valgrind-users

[Valgrind-users] use libc calls like 'pow' 'log' in tool code

[Bin X. <xi...@pu...>]

Hello,

  I was wondering how to get around using libc calls like "pow", "log", "setjmp/longjmp" inside
Valgrind tool code?  I know there are 'VG_(log2)' and shift operator, but suppose one really wants
the range of a 'double'.  Or generally, how much support is there for floating point code and
unstructured control flow.

Thanks,
-B

Re: [Valgrind-users] use libc calls like 'pow' 'log' in tool code

[Julian S. <js...@ac...>]

>   I was wondering how to get around using libc calls like "pow", "log",

You'll have to write your own, or import implementations from a 
GPL2+'d C library.  I find dietlibc often easier to navigate than
glibc.

> "setjmp/longjmp"

Use __builtin_setjmp, __builtin_longjmp.  Those are used already.
Grep the source code.

> inside Valgrind tool code?  I know there are 'VG_(log2)' 
> and shift operator, but suppose one really wants the range of a 'double'. 
> Or generally, how much support is there for floating point code and
> unstructured control flow.

Nobody (afaik) has used FP in a tool much so far.  There may be code
generation issues due to the JIT not saving/restoring FP registers
properly around helper function calls.  If you see anything strange
like that let me know; it should be easy enough to fix.

J

Re: [Valgrind-users] use libc calls like 'pow' 'log' in tool code

[Bin X. <xi...@pu...>]

Julian Seward wrote:
>>   I was wondering how to get around using libc calls like "pow", "log",
> 
> You'll have to write your own, or import implementations from a 
> GPL2+'d C library.  I find dietlibc often easier to navigate than
> glibc.
> 
>> "setjmp/longjmp"
> 
> Use __builtin_setjmp, __builtin_longjmp.  Those are used already.
> Grep the source code.
> 
>> inside Valgrind tool code?  I know there are 'VG_(log2)' 
>> and shift operator, but suppose one really wants the range of a 'double'. 
>> Or generally, how much support is there for floating point code and
>> unstructured control flow.
> 
> Nobody (afaik) has used FP in a tool much so far.  There may be code
> generation issues due to the JIT not saving/restoring FP registers
> properly around helper function calls.  If you see anything strange
> like that let me know; it should be easy enough to fix.
> 

That was fast, thanks. And thanks for such a great tool in Valgrind, if you guys haven't heard enough.

-B