This commit fixes an issue in the large code model where non-dso_local
function calls did not use the GOT as expected in PIC mode. Instead,
direct PC-relative access was incorrectly applied, leading to linker
errors when building shared libraries.
For `ExternalSymbol`, it is not possible to determine whether it is
dso_local during pseudo-instruction expansion. We use target flags to
differentiate whether GOT should be used.
Reviewed By: heiher, SixWeining
Pull Request: https://github.com/llvm/llvm-project/pull/117099
Prior to this patch, both `pcaddu18i` and `jirl` were marked as
scheduling boundaries to prevent instruction reordering that would
disrupt their adjacency. However, in certain cases, epilogues were still
being inserted between these two instructions, breaking the required
proximity. This patch ensures that `pcaddu18i` and `jirl` remain
adjacent even in the presence of epilogues, maintaining correct
relocation behavior for tail calls on LoongArch.
The Pseudo{CALL, LA*}_LARGE instruction patterns specified in psABI
v2.30 cannot be reordered. This patch sets scheduling boundaries for
these instructions to prevent reordering. The Pseudo{CALL, LA*}_LARGE
instruction is moved back to Pre-RA expansion, which will help with
subsequent address calculation optimizations.
Because most of tests assume target-abi=`lp64d`, adding the
corresponding feature is reasonable.
rg -l loongarch -g '!*.s' | xargs sed -i '/mtriple=loongarch/ {/-mattr=/!{/target-abi/! s/mtriple=loongarch.. /&-mattr=+d /}}'
According to the description of the psABI v2.30:
https://github.com/loongson/la-abi-specs/releases/tag/v2.30, moved the
expansion of relevant pseudo-instructions from
`LoongArchPreRAExpandPseudo` pass to `LoongArchExpandPseudo` pass, to
ensure that the code sequences of `PseudoLA*_LARGE` instructions and
Medium code model's function call are not scheduled.
According to the description of the psABI v2.20:
https://github.com/loongson/la-abi-specs/releases/tag/v2.20, adjustments
are made to the function call instructions under the medium code model.
At the same time, AsmParser has already supported parsing the call36 and
tail36 macro instructions.
This is intended to behave like GCC's `-mcmodel=extreme`.
Technically the true GCC equivalent would be `-mcmodel=large` which is
not yet implemented there, and we probably do not want to take the
"Large" name until things settle in GCC side, but:
* LLVM does not have a `CodeModel::Extreme`, and it seems too early to
have such a variant added just for enabling LoongArch; and
* `CodeModel::Small` is already being used for GCC `-mcmodel=normal`
which is already a case of divergent naming.
Regarding the codegen, loads/stores immediately after a PC-relative
large address load (that ends with something like `add.d $addr, $addr,
$tmp`) should get merged with the addition into corresponding `ldx/stx`
ops, but is currently not done. This is because pseudo-instructions are
expanded after instruction selection, and is best fixed with a separate
change.
Reviewed By: SixWeining
Differential Revision: https://reviews.llvm.org/D150522
