Mercurial > pub > dyncall > dyncall
comparison doc/manual/callconvs/callconv_x86.tex @ 530:585dcb68f55d
- more doc and disas examples for x86 fastcall and non-trivial aggregates
| author | Tassilo Philipp |
|---|---|
| date | Sat, 16 Apr 2022 12:10:02 +0200 |
| parents | fc614cb865c6 |
| children |
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| 529:fe694c7677b4 | 530:585dcb68f55d |
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| 186 \clearpage | 186 \clearpage |
| 187 | 187 |
| 188 \paragraph{Return values} | 188 \paragraph{Return values} |
| 189 | 189 |
| 190 \begin{itemize} | 190 \begin{itemize} |
| 191 \item return values of pointer or integral type (\textless=\ 32 bits) are returned via the eax register | 191 \item return values of pointer or integral type, as well as aggregates (structs, unions) \textless=\ 64 are returned via the eax and edx registers |
| 192 \item for {\it non-trivial} C++ aggregates, the caller allocates space, passes pointer to it to the callee as a hidden first param | 192 \item for {\it non-trivial} C++ aggregates, the caller allocates space, passes pointer to it to the callee as a hidden first param |
| 193 (meaning via ecx), and callee writes return value to this space; the ptr to the aggregate is returned in eax | 193 (meaning via ecx), and callee writes return value to this space; the ptr to the aggregate is returned in eax |
| 194 \item integers and aggregates (structs, unions) \textgreater\ 32 and \textless=\ 64 bits are returned via the eax and edx registers | |
| 195 \item return values \textgreater\ 64 bits (e.g. aggregates) are returned by the caller allocating the space and | 194 \item return values \textgreater\ 64 bits (e.g. aggregates) are returned by the caller allocating the space and |
| 196 passing a pointer to the callee as a new, implicit first parameter (always via the stack, never via a register) | 195 passing a pointer to the callee as a new, implicit first parameter (always via the stack, never via a register) |
| 197 \item floating point types are returned via the st0 register | 196 \item floating point types are returned via the st0 register |
| 198 \end{itemize} | 197 \end{itemize} |
| 199 | 198 |
| 508 \item called function cleans up the stack | 507 \item called function cleans up the stack |
| 509 \item all parameters are pushed onto the stack (as dwords) | 508 \item all parameters are pushed onto the stack (as dwords) |
| 510 \item arguments \textgreater\ 64 bits are pushed as a sequence of dwords | 509 \item arguments \textgreater\ 64 bits are pushed as a sequence of dwords |
| 511 \item aggregates (structs, unions) are pushed as a sequence of dwords | 510 \item aggregates (structs, unions) are pushed as a sequence of dwords |
| 512 \item {\it non-trivial} C++ aggregates (as defined by the language) of any size, are passed indirectly via a pointer to a copy of the aggregate | 511 \item {\it non-trivial} C++ aggregates (as defined by the language) of any size, are passed indirectly via a pointer to a copy of the aggregate |
| 513 \item stack is usually 4 byte aligned (GCC \textgreater=\ 3.x seems to use a 16byte alignement) | 512 \item stack is usually 4 byte aligned (GCC \textgreater=\ 3.x seems to use a 16byte alignment) |
| 514 \item the direction flag is clear on entry and must be returned clear % mention it first, above @@@ | 513 \item the direction flag is clear on entry and must be returned clear % mention it first, above @@@ |
| 515 \end{itemize} | 514 \end{itemize} |
| 516 | 515 |
| 517 % introduce mangling section? \item Function name is decorated by prepending an underscore character and appending a '@' character and the number of bytes of stack space required | 516 % introduce mangling section? \item Function name is decorated by prepending an underscore character and appending a '@' character and the number of bytes of stack space required |
| 518 | 517 |