Mercurial > pub > dyncall > dyncall
annotate doc/manual/callconvs/callconv_mips.tex @ 108:bf8aef292216
- mips clarifications in doc
| author | cslag |
|---|---|
| date | Sat, 11 Jun 2016 21:38:46 +0200 |
| parents | dbca6763f2be |
| children | 9aa75a74614c |
| rev | line source |
|---|---|
| 0 | 1 %////////////////////////////////////////////////////////////////////////////// |
| 2 % | |
| 3 % Copyright (c) 2007,2009 Daniel Adler <dadler@uni-goettingen.de>, | |
| 4 % Tassilo Philipp <tphilipp@potion-studios.com> | |
| 5 % | |
| 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 | |
| 8 % copyright notice and this permission notice appear in all copies. | |
| 9 % | |
| 10 % THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES | |
| 11 % WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
| 12 % MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
| 13 % ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
| 14 % WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
| 15 % ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
| 16 % OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
| 17 % | |
| 18 %////////////////////////////////////////////////////////////////////////////// | |
| 19 | |
| 20 \subsection{MIPS Calling Convention} | |
| 21 | |
| 22 \paragraph{Overview} | |
| 23 | |
| 24 The MIPS family of processors is based on the MIPS processor architecture. | |
| 25 Multiple revisions of the MIPS Instruction set exist, namely MIPS I, MIPS II, MIPS III, MIPS IV, MIPS32 and MIPS64. | |
| 26 Today, MIPS32 and MIPS64 for 32-bit and 64-bit respectively.\\ | |
| 27 Several add-on extensions exist for the MIPS family: | |
| 28 | |
| 29 \begin{description} | |
| 30 \item [MIPS-3D] simple floating-point SIMD instructions dedicated to common 3D tasks. | |
| 31 \item [MDMX] (MaDMaX) more extensive integer SIMD instruction set using 64 bit floating-point registers. | |
| 32 \item [MIPS16e] adds compression to the instruction stream to make programs take up less room (allegedly a response to the THUMB instruction set of the ARM architecture). | |
| 33 \item [MIPS MT] multithreading additions to the system similar to HyperThreading. | |
| 34 \end{description} | |
| 35 | |
| 36 Unfortunately, there is actually no such thing as "The MIPS Calling Convention". Many possible conventions are used | |
| 98 | 37 by many different environments such as \emph{O32}\cite{MIPSo32}, \emph{O64}, \emph{N32}, \emph{N64} and \emph{EABI}.\\ |
| 0 | 38 |
| 39 \paragraph{\product{dyncall} support} | |
| 40 | |
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41 Currently, dyncall supports for MIPS 32-bit architectures the O32 calling convention, as well as EABI (which is used on the Homebrew SDK for |
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42 the Playstation Portable). For MIPS 64-bit machines, dyncall supports the N32 and N64 calling conventions. |
| 0 | 43 |
| 44 \subsubsection{MIPS EABI 32-bit Calling Convention} | |
| 45 | |
| 46 \paragraph{Register usage} | |
| 47 | |
| 48 \begin{table}[h] | |
| 77 | 49 \begin{tabular*}{0.95\textwidth}{lll} |
| 108 | 50 Name & Alias & Brief description\\ |
| 51 \hline | |
| 52 {\bf \$0} & {\bf \$zero} & Hardware zero \\ | |
| 53 {\bf \$1} & {\bf \$at} & Assembler temporary \\ | |
| 54 {\bf \$2-\$3} & {\bf \$v0-\$v1} & Integer results \\ | |
| 55 {\bf \$4-\$11} & {\bf \$a0-\$a7} & Integer arguments\\ | |
| 56 {\bf \$12-\$15,\$24} & {\bf \$t4-\$t7,\$t8} & Integer temporaries \\ | |
| 57 {\bf \$25} & {\bf \$t9} & Integer temporary, hold the address of the called function for all PIC calls (by convention) \\ | |
| 58 {\bf \$16-\$23} & {\bf \$s0-\$s7} & Preserved \\ | |
| 59 {\bf \$26,\$27} & {\bf \$kt0,\$kt1} & Reserved for kernel \\ | |
| 60 {\bf \$28} & {\bf \$gp} & Global pointer, preserve \\ | |
| 61 {\bf \$29} & {\bf \$sp} & Stack pointer, preserve \\ | |
| 62 {\bf \$30} & {\bf \$s8} & Frame pointer, preserve \\ | |
| 63 {\bf \$31} & {\bf \$ra} & Return address, preserve \\ | |
| 64 {\bf hi, lo} & & Multiply/divide special registers \\ | |
| 65 {\bf \$f0,\$f2} & & Float results \\ | |
| 66 {\bf \$f1,\$f3,\$f4-\$f11,\$f20-\$f23} & & Float temporaries \\ | |
| 67 {\bf \$f12-\$f19} & & Float arguments \\ | |
| 76 | 68 \end{tabular*} |
| 98 | 69 \caption{Register usage on MIPS32 EABI calling convention} |
| 0 | 70 \end{table} |
| 71 | |
| 72 \paragraph{Parameter passing} | |
| 73 | |
| 74 \begin{itemize} | |
| 98 | 75 \item Stack grows down |
| 0 | 76 \item Stack parameter order: right-to-left |
| 77 \item Caller cleans up the stack | |
| 78 \item Stack always aligned to 8 bytes. | |
| 108 | 79 \item first 8 integers or floats are passed independently in registers using \$a0-\$a7 and \$f12-\$f19, respectively. |
| 80 \item if either integer or float registers are used up, the stack is used | |
| 81 \item 64-bit integers or floats are passed on two integer registers starting at an even register number, skipping one odd register. | |
| 0 | 82 \item \$a0-\$a7 and \$f12-\$f19 are not required to be preserved. |
| 108 | 83 \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). |
| 0 | 84 \end{itemize} |
| 85 | |
| 86 \paragraph{Stack layout} | |
| 87 | |
| 88 Stack directly after function prolog:\\ | |
| 89 | |
| 90 \begin{figure}[h] | |
| 91 \begin{tabular}{5|3|1 1} | |
| 92 \hhline{~-~~} | |
| 92 | 93 & \vdots & & \\ |
| 94 \hhline{~=~~} | |
| 95 register save area & \hspace{4cm} & & \mrrbrace{5}{caller's frame} \\ | |
| 96 \hhline{~-~~} | |
| 97 local data & & & \\ | |
| 98 \hhline{~-~~} | |
| 99 \mrlbrace{3}{parameter area} & \ldots & \mrrbrace{3}{stack parameters} & \\ | |
| 100 & \ldots & & \\ | |
| 101 & \ldots & & \\ | |
| 0 | 102 \hhline{~=~~} |
| 92 | 103 register save area (with return address) & & & \mrrbrace{5}{current frame} \\ |
| 0 | 104 \hhline{~-~~} |
| 92 | 105 local data & & & \\ |
| 0 | 106 \hhline{~-~~} |
| 92 | 107 parameter area & & & \\ |
| 0 | 108 \hhline{~-~~} |
| 92 | 109 & \vdots & & \\ |
| 0 | 110 \hhline{~-~~} |
| 111 \end{tabular} | |
| 112 \caption{Stack layout on mips32 eabi calling convention} | |
| 113 \end{figure} | |
| 114 | |
| 98 | 115 \newpage |
| 116 | |
| 95 | 117 \subsubsection{MIPS O32 32-bit Calling Convention} |
| 118 | |
| 98 | 119 \paragraph{Register usage} |
| 120 | |
| 121 \begin{table}[h] | |
| 122 \begin{tabular*}{0.95\textwidth}{lll} | |
| 108 | 123 Name & Alias & Brief description\\ |
| 98 | 124 \hline |
| 108 | 125 {\bf \$0} & {\bf \$zero} & hardware zero \\ |
| 126 {\bf \$1} & {\bf \$at} & assembler temporary \\ | |
| 127 {\bf \$2-\$3} & {\bf \$v0-\$v1} & return value, scratch \\ | |
| 128 {\bf \$4-\$7} & {\bf \$a0-\$a3} & first integer arguments, scratch\\ | |
| 129 {\bf \$8-\$15,\$24} & {\bf \$t0-\$t7,\$t8} & temporaries, scratch \\ | |
| 130 {\bf \$25} & {\bf \$t9} & temporary, hold the address of the called function for all PIC calls (by convention) \\ | |
| 131 {\bf \$16-\$23} & {\bf \$s0-\$s7} & preserved \\ | |
| 132 {\bf \$26,\$27} & {\bf \$k0,\$k1} & reserved for kernel \\ | |
| 133 {\bf \$28} & {\bf \$gp} & global pointer, preserve \\ | |
| 134 {\bf \$29} & {\bf \$sp} & stack pointer, preserve \\ | |
| 135 {\bf \$30} & {\bf \$fp} & frame pointer, preserve \\ | |
| 136 {\bf \$31} & {\bf \$ra} & return address, preserve \\ | |
| 137 {\bf hi, lo} & & multiply/divide special registers \\ | |
| 138 {\bf \$f0-\$f3} & & float return value, scratch \\ | |
| 139 {\bf \$f4-\$f11,\$f16-\$f19} & & float temporaries, scratch \\ | |
| 140 {\bf \$f12-\$f15} & & first floating point arguments, scratch \\ | |
| 141 {\bf \$f20-\$f31} & & preserved \\ | |
| 98 | 142 \end{tabular*} |
| 143 \caption{Register usage on MIPS O32 calling convention} | |
| 144 \end{table} | |
| 145 | |
| 146 \paragraph{Parameter passing} | |
| 147 | |
| 148 \begin{itemize} | |
| 149 \item Stack grows down | |
| 150 \item Stack parameter order: right-to-left | |
| 151 \item Caller cleans up the stack | |
| 108 | 152 \item Caller is required to always leave a 16-byte spill area for\$a0-\$a3 at the and of {\bf its} frame, to be used and spilled to by the callee, if needed |
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153 \item The different stack areas (local data, register save area, parameter area) are each aligned to 8 bytes. |
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154 \item generally, first four 32bit arguments are passed in registers \$a0-\$a3, respectively (see below for exceptions if first arg is a float) |
| 98 | 155 \item subsequent parameters are passed vie the stack |
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156 \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 |
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157 \item 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 |
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158 \item if any arguments are passed via float registers, skip \$a0-\$a3 for subsequent arguments as if the values were passed via them |
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159 \item note that if the first argument is not a float, but the second, it'll get passed via the \$a? registers |
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160 \item results are returned in \$v0 (32-bit int return values), \$f0 (32-bit float), \$v0 and \$v1 (64-bit int), \$f0 and \$f3 (64bit float) |
| 98 | 161 \end{itemize} |
| 162 | |
| 163 \paragraph{Stack layout} | |
| 164 | |
| 165 Stack directly after function prolog:\\ | |
| 166 | |
| 167 \begin{figure}[h] | |
| 168 \begin{tabular}{5|3|1 1} | |
| 169 \hhline{~-~~} | |
| 170 & \vdots & & \\ | |
| 171 \hhline{~=~~} | |
| 172 local data & \hspace{4cm} & & \mrrbrace{12}{caller's frame} \\ | |
| 173 \hhline{~-~~} | |
| 174 register save area & return address & & \\ | |
| 175 & s7 & & \\ | |
| 176 & \vdots & & \\ | |
| 177 & s0 & & \\ | |
| 178 \hhline{~-~~} | |
| 179 \mrlbrace{7}{parameter area} & \ldots & \mrrbrace{3}{stack parameters} & \\ | |
| 180 & \ldots & & \\ | |
| 181 & \ldots & & \\ | |
| 182 & a3 & \mrrbrace{4}{spill area} & \\ | |
| 183 & a2 & & \\ | |
| 184 & a1 & & \\ | |
| 185 & a0 & & \\ | |
| 186 \hhline{~=~~} | |
| 187 local data & & & \mrrbrace{5}{current frame} \\ | |
| 188 \hhline{~-~~} | |
| 189 register save area (with return address) & & & \\ | |
| 190 \hhline{~-~~} | |
| 191 parameter area & & & \\ | |
| 192 & \vdots & & \\ | |
| 193 \hhline{~-~~} | |
| 194 \end{tabular} | |
| 195 \caption{Stack layout on MIPS O32 calling convention} | |
| 196 \end{figure} | |
| 197 | |
| 198 \newpage | |
| 95 | 199 |
| 200 \subsubsection{MIPS N32 32-bit Calling Convention} | |
| 201 | |
| 202 @@@ | |
| 203 |