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Define portable macros for packed struct definitions: 

1. A macro with argument: LLVM_PACKED(StructDefinition)
 2. A pair of macros defining scope of region with packing:
    LLVM_PACKED_START
     struct A { ... };
     struct B { ... };
    LLVM_PACKED_END

Differential Revision: http://reviews.llvm.org/D14337

llvm-svn: 252099
This commit is contained in:
Xinliang David Li 2015-11-04 23:42:56 +00:00
parent 51507d2ad8
commit f5aff03630
1 changed files with 28 additions and 0 deletions
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28
llvm/include/llvm/Support/Compiler.h
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@ -293,6 +293,34 @@
# define LLVM_ALIGNAS(x) alignas(x)
#endif
/// \macro LLVM_PACKED
/// \brief Used to specify a packed structure.
/// LLVM_PACKED(
/// struct A {
/// int i;
/// int j;
/// int k;
/// long long l;
/// });
///
/// LLVM_PACKED_START
/// struct B {
/// int i;
/// int j;
/// int k;
/// long long l;
/// };
/// LLVM_PACKED_END
#ifdef _MSC_VER
# define LLVM_PACKED(d) __pragma(pack(push, 1)) d __pragma(pack(pop))
# define LLVM_PACKED_START __pragma(pack(push, 1))
# define LLVM_PACKED_END __pragma(pack(pop))
#else
# define LLVM_PACKED(d) d __attribute__((packed))
# define LLVM_PACKED_START _Pragma("pack(push, 1)")
# define LLVM_PACKED_END _Pragma("pack(pop)")
#endif
/// \macro LLVM_PTR_SIZE
/// \brief A constant integer equivalent to the value of sizeof(void*).
/// Generally used in combination with LLVM_ALIGNAS or when doing computation in