[Tinycc-devel] TinyCC failure on i386

[Giovanni Mascellani]

Hi,

TinyCC fails to test on i386 on the CI that I just set up. Apparently,
though, the problem is not in tcc, but in gcc, which is used to compile
the test program too and compare the results.

I managed to trim down the offending example to this:

int main() {
    asm volatile ("mov %%eax, %%eax\n" : : "i" ("A string"));
    return 0;
}

If I compile this with gcc (9.2) on Debian this happens:

$ gcc -g -m32 test.c
test.c: In function ‘main’:
test.c:3:5: warning: asm operand 0 probably doesn’t match constraints
    3 |     asm volatile ("mov %%eax, %%eax\n" : : "i" ("A string"));
      |     ^~~
test.c:3:5: error: impossible constraint in ‘asm’

I believe this is wrong, "i" should accept a literal string as value.
Also, the same program works on Compiler Explorer[1].

 [1] https://godbolt.org/z/xAP-dy

I suspect this might be a bug in Debian's gcc. Anybody not using Debian
could please try to compile this program and see what happens?

Thanks, Giovanni.
-- 
Giovanni Mascellani <address@hidden>
Postdoc researcher - Université Libre de Bruxelles

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