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comparison doc/manual/callconvs/callconv_sparc32.tex @ 476:c73c59c8b553

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- sparc32 doc clarifications w/ respect to aggregate passing and returning
author Tassilo Philipp
date Sat, 19 Feb 2022 19:54:20 +0100
parents 4e6f63b7020e
children fc614cb865c6
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475:5be9f5ccdd35 476:c73c59c8b553
1 %////////////////////////////////////////////////////////////////////////////// 1 %//////////////////////////////////////////////////////////////////////////////
2 % 2 %
3 % Copyright (c) 2012-2019 Daniel Adler <dadler@uni-goettingen.de>, 3 % Copyright (c) 2012-2022 Daniel Adler <dadler@uni-goettingen.de>,
4 % Tassilo Philipp <tphilipp@potion-studios.com> 4 % Tassilo Philipp <tphilipp@potion-studios.com>
5 % 5 %
6 % Permission to use, copy, modify, and distribute this software for any 6 % Permission to use, copy, modify, and distribute this software for any
7 % purpose with or without fee is hereby granted, provided that the above 7 % purpose with or without fee is hereby granted, provided that the above
8 % copyright notice and this permission notice appear in all copies. 8 % copyright notice and this permission notice appear in all copies.
61 \begin{itemize} 61 \begin{itemize}
62 \item stack grows down 62 \item stack grows down
63 \item stack parameter order: right-to-left 63 \item stack parameter order: right-to-left
64 \item caller cleans up the stack 64 \item caller cleans up the stack
65 \item stack always aligned to 8 bytes 65 \item stack always aligned to 8 bytes
66 \item first 6 integers and floats are passed independently in registers using \%o0-\%o5 66 \item first 6 integers/pointers and floats are passed independently in registers using \%o0-\%o5
67 \item for every other argument the stack is used 67 \item for every other argument the stack is used
68 \item all arguments \textless=\ 32 bit are passed as 32 bit values 68 \item all arguments \textless=\ 32 bit are passed as 32 bit values
69 \item 64 bit arguments are passed like two consecutive \textless=\ 32 bit values (which allows for an argument to be split between the stack and \%i5) 69 \item 64 bit arguments are passed like two consecutive \textless=\ 32 bit values (which allows for an argument to be split between the stack and \%i5)
70 \item aggregates (struct, union) of any size, as well as quad precision values are passed indirectly as a pointer to a {\bf copy} of the aggregate (like: struct s2 = s; callee(\&s2);)
70 \item minimum stack size is 64 bytes, b/c stack pointer must always point at enough space to store all \%i* and \%l* registers, used when running out of register windows 71 \item minimum stack size is 64 bytes, b/c stack pointer must always point at enough space to store all \%i* and \%l* registers, used when running out of register windows
71 \item if needed, register spill area is adjacent to parameters 72 \item if needed, register spill area is adjacent to parameters
72 \end{itemize} 73 \end{itemize}
73 74
74 \paragraph{Return values} 75 \paragraph{Return values}
75 76
76 \begin{itemize} 77 \begin{itemize}
77 \item results are expected by caller to be returned in \%o0/\%o1 (after reg window restore, meaning callee writes to \%i0/\%i1) for integers 78 \item results are expected by caller to be returned in \%o0/\%o1 (after reg window restore, meaning callee writes to \%i0/\%i1) for integers
78 \item \%f0/\%f1 are used for floating point values 79 \item \%f0/\%f1 are used for floating point values
79 \item structs/unions are returned in a space allocated by the caller, with a pointer to it passed as a {\bf additional}, hidden stack parameter (see below) 80 \item aggregates (struct, union) and quad precision values are returned in a space allocated by the caller, with a pointer to it passed
81 as an {\bf additional}, hidden {\bf stack} parameter (always at \%sp+64 for the caller, see below); that pointer is returned in \%o0
80 \end{itemize} 82 \end{itemize}
81 83
82 \paragraph{Stack layout} 84 \paragraph{Stack layout}
83 85
84 % verified/amended: TP nov 2019 (see also doc/disas_examples/sparc.sparc.disas) 86 % verified/amended: TP nov 2019 (see also doc/disas_examples/sparc.sparc.disas)