Move endian constant from Host.h to SwapByteOrder.h, prune include

Works on this dependency chain:
  ArrayRef.h ->
  Hashing.h -> --CUT--
  Host.h ->
  StringMap.h / StringRef.h

ArrayRef is very popular, but Host.h is rarely needed. Move the
IsBigEndianHost constant to SwapByteOrder.h. Clients of that header are
more likely to need it.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375316 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rnk

include/llvm/ADT/Hashing.h

@@ -45,7 +45,6 @@
 #define LLVM_ADT_HASHING_H
 
 #include "llvm/Support/DataTypes.h"
-#include "llvm/Support/Host.h"
 #include "llvm/Support/SwapByteOrder.h"
 #include "llvm/Support/type_traits.h"
 #include <algorithm>

include/llvm/BinaryFormat/Wasm.h

@@ -16,6 +16,7 @@
 
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
 
 namespace llvm {
 namespace wasm {

include/llvm/Support/Host.h

@@ -15,39 +15,11 @@
 
 #include "llvm/ADT/StringMap.h"
 
-#if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__)
-#include <endian.h>
-#elif defined(_AIX)
-#include <sys/machine.h>
-#elif defined(__sun)
-/* Solaris provides _BIG_ENDIAN/_LITTLE_ENDIAN selector in sys/types.h */
-#include <sys/types.h>
-#define BIG_ENDIAN 4321
-#define LITTLE_ENDIAN 1234
-#if defined(_BIG_ENDIAN)
-#define BYTE_ORDER BIG_ENDIAN
-#else
-#define BYTE_ORDER LITTLE_ENDIAN
-#endif
-#else
-#if !defined(BYTE_ORDER) && !defined(_WIN32)
-#include <machine/endian.h>
-#endif
-#endif
-
 #include <string>
 
 namespace llvm {
 namespace sys {
 
-#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN
-constexpr bool IsBigEndianHost = true;
-#else
-constexpr bool IsBigEndianHost = false;
-#endif
-
-  static const bool IsLittleEndianHost = !IsBigEndianHost;
-
   /// getDefaultTargetTriple() - Return the default target triple the compiler
   /// has been configured to produce code for.
   ///

include/llvm/Support/SHA1.h

@@ -16,13 +16,13 @@
 #define LLVM_SUPPORT_SHA1_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/StringRef.h"
 
 #include <array>
 #include <cstdint>
 
 namespace llvm {
 template <typename T> class ArrayRef;
-class StringRef;
 
 /// A class that wrap the SHA1 algorithm.
 class SHA1 {

include/llvm/Support/SwapByteOrder.h

@@ -22,9 +22,37 @@
 #include <stdlib.h>
 #endif
 
+#if defined(__linux__) || defined(__GNU__) || defined(__HAIKU__)
+#include <endian.h>
+#elif defined(_AIX)
+#include <sys/machine.h>
+#elif defined(__sun)
+/* Solaris provides _BIG_ENDIAN/_LITTLE_ENDIAN selector in sys/types.h */
+#include <sys/types.h>
+#define BIG_ENDIAN 4321
+#define LITTLE_ENDIAN 1234
+#if defined(_BIG_ENDIAN)
+#define BYTE_ORDER BIG_ENDIAN
+#else
+#define BYTE_ORDER LITTLE_ENDIAN
+#endif
+#else
+#if !defined(BYTE_ORDER) && !defined(_WIN32)
+#include <machine/endian.h>
+#endif
+#endif
+
 namespace llvm {
 namespace sys {
 
+#if defined(BYTE_ORDER) && defined(BIG_ENDIAN) && BYTE_ORDER == BIG_ENDIAN
+constexpr bool IsBigEndianHost = true;
+#else
+constexpr bool IsBigEndianHost = false;
+#endif
+
+static const bool IsLittleEndianHost = !IsBigEndianHost;
+
 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
 /// the 16-bit argument.
 inline uint16_t SwapByteOrder_16(uint16_t value) {

lib/ExecutionEngine/Orc/JITTargetMachineBuilder.cpp

@@ -8,6 +8,7 @@
 
 #include "llvm/ExecutionEngine/Orc/JITTargetMachineBuilder.h"
 
+#include "llvm/Support/Host.h"
 #include "llvm/Support/TargetRegistry.h"
 
 namespace llvm {

lib/Support/Windows/WindowsSupport.h

@@ -38,6 +38,7 @@
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Config/config.h" // Get build system configuration settings
+#include "llvm/Support/Allocator.h"
 #include "llvm/Support/Chrono.h"
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/VersionTuple.h"

lib/Target/X86/Disassembler/X86DisassemblerDecoder.cpp

@@ -12,13 +12,14 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "X86DisassemblerDecoder.h"
+#include "llvm/ADT/StringRef.h"
+
 #include <cstdarg> /* for va_*()       */
 #include <cstdio>  /* for vsnprintf()  */
 #include <cstdlib> /* for exit()       */
 #include <cstring> /* for memset()     */
 
-#include "X86DisassemblerDecoder.h"
-
 using namespace llvm::X86Disassembler;
 
 /// Specifies whether a ModR/M byte is needed and (if so) which

tools/llvm-exegesis/lib/RegisterValue.cpp

@@ -8,6 +8,7 @@
 
 #include "RegisterValue.h"
 #include "llvm/ADT/APFloat.h"
+#include "llvm/ADT/StringRef.h"
 
 namespace llvm {
 namespace exegesis {