llvm dev - Sep 2006 - [LLVMdev] bug in llvm-gcc implementation of long long

Compiling the following C code

--------------------------------------------
long long f4(void) {
  return (long long)INT_MAX + 1;
}
-------------------------------------------

produces

------------------------------------------
long %f4() {
entry:
        ret long -2147483648
}
------------------------------------------

but in 64 bits, -2147483648 != 2147483648. As a result, the x86 output has

eax = 2147483648
edx = 4294967295

the correct output is
eax = 2147483648
edx = 0

Best Regards,
Rafael

> What does the preprocessed output of that function look like?
long long f4(void) {
  return (long long)2147483647 + 1;
}

Using 2147483648LL directly causes the same problem.
> -Chris
Best Regards,
Rafael

On Mon, 4 Sep 2006, [UTF-8] Rafael Esp?ndola wrote:
> Compiling the following C code
> ------------------------------------------
> long %f4() {
> entry:
>        ret long -2147483648
> }
> ------------------------------------------
I get this:

long %f4() {
entry:
         ret long 2147483648
}

What does the preprocessed output of that function look like?

-Chris

-- 
http://nondot.org/sabre/
http://llvm.org/

Rafael Espíndola wrote:

 > return (long long)INT_MAX + 1;

does it work in ordinary gcc? I recall I had a problem with this in an earlier
version of gcc, maybe they still haven't
fixed it.

m.

> does it work in ordinary gcc? I recall I had a problem with this in an
earlier version of gcc, maybe they still haven't
> fixed it.
Works in vanilla 4.1

Rafael

> does it work in ordinary gcc? I recall I had a problem with this in an
earlier version of gcc, maybe they still haven't
> fixed it.
I have just compiled revision 102 without --enable-llvm and the
resulting code correctly sets edx to 0.

Time to try gdb.

Rafael