[Mono-dev] Big Arrays, Many Changes --- Request for Advice
Luis F. Ortiz
LuisOrtiz at Verizon.Net
Mon Sep 3 14:48:22 EDT 2007
I was porting a small test application that was written in C# that
an array with a large number of elements (> 2^32). While it
compiled and ran
in Visual Studio's C# under WindowsXP-64bit without a hitch, when I
and ran it under mcs/mono (1.2.4) on the same hardware, but booted up
Fedora7-x86_64, I ran into a few problems.
Digging into it a bit, I discovered that:
1) MCS assumed that the arguments to NEWARR were always U4 or I4,
which does not seem
to be the case as far as ECMA-335v4.
2) MONO assumes that array lengths and bounds can always be
represented as guint32's,
[ like mono_array_new_specific (MonoVTable *vtable, guint32 n) ]
Would folks object to a series of patches to:
A) Fix mcs/expression.cs to emit OpCodes.Conv_Ovf_U/I instead of
for array size arguments,
B) Modify mono/metadata/object.h to change the base type for array
XXX instead of guint32,
C) Change mono/metadata/object.c to change the functions that create/
access arrays to
take XXX instead of guint32 length/bounds arguments. Also
perhaps update some of
the lower level object allocation functions to use XXX as needed.
D) Modify the execution of NEWARR be able to deal with I/U native
types. No doubt something
in the JIT needs tweaking as well.
E) Double check that array indexing not only takes native int types,
but uses them right.
F) Add a few new test cases for large array allocation.
G) Whatever else needs to be done that I'll bump into after I try
making the above changes
and realize what I forgot. Warnings of known hazards gratefully
My big question is what the right type for the size ought to be?
I've seen int, size_t, gsize,
and guint32 used in Mono. I suspect that int and guint32 are wrong
from a portability perspective,
but would prefer that someone more intimately involved with Mono to
say if guint or gsize or size_t
were preferred. I'm guessing Bug 81774 is related to this as well.
BTW, is this too big for a newby to tackle?
--Luis F. Ortiz
Follower of the "Selfish Way"
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