llvm dev - Jan 2015 - [LLVMdev] RFC: Another go at a cross compiler config file. (with an example using clang to compile for Windows on Linux)

Hi,

Did this make it into review / commit?  It's probably too late for 3.6 if it
didn't, but I'd love to see it in 3.7.  It would also be nice if this
support could be something a bit more general in LLVM, rather than specifically
in clang, so that other llvm tools (e.g. llvm-objdump) could take advantage of a
similar format for target description files if they need something more than
just the triple argument.

David
> On 15 Sep 2014, at 13:09, Richard Pennington <rich at pennware.com>
wrote:
> 
> I've updated my blog with the current state of my compilation
configuration prototype. http://ellcc.org/blog/?p=13246
> Again, any comments/criticisms greatly appreciated.
> 
> -Rich
> 
> On 09/05/2014 09:23 PM, Richard Pennington wrote:
>> A while back (2012) there were a few messages related to using YAML
config files to set up how clang would build stuff, especially for cross
compilers. My ELLCC project is entirely cross compilation focused, so today I
decided to play around with the config file idea. Right now it only handles
replacing a "-target foo" option with the options defined in the file
foo in the resource/config directory, but I think it has potential for doing
quite a bit more.
>> 
>> I describe it a little more on my blog at
http://ellcc.org/blog/?p=11877
>> 
>> Any comments/criticisms would be greatly appreciated.
>> 
> 
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On 01/12/2015 01:18 PM, David Chisnall wrote:
> Hi,
>
> Did this make it into review / commit?  It's probably too late for 3.6
if it didn't, but I'd love to see it in 3.7.  It would also be nice if
this support could be something a bit more general in LLVM, rather than
specifically in clang, so that other llvm tools (e.g. llvm-objdump) could take
advantage of a similar format for target description files if they need
something more than just the triple argument.
>
> David
>
Hi David,

When I posted that there wasn't a lot of enthusiasm for the approach. I 
am using it but people thought it would complicate the driver and didn't 
like the fact that a file might need to be read each time the compiler 
is invoked (it doesn't really require that a file be read, the YAML can 
be compiled in, but anyway).

I still think the approach is useful, so after I saw your post I made 
another example that makes clang a Windows cross compiler using the 
MinGW linker and libraries. I've posted it here: 
http://ellcc.org/blog/?p=23077

I like the idea of making it more general and allowing it to be used for 
other LLVM utilities.

-Rich

On 12 Jan 2015, at 22:58, Richard Pennington <rich at pennware.com>
wrote:
> 
> When I posted that there wasn't a lot of enthusiasm for the approach. I
am using it but people thought it would complicate the driver and didn't
like the fact that a file might need to be read each time the compiler is
invoked (it doesn't really require that a file be read, the YAML can be
compiled in, but anyway).
I probably wouldn't want it to be required, but reading one extra file is
not likely to be a major performance issue when compiling C code, because (at
least until modules are ubiquitous) you're likely to be reading a load of C
files anyway.  It seems a shame currently that we build clang, which is
intrinsically a cross-compiler, but actually using it as such with existing
build systems is often painful because certain CFLAGS must be inserted into
every call at a specific place to make sure that it picks up the right things.

Once you have something that's ready for general review, I'd be happy to
take a look.

David