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Diffstat (limited to 'html/baremetal/302stack_allocate.subx.html')
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diff --git a/html/baremetal/302stack_allocate.subx.html b/html/baremetal/302stack_allocate.subx.html new file mode 100644 index 00000000..73e18ff6 --- /dev/null +++ b/html/baremetal/302stack_allocate.subx.html @@ -0,0 +1,122 @@ +<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> +<html> +<head> +<meta http-equiv="content-type" content="text/html; charset=UTF-8"> +<title>Mu - baremetal/302stack_allocate.subx</title> +<meta name="Generator" content="Vim/8.1"> +<meta name="plugin-version" content="vim8.1_v1"> +<meta name="syntax" content="none"> +<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> +<meta name="colorscheme" content="minimal-light"> +<style type="text/css"> +<!-- +pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #c6c6c6; } +body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; } +a { color:inherit; } +* { font-size:12pt; font-size: 1em; } +.subxComment { color: #005faf; } +.LineNr { } +.SpecialChar { color: #d70000; } +.CommentedCode { color: #8a8a8a; } +.subxFunction { color: #af5f00; text-decoration: underline; } +.Constant { color: #008787; } +--> +</style> + +<script type='text/javascript'> +<!-- + +/* function to open any folds containing a jumped-to line before jumping to it */ +function JumpToLine() +{ + var lineNum; + lineNum = window.location.hash; + lineNum = lineNum.substr(1); /* strip off '#' */ + + if (lineNum.indexOf('L') == -1) { + lineNum = 'L'+lineNum; + } + var lineElem = document.getElementById(lineNum); + /* Always jump to new location even if the line was hidden inside a fold, or + * we corrected the raw number to a line ID. + */ + if (lineElem) { + lineElem.scrollIntoView(true); + } + return true; +} +if ('onhashchange' in window) { + window.onhashchange = JumpToLine; +} + +--> +</script> +</head> +<body onload='JumpToLine();'> +<a href='https://github.com/akkartik/mu/blob/main/baremetal/302stack_allocate.subx'>https://github.com/akkartik/mu/blob/main/baremetal/302stack_allocate.subx</a> +<pre id='vimCodeElement'> +<span id="L1" class="LineNr"> 1 </span><span class="subxComment"># A function which pushes n zeros on the stack.</span> +<span id="L2" class="LineNr"> 2 </span><span class="subxComment"># Really only intended to be called from code generated by mu.subx (for array</span> +<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># vars on the stack).</span> +<span id="L4" class="LineNr"> 4 </span> +<span id="L5" class="LineNr"> 5 </span>== code +<span id="L6" class="LineNr"> 6 </span> +<span id="L7" class="LineNr"> 7 </span><span class="CommentedCode">#? Entry:</span> +<span id="L8" class="LineNr"> 8 </span><span class="CommentedCode">#? # . prologue</span> +<span id="L9" class="LineNr"> 9 </span><span class="CommentedCode">#? 89/<- %ebp 4/r32/esp</span> +<span id="L10" class="LineNr">10 </span><span class="CommentedCode">#? #</span> +<span id="L11" class="LineNr">11 </span><span class="CommentedCode">#? 68/push 0xfcfdfeff/imm32</span> +<span id="L12" class="LineNr">12 </span><span class="CommentedCode">#? b8/copy-to-eax 0x34353637/imm32</span> +<span id="L13" class="LineNr">13 </span><span class="CommentedCode">#? $dump-stack0:</span> +<span id="L14" class="LineNr">14 </span><span class="CommentedCode">#? (push-n-zero-bytes 4)</span> +<span id="L15" class="LineNr">15 </span><span class="CommentedCode">#? 68/push 0x20/imm32</span> +<span id="L16" class="LineNr">16 </span><span class="CommentedCode">#? $dump-stack9:</span> +<span id="L17" class="LineNr">17 </span><span class="CommentedCode">#? b8/copy-to-eax 1/imm32/exit</span> +<span id="L18" class="LineNr">18 </span><span class="CommentedCode">#? cd/syscall 0x80/imm8</span> +<span id="L19" class="LineNr">19 </span> +<span id="L20" class="LineNr">20 </span><span class="subxComment"># This is not a regular function, so it won't be idiomatic.</span> +<span id="L21" class="LineNr">21 </span><span class="subxComment"># Registers must be properly restored.</span> +<span id="L22" class="LineNr">22 </span><span class="subxComment"># Registers can be spilled, but that modifies the stack and needs to be</span> +<span id="L23" class="LineNr">23 </span><span class="subxComment"># cleaned up.</span> +<span id="L24" class="LineNr">24 </span> +<span id="L25" class="LineNr">25 </span><span class="subxComment"># Overhead:</span> +<span id="L26" class="LineNr">26 </span><span class="subxComment"># 62 + n*6 instructions to push n bytes.</span> +<span id="L27" class="LineNr">27 </span><span class="subxComment"># If we just emitted code to push n zeroes, it would be:</span> +<span id="L28" class="LineNr">28 </span><span class="subxComment"># 5 bytes for 4 zero bytes, so 1.25 bytes per zero. And that's not even</span> +<span id="L29" class="LineNr">29 </span><span class="subxComment"># instructions.</span> +<span id="L30" class="LineNr">30 </span><span class="subxComment"># But on the other hand it would destroy the instruction cache, where this</span> +<span id="L31" class="LineNr">31 </span><span class="subxComment"># approach requires 15 instructions, fixed.</span> +<span id="L32" class="LineNr">32 </span> +<span id="L33" class="LineNr">33 </span><span class="subxComment"># n must be positive</span> +<span id="L34" class="LineNr">34 </span><span class="subxFunction">push-n-zero-bytes</span>: <span class="subxComment"># n: int</span> +<span id="L35" class="LineNr">35 </span><span class="Constant">$push-n-zero-bytes:prologue</span>: +<span id="L36" class="LineNr">36 </span> 89/<- *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L56'>Push-n-zero-bytes-ebp</a></span> 5/r32/ebp <span class="subxComment"># spill ebp without affecting stack</span> +<span id="L37" class="LineNr">37 </span> 89/<- %ebp 4/r32/esp +<span id="L38" class="LineNr">38 </span><span class="Constant">$push-n-zero-bytes:copy-ra</span>: +<span id="L39" class="LineNr">39 </span> <span class="subxComment"># -- esp = ebp</span> +<span id="L40" class="LineNr">40 </span> 89/<- *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L60'>Push-n-zero-bytes-eax</a></span> 0/r32/eax +<span id="L41" class="LineNr">41 </span> 8b/-> *esp 0/r32/eax +<span id="L42" class="LineNr">42 </span> 2b/subtract *(ebp+4) 4/r32/esp +<span id="L43" class="LineNr">43 </span> <span class="subxComment"># -- esp+n = ebp</span> +<span id="L44" class="LineNr">44 </span> 89/<- *esp 0/r32/eax +<span id="L45" class="LineNr">45 </span> 8b/-> *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L60'>Push-n-zero-bytes-eax</a></span> 0/r32/eax +<span id="L46" class="LineNr">46 </span><span class="Constant">$push-n-zero-bytes:bulk-cleaning</span>: +<span id="L47" class="LineNr">47 </span> 89/<- *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L58'>Push-n-zero-bytes-esp</a></span> 4/r32/esp +<span id="L48" class="LineNr">48 </span> 81 0/subop/add *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L58'>Push-n-zero-bytes-esp</a></span> 4/imm32 +<span id="L49" class="LineNr">49 </span> 81 0/subop/add *(ebp+4) 4/imm32 +<span id="L50" class="LineNr">50 </span> (<a href='120allocate.subx.html#L6'>zero-out</a> *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L58'>Push-n-zero-bytes-esp</a></span> *(ebp+4)) <span class="subxComment"># n+4</span> +<span id="L51" class="LineNr">51 </span><span class="Constant">$push-n-zero-bytes:epilogue</span>: +<span id="L52" class="LineNr">52 </span> 8b/-> *<span class="SpecialChar"><a href='302stack_allocate.subx.html#L56'>Push-n-zero-bytes-ebp</a></span> 5/r32/ebp <span class="subxComment"># restore spill</span> +<span id="L53" class="LineNr">53 </span> c3/return +<span id="L54" class="LineNr">54 </span> +<span id="L55" class="LineNr">55 </span>== data +<span id="L56" class="LineNr">56 </span><span class="SpecialChar">Push-n-zero-bytes-ebp</span>: <span class="subxComment"># (addr int)</span> +<span id="L57" class="LineNr">57 </span> 0/imm32 +<span id="L58" class="LineNr">58 </span><span class="SpecialChar">Push-n-zero-bytes-esp</span>: <span class="subxComment"># (addr int)</span> +<span id="L59" class="LineNr">59 </span> 0/imm32 +<span id="L60" class="LineNr">60 </span><span class="SpecialChar">Push-n-zero-bytes-eax</span>: +<span id="L61" class="LineNr">61 </span> 0/imm32 +</pre> +</body> +</html> +<!-- vim: set foldmethod=manual : --> |