[llvm-dev] Need help with code generation

[Rui Ueyama via llvm-dev]

On Mon, Mar 21, 2016 at 8:04 PM, James Molloy <james at jamesmolloy.co.uk>
wrote:

> > A corrupted file could cause a fatal error or SEGV.
>
> Uhhh, that's not particularly useful.
>

"Corrupted" means really corrupted, like ELF header is broken. Is this
really the case?


> On Mon, 21 Mar 2016 at 19:02 Rui Ueyama <ruiu at google.com> wrote:
>
>> On Sat, Mar 19, 2016 at 9:51 PM, James Molloy via llvm-dev <
>> llvm-dev at lists.llvm.org> wrote:
>>
>>> Hi Lorenzo,
>>>
>>> Clang doesn't call llc; LLVM is compiled into Clang. Clang does call the
>>> system linker though.
>>>
>>> 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.
>>>
>>> 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?
>>>
>>
>> You can use LLD as a library.
>>
>> https://github.com/llvm-mirror/lld/blob/master/docs/NewLLD.rst#the-elf-linker-as-a-library
>>
>>
>>> Cheers,
>>>
>>> James
>>>
>>> On Sat, 19 Mar 2016 at 13:32 Lorenzo Laneve via llvm-dev <
>>> llvm-dev at lists.llvm.org> wrote:
>>>
>>>> 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.
>>>> 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?
>>>>
>>>> On Mar 19, 2016, at 11:48 AM, Bruce Hoult <bruce at hoult.org> wrote:
>>>>
>>>> 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.
>>>>
>>>> If you don't want to link, then pass flags such as -c to clang as usual.
>>>>
>>>> e.g.
>>>>
>>>> ---- hello.ll ----
>>>> declare i32 @puts(i8*)
>>>> @str = constant [12 x i8] c"Hello World\00"
>>>>
>>>> define i32 @main() {
>>>>   %1 = call i32 @puts(i8* getelementptr inbounds ([12 x i8]* @str, i64
>>>> 0, i64 0))
>>>>   ret i32 0
>>>> }
>>>> ----------------
>>>>
>>>> $ clang hello.ll -o hello && ./hello
>>>> warning: overriding the module target triple with
>>>> x86_64-apple-macosx10.10.0
>>>> 1 warning generated.
>>>> Hello World
>>>>
>>>>
>>>> On Sat, Mar 19, 2016 at 3:03 AM, Lorenzo Laneve via llvm-dev <
>>>> llvm-dev at lists.llvm.org> wrote:
>>>>
>>>>> 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.
>>>>>
>>>>> 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).
>>>>> _______________________________________________
>>>>> LLVM Developers mailing list
>>>>> llvm-dev at lists.llvm.org
>>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>>
>>>>
>>>> _______________________________________________
>>>> LLVM Developers mailing list
>>>> llvm-dev at lists.llvm.org
>>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>>
>>>
>>> _______________________________________________
>>> LLVM Developers mailing list
>>> llvm-dev at lists.llvm.org
>>> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160321/a1b4d4cd/attachment.html>