[LLVMdev] x86-64 sign extension for parameters and return values

[Evan Cheng]

Hi Meador,

Have you filed a bugzilla report? What's the PR number?

Evan

On Feb 23, 2012, at 3:11 PM, Meador Inge wrote:

> On Thu, Feb 23, 2012 at 3:54 PM, Eli Friedman <eli.friedman at gmail.com> wrote:
> 
>> LLVM has traditionally assumed that all integer argument and return
>> types narrower than int are promoted to int on all architectures.
>> Nobody has actually noticed any issues with this before now, as far as
>> I know.
> 
> The only reason that I noticed was that Python ctypes started misbehaving
> when we went to build/test it on OS X Lion (http://bugs.python.org/issue13370).
> After investigating the failure I found this.  Python uses libffi and
> libffi implements
> the GCC ABI.  So I would expect any project using libffi with clang to
> have problems.
> 
>> If gcc has decided to assume no sign/zero-extension on x86-64, we need
>> to follow their lead, at least on Linux. Please file at
>> http://llvm.org/bugs/ ; an executable testcase to go with this would
>> be nice, so we can compare various compilers and different platforms.
> 
> Will do.  Thanks.
> 
> -- Meador
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