Add getSwappedBytes implementations for float / double

[arsenm]

Summary

Alternatively these could be special cased in endian::Writer

[arsenm]

ping

[arsenm]

ping

[arsenm]

ping

[mehdi_amini]

Why are you using a memcpy for the implementation?
You may have a good reason, but since it is not obvious to me it may deserve a comment so it won't get remove in the future.

[mehdi_amini]

It does not seems true in C, I'm unsure for C++.

See the first answer here for instance: http://stackoverflow.com/questions/11442708/type-punning-and-unions-in-c

[mehdi_amini]

Because we are writing C++ and not C I tried to find what C++11 says about type punning:

"An lvalue expression of type T1 can be cast to the type “reference to T2” if an expression of type “pointer to T1” can be explicitly converted to the type “pointer to T2” using a reinterpret_cast. That is, a reference cast reinterpret_cast<T&>(x) has the same effect as the conversion *reinterpret_cast<T*>(&x) with the built-in & and * operators (and similarly for reinterpret_cast<T&&>(x)). The result refers to the same object as the source lvalue, but with a different type. The result is an lvalue for an lvalue reference type or an rvalue reference to function type and an xvalue for an rvalue reference to object type. No temporary is created, no copy is made, and constructors (12.1) or conversion functions (12.3) are not called."

So I assume this should be valid:

return SwapByteOrder_64(reinterpret_cast<int &>(C));

[arsenm]

Alternative version which specializes endian::Writer

[arsenm]

ping

[arsenm]

ping

[arsenm]

Add tests for EndianStream

[arsenm]

r228269

include/llvm/Support/SwapByteOrder.h

 
 #ifndef LLVM_SUPPORT_SWAPBYTEORDER_H
 #define LLVM_SUPPORT_SWAPBYTEORDER_H
 
 #include "llvm/Support/Compiler.h"
 #include "llvm/Support/DataTypes.h"
 #include <cstddef>
 #include <limits>
+#include <string>
 
 namespace llvm {
 namespace sys {
 
 /// SwapByteOrder_16 - This function returns a byte-swapped representation of
 /// the 16-bit argument.
 inline uint16_t SwapByteOrder_16(uint16_t value) {
 #if defined(_MSC_VER) && !defined(_DEBUG)

 inline          char  getSwappedBytes(char C) { return C; }
 
 inline unsigned short getSwappedBytes(unsigned short C) { return SwapByteOrder_16(C); }
 inline   signed short getSwappedBytes(  signed short C) { return SwapByteOrder_16(C); }
 
 inline unsigned int   getSwappedBytes(unsigned int   C) { return SwapByteOrder_32(C); }
 inline   signed int   getSwappedBytes(  signed int   C) { return SwapByteOrder_32(C); }
 
+inline uint32_t getSwappedBytes(float C) {
+  union {
+    uint32_t I;
+    float F;
+  } Tmp;
+
+  std::memcpy(&Tmp, &C, sizeof(float));
+  return SwapByteOrder_32(Tmp.I);
+}
+
+inline uint64_t getSwappedBytes(double C) {
+  union {
+    uint64_t I;
+    double F;
+  } Tmp;
+
+  std::memcpy(&Tmp, &C, sizeof(double));
+  return SwapByteOrder_64(Tmp.I);
+}
+
 #if __LONG_MAX__ == __INT_MAX__
 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_32(C); }
 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_32(C); }
 #elif __LONG_MAX__ == __LONG_LONG_MAX__
 inline unsigned long  getSwappedBytes(unsigned long  C) { return SwapByteOrder_64(C); }
 inline   signed long  getSwappedBytes(  signed long  C) { return SwapByteOrder_64(C); }
 #else
 #error "Unknown long size!"