Some patches are mandatory for Windows or other strictly linked platforms (AIX), some are recommended to produce smaller and faster code.
You need to run
perlall build --allpatches or
perlall build --patches=Compiler to apply these.
This list is complete for all perl versions 5.6 - 5.17.8, for all three threaded, non-threaded and multiplicity variants.
5.13.7-now: RT#81332 revert 744aaba0 bloats the B compilers 5.10-5.15.1: 8375c93e Export store_cop_label for the perl compiler 5.15.2-3: 4497a11a Export DynaLoader symbols from libperl again
Apply patches in Devel::PatchPerl::Plugin::Compiler depending on the perl version. See Devel::PatchPerl::Plugin
Every patch is recorded in patchlevel.h, visible in myconfig. If a patch fails the script dies.