[cfe-dev] clang bug? Miscompilation of array of unsigned long long

[Douglas Gregor]

On Jul 24, 2010, at 7:09 AM, Edward Meewis wrote:

>  Hi all,
> 
> I was toying around with the compiler-rt library and looking into why 
> the udivmoddi4_test fails on FreeBSD and on MinGW when compiled with clang.
> 
> I narrowed it down to the initalization of the test array:
> 
> -- arrTest.c
> #include <stdio.h>
> 
> unsigned long long globalArray[4] =
> {0x078644FA00000000uLL, 0xFFFFFFFD00000000uLL, 0x0000000000000000uLL, 
> 0x078644FA00000000uLL};
> 
> int main()
> {
>     unsigned long long t1 = 0xFFFFFFFD00000000uLL;
>     unsigned long long t2 = 0xFFFFFFFFFFFFFFFFuLL;
>     unsigned long long localArray[4] =
>     {0xEFFFFFFD00000000uLL, 0xFFFFFFFD00000000uLL, 
> 18446744060824649728uLL, 0xFFFFFFFFFFFFFFFFuLL};
> 
>     printf("0x%016llX, %016llu\n", t1, t1);
>     printf("0x%016llX, %016llu\n", t2, t2);
>     printf("globalArray: 0x%016llX, 0x%016llX, 0x%016llX, 0x%016llX\n",
>             globalArray[0], globalArray[1], globalArray[2], 
> globalArray[3]);
>     printf("localArray:  0x%016llX, 0x%016llX,   %16llu, 0x%016llX\n",
>             localArray[0], localArray[1], localArray[2], localArray[3]);
> 
>     return 0;
> }
> --- clang -o arrTest arrTest.c
> 
> ./arrTest
> 0xFFFFFFFD00000000, 18446744060824649728
> 0xFFFFFFFFFFFFFFFF, 18446744073709551615
> globalArray: 0x078644FA00000000, 0x0000FFFD00000000, 0x0000000000000000, 
> 0x078644FA00000000
> localArray:  0xEFFFFFFD00000000, 0x0000FFFD00000000,    281462091808768, 
> 0xFFFFFFFFFFFFFFFF
> ---
> 
> The second element should be 0xFFFFFFFD00000000 and not 
> 0x0000FFFD00000000. Note that is doesn't make any difference whether the 
> element is initialized in hex of decimal. The third element of the local 
> array is set to 18446744060824649728, but returns 281462091808768. A 
> normal variable (t1) is handled correctly.
> 
> GCC behaves correctly.
> 
> Anybody any ideas what's going on?


No idea, and I'm not able to reproduce it on my platform (Darwin). Could you give me the output of clang -v arrTest.c
  and clang -### arrTest.c , so I can get all of the version/triple information?

	- Doug