On Fri, Sep 2, 2016 at 7:17 PM, Richard Henderson <r...@twiddle.net> wrote: > On 09/02/2016 02:35 AM, Uros Bizjak wrote: >> --q-- >> /* Pass float and _Complex float variable arguments by reference. >> This avoids 64-bit store from a FP register to a pretend args save area >> and subsequent 32-bit load from the saved location to a FP register. >> >> Note that 32-bit loads and stores to/from a FP register on alpha reorder >> bits to form a canonical 64-bit value in the FP register. This fact >> invalidates compiler assumption that 32-bit FP value lives in the lower >> 32-bits of the passed 64-bit FP value, so loading the 32-bit value from >> the stored 64-bit location using 32-bit FP load is invalid on alpha. >> >> This introduces sort of ABI incompatibility, but until _Float32 was >> introduced, C-family languages promoted 32-bit float variable arg to >> a 64-bit double, and it was not allowed to pass float as a varible >> argument. Passing _Complex float as a variable argument never >> worked on alpha. Thus, we have no backward compatibility issues >> to worry about, and passing un-promoted _Float32 and _Complex float >> as a variable argument will actually work in the future. */ >> --/q-- > > This sounds like a good plan to me.
Thanks! >> (I was not able to find the >> authoritative OSF/1 ABI document on the net...) > > As far as I know, it was never available online. > I have a paper copy. FYI, after some more involved deep searching (and luck ;) I found one at [1]. It is under "Programming Documentation Bookshelf" section, the document is called "Calling Standard for Alpha Systems" [2]. [1] http://h41361.www4.hpe.com/docs/pub_page/V51B_DOCS/v51b_doclist.htm [2] http://h41361.www4.hpe.com/docs/base_doc/DOCUMENTATION/V51B_ACRO_DUX/ARH9MCTE.PDF Uros.
