Re: Warning: conditional outside an IT block for Thumb.

[Richard Earnshaw <Richard.Earnshaw@foss.arm.com>]

On 25/08/2022 07:40, Mathieu Malaterre via Gcc-help wrote:
> Hi all,
> 
> I am seeing a flood of warnings when compiling openvdb+tbb on Debian/armel:
> 
> [...]
>   [  2%] Building CXX object
> openvdb/openvdb/CMakeFiles/openvdb_shared.dir/io/Archive.cc.o
>   cd /<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb &&
> /usr/bin/c++ -DBOOST_ALL_NO_LIB -DBOOST_IOSTREAMS_DYN_LINK
> -DOPENVDB_DLL -DOPENVDB_PRIVATE -DOPENVDB_USE_LOG4CPLUS
> -Dopenvdb_shared_EXPORTS -I/<<PK
> GBUILDDIR>>/openvdb/openvdb/..
> -I/<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb
> -I/<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb/openvdb
> -I/<<PKGBUILDDIR>>/openvdb/openvdb/. -I/usr/include/Imat
> h -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong
> -Wformat -Werror=format-security -Wno-psabi -fvisibility=hidden
> -fvisibility-inlines-hidden -Wa,-mimplicit-it=thumb -Wdate-time
> -D_FORTIFY
> _SOURCE=2 -fPIC -std=c++17 -MD -MT
> openvdb/openvdb/CMakeFiles/openvdb_shared.dir/Grid.cc.o -MF
> CMakeFiles/openvdb_shared.dir/Grid.cc.o.d -o
> CMakeFiles/openvdb_shared.dir/Grid.cc.o -c /<<PKGBUILDDIR>>/openvdb/o
> penvdb/Grid.cc
>   cd /<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb &&
> /usr/bin/c++ -DBOOST_ALL_NO_LIB -DBOOST_IOSTREAMS_DYN_LINK
> -DOPENVDB_DLL -DOPENVDB_PRIVATE -DOPENVDB_USE_LOG4CPLUS
> -Dopenvdb_shared_EXPORTS -I/<<PK
> GBUILDDIR>>/openvdb/openvdb/..
> -I/<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb
> -I/<<PKGBUILDDIR>>/obj-arm-linux-gnueabi/openvdb/openvdb/openvdb
> -I/<<PKGBUILDDIR>>/openvdb/openvdb/. -I/usr/include/Imat
> h -g -O2 -ffile-prefix-map=/<<PKGBUILDDIR>>=. -fstack-protector-strong
> -Wformat -Werror=format-security -Wno-psabi -fvisibility=hidden
> -fvisibility-inlines-hidden -Wa,-mimplicit-it=thumb -Wdate-time
> -D_FORTIFY
> _SOURCE=2 -fPIC -std=c++17 -MD -MT
> openvdb/openvdb/CMakeFiles/openvdb_shared.dir/io/Archive.cc.o -MF
> CMakeFiles/openvdb_shared.dir/io/Archive.cc.o.d -o
> CMakeFiles/openvdb_shared.dir/io/Archive.cc.o -c /<<PKGBU
> ILDDIR>>/openvdb/openvdb/io/Archive.cc
> /tmp/ccFlliCl.s: Assembler messages:
> /tmp/ccFlliCl.s:294: Warning: conditional outside an IT block for Thumb.
> /tmp/ccFlliCl.s:338: Warning: conditional outside an IT block for Thumb.
> [...]
> 
> There are so many warnings that it eventually times out the compilation.
> 
> I could not find a way to tell gcc not to print a warning. Is there a
> way to remove this warning ?

The warning is coming from the assembler.  But I don't think it should 
be just 'ignored'.  You'll need to track down why it's happening at all. 
  The most likely case is that there is some inlined assembly code 
somewhere that was written on the assumption that the compiler would be 
targeting the A32 state rather than the T32 state (thumb), but there's 
not enough information here to work out what's happened for sure.

What we need is a snippet of the assembler output when compiled with 
debugging information, so that we can track back to the source code that 
is generating this.

> 
> For reference the very large log:
> 
> * https://buildd.debian.org/status/fetch.php?pkg=openvdb&arch=armel&ver=9.1.0-4&stamp=1661358853&raw=0
> 
> Thanks much,

The log isn't much help, it's the contents of the file that's being 
assembled that will tell us what we need to know.

R.