[Mono-dev] SIZEOF_VOID_P in the JIT
mmason at upwardaccess.com
Wed Dec 10 22:56:40 EST 2008
On Thu, 2008-12-11 at 01:40 -0200, Rodrigo Kumpera wrote:
> Hi Mark,
> Do you have an idea of how big such change would be?
There's ~154 uses of SIZEOF_VOID_P under mono/.
What I'm proposing would actually leave them all alone to begin with -
and I'm fairly certain that most all of them would never need to be
touched. I'd just introduce a new define, and propagate it through the
code base on a case-by-case basis as I find pieces that do need to be
For everyone except mips/n32, SIZEOF_VOID_P == SIZEOF_REGISTER, so even
when I do the substitution, there will be no change in behavior.
But - before I go introducing such changes, I'd like to get a blessing
on the concept, and on the name of the new macro.
This just seems a lot cleaner to me than putting:
#if defined(__mips__) && (_MIPS_SIM == _ABIN32)
tests in the non-mips specific files instead.
> On Thu, Dec 11, 2008 at 1:21 AM, Mark Mason <mmason at upwardaccess.com>
> Hello all,
> The current JIT code assumes that SIZEOF_VOID_P is also the
> size of
> registers (as per the calling convention that we're generating
> for). There's a fair number of #if tests for this in the
> directory (as well as in a few others).
> What brings this up is porting to mips/n32, a calling
> convention which
> uses the 'usual' 32-bit types for C language constructs:
> sizeof(int) = 4
> sizeof(void *) = 4
> sizeof(long) = 4
> sizeof(float) = 8
> sizeof(double) = 8
> sizeof(long long) = 8
> But where registers are 64-bits instead of 32-bits, and we
> need to
> generate any number of 64-bit operations under the hood for
> into stack slots, parameter passing, return values, etc.
> Since SIZEOF_VOID_P is still 4 on this target,
> mono_decompose_long_opts() insists on breaking up long
> operands that I'd
> rather stayed together. Rather than putting in a lot of MIPS
> #ifdef tests in the generic code, I'd like to suggest
> splitting the
> current usage of SIZEOF_VOID_P -- using SIZEOF_VOID_P to
> represent the
> size of addresses, and a new define (SIZEOF_REGISTER maybe?)
> represent the size of general purpose machine registers. On
> most all
> targets, SIZEOF_VOID_P == SIZEOF_REGISTER and everything will
> behave as
> it does today. For mips/n32, SIZEOF_VOID_P=4,
> SIZEOF_REGISTER=8 and
> we'll get the desired behavior we want there.
> Thoughts? Does someone see a better way to handle this?
> Thanks in advance.
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