Re: [Tinycc-devel] Call for testing
Le dimanche 6 janvier 2013 11:28:39, Didier Barvaux a écrit :
=== Build of TCC GIT with Clang 3.2 ===
Build OK (with some warnings, I can provide them to you if you want).
[SNIP]
With the 'return' statement removed from the cmp_comparison_test()
function, tests seem to be still KO. Example with 'test1':
test1
../tcc -B.. -DTCC_TARGET_I386 -run tcctest.c test.out1
--- test.ref 2013-01-06 10:59:06.0 +0100
+++ test.out1 2013-01-06 10:59:06.0 +0100
@@ -299,7 +299,7 @@
sizeof(+(char)'a') = 4
sizeof(-(char)'a') = 4
sizeof(~(char)'a') = 4
--66 -66 -66 -66 4294967230 4294967230
+-66 -66 -66 -66 -66 -66
0x1 0xf0f0 (nil) 0xfff0
bitfield_test:sizeof(st1) = 8
3 -1 15 -8 121
I can do other tests and/or try patches to fix that problem if you want.
Interesting. I misread that first but the line with -- is the output of clang.
It seems clang and gcc disagree:
$ cat long_long.c
#include stdio.h
int main(void)
{
char *p = NULL;
p -= 0x7042;
/* from pointer to integer types */
printf(%d %d %ld %ld %lld %lld\n,
(int)p, (unsigned int)p,
(long)p, (unsigned long)p,
(long long)p, (unsigned long long)p);
return 0;
}
$ gcc -o long_long long_long.c ./long_long
[SNIP gcc warnings]
-66 -66 -66 -66 -66 -66
$ clang -o long_long long_long.c ./long_long
-66 -66 -66 -66 4294967230 4294967230
So at least tcc is consistent to gcc. I'm not sure what the correct value (if
any) should be though.
Best regards,
Thomas Preud'homme
signature.asc
Description: This is a digitally signed message part.
___
Tinycc-devel mailing list
Tinycc-devel@nongnu.org
https://lists.nongnu.org/mailman/listinfo/tinycc-devel
Re: [Tinycc-devel] Call for testing
Hi,
On Wed, 16 Jan 2013, Thomas Preud'homme wrote:
$ cat long_long.c
#include stdio.h
int main(void)
{
char *p = NULL;
p -= 0x7042;
/* from pointer to integer types */
printf(%d %d %ld %ld %lld %lld\n,
(int)p, (unsigned int)p,
(long)p, (unsigned long)p,
(long long)p, (unsigned long long)p);
return 0;
}
Pointer to integer conversions (and back) are implementation defined, the
only requirement being that if the integer type is (u)intptr_t that a
pointer converted to that one and back to a pointer shall compare equal to
the original pointer.
So, depending on how the compiler implements this conversion (and
documents this) one might get different results:
$ gcc -o long_long long_long.c ./long_long
[SNIP gcc warnings]
-66 -66 -66 -66 -66 -66
This is a correct result for ILP32 (i.e. 32bit code). GCC sign extends
pointers when the pointer representation needs fewer bits than the target
type.
$ clang -o long_long long_long.c ./long_long
-66 -66 -66 -66 4294967230 4294967230
And this is also a correct result for 32bit code, when the compiler
defines pointer to integer conversion to be zero-extending when the target
type has more bits than a pointer. IMO sign-extending is more useful, and
as GCC set the precedent a long time ago I would declare clang to at least
have an QoI issue with compatibility with GCC. In other words: tcc has no
bug here.
Ciao,
Michael.
___
Tinycc-devel mailing list
Tinycc-devel@nongnu.org
https://lists.nongnu.org/mailman/listinfo/tinycc-devel
