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soft float ABI used instead of hard float for riscv64gc-unknown-none-elf #83229

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DieracDelta opened this issue Mar 17, 2021 · 1 comment
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soft float ABI used instead of hard float for riscv64gc-unknown-none-elf #83229

DieracDelta opened this issue Mar 17, 2021 · 1 comment
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C-bug Category: This is a bug.

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@DieracDelta
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DieracDelta commented Mar 17, 2021 •
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A incorrect ABI is used by llvm on the riscv64gc-unknown-none-elf target. The ABI used should be lp64d. I've included a minimum working example of this here.

Expected behavior:

cargo build --target riscv64gc-unknown-none-elf --lib

would produce a library with double float ABI due to the +d extension. What is produced is a library with a single float ABI. The ABI used can be checked by looking at the ELF header:

readelf -h target/riscv64gc-unknown-none-elf/debug/librust_uland.a

This gives back:

...
Flags:                             0x1, RVC, soft-float ABI
...

I'm expecting:

...
Flags:                             0x1, RVC, double-float ABI
...

Note that the riscv64-unknown-linux-gnu target uses the lp64d ABI as expected. Note that it's actually using the wrong ABI (not just setting bits incorrectly in the header). I'm trying to link to a C library that is compiled with the d extension and this fails during linking due to the differing ABIs in use.
@DieracDelta DieracDelta added the C-bug Category: This is a bug. label Mar 17, 2021
@DieracDelta DieracDelta mentioned this issue Mar 17, 2021
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Dylan-DPC-zz pushed a commit to Dylan-DPC-zz/rust that referenced this issue Mar 17, 2021
@Dylan-DPC
Rollup merge of rust-lang#83231 - DieracDelta:lp64d-abi-for-riscvgc-u…
1839d1d 
…nknown-none-elf, r=estebank

Switch riscvgc-unknown-none-elf use lp64d ABI

Corrects rust-lang#83229 by directly specifying the target abi in the spec in the same way as is done for the `riscv64gc-unknown-linux-gnu` target [here](https://github.com/rust-lang/rust/blob/master/compiler/rustc_target/src/spec/riscv64gc_unknown_linux_gnu.rs).
@JohnTitor
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Fixed by #83231.

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