C11 support for aligned_alloc()?

Question

Created Jun ’17

Replies 1

Boosts 0

Views 3.3k

Participants 2

I am running the following version of Clang on a Mac OS X 10.12.5 host, installed via Xcode 8.3.3:

$ clang -v

Apple LLVM version 8.1.0 (clang-802.0.42)

I have some code that uses the

aligned_alloc()

C11 function to allocate an aligned chunk of memory.

I am compiling my binary with the

-std=c11

flag:

...

clang -g -Wall -Wextra -mavx -std=c11 -D__USE_POSIX -D__STDC_CONSTANT_MACROS -D__STDINT_MACROS -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE=1 -O2 -c my_binary.c -o my_binary.o; \

clang -g -Wall -Wextra -mavx -std=c11 -D__USE_POSIX -D__STDC_CONSTANT_MACROS -D__STDINT_MACROS -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE=1 -O2 my_binary.o -o my_binary -lm; \

...

I am including

stdlib.h

and adding POSIX flags. From

my_binary.h

:

...

#ifndef _POSIX_C_SOURCE

#define _POSIX_C_SOURCE 200809L

#endif /* getline() support */

#ifndef _XOPEN_SOURCE

#define _XOPEN_SOURCE 600

#endif

#include <stdlib.h>

...

I get the following compilation warning:

my_binary.c:245:15: warning: implicit declaration of function 'aligned_alloc' is invalid in C99 [-Wimplicit-function-declaration] s->data = aligned_alloc(32, s->n * sizeof(*s->data));

Which follows with this error:

Undefined symbols for architecture x86_64:

  "_aligned_alloc", referenced from:

    _bs_initialize_signal_avx in my_binary.o

    _bs_copy_signal_avx in my_binary.o

ld: symbol(s) not found for architecture x86_64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

make: *** [build] Error 1

What am I doing incorrectly with Clang, such that compilation ignores the

std

C11 flag? Or does the version of Clang shipped with Xcode 8.3.3 not support aligned_alloc()?

As a positive control, I am able to compile without errors on a CentOS 7 (Linux) host with gcc 5.3.0 and glibc 2.22.

Boost

Answer 1

Stokestack OP

Feb ’19

Same problem. I'm using a third-party library that wants aligned buffers. Although I've selected C++17 as my language dialect, there's no aligned_alloc, not even the C11 one. I've tried including stdlib and cstdlib. No dice. Seems like this should be available 7+ years after the fact.

0