{"id":20786,"date":"2022-11-10T22:14:44","date_gmt":"2022-11-10T16:44:44","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/"},"modified":"2022-11-10T22:14:44","modified_gmt":"2022-11-10T16:44:44","slug":"solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/","title":{"rendered":"[Solved] Unroll a loop using a macro that has a goto and a label in it"},"content":{"rendered":"<p> [ad_1]<br \/>\n<\/p>\n<div id=\"answer-29079754\" class=\"answer js-answer accepted-answer js-accepted-answer\" data-answerid=\"29079754\" data-parentid=\"29079595\" data-score=\"3\" data-position-on-page=\"1\" data-highest-scored=\"1\" data-question-has-accepted-highest-score=\"1\" itemprop=\"acceptedAnswer\" itemscope itemtype=\"https:\/\/schema.org\/Answer\">\n<div class=\"post-layout\">\n<div class=\"votecell post-layout--left\"><\/div>\n<div class=\"answercell post-layout--right\">\n<div class=\"s-prose js-post-body\" itemprop=\"text\">\n<p>You really should make it a <code>do<\/code>&#8230;<code>while<\/code>  loop:<\/p>\n<pre><code>#define BROP(num, sum)  do{                \\\n   bool again = false;                     \\\n   num = rand_lcg(generated);              \\\n   if (num % 2)  {                         \\\n   do { again = false;                     \\\n     generated = rand_lcg(generated);      \\\n     if (generated &lt; 512)                  \\\n           sum -= generated;               \\\n     else                                  \\\n        again = true;                      \\\n   } while(again); } while(0)\n<\/code><\/pre>\n<p>See this for the old  outer<code>do{<\/code>&#8230;<code>}while(0)<\/code> trick.<\/p>\n<p>If you (wrongly) insist on having a label and are using the <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/gcc.gnu.org\/\">GCC<\/a> compiler (or <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/clang.llvm.org\/\">Clang\/LLVM<\/a> which should be compatible on that), you could use <a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/gcc.gnu.org\/onlinedocs\/gcc\/Local-Labels.html\">local labels<\/a> extension (i.e. with <code>__label__<\/code> &#8230;)<\/p>\n<p>You might also generate the label from the <code>__LINE__<\/code> number using <a rel=\"nofollow noopener\" target=\"_blank\" href=\"https:\/\/gcc.gnu.org\/onlinedocs\/cpp\/Concatenation.html\">concatenation<\/a> in the preprocessor. Take inspiration from<\/p>\n<pre><code>#define STUPID_LOOP_BIS(Test,Lin) do { \\\n lab##Lin: if (Test) goto lab##Lin; } while(0)\n#define STUPID_LOOP_AT(Test,Lin) STUPID_LOOP_BIS(Test,Lin)\n#define STUPID_LOOP(Test) STUPID_LOOP_AT(Test,__LINE__)\n<\/code><\/pre>\n<p><sup>for obscure reasons you need all the three macros!<\/sup><\/p>\n<p>And use<\/p>\n<pre><code>  STUPID_LOOP(x++ &lt; 100);\n  STUPID_LOOP(y-- &gt; 0);\n<\/code><\/pre>\n<p>on separate lines. Of course adapt and improve for your need.<\/p>\n<p>You definitely should <strong>use and <em>trust<\/em> more the compiler optimization abilities<\/strong> and have <code>static inline<\/code> functions. Not every test is compiled to a machine branch (e.g. because of CMOV instructions); not every loop is compiled to a machine loop (e.g. because of <a rel=\"nofollow noopener\" target=\"_blank\" href=\"http:\/\/en.wikipedia.org\/wiki\/Loop_unrolling\">loop unrolling<\/a>). You are probably losing your developer&#8217;s time, and more importantly, you are <em>disabling<\/em> optimizations by your tricks (so your code will likely go slower, not faster).<\/p>\n<p>If using GCC or Clang enable optimizations and warnings:  so compile with <br \/><code>gcc -Wall -Wextra -O3 -mtune=native<\/code><\/p>\n<\/p><\/div>\n<div class=\"mt24\"><\/div>\n<\/div>\n<p>            <span class=\"d-none\" itemprop=\"commentCount\">2<\/span> <\/p><\/div>\n<\/div>\n<p>[ad_2]<\/p>\n<p>solved Unroll a loop using a macro that has a goto and a label in it <\/p>\n","protected":false},"excerpt":{"rendered":"<p>[ad_1] You really should make it a do&#8230;while loop: #define BROP(num, sum) do{ \\ bool again = false; \\ num = rand_lcg(generated); \\ if (num % 2) { \\ do { again = false; \\ generated = rand_lcg(generated); \\ if (generated &lt; 512) \\ sum -= generated; \\ else \\ again = true; \\ } &#8230; <a title=\"[Solved] Unroll a loop using a macro that has a goto and a label in it\" class=\"read-more\" href=\"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/\" aria-label=\"More on [Solved] Unroll a loop using a macro that has a goto and a label in it\">Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[324,943],"class_list":["post-20786","post","type-post","status-publish","format-standard","hentry","category-solved","tag-c","tag-compiler-errors"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v27.4 - https:\/\/yoast.com\/product\/yoast-seo-wordpress\/ -->\n<title>[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] You really should make it a do&#8230;while loop: #define BROP(num, sum) do{  bool again = false;  num = rand_lcg(generated);  if (num % 2) {  do { again = false;  generated = rand_lcg(generated);  if (generated &lt; 512)  sum -= generated;  else  again = true;  } ... Read more\" \/>\n<meta property=\"og:url\" content=\"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/\" \/>\n<meta property=\"og:site_name\" content=\"JassWeb\" \/>\n<meta property=\"article:published_time\" content=\"2022-11-10T16:44:44+00:00\" \/>\n<meta name=\"author\" content=\"Kirat\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Kirat\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/\"},\"author\":{\"name\":\"Kirat\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/person\\\/65c9c7b7958150c0dc8371fa35dd7c31\"},\"headline\":\"[Solved] Unroll a loop using a macro that has a goto and a label in it\",\"datePublished\":\"2022-11-10T16:44:44+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/\"},\"wordCount\":202,\"publisher\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\"},\"keywords\":[\"c++\",\"compiler-errors\"],\"articleSection\":[\"Solved\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/\",\"name\":\"[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#website\"},\"datePublished\":\"2022-11-10T16:44:44+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\\\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"[Solved] Unroll a loop using a macro that has a goto and a label in it\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#website\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\",\"name\":\"JassWeb\",\"description\":\"Build High-quality Websites\",\"publisher\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#organization\",\"name\":\"Jass Web\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/logo\\\/image\\\/\",\"url\":\"https:\\\/\\\/jassweb.com\\\/wp-content\\\/uploads\\\/2021\\\/02\\\/jass-website-logo-1.png\",\"contentUrl\":\"https:\\\/\\\/jassweb.com\\\/wp-content\\\/uploads\\\/2021\\\/02\\\/jass-website-logo-1.png\",\"width\":693,\"height\":132,\"caption\":\"Jass Web\"},\"image\":{\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/logo\\\/image\\\/\"}},{\"@type\":\"Person\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/#\\\/schema\\\/person\\\/65c9c7b7958150c0dc8371fa35dd7c31\",\"name\":\"Kirat\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"contentUrl\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/wp-content\\\/litespeed\\\/avatar\\\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400\",\"caption\":\"Kirat\"},\"sameAs\":[\"http:\\\/\\\/jassweb.com\"],\"url\":\"https:\\\/\\\/jassweb.com\\\/solved\\\/author\\\/jaspritsinghghumangmail-com\\\/\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/","og_locale":"en_US","og_type":"article","og_title":"[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb","og_description":"[ad_1] You really should make it a do&#8230;while loop: #define BROP(num, sum) do{  bool again = false;  num = rand_lcg(generated);  if (num % 2) {  do { again = false;  generated = rand_lcg(generated);  if (generated &lt; 512)  sum -= generated;  else  again = true;  } ... Read more","og_url":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/","og_site_name":"JassWeb","article_published_time":"2022-11-10T16:44:44+00:00","author":"Kirat","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Kirat","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/#article","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/"},"author":{"name":"Kirat","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31"},"headline":"[Solved] Unroll a loop using a macro that has a goto and a label in it","datePublished":"2022-11-10T16:44:44+00:00","mainEntityOfPage":{"@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/"},"wordCount":202,"publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"keywords":["c++","compiler-errors"],"articleSection":["Solved"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/","url":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/","name":"[Solved] Unroll a loop using a macro that has a goto and a label in it - JassWeb","isPartOf":{"@id":"https:\/\/jassweb.com\/solved\/#website"},"datePublished":"2022-11-10T16:44:44+00:00","breadcrumb":{"@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/jassweb.com\/solved\/solved-unroll-a-loop-using-a-macro-that-has-a-goto-and-a-label-in-it\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/jassweb.com\/solved\/"},{"@type":"ListItem","position":2,"name":"[Solved] Unroll a loop using a macro that has a goto and a label in it"}]},{"@type":"WebSite","@id":"https:\/\/jassweb.com\/solved\/#website","url":"https:\/\/jassweb.com\/solved\/","name":"JassWeb","description":"Build High-quality Websites","publisher":{"@id":"https:\/\/jassweb.com\/solved\/#organization"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/jassweb.com\/solved\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/jassweb.com\/solved\/#organization","name":"Jass Web","url":"https:\/\/jassweb.com\/solved\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/","url":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","contentUrl":"https:\/\/jassweb.com\/wp-content\/uploads\/2021\/02\/jass-website-logo-1.png","width":693,"height":132,"caption":"Jass Web"},"image":{"@id":"https:\/\/jassweb.com\/solved\/#\/schema\/logo\/image\/"}},{"@type":"Person","@id":"https:\/\/jassweb.com\/solved\/#\/schema\/person\/65c9c7b7958150c0dc8371fa35dd7c31","name":"Kirat","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","url":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","contentUrl":"https:\/\/jassweb.com\/solved\/wp-content\/litespeed\/avatar\/1261af3c9451399fa1336d28b98ea3bb.jpg?ver=1777008400","caption":"Kirat"},"sameAs":["http:\/\/jassweb.com"],"url":"https:\/\/jassweb.com\/solved\/author\/jaspritsinghghumangmail-com\/"}]}},"_links":{"self":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/20786","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/comments?post=20786"}],"version-history":[{"count":0,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/posts\/20786\/revisions"}],"wp:attachment":[{"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/media?parent=20786"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/categories?post=20786"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/jassweb.com\/solved\/wp-json\/wp\/v2\/tags?post=20786"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}