llvm dev - Aug 2016 - Issue with HelloWorld pass

Dear all,
I'm new to the LLVM world and I'm trying to run reproduce the hello
world example described here
http://llvm.org/releases/3.8.1/docs/WritingAnLLVMPass.html.

I started with a fresh new llvm-3.8.1 installation based on cmake
(running on Linux x86) using the following command:

cmake -DCMAKE_INSTALL_PREFIX=/path/to/llvm
-DLLVM_TARGETS_TO_BUILD="X86" ../

The build directory was inside the top directory of the llvm-3.8.1 source.

I copied and pasted the pass example reported at the end of the "Basic
code required" section and I managed to compile everything correctly
with CMake.
Because there is already a Hello example (with the correspondent
LLVMHello.so file), I decided to call it NewHello.

When I try to test the pass with the following string

opt -load /path/to/llvm-3.8.1.src/build/lib/LLVMNewHello.so -hello <
new_hello.bc > /dev/null

I get the following error:
Expected no forward declarations!
!0 = <temporary!> !{}
incorrect number of operands in llvm.ident metadata
!0 = <temporary!> !{}
opt: -: error: input module is broken!

I've also tried with the LLVMHello.so file but I got the same error message.

Do you have any suggestions?

> On Aug 2, 2016, at 6:12 PM, Alessandro Fanfarillo via llvm-dev <llvm-dev
at lists.llvm.org> wrote:
> 
> Dear all,
> I'm new to the LLVM world and I'm trying to run reproduce the hello
> world example described here
> http://llvm.org/releases/3.8.1/docs/WritingAnLLVMPass.html.
> 
> I started with a fresh new llvm-3.8.1 installation based on cmake
> (running on Linux x86) using the following command:
> 
> cmake -DCMAKE_INSTALL_PREFIX=/path/to/llvm
-DLLVM_TARGETS_TO_BUILD="X86" ../
> 
> The build directory was inside the top directory of the llvm-3.8.1 source.
> 
> I copied and pasted the pass example reported at the end of the "Basic
> code required" section and I managed to compile everything correctly
> with CMake.
> Because there is already a Hello example (with the correspondent
> LLVMHello.so file), I decided to call it NewHello.
> 
> When I try to test the pass with the following string
> 
> opt -load /path/to/llvm-3.8.1.src/build/lib/LLVMNewHello.so -hello <
> new_hello.bc > /dev/null
Is “opt” here the same version as LLVMNewHello.so?
> 
> I get the following error:
> Expected no forward declarations!
> !0 = <temporary!> !{}
> incorrect number of operands in llvm.ident metadata
> !0 = <temporary!> !{}
> opt: -: error: input module is broken!
> 
> I've also tried with the LLVMHello.so file but I got the same error
message.
> 
> Do you have any suggestions?
Does round-tripping without loading your own pass work?
Something like: opt < new_hello.bc > /dev/null

How did you generate the new_hello.bc file?
Did you use clang? If so, did you use the same version of clang as your opt and
your pass?

— 
Mehdi

Hi,

Why don't you use https://github.com/sampsyo/llvm-pass-skeleton ?

If cmake doesn't pick up the path automatically, just export

If you have problems in setting up LLVM, you can use docker as a 
development container.

https://github.com/d11wtq/llvm-docker/blob/master/Dockerfile

I faced some problem initially, I use docker container and it works.

On 8/3/2016 03:12, Alessandro Fanfarillo via llvm-dev
wrote:
> Dear all,
> I'm new to the LLVM world and I'm trying to run reproduce the hello
> world example described here
> http://llvm.org/releases/3.8.1/docs/WritingAnLLVMPass.html.
>
> I started with a fresh new llvm-3.8.1 installation based on cmake
> (running on Linux x86) using the following command:
>
> cmake -DCMAKE_INSTALL_PREFIX=/path/to/llvm
-DLLVM_TARGETS_TO_BUILD="X86" ../
>
> The build directory was inside the top directory of the llvm-3.8.1 source.
>
> I copied and pasted the pass example reported at the end of the "Basic
> code required" section and I managed to compile everything correctly
> with CMake.
> Because there is already a Hello example (with the correspondent
> LLVMHello.so file), I decided to call it NewHello.
>
> When I try to test the pass with the following string
>
> opt -load /path/to/llvm-3.8.1.src/build/lib/LLVMNewHello.so -hello <
> new_hello.bc > /dev/null
>
> I get the following error:
> Expected no forward declarations!
> !0 = <temporary!> !{}
> incorrect number of operands in llvm.ident metadata
> !0 = <temporary!> !{}
> opt: -: error: input module is broken!
>
> I've also tried with the LLVMHello.so file but I got the same error
message.
>
> Do you have any suggestions?
> _______________________________________________
> LLVM Developers mailing list
> llvm-dev at lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-dev
-- 
Warm Regards,
Asit Dhal
http://asit-dhal.github.io/

2016-08-02 19:18 GMT-06:00 Mehdi Amini <mehdi.amini at
apple.com>:
>
> Is “opt” here the same version as LLVMNewHello.so?
Yes, it is.
>
> Does round-tripping without loading your own pass work?
> Something like: opt < new_hello.bc > /dev/null
>
Apparently, even without the pass, I still get the same error.
> How did you generate the new_hello.bc file?
With this command: clang -O3 -emit-llvm testHello.c -c -o new_hello.bc
> Did you use clang? If so, did you use the same version of clang as your opt
and your pass?
>
Here is the problem, thanks for asking this. Even though I installed
clang 3.8.1 with LLVM and I put the /llvm/bin path in my $PATH env
var, my system was using a different version of clang (installed in
/usr/local/bin).
Apparently, the llvm/bin patch doesn't get added to the $PATH
(https://github.com/Homebrew/legacy-homebrew/issues/29733).
Thanks for the support (thanks to Asit as well).
> —
> Mehdi
>