<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>You're right well, it's just like fputc(stdout, x).</div><div id="AppleMailSignature">Last thing. Are 4 calls to fputc as fast as a call to fputs with a 4-char string? Or fputs may be faster?</div><div id="AppleMailSignature">If they're completely equivalent maybe implementing a string printer in the compiler's language is better</div><div id="AppleMailSignature"><br></div><div><br>On Mar 19, 2016, at 11:51 PM, Bruce Hoult <<a href="mailto:bruce@hoult.org">bruce@hoult.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">Yes, you shouldn't have any trouble just declaring and using C functions such as fopen, fclose, puts, fputs, fputc.<div><br></div><div>You're likely to find that putc is a macro not a function, in which case you won't be able to use that.</div><div><br></div><div>Depending on whether it's important, if you're running on a Unix-like system then you could save quite a bit of size in your binary by using open(2), close(2), read(2), write(2) directly, as they're not any harder to use. But the C standard library is available in more places.</div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Mar 20, 2016 at 1:15 AM, Lorenzo Laneve via llvm-dev <span dir="ltr"><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div>@james</div><div>Yeah for code generation I figured out that clang doesn't actually use llc, and I already started reading its code to see how it works.</div><div>For the ld, there's not an "helper" in the llvm library that calls it, is there?</div><div>By the way, I thought about calling ld with things like execl() or std::system(), I don't know if it's a good idea, I'm always afraid there are better ways than mine!</div><div><br></div><div><br></div><div>@mats</div><div>Yea, I haven't used C's system calls in my own code yet but if I just have to declare the function puts in the IR modules (e.g.: putc) and then link against libc, am I right?</div><div>Should I use basic C functions such as putc() and getc(), in my runtime library or is there a more efficient way to set up my runtime library?</div><div><div class="h5"><div><br>On Mar 19, 2016, at 9:58 PM, mats petersson <<a href="mailto:mats@planetcatfish.com" target="_blank">mats@planetcatfish.com</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr"><div><div><div>If you plan on calling C runtime library functions, you probably want to do what I did:<br></div>Cheat, and make a libruntime.a (with C functions to do stuff your compiler can't do natively) and then link that using clang or gcc. <br><br><a href="https://github.com/Leporacanthicus/lacsap/blob/master/binary.cpp#L124" target="_blank">https://github.com/Leporacanthicus/lacsap/blob/master/binary.cpp#L124</a><br><br></div>At some point, I plan to replace my runtime library with native Pascal code, at which point I will be able to generate the ELF binary straight from my compiler without the runtime library linking in the C runtime library, but that's not happening anytime real soon. Getting the compiler to compile v5 of Wirth's original Pascal compiler is higher on the list... :)<br><br>--<br></div>Mats<br></div><div class="gmail_extra"><br><div class="gmail_quote">On 19 March 2016 at 20:51, James Molloy via llvm-dev <span dir="ltr"><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">Hi Lorenzo,<div><br></div><div>Clang doesn't call llc; LLVM is compiled into Clang. Clang does call the system linker though.</div><div><br></div><div>Making your compiler generate *object* code is very simple. Making it fixup that object code and execute it in memory (JIT style) is also simple. Linking it properly and creating a fixed up ELF file is less simple. For that, you need to compile to object (using addPassesToEmitFile() - see llc.cpp) then invoke a linker. Getting that command line right can be quite difficult.</div><div><br></div><div>Rafael, This would be a good usecase for LLD as a library. I heard that this is is an explicit non-goal, which really surprised me. Is that indeed the case?</div><div><br></div><div>Cheers,</div><div><br></div><div>James</div><div><div><br><div class="gmail_quote"><div dir="ltr">On Sat, 19 Mar 2016 at 13:32 Lorenzo Laneve via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="auto"><div><div><span style="background-color:rgba(255,255,255,0)">I'd like to make my compiler independent, just like Clang. Doesn't Clang call llc and then system's ld by itself? I don't want my compiler to depend by any other program.</span></div><div><span style="background-color:rgba(255,255,255,0)">I guess there will be a class in the llvm library that generates the object files based on the system's triple and data layout, and then call the system's ld?</span></div></div></div><div dir="auto"><div><br></div><div>On Mar 19, 2016, at 11:48 AM, Bruce Hoult <<a href="mailto:bruce@hoult.org" target="_blank">bruce@hoult.org</a>> wrote:<br><br></div><blockquote type="cite"><div><div dir="ltr">If you've created a .bc or a .ll file then the simplest thing is to just give it to clang exactly the same as you would for a .c file. Clang will just Do The Right Thing with it.<div><br></div><div>If you don't want to link, then pass flags such as -c to clang as usual.<br><div><br></div><div>e.g.</div><div><br></div><div>---- hello.ll ----</div><div><div>declare i32 @puts(i8*)</div><div>@str = constant [12 x i8] c"Hello World\00"</div><div><br></div><div>define i32 @main() {</div><div> %1 = call i32 @puts(i8* getelementptr inbounds ([12 x i8]* @str, i64 0, i64 0))</div><div> ret i32 0</div><div>}</div></div><div>----------------</div><div><br></div><div>$ clang hello.ll -o hello && ./hello<br></div><div>warning: overriding the module target triple with x86_64-apple-macosx10.10.0</div><div>1 warning generated.</div><div>Hello World</div><div><br></div></div></div><div class="gmail_extra"><br><div class="gmail_quote">On Sat, Mar 19, 2016 at 3:03 AM, Lorenzo Laneve via llvm-dev <span dir="ltr"><<a href="mailto:llvm-dev@lists.llvm.org" target="_blank">llvm-dev@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">I wrote my compiler and now it generates LLVM IR modules. Now i’d like to go ahead and make object file and then executable, just like clang does.<br>
<br>
What should I have to use to create the object files? and then how do I call the ld? (not llvm-ld, I want my compiler to work like Clang and I read that Clang doesn’t use llvm-ld).<br>
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