Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld #66957
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src/rustllvm/PassWrapper.cpp
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| @@ -419,6 +420,10 @@ extern "C" LLVMTargetMachineRef LLVMRustCreateTargetMachine( | |||
| Options.MCOptions.PreserveAsmComments = AsmComments; | |||
| Options.MCOptions.ABIName = ABIStr; | |||
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| if (LinkerIsLLD) { | |||
| Options.RelaxELFRelocations = true; | |||
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Testing the effects of this is difficult, but I've filed fortanix/rust-sgx#202 to track possible future improvements.
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Could relaxation of elf relocations be a separate parameter in the target configuration? There are existing targets using LLD and this may run a risk of breaking them if they weren't expecting this to be turned on. |
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From what I understand, the only reason to not use the relaxations is if you're using a linker that doesn't understand them. LLD does, so there is no reason to turn them off then. Code generation might be improved if the option is turned on. I might be wrong since the feature isn't documented that well. |
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If you'd like to pursue this change as-is, then I'd have a similar comment I left on another PR. I do not have the confidence to r+ this change as-is, so you'll need to find a different reviewer. I unfortunately don't know who that different reviewer would be, but you'd likely want to start with the Compiler team. |
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cc @rust-lang/compiler-contributors for possible other reviewer |
For SGX, the relocation using the relocation table is done by the code in rust/src/libstd/sys/sgx/abi/reloc.rs and this code should not require relocation. Setting RelaxELFRelocations flag if allows this to happen, hence adding a Target Option for it.
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LGTM |
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I have added |
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@bors: r+ 👍 |
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📌 Commit 54b2060 has been approved by |
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…xcrichton Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld Changed linker for `x86_64-fortanix-unknown-sgx` target to `rust-lld` This change needed the RelaxELFRelocations flag to be set for it to work correctly r? @jethrogb
…xcrichton Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld Changed linker for `x86_64-fortanix-unknown-sgx` target to `rust-lld` This change needed the RelaxELFRelocations flag to be set for it to work correctly r? @jethrogb
Rollup of 7 pull requests Successful merges: - #66750 (Update the `wasi` crate for `wasm32-wasi`) - #66878 (Move Sessions into (new) librustc_session) - #66903 (parse_enum_item -> parse_enum_variant) - #66951 (miri: add throw_machine_stop macro) - #66957 (Change Linker for x86_64-fortanix-unknown-sgx target to rust-lld) - #66960 ([const-prop] Fix ICE calculating enum discriminant) - #66973 (Update the minimum external LLVM to 7) Failed merges: r? @ghost
Bootstrap: change logic for choosing linker and rpath This is a follow-up from #66957 and #67023. Apparently there was one more location with a hard-coded list of targets to influence linking. I've filed #67171 to track this madness. r? @alexcrichton
Changed linker for
x86_64-fortanix-unknown-sgxtarget torust-lldThis change needed the RelaxELFRelocations flag to be set for it to work correctly
r? @jethrogb