Use maximum compression when packaging release tarballs.

[dim]

Summary

Since a full run of test-release.sh takes many hours (at least on my
poor systems), we might as well spend some extra time compressing the
tarball, in return for a quite a bit of gains for uploading and
downloading it.

As an example, the 10.0.0-rc4 .tar.xz tarball shrinks from 465MiB to
306MiB, about 52% smaller.

[hans]

This seems reasonable, but can we wait until after the release? I would prefer to not change these things right now.

Also, can you make the same change to llvm/utils/release/export.sh?

[dim]

In D76192#1923936, @hans wrote:

This seems reasonable, but can we wait until after the release? I would prefer to not change these things right now.

Of course, there is no hurry. I just accumulated a few of these small changes during earlier release cycles, and kept forgetting about submitting them. So I'll commit this after the release is shipped.

Also, can you make the same change to llvm/utils/release/export.sh?

Sure.

llvm/utils/release/test-release.sh

 }
 
 # Create a package of the release binaries.
 function package_release() {
     cwd=`pwd`
     cd $BuildDir/Phase3/Release
     mv llvmCore-$Release-$RC.install/usr/local $Package
     if [ "$use_gzip" = "yes" ]; then
-      tar cfz $BuildDir/$Package.tar.gz $Package
+      tar cf - $Package | gzip -9c > $BuildDir/$Package.tar.gz
     else
-      tar cfJ $BuildDir/$Package.tar.xz $Package
+      tar cf - $Package | xz -9ce > $BuildDir/$Package.tar.xz
     fi
     mv $Package llvmCore-$Release-$RC.install/usr/local
     cd $cwd
 }
 
 # Exit if any command fails
 # Note: pipefail is necessary for running build commands through
 # a pipe (i.e. it changes the output of ``false | tee /dev/null ; echo $?``)