[PATCH] D50845: [CUDA/OpenMP] Define only some host macros during device compilation

[Artem Belevich via Phabricator via llvm-commits]

tra added a comment.

In our case the headers from a relatively old glibc and compiler errors out on this:

  /* This function is used in the `isfinite' macro.  */
  __MATH_INLINE int
  __NTH (__finite (double __x))
  {
    return (__extension__
  	  (((((union { double __d; int __i[2]; }) {__d: __x}).__i[1]
  	     | 0x800fffffu) + 1) >> 31));
  }

expanded to this:

  extern __inline __attribute__ ((__always_inline__)) __attribute__ ((__gnu_inline__)) int
   __finite (double __x) throw ()
  {
    return (__extension__
     (((((union { double __d; int __i[2]; }) {__d: __x}).__i[1]
        | 0x800fffffu) + 1) >> 31));
  }

The error:

  .../include/bits/mathinline.h:945:9: error: '(anonymous union at .../include/bits/mathinline.h:945:9)' cannot be defined in a type specifier
            (((((union { double __d; int __i[2]; }) {__d: __x}).__i[1]
                 ^
  .../include/bits/mathinline.h:945:55: error: member reference base type 'void' is not a structure or union
            (((((union { double __d; int __i[2]; }) {__d: __x}).__i[1]
               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~

Also, whatever macros we generate do not prevent headers from using x86 inline assembly. I see quite a few inline asm code in preprocessed output. The headers are from libc ~2.19.


Repository:
  rL LLVM

https://reviews.llvm.org/D50845