Hello again tcc list,
gcc, clang, and even pcc take this code just fine, but tcc won't
compile it I can tell you that I did build tcc from git commit id
9e0d23cc47359149a39eafffdbb133963980b6ed and that version of tcc works
for most things.
I realize there are other ways to get this cpuid information, but if I
wanted to use cmovcl in some other code I think the inline assembler
really is broken. I tried the synonym cmovbl, but it didn't work
either. Both cmovc and cmovb are listed in intel's manual as
generating 0x04 0x42 /r, so I think they are just two mnemonics for
the same instruction. If I delete the 'l' suffix, and use bare
'cmovc' (or bare 'cmovb'), it will compile. Since push, mov, etc.
accept the suffixes, cmovc should too.
$ cat bob.c
#include <stdlib.h>
#include <stdio.h>
unsigned long int haverdrand(void);
unsigned long int haverdrand(void) {
unsigned long int ret;
__asm__ volatile (
"pushfq\n\
pushq %%rcx\n\
movl $1,%%eax # get leaf #1\n\
cpuid\n\
xorl %%eax,%%eax\n\
btl $30,%%ecx # RDRAND\n\
movl $1,%%ecx\n\
cmovcl %%ecx,%%eax\n\
popq %%rcx\n\
popfq"
: "=a" (ret)
);
return ret;
}
int main(void) {
fputs("YOU DO ",stdout);
if (!haverdrand())
fputs("NOT ",stdout);
fputs("HAVE RDRAND SUPPORT.\n",stdout);
return EXIT_SUCCESS;
}
$ gcc bob.c -o bob
$ ./bob
YOU DO HAVE RDRAND SUPPORT.
$ rm bob
$ clang bob.c -o bob
$ ./bob
YOU DO HAVE RDRAND SUPPORT.
$ rm bob
$ pcc bob.c -o bob
$ ./bob
YOU DO HAVE RDRAND SUPPORT.
$ rm bob
$ tcc bob.c -o bob
bob.c:20: error: unknown opcode 'cmovcl'
$ ls -ld bob
ls: cannot access 'bob': No such file or directory
$
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