Building gcc with AMD offloading fails building libssp

[Andrew Ho <helloworld922@gmail.com>]

Hi, I'm trying to build GCC 12.1.0 with amdgcn-amdhsa offload support, but
I'm running into a problem when it tries to compile libssp.

I am on Ubuntu 20.04.1 LTS, and have an AMD RX 480 gpu. The compiler I'm
using to try and build gcc with is the one which comes with Ubuntu (9.4.0).

I checked out the git repo on tag releases/gcc-12.1.0, and softlinked the
following files from AMD's rocm installed llvm:

ln -s /opt/rocm/llvm/bin/llvm-ar
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/gcc-bin/12.1.0/ar
ln -s /opt/rocm/llvm/bin/llvm-mc
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/gcc-bin/12.1.0/as
ln -s /opt/rocm/llvm/bin/lld
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/gcc-bin/12.1.0/ld
ln -s /opt/rocm/llvm/bin/llvm-ar
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/gcc-bin/12.1.0/ranlib

Configure and build command:
${gccsrc}/configure --target=amdgcn-amdhsa --disable-sjlj-exceptions
--with-newlib --enable-as-accelerator-for=x86_64-pc-linux-gnu
--with-build-time-tools=$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/gcc-bin/12.1.0
--prefix=$HOME/opt/gcc/12.1.0 --enable-languages=c,lto,c++,fortran
--enable-libgomp
make

When it tries to compile gcc/libssp/ssp.c, it can't find some common C
functions/types:

make[3]: Entering directory '${gccobj}/amdgcn-amdhsa/libssp'
/bin/bash ./libtool  --tag=CC   --mode=compile ${gccobj}/./gcc/xgcc
-B${gccobj}/./gcc/ -B$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/bin/
-B$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/lib/ -isystem
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/include -isystem
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/sys-include    -DHAVE_CONFIG_H -I.
-I../../../gcc/libssp    -Wall  -g -O2 -MT ssp.lo -MD -MP -MF .deps/ssp.Tpo
-c -o ssp.lo ../../../gcc/libssp/ssp.c
libtool: compile:  ${gccobj}/./gcc/xgcc -B${gccobj}/./gcc/
-B$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/bin/
-B$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/lib/ -isystem
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/include -isystem
$HOME/opt/gcc/12.1.0/amdgcn-amdhsa/sys-include -DHAVE_CONFIG_H -I.
-I../../../gcc/libssp -Wall -g -O2 -MT ssp.lo -MD -MP -MF .deps/ssp.Tpo -c
../../../gcc/libssp/ssp.c -o ssp.o
../../../gcc/libssp/ssp.c: In function ‘__guard_setup’:
../../../gcc/libssp/ssp.c:93:12: warning: implicit declaration of function
‘open’ [-Wimplicit-function-declaration]
   93 |   int fd = open ("/dev/urandom", O_RDONLY);
      |            ^~~~
../../../gcc/libssp/ssp.c:93:34: error: ‘O_RDONLY’ undeclared (first use in
this function)
   93 |   int fd = open ("/dev/urandom", O_RDONLY);
      |                                  ^~~~~~~~
../../../gcc/libssp/ssp.c:93:34: note: each undeclared identifier is
reported only once for each function it appears in
../../../gcc/libssp/ssp.c:96:7: error: unknown type name ‘ssize_t’
   96 |       ssize_t size = read (fd, &__stack_chk_guard,
      |       ^~~~~~~
../../../gcc/libssp/ssp.c:96:22: warning: implicit declaration of function
‘read’ [-Wimplicit-function-declaration]
   96 |       ssize_t size = read (fd, &__stack_chk_guard,
      |                      ^~~~
../../../gcc/libssp/ssp.c:98:7: warning: implicit declaration of function
‘close’ [-Wimplicit-function-declaration]
   98 |       close (fd);
      |       ^~~~~
../../../gcc/libssp/ssp.c: At top level:
../../../gcc/libssp/ssp.c:113:25: error: unknown type name ‘size_t’
  113 | fail (const char *msg1, size_t msg1len, const char *msg3)
      |                         ^~~~~~
../../../gcc/libssp/ssp.c:36:1: note: ‘size_t’ is defined in header
‘<stddef.h>’; did you forget to ‘#include <stddef.h>’?
   35 | #include "config.h"
  +++ |+#include <stddef.h>
   36 | #ifdef HAVE_ALLOCA_H
../../../gcc/libssp/ssp.c: In function ‘__stack_chk_fail’:
../../../gcc/libssp/ssp.c:185:3: warning: implicit declaration of function
‘fail’ [-Wimplicit-function-declaration]
  185 |   fail (msg, strlen (msg), "stack smashing detected: terminated");
      |   ^~~~
../../../gcc/libssp/ssp.c:185:14: warning: implicit declaration of function
‘strlen’ [-Wimplicit-function-declaration]
  185 |   fail (msg, strlen (msg), "stack smashing detected: terminated");
      |              ^~~~~~
../../../gcc/libssp/ssp.c:36:1: note: include ‘<string.h>’ or provide a
declaration of ‘strlen’
   35 | #include "config.h"
  +++ |+#include <string.h>
   36 | #ifdef HAVE_ALLOCA_H
../../../gcc/libssp/ssp.c:185:14: warning: incompatible implicit
declaration of built-in function ‘strlen’ [-Wbuiltin-declaration-mismatch]
  185 |   fail (msg, strlen (msg), "stack smashing detected: terminated");
      |              ^~~~~~
../../../gcc/libssp/ssp.c:185:14: note: include ‘<string.h>’ or provide a
declaration of ‘strlen’
../../../gcc/libssp/ssp.c: In function ‘__chk_fail’:
../../../gcc/libssp/ssp.c:192:14: warning: incompatible implicit
declaration of built-in function ‘strlen’ [-Wbuiltin-declaration-mismatch]
  192 |   fail (msg, strlen (msg), "buffer overflow detected: terminated");
      |              ^~~~~~
../../../gcc/libssp/ssp.c:192:14: note: include ‘<string.h>’ or provide a
declaration of ‘strlen’
make[3]: *** [Makefile:576: ssp.lo] Error 1
make[3]: Leaving directory '${gccobj}/amdgcn-amdhsa/libssp'
make[2]: *** [Makefile:441: all] Error 2
make[2]: Leaving directory '${gccobj}/amdgcn-amdhsa/libssp'
make[1]: *** [Makefile:13103: all-target-libssp] Error 2
make[1]: Leaving directory '${gccobj}'
make: *** [Makefile:1013: all] Error 2

Is there some dependency I could be missing?