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comparison doc/manual/callconvs/callconv_mips32.tex @ 478:6c72cb768099

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callconv doc: - mips o32 update w/ regards to aggregates - mips o32 disas examples - sparc64 doc fixes
author Tassilo Philipp
date Tue, 01 Mar 2022 00:16:50 +0100
parents b47168dacba6
children a55506bf924e
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477:75c19f11b86a 478:6c72cb768099
1 %////////////////////////////////////////////////////////////////////////////// 1 %//////////////////////////////////////////////////////////////////////////////
2 % 2 %
3 % Copyright (c) 2007-2019 Daniel Adler <dadler@uni-goettingen.de>, 3 % Copyright (c) 2007-2022 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.
86 \item 64-bit stack arguments are always aligned to 8 bytes 86 \item 64-bit stack arguments are always aligned to 8 bytes
87 \item 64-bit integers or double precision floats are passed in two general purpose registers starting at an even register number, skipping one odd register 87 \item 64-bit integers or double precision floats are passed in two general purpose registers starting at an even register number, skipping one odd register
88 \item if either integer or float registers are used up, the stack is used 88 \item if either integer or float registers are used up, the stack is used
89 \item if the callee takes the address of one of the parameters and uses it to address other unnamed parameters (e.g. varargs) it has to copy - in its prolog - the the argument registers to a reserved stack area adjacent to the other parameters on the stack (only the unnamed integer parameters require saving, though) % @@@ seems to *ONLY* spill with varargs, never for any other reason 89 \item if the callee takes the address of one of the parameters and uses it to address other unnamed parameters (e.g. varargs) it has to copy - in its prolog - the the argument registers to a reserved stack area adjacent to the other parameters on the stack (only the unnamed integer parameters require saving, though) % @@@ seems to *ONLY* spill with varargs, never for any other reason
90 \item float registers don't seem to ever need to be saved that way, because floats passed to an ellipsis function are promoted to doubles, which in turn are passed in a? register pairs, so only \$a0-\$a7 are need to be spilled 90 \item float registers don't seem to ever need to be saved that way, because floats passed to an ellipsis function are promoted to doubles, which in turn are passed in a? register pairs, so only \$a0-\$a7 are need to be spilled
91 \end{itemize}
92
93 \paragraph{Return values}
94
95 \begin{itemize}
91 \item results are returned in \$v0 (32-bit), \$v0 and \$v1 (64-bit), \$f0 or \$f0 and \$f2 (2 $\times$ 32 bit float e.g. complex) 96 \item results are returned in \$v0 (32-bit), \$v0 and \$v1 (64-bit), \$f0 or \$f0 and \$f2 (2 $\times$ 32 bit float e.g. complex)
92 \end{itemize} 97 \end{itemize}
93 98
94 \paragraph{Stack layout} 99 \paragraph{Stack layout}
95 100
166 \item subsequent parameters are passed vie the stack 171 \item subsequent parameters are passed vie the stack
167 \item 64-bit params passed via registers are passed using either two registers (starting at an even register number, skipping an odd one if necessary), or via the stack using an 8-byte alignment 172 \item 64-bit params passed via registers are passed using either two registers (starting at an even register number, skipping an odd one if necessary), or via the stack using an 8-byte alignment
168 \item only on hard-float targets: if the very first call argument is a float, up to 2 floats or doubles can be passed via \$f12 and \$f14, respectively, for first and second argument 173 \item only on hard-float targets: if the very first call argument is a float, up to 2 floats or doubles can be passed via \$f12 and \$f14, respectively, for first and second argument
169 \item only on hard-float targets: if any arguments are passed via float registers, skip \$a0-\$a3 for subsequent arguments as if the values were passed via them 174 \item only on hard-float targets: if any arguments are passed via float registers, skip \$a0-\$a3 for subsequent arguments as if the values were passed via them
170 \item only on hard-float targets: note that if the first argument is not a float, but the second, it'll get passed via the \$a? registers 175 \item only on hard-float targets: note that if the first argument is not a float, but the second, it'll get passed via the \$a? registers
176 \item single precision float parameters (32 bit) are right-justified in their 8-byte slot on the stack on big endian targets, as they aren't promoted % @@@ verify
177 \item aggregates (struct, union) are passed as a sequence of words like integers, no matter the fields or if hard-float target (splitting across registers and stack is allowed)
178 \end{itemize}
179
180 \paragraph{Return values}
181
182 \begin{itemize}
171 \item results are returned in \$v0 and \$v1, with \$v0 for all values \textless\ 64bit (only integer on hard-float targets) 183 \item results are returned in \$v0 and \$v1, with \$v0 for all values \textless\ 64bit (only integer on hard-float targets)
172 \item only on hard-float targets: floating point results are returned in \$f0 (32-bit float), or \$f0 and \$f3 (64bit float) 184 \item only on hard-float targets: floating point results are returned in \$f0 (32-bit float), or \$f0 and \$f3 (64bit float)
173 \item single precision float parameters (32 bit) are right-justified in their 8-byte slot on the stack on big endian targets, as they aren't promoted @@@ 185 \item aggregates (struct, union) of any size are returned in a space allocated by the caller, with a pointer to it
186 passed as first parameter to the function called (meaning in \%a0)
174 \end{itemize} 187 \end{itemize}
175 188
176 \paragraph{Stack layout} 189 \paragraph{Stack layout}
177 190
178 % verified/amended: TP nov 2019 (see also doc/disas_examples/mips.o32.disas) 191 % verified/amended: TP nov 2019 (see also doc/disas_examples/mips.o32.disas)