Figured out I can use --target thumbv6m-linux-eabi, which implies -mthumb. Now the problem is that if I use
rustc --target thumbv6m-linux-eabi -O --emit obj main.rs -o main.o instead of three-step process I mentioned before, I get a valid object file for cortex-m0, but functions have big prologues and symbol table is much bigger: U STACK_LIMIT U _GLOBAL_OFFSET_TABLE_ 00000000 D _ZN20_rust_crate_map_main16ad67637f924a5c794v0.0E 00000008 r _ZN2hw11GPIO_PIN_NO20hb0b70c1482b61788Gaa4v0.0E 00000000 r _ZN2hw12GPIO_DIR_REG20hb0b70c1482b61788yaa4v0.0E 00000004 r _ZN2hw12GPIO_REG_VAL20hb0b70c1482b61788Caa4v0.0E 00000078 t _ZN4main10__rust_abiE 00000000 t _ZN4wait20h53ffb23463e08f19Maa4v0.0E U __aeabi_unwind_cpp_pr0 U __morestack 0000004c T main vs. 00000000 D _ZN23_rust_crate_map_main.c016ad67637f924a5c794v0.0E 00000000 T main in the initial version. Also, I now need to provide __morestack (no idea what's that about). On Sun, Mar 23, 2014 at 5:17 PM, Alex Crichton <a...@crichton.co> wrote: > You should be able to assemble standalone objects for any triple > through rustc itself, you'll likely have to specify a different linker > or assembler though: > > rustc foo.rs --target arm-non-linux-gnueabi \ > -C linker=arm-non-linux-gnueabi-ld \ > -C ar=arm-non-linux-gnueabi-ar > > As you discovered, you can pass through arguments to LLVM via the "-C > llvm-args=foo" command line option to rustc. If you get complaints > that it's an unknown command line argument, it's LLVM telling you > those complaints, not rustc. > > On Sun, Mar 23, 2014 at 8:54 AM, Vladimir Pouzanov <farcal...@gmail.com> > wrote: > > I'm trying to experiment with rust and some embedded code. Currently I > have > > to do a three-pass compilation: > > > > rustc --target arm-linux-eabi -O --emit bc main.rs -o main.bc > > llc -mtriple arm-none-eabi -march=thumb -mcpu=cortex-m0 main.bc -o main.s > > arm-none-linux-gnueabi-as main.s -o main.o > > > > First, I'm not sure how relevant is --target flag for rustc. I seems to > > change target datalayout/triple in generated bc, but that should be > > overriden by llc -mtriple anyway, right? > > > > Second, I can pass -Ctarget-cpu=cortex-m0, but I cannot pass down > > -march=thumb, tried this way: -Cllvm-args='--march=thumb', failed with > > "rustc: Unknown command line argument '--march=thumb'". > > > > Any hints on how can I drop explicit llc and as steps here? > > > > -- > > Sincerely, > > Vladimir "Farcaller" Pouzanov > > http://farcaller.net/ > > > > _______________________________________________ > > Rust-dev mailing list > > Rust-dev@mozilla.org > > https://mail.mozilla.org/listinfo/rust-dev > > > -- Sincerely, Vladimir "Farcaller" Pouzanov http://farcaller.net/
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