This PR allows mixing `-basic-block-sections` with `-enable-machine-function-splitter`. The strategy is to let `-basic-block-sections` take precedence over functions with profiles.
D33412/D33413 introduced this to support a clang pragma to set section names for a symbol depending on if it would be placed in bss/data/rodata/text, which may not be known until the backend. However, for text we know that only functions will go there, so just directly set the section in clang instead of going through a completely separate attribute. Autoupgrade the "implicit-section-name" attribute to directly setting the section on a Fuction.
c9f3288 introduced unconditional branch deduplication for basic block sections and machine function splitting, but it didn't add tests for AArch64 since prior behavior crashed the test. This change adds tests for AArch64 and has no functional change.
There are some workloads that are negatively impacted by using jump tables when the number of entries is small. The SPEC2017 perlbench benchmark is one example of this, where increasing the threshold to around 13 gives a ~1.5% improvement on neoverse-v1. I chose the minimum threshold based on empirical evidence rather than science, and just manually increased the threshold until I got the best performance without impacting other workloads. For neoverse-v1 I saw around ~0.2% improvement in the SPEC2017 integer geomean, and no overall change for neoverse-n1. If we find issues with this threshold later on we can always revisit this. The most significant SPEC2017 score changes on neoverse-v1 were: 500.perlbench_r: +1.6% 520.omnetpp_r: +0.6% and the rest saw changes < 0.5%. I updated CodeGen/AArch64/min-jump-table.ll to reflect the new threshold. For most of the affected tests I manually set the min number of entries back to 4 on the RUN line because the tests seem to rely upon this behaviour.
Machine function splitting + branch relaxation currently don't properly handle inline asm goto blocks that conditional branch to cold goto labels. While such inline asm is technically invalid, machine function splitting is the only thing that exposes it as such. Since machine function splitting doesn't help too much in these circumstances anyway, disable it for asm goto blocks and their targets. Differential Revision: https://reviews.llvm.org/D158647
Jump tables on AArch64 are label-relative rather than table-relative, so having jump table destinations that are in different sections causes problems with relocation. Jump table lookups have a max range of 1MB, so all destinations must be in the same section as the lookup code. Both of these restrictions can be mitigated with some careful and complex logic, but doing so doesn't gain a huge performance benefit. Efficiently ensuring jump tables are correct and can be compressed on AArch64 is a TODO item. In the meantime, don't split blocks that can cause problems. Differential Revision: https://reviews.llvm.org/D157124
The option was added in github.com/llvm/llvm-project/commit/90ab85a but it doesn't seem to be used. The triple check has been removed so this shouldn't be required going forward. Reviewed By: MaskRay Differential Revision: https://reviews.llvm.org/D158885
Because unconditional branch relaxation on AArch64 grows the stack to spill a register, splitting a function would cause the red zone to be overwritten. Explicitly disable MFS for such functions. Differential Revision: https://reviews.llvm.org/D157127
Reverted in 4c8d056f50342d5401f5930ed60e5e48b211c3fb because it broke buildbot `llvm-clang-x86_64-expensive-checks-debian` due to the AArch64 test generating invalid code. The issue still exists, but it's fixed in D156767, so the AArch64 test should be added there. Differential Revision: https://reviews.llvm.org/D158674
This reverts commit 994eb5adc40cd001d82d0f95d18d1827b57e496c. Breaks buildbot `llvm-clang-x86_64-expensive-checks-debian` https://lab.llvm.org/buildbot/#/builders/16/builds/53620