www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.ldc - Asserts in C++ code not working for debug builds?

reply Johan Engelen <j j.nl> writes:
Hi all,
   I just had a PR fail a CI test because of an assert being 
triggered. But... I am on the same platform (Mac), doing the same 
build (Debug), or so I thought.
Indeed, if I change an assert to something bad (i.e. remove a 
"!"), nothing happens.

What's wrong with my setup? I am compiling LDC in debug mode, but 
I am using a release-mode LLVM (speed...). This means llvm-config 
will return "-DNDEBUG" as one of the --cxxflags, and all my 
asserts are disabled. (It also sets "-O3" for the LDC build)

Advice?

-Johan
Jul 08 2016
next sibling parent Johan Engelen <j j.nl> writes:
On Friday, 8 July 2016 at 20:10:37 UTC, Johan Engelen wrote:

 Hi all,
   I just had a PR fail a CI test because of an assert being 
 triggered.


Btw, asserts are apparently disabled for all our Linux CI builds.
Mac and Windows CI systems do build with asserts; Windows also 
for release builds (!)
Jul 08 2016
prev sibling parent reply David Nadlinger via digitalmars-d-ldc <digitalmars-d-ldc puremagic.com> writes:
On 8 Jul 2016, at 21:10, Johan Engelen via digitalmars-d-ldc wrote:

 What's wrong with my setup? I am compiling LDC in debug mode, but I am 
 using a release-mode LLVM (speed...). This means llvm-config will 
 return "-DNDEBUG" as one of the --cxxflags, and all my asserts are 
 disabled. (It also sets "-O3" for the LDC build)

 Advice?


IIRC, the LLVM ABI changes depending on whether (N)DEBUG is enabled when 
including the headers, which has actually led to hard to debug issues in 
the past.

A Google or Git history search will probably turn up the exact places it 
does. Assuming you want to disable the LLVM assertions for speed and not 
just have an optimised build (which would of course easily be possible), 
you would need to look into whether there is a way (a preprocessor flag 
separate from NDEBUG, etc.) to keep the ABI the same as for debug builds 
while eliding assertions.

  — David
Jul 08 2016
next sibling parent reply Johan Engelen <j j.nl> writes:
On Friday, 8 July 2016 at 20:55:50 UTC, David Nadlinger wrote:

 On 8 Jul 2016, at 21:10, Johan Engelen via digitalmars-d-ldc 
 wrote:

 What's wrong with my setup? I am compiling LDC in debug mode, 
 but I am using a release-mode LLVM (speed...). This means 
 llvm-config will return "-DNDEBUG" as one of the --cxxflags, 
 and all my asserts are disabled. (It also sets "-O3" for the 
 LDC build)

 Advice?


 IIRC, the LLVM ABI changes depending on whether (N)DEBUG is 
 enabled when including the headers, which has actually led to 
 hard to debug issues in the past.


Every now and then, the need to remove NDEBUG dependency in 
headers pops up on the LLVM maillist. I don't think it's solved 
yet.


 A Google or Git history search will probably turn up the exact 
 places it does. Assuming you want to disable the LLVM 
 assertions for speed and not just have an optimised build 
 (which would of course easily be possible)


Yeah, I think this is the solution. I'm going to try with a 
Release build of LLVM with assertions explicitly enabled.

  We have to keep in mind that none of the Linux builds are with 
assertions enabled!
Jul 09 2016
next sibling parent kinke <noone nowhere.com> writes:
On Saturday, 9 July 2016 at 08:28:22 UTC, Johan Engelen wrote:

 On Friday, 8 July 2016 at 20:55:50 UTC, David Nadlinger wrote:

 IIRC, the LLVM ABI changes depending on whether (N)DEBUG is 
 enabled when including the headers, which has actually led to 
 hard to debug issues in the past.


 Every now and then, the need to remove NDEBUG dependency in 
 headers pops up on the LLVM maillist. I don't think it's solved 
 yet.


Nope, e.g., I can't build a debug LDC with a RelWithDebInfo LLVM 
and LLVM assertions explicitly enabled (on Windows, with MSVC). 
So I simply use a RelWithDebInfo LDC, assertions enabled.
Jul 09 2016
prev sibling parent Johan Engelen <j j.nl> writes:
On Saturday, 9 July 2016 at 08:28:22 UTC, Johan Engelen wrote:

 I'm going to try with a Release build of LLVM with assertions 
 explicitly enabled.


This seems to work for me now
-DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=ON
Jul 09 2016
prev sibling parent Kai Nacke <kai redstar.de> writes:
On Friday, 8 July 2016 at 20:55:50 UTC, David Nadlinger wrote:

 IIRC, the LLVM ABI changes depending on whether (N)DEBUG is 
 enabled when including the headers, which has actually led to 
 hard to debug issues in the past.


As long as I am reading the LLVM mailing list this is an issue 
which is discussed every half year. Don't know if they resolved 
it.

Regards,
Kai
Jul 10 2016