tree 4dd620f6bfe8c96a8a60047aea51cad98de95a59
parent dd25c096870860a544d7752f0fae98c24e564635
author Sean Fertile <sfertile@ca.ibm.com> 1548277443 +0000
committer Sean Fertile <sfertile@ca.ibm.com> 1548277443 +0000

[PPC64] Sort .toc sections accessed with small code model relocs close to .got.

Small code model global variable access on PPC64 has a very limited range of
addressing. The instructions the relocations are used on add an offset in the
range [-0x8000, 0x7FFC] to the toc pointer which points to .got +0x8000, giving
an addressable range of [.got, .got + 0xFFFC]. While user code can be recompiled
with medium and large code models when the binary grows too large for small code
model, there are small code model relocations in the crt files and libgcc.a
which are typically shipped with the distros, and the ABI dictates that linkers
must allow linking of relocatable object files using different code models.

To minimze the chance of relocation overflow, any file that contains a small
code model relocation should have its .toc section placed closer to the .got
then any .toc from a file without small code model relocations.

Differential Revision: https://reviews.llvm.org/D56920

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@351978 91177308-0d34-0410-b5e6-96231b3b80d8