Mercurial > pub > dyncall > dyncall
comparison doc/manual/callconvs/callconv_arm32.tex @ 148:12729fd52ab7
- performance improvement and more correct handling of arm32 armhf calls, not copying bogus data just to reserve spill area space
- added armhf callconv stack layout diagram to doc
| author | cslag |
|---|---|
| date | Sun, 11 Sep 2016 01:19:27 +0200 |
| parents | 4a64b733dc76 |
| children | 8402121e1737 |
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| 147:8ce75240a0f1 | 148:12729fd52ab7 |
|---|---|
| 331 \item float and double vararg function parameters (no matter if in ellipsis part of function, or not) are passed like int or long long parameters, vfp registers aren't used | 331 \item float and double vararg function parameters (no matter if in ellipsis part of function, or not) are passed like int or long long parameters, vfp registers aren't used |
| 332 \item if the callee takes the address of one of the parameters and uses it to address other parameters (e.g. varargs) it has to copy - in its prolog - the first four words (for first 4 integer arguments) to a reserved stack area adjacent to the other parameters on the stack | 332 \item if the callee takes the address of one of the parameters and uses it to address other parameters (e.g. varargs) it has to copy - in its prolog - the first four words (for first 4 integer arguments) to a reserved stack area adjacent to the other parameters on the stack |
| 333 \item parameters \textless=\ 32 bits are passed as 32 bit words | 333 \item parameters \textless=\ 32 bits are passed as 32 bit words |
| 334 \item structures and unions are passed by value, with the first four words of the parameters in r0-r3 @@@?check doc | 334 \item structures and unions are passed by value, with the first four words of the parameters in r0-r3 @@@?check doc |
| 335 \item if return value is a structure, a pointer pointing to the return value's space is passed in r0, the first parameter in r1, etc. (see {\bf return values}) | 335 \item if return value is a structure, a pointer pointing to the return value's space is passed in r0, the first parameter in r1, etc. (see {\bf return values}) |
| 336 \item callee spills, caller reserves spill area space, though | |
| 336 \end{itemize} | 337 \end{itemize} |
| 337 | 338 |
| 338 \paragraph{Return values} | 339 \paragraph{Return values} |
| 339 \begin{itemize} | 340 \begin{itemize} |
| 340 \item non floating point return values \textless=\ 32 bits use r0 | 341 \item non floating point return values \textless=\ 32 bits use r0 |
| 342 \item single precision floating point return value uses s0 | 343 \item single precision floating point return value uses s0 |
| 343 \item double precision floating point return value uses d0 | 344 \item double precision floating point return value uses d0 |
| 344 \item if return value is a structure, the caller allocates space for the return value on the stack in its frame and passes a pointer to it in r0 | 345 \item if return value is a structure, the caller allocates space for the return value on the stack in its frame and passes a pointer to it in r0 |
| 345 \end{itemize} | 346 \end{itemize} |
| 346 | 347 |
| 347 | 348 \paragraph{Stack layout} |
| 349 | |
| 350 Stack directly after function prolog:\\ | |
| 351 | |
| 352 \begin{figure}[h] | |
| 353 \begin{tabular}{5|3|1 1} | |
| 354 \hhline{~-~~} | |
| 355 & \vdots & & \\ | |
| 356 \hhline{~=~~} | |
| 357 register save area & \hspace{4cm} & & \mrrbrace{6}{caller's frame} \\ | |
| 358 \hhline{~-~~} | |
| 359 local data & & & \\ | |
| 360 \hhline{~-~~} | |
| 361 \mrlbrace{7}{parameter area} & r0-r3 & \mrrbrace{1}{spill area (if needed)} & \\ | |
| 362 \hhline{~-~~} | |
| 363 & \ldots & \mrrbrace{3}{stack parameters} & \\ | |
| 364 & \ldots & & \\ | |
| 365 & \ldots & & \\ | |
| 366 \hhline{~=~~} | |
| 367 register save area (with return address) & & & \mrrbrace{3}{current frame} \\ | |
| 368 \hhline{~-~~} | |
| 369 local data & & & \\ | |
| 370 \hhline{~-~~} | |
| 371 parameter area & \vdots & & \\ | |
| 372 \hhline{~-~~} | |
| 373 \end{tabular} | |
| 374 \caption{Stack layout on arm32 armhf} | |
| 375 \end{figure} | |
| 376 | |
| 377 | |
| 378 \newpage | |
| 348 | 379 |
| 349 | 380 |
| 350 \subsubsection{Architectures} | 381 \subsubsection{Architectures} |
| 351 | 382 |
| 352 The ARM architecture family contains several revisions with capabilities and | 383 The ARM architecture family contains several revisions with capabilities and |