@ -1,5 +1,5 @@
 /*
- * Copyright 2013 Facebook, Inc.
+ * Copyright 2014 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -57,15 +57,21 @@
 
 #include "folly/Portability.h"
 
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE 1
-#endif
-
 #ifndef __GNUC__
 #error GCC required
 #endif
 
+#ifndef __clang__
+#define FOLLY_INTRINSIC_CONSTEXPR constexpr
+#else
+// Unlike GCC, in Clang (as of 3.2) intrinsics aren't constexpr.
+#define FOLLY_INTRINSIC_CONSTEXPR const
+#endif
+
+#ifndef FOLLY_NO_CONFIG
 #include "folly/folly-config.h"
+#endif
+
 #include "folly/detail/BitsDetail.h"
 #include "folly/detail/BitIteratorDetail.h"
 #include "folly/Likely.h"
@@ -76,7 +82,6 @@
 
 #include <cassert>
 #include <cinttypes>
-#include <endian.h>
 #include <iterator>
 #include <limits>
 #include <type_traits>
@@ -88,7 +93,7 @@ namespace folly {
 // Generate overloads for findFirstSet as wrappers around
 // appropriate ffs, ffsl, ffsll gcc builtins
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -99,7 +104,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -111,7 +116,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -123,7 +128,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value && std::is_signed<T>::value),
   unsigned int>::type
@@ -137,7 +142,7 @@ typename std::enable_if<
 // findLastSet: return the 1-based index of the highest bit set
 // for x > 0, findLastSet(x) == 1 + floor(log2(x))
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -148,7 +153,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -160,7 +165,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_unsigned<T>::value &&
@@ -172,7 +177,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   (std::is_integral<T>::value &&
    std::is_signed<T>::value),
@@ -182,7 +187,7 @@ typename std::enable_if<
 }
 
 template <class T>
-inline constexpr
+inline FOLLY_INTRINSIC_CONSTEXPR
 typename std::enable_if<
   std::is_integral<T>::value && std::is_unsigned<T>::value,
   T>::type
@@ -268,7 +273,7 @@ FB_GEN(uint16_t, our_bswap16)
 
 #undef FB_GEN
 
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
 
 template <class T>
 struct EndianInt : public detail::EndianIntBase<T> {
@@ -277,7 +282,7 @@ struct EndianInt : public detail::EndianIntBase<T> {
   static T little(T x) { return x; }
 };
 
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
 
 template <class T>
 struct EndianInt : public detail::EndianIntBase<T> {
@@ -288,7 +293,7 @@ struct EndianInt : public detail::EndianIntBase<T> {
 
 #else
 # error Your machine uses a weird endianness!
-#endif  /* __BYTE_ORDER */
+#endif  /* __BYTE_ORDER__ */
 
 }  // namespace detail
 
@@ -318,13 +323,13 @@ class Endian {
   };
 
   static constexpr Order order =
-#if __BYTE_ORDER == __LITTLE_ENDIAN
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
     Order::LITTLE;
-#elif __BYTE_ORDER == __BIG_ENDIAN
+#elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
     Order::BIG;
 #else
 # error Your machine uses a weird endianness!
-#endif  /* __BYTE_ORDER */
+#endif  /* __BYTE_ORDER__ */
 
   template <class T> static T swap(T x) {
     return detail::EndianInt<T>::swap(x);
@@ -380,11 +385,14 @@ class BitIterator
    * Construct a BitIterator that points at a given bit offset (default 0)
    * in iter.
    */
+  #pragma GCC diagnostic push // bitOffset shadows a member
+  #pragma GCC diagnostic ignored "-Wshadow"
   explicit BitIterator(const BaseIter& iter, size_t bitOffset=0)
     : bititerator_detail::BitIteratorBase<BaseIter>::type(iter),
       bitOffset_(bitOffset) {
     assert(bitOffset_ < bitsPerBlock());
   }
+  #pragma GCC diagnostic pop
 
   size_t bitOffset() const {
     return bitOffset_;
@@ -516,6 +524,7 @@ template <class T, class Enable=void> struct Unaligned;
 /**
  * Representation of an unaligned value of a POD type.
  */
+FOLLY_PACK_PUSH
 template <class T>
 struct Unaligned<
     T,
@@ -523,7 +532,8 @@ struct Unaligned<
   Unaligned() = default;  // uninitialized
   /* implicit */ Unaligned(T v) : value(v) { }
   T value;
-} __attribute__((packed));
+} FOLLY_PACK_ATTR;
+FOLLY_PACK_POP
 
 /**
  * Read an unaligned value of type T and return it.
@@ -548,4 +558,3 @@ inline void storeUnaligned(void* p, T value) {
 }  // namespace folly
 
 #endif /* FOLLY_BITS_H_ */
-