tree fe060b79e39c3117ad213ceed2b26977eb7c1d2a
parent bf9f44747948b86dc9da0da3fa5ea02a4f658e66
author Sean Fertile <sfertile@ca.ibm.com> 1542218203 +0000
committer Sean Fertile <sfertile@ca.ibm.com> 1542218203 +0000

[PPC64] Long branch thunks.

On PowerPC64, when a function call offset is too large to encode in a call
instruction the address is stored in a table in the data segment. A thunk is
used to load the branch target address from the table relative to the
TOC-pointer and indirectly branch to the callee. When linking position-dependent
code the addresses are stored directly in the table, for position-independent
code the table is allocated and filled in at load time by the dynamic linker.

For position-independent code the branch targets could have gone in the .got.plt
but using the .branch_lt section for both position dependent and position
independent binaries keeps it consitent and helps keep this PPC64 specific logic
seperated from the target-independent code handling the .got.plt.

Differential Revision: https://reviews.llvm.org/D53408

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@346877 91177308-0d34-0410-b5e6-96231b3b80d8