{"id":345,"date":"2024-07-12T23:09:31","date_gmt":"2024-07-13T03:09:31","guid":{"rendered":"http:\/\/www.schveiguy.com\/blog\/?p=345"},"modified":"2024-07-13T02:00:09","modified_gmt":"2024-07-13T06:00:09","slug":"dlang-psa-dont-use-release","status":"publish","type":"post","link":"https:\/\/www.schveiguy.com\/blog\/2024\/07\/dlang-psa-dont-use-release\/","title":{"rendered":"Dlang PSA: Don’t use -release"},"content":{"rendered":"\n

Don’t use the -release<\/code> command line switch for the D compiler.<\/p>\n\n\n\n

Why? Because it removes bounds checks from arrays in @system<\/code> code. Why is this a problem? It is a problem because the #1 problem with all exploits in the world is buffer overflows — writing or reading data that you are not supposed to have access to.<\/p>\n\n\n\n

In other words, if you have a bug in your code where you don’t validate your array usage is within bounds, then bound checks will prevent a catastrophic error, or an exploit. If you are lucky, you get a segmentation fault that crashes your program.<\/p>\n\n\n\n

Note that -release<\/code> doesn’t even optimize the code! You still need to use -O -inline<\/code> to get maximum performance. If you are feeling a bit adventurous, you might use -check=assert=off<\/code>, but that’s only if you really have expensive asserts that are causing performance problems. Even then, I might look into selectively compiling some modules with asserts off to achieve the desired performance.<\/p>\n\n\n\n

In general, turning off safety checks is only crucial for performance critical<\/em> code. It should not be project-wide. And for bounds checks? You can easily omit bounds checks in @system<\/code> code by using the .ptr[index]<\/code> mechanism.<\/p>\n\n\n\n

What about dub?<\/h2>\n\n\n\n

For those who use dub, you can actually override the release<\/code> build option. Here is how I do it (dub.json format):<\/p>\n\n\n\n

"buildTypes": {\n    "release": {\n        "buildOptions": [\n            "inline",\n            "optimize"\n        ]\n    }\n}<\/code><\/pre>\n\n\n\n
This means, when you type dub -b release<\/code> you won’t accidentally remove the most important checks present in your code.<\/p>\n\n\n\n
But I want my code to be the fastest ever!!!<\/h2>\n\n\n\n
No, you don’t. You don’t care if it takes 200ms vs 250ms. Trust me. Just don’t do it.<\/p>\n\n\n\n
Here is a case where D beat pretty much all the competition, and never turned off bounds checks: https:\/\/github.com\/jinyus\/related_post_gen<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"
Don’t use the -release command line switch for the D compiler. Why? Because it removes bounds checks from arrays in @system code. Why is this a problem? It is a problem because the #1 problem with all exploits in the world is buffer overflows — writing or reading data that you are not supposed to […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-345","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/posts\/345"}],"collection":[{"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/comments?post=345"}],"version-history":[{"count":3,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/posts\/345\/revisions"}],"predecessor-version":[{"id":348,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/posts\/345\/revisions\/348"}],"wp:attachment":[{"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/media?parent=345"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/categories?post=345"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.schveiguy.com\/blog\/wp-json\/wp\/v2\/tags?post=345"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}