On 6/29/2014 9:38 PM, Manu via Digitalmars-d wrote:
It's news to me that x86, x86-64, etc., are deprecated, despite being used
to run pretty much all desktops and laptops and even servers. The 80 bit
reals are also part of the C ABI for Linux, OSX, and FreeBSD, 32 and 64 bit.
x86_64 and x86 are different architectures, and they have very different ABI's.
Nobody is manufacturing x86 (exclusive) cpu's.
Current x86_64 cpu's maintain a backwards compatibility mode, but
that's not a part of the x86-64 spec, and may go away when x86_64 is
deemed sufficiently pervasive and x86 sufficiently redundant.
It's still part of the C ABI for both 32 and 64 bit code.
Correct, so they are deliberately treated separately.
I argued for strong separation between simd and float, and you agreed.
floats & doubles are implemented using SIMD instructions.
Since they are part of the 64 bit C ABI, that would seem to be in the
category of "nevah hoppen".
Not in windows.
Correct.
You say they are in linux? I don't know.
Since you don't believe me, I recommend looking it up. The document is entitled
"System V Application Binary Interface AMD64 Architecture Processor Supplement"
Furthermore, just try using "long double" on Linux, and disassemble the
resulting code.
How do you distinguish x87 double and xmm double in C?
You don't. It's a compiler implementation issue.
The only way I know to access x87 is with inline asm.
I suggest using "long double" on Linux and look at the compiler output. You
don't have to believe me - use gcc or clang.
Huh? I think you misunderstood my point. I'm saying that fpu/simd
units are distinct, and they are distanced by the type system in order
to respect that separation.
I think that's not correct. There's nothing in the C Standard that says you have
to implement float semantics with any particular FPU, nor does the C type system
distinguish FPUs.
