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Post Au94exGnS6mGLdbv1s by [email protected] |
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More posts by [email protected] |
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Post #Au7UzQJbNiMQiKQKLg by [email protected] |
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You might not like it, but this is what peak compiler performance looks like. |
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Post #Au7b4RHhnurMtSJN9k by [email protected] |
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@ela how can the compiler break down a recursive function to a mathematical sta… |
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Post #Au7b4ROROsFPELSkee by [email protected] |
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@viduq It's not exactly brute force, but it does involve some heavy lifting… |
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Post #Au8lQ6LbWPfT1q3yDY by [email protected] |
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@ela This is brilliant! I'd like to put this into my uni lecture on C/C++. … |
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Post #Au8lQ6Rz8glvLd34AC by [email protected] |
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@josch This code snipped has been floating around for a while, here's a blo… |
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Post #Au8tnTcJyHJJUYXVOS by [email protected] |
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@ela Unfortunately this does not work for the mutually recursive isEven and isO… |
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Post #Au8tnTihaYPloLWbL6 by [email protected] |
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@realleif Inline harder! |
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Post #Au8uOueiPBK646VgrQ by [email protected] |
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@ela Actually, this is what bad code writing looks like. |
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Post #Au8uOulnyoziQ5pLua by [email protected] |
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@caravantraveller This might be an extreme case of bad code, yes. But the moral… |
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Post #Au92jDlxq0UumR5yts by [email protected] |
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@ela This is quite impressive, and I wonder how complex you could make these ki… |
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Post #Au92jDtlN0jhAckD3Y by [email protected] |
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@loke @ela I would expect that this is the combination of a few things:First, t… |
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Post #Au939I9w9Ps9ukjwci by [email protected] |
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@ela @viduq Uh, I need Alt text to help me understand this.😢 |
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Post #Au93GVpXijkkLEdz28 by [email protected] |
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@ela this stumped me until I saw clang decides to return bool in al, not eax, f… |
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Post #Au93GW0B5CGAsDcTbs by [email protected] |
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@mirabilos @ela does "and al,1" clear the upper bits? |
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Post #Au93JJOyNzt4fDYDmC by [email protected] |
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@ela wild. |
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Post #Au93JLljaLHa0ODQX2 by [email protected] |
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@waldi @ela only seven of them |
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Post #Au93JLtB8fEmNThN8S by [email protected] |
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@mirabilos @waldi To be unfathomably pedantic, that would be all of them for al. |
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Post #Au93JM0yffTYlfLbI8 by [email protected] |
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@ela @waldi yes, but it using only al ipv eax for the return value strikes me a… |
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Post #Au93JM8QDzQl8kpXtY by [email protected] |
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@mirabilos @waldi Well, it's what the spec says. |
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Post #Au93MDdOHmNBe3gHEu by [email protected] |
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@ela It seems rustc is doing the same thing: |
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Post #Au93MDpnXeIWGXUBZw by [email protected] |
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@sergi @ela LLVM ftw |
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Post #Au93N28eVp5YHUgwuO by [email protected] |
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@ela “The computers rebelled but quietly and very performantly so no one noti… |
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Post #Au93NJi1BaTkm6MvtQ by [email protected] |
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@ela I love how the ALT text really explains what's going on even for peopl… |
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Post #Au93NJqAhH07BOBRbM by [email protected] |
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@tante @ela thanks for the hint, wouldn't have looked at it otherwise. |
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Post #Au93ZN8mFkjotPdLoO by [email protected] |
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@viduqIt uses an LLM to explain the code (no I'm joking, we're not ther… |
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Post #Au93bxFMyv53SBwsIi by [email protected] |
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@ela no way... |
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Post #Au93bxQMK3s40H5eQi by [email protected] |
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@plusmid Way! Try for yourself. |
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Post #Au93cUJm1ZDA1PGMFM by [email protected] |
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@ela This is INSANE .. I mean it's insane the C code written could not be w… |
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Post #Au93cURvXFjWQh4rxI by [email protected] |
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@gilesgoat @ela, it's not “i % 2”, as that would give an inverted resul… |
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Post #Au93cUa52wFspytNfE by [email protected] |
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@lp0_on_fire @ela yes but if you want an isODD(x) that returns '1' if i… |
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Post #Au93f6otqUMo0r4VFo by [email protected] |
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@ela I wrote a blog post years ago that shows all the intermediate steps of per… |
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Post #Au93fvkOV049xeM7oO by [email protected] |
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@ela Nice! I wonder how this feat is performed? I suppose the tail-call is elim… |
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Post #Au93fwLyFI7jqBw8Nk by [email protected] |
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@ela ah whelp u answered this while I was typing :'Dhttps://infosec.exchang… |
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Post #Au93oOHqH2Amn82EhE by [email protected] |
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@ela Interestingly clang does not think that "bool isEven(unsigned int i) … |
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Post #Au93vWWg2SfUN8NKBU by [email protected] |
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@ljrk @ela the truly amazing thing about compiler explorer with clang is, that … |
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Post #Au93yjanujDBlYpvkG by [email protected] |
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@ela @naoEhAlexa |
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Post #Au940itrSaXYCHhO1g by [email protected] |
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@ela phew, at least the Go compiler is calmingly unoptimized 😅 |
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Post #Au9418FLDrZoo8wOTg by [email protected] |
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@porglezomp @ela very cool. I have no idea about compiler internals but were ab… |
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Post #Au941WKpf6EHW7h7Mu by [email protected] |
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@plusmid There's more than one go with llvm backend project. :) |
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Post #Au943qBwo2gVgGe3Vo by [email protected] |
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@viduq @ela Check out how examples like this are also reduced to simple polyno… |
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Post #Au944H30xMa8yNfnpw by [email protected] |
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@gilesgoat No, that's purely by analysis. |
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Post #Au947DUGeOWUnbp8aG by [email protected] |
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@ela holly shit... |
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Post #Au948CctKwfOQ1KNzk by [email protected] |
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@[email protected] so from now on write your isEven function recursive? Got … |
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Post #Au94BCvQgK0sDNQoiG by [email protected] |
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@lbehm @ela Wow, I didn't even know that! I knew that clang has this featur… |
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Post #Au94BGaJ4nUfZ1a0LQ by [email protected] |
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@mirabilos @ela Ah, because _Bool is defined as 8bit value where only bit 0 mat… |
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Post #Au94BGgKiOJXriOojo by [email protected] |
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@waldi @ela except for actual storage (where one bit would be better in structs… |
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Post #Au94MlUcV5b4brP1yC by [email protected] |
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@ela But then it is not fair to call the source code "very inefficient&quo… |
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Post #Au94Qdmf6WdHrJgpPc by [email protected] |
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@loke The problem here is that the compiler can't tell if something is just… |
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Post #Au94RATfYA33Fy3ctE by [email protected] |
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@ela A sane implementation of the function would result in more machine code, I… |
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Post #Au94RTzuyU8LnUI9IG by [email protected] |
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@ela @viduq Black magic, but as a beauty. |
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Post #Au94S0xaQAsQ1oSFk0 by [email protected] |
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@ela It's insane ( in a good way for the compiler ). |
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Post #Au94TEogOAudICsDPk by [email protected] |
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@ela there certainly is. I think TinyGo uses the LLVM under the hood. Would be … |
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Post #Au94Vkp6MLwL8gGkj2 by [email protected] |
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@elaWow |
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Post #Au94WeZR5mgQ2JN25A by [email protected] |
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@ela @viduq compiler design is so beautiful ♥️ |
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Post #Au94YHxM8spUTkL3tA by [email protected] |
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@ela Or maybe a raw bitshift to take the last digit and check if its 0,2,4,6 or… |
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Post #Au94aqGHZDqjSCPPKC by [email protected] |
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@Ehay2k @viduq alt text is right here: https://archive.org/details/advancedcomp… |
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Post #Au94azzzMel3eYrXJg by [email protected] |
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@loke @ela In general, this would be at least as hard as the halting problem. P… |
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Post #Au94exGnS6mGLdbv1s by [email protected] |
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@ela Love it! |
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Post #Au94hWXdHhigJti6qW by [email protected] |
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@waldi @mirabilos Indeed. |
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Post #Au94siphvQXZcvVLN2 by [email protected] |
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@ela This is the “give them something better than they would choose to give t… |
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Post #Au94wjQTf7JIcmcD7A by [email protected] |
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@ela This is nice. I knew that C and C++ compiler pipelines and toolchains are … |
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Post #Au9IpFoyjTjY8cP7Q0 by [email protected] |
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@ela @waldi I admit only vague familiarity with the psABI for amd64 (normally p… |
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Post #Au9JObPaS3s3EdNnAO by [email protected] |
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@ela @loke There's a lot of examples of this. Like mergesort vs quicksort (… |
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Post #Au9Lr3wi9ga1kVZi40 by [email protected] |
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@ela @viduq 🤩 |
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Post #AuB6KsqGnH7n32gCm0 by [email protected] |
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@ela i have no idea what i'm saying but i did checked what this means.you p… |
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Post #AuB6kVbfnybYVv4U88 by [email protected] |
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@ela i have no idea what i'm saying but i did some research on it...We put … |
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Post #AuB8D80OjUV1fTqYds by [email protected] |
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@ela perhaps `AND` works this way when we compare digits:if 2 digits are equals… |
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Post #AuBN1DOyLGcQF47Q3s by [email protected] |
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@porglezomp @ela you start with the tail recursion optimization but here isEven… |
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Post #AuBN1DXpoJhwgYGUsK by [email protected] |
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@nrab @porglezomp LLVM extends that basic algorithm a tad bit by trying to move… |
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Post #AuUePfu5Pl8ioT9xmi by [email protected] |
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@elaIt would be cool if the compiler could create a logfile where it explains a… |
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Post #AuUePsx2u4EPHPe0hc by [email protected] |
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@jaj It can! At least in the specific case of llvm/clang. |
