[LLVMdev] Calling Conventions Cont'd
sabre at nondot.org
Mon Apr 14 12:35:02 PDT 2008
On Mon, 14 Apr 2008, Jon Sargeant wrote:
> Ugh, this isn't what I wanted to hear. Passing "complex" differently
> than a structure containing two doubles is a bad design, but alas,
> calling conventions are beyond our control. How many special cases like
> this are there? If "complex" is the only special case, LLVM could
There are a huge number of special cases. Take a look at the craziness in
the x86-64 ABI structure passing rules for an example.
> entirely in the back end. Apart from calling conventions, the front end
> doesn't need to know the specific target, only the data layout and which
> intrinsics the target supports. This approach makes a clean division
> between the front end and back end.
If you want to map from a C type/calling convetion to LLVM IR, clang is a
good way to go. It isn't fully up to snuff with all the ABIs out there,
but will be doing much better over the next few months.
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