Stop emitting duplicate symbols for armv7-linux-androideabi

[dcsommer]

The change in 186517b was intended to
affect only arm-linux-androideabi but also affected
armv7-linux-androideabi which is not a pre-ARMv6 architecture.
Fixes #449

[dcsommer]

To test, I did the following:
Downloaded the NDK used by rust-lang/rust as the docker scripts for rust-lang/rust do. Then I ran python3 android-ndk-r15c/build/tools/make_standalone_toolchain.py --install-dir /path/to/android-ndk-r15c-arm-14 --arch arm --api 14 as the docker scripts do too.

With HEAD at rust-lang/rust@6abb638 I set my config.toml to:

profile = "library"
changelog-seen = 2

[build]
target = ["armv7-linux-androideabi"]
docs = false
extended = true

[target.armv7-linux-androideabi]
android-ndk = "/path/to/android-ndk-r15c-arm-14"

Then I built the distribution artifacts:

./x.py dist --host='' --target=armv7-linux-androideabi

Then I looked at the contents of build/x86_64-unknown-linux-gnu/stage2/lib/rustlib/armv7-linux-androideabi/lib/libcompiler_builtins-3d9661a82c59c66a.rlib

Summary of changes in dist libcompiler_builtins-XXXXX.rlib before and after this change:

301,337d300
< 00000000 T __sync_fetch_and_add_1
< 00000000 T __sync_fetch_and_add_2
< 00000000 T __sync_fetch_and_add_4
< 00000000 T __sync_fetch_and_and_1
< 00000000 T __sync_fetch_and_and_2
< 00000000 T __sync_fetch_and_and_4
< 00000000 T __sync_fetch_and_max_1
< 00000000 T __sync_fetch_and_max_2
< 00000000 T __sync_fetch_and_max_4
< 00000000 T __sync_fetch_and_min_1
< 00000000 T __sync_fetch_and_min_2
< 00000000 T __sync_fetch_and_min_4
< 00000000 T __sync_fetch_and_nand_1
< 00000000 T __sync_fetch_and_nand_2
< 00000000 T __sync_fetch_and_nand_4
< 00000000 T __sync_fetch_and_or_1
< 00000000 T __sync_fetch_and_or_2
< 00000000 T __sync_fetch_and_or_4
< 00000000 T __sync_fetch_and_sub_1
< 00000000 T __sync_fetch_and_sub_2
< 00000000 T __sync_fetch_and_sub_4
< 00000000 T __sync_fetch_and_umax_1
< 00000000 T __sync_fetch_and_umax_2
< 00000000 T __sync_fetch_and_umax_4
< 00000000 T __sync_fetch_and_umin_1
< 00000000 T __sync_fetch_and_umin_2
< 00000000 T __sync_fetch_and_umin_4
< 00000000 T __sync_fetch_and_xor_1
< 00000000 T __sync_fetch_and_xor_2
< 00000000 T __sync_fetch_and_xor_4
< 00000000 T __sync_lock_test_and_set_1
< 00000000 T __sync_lock_test_and_set_2
< 00000000 T __sync_lock_test_and_set_4
< 00000000 T __sync_synchronize
< 00000000 T __sync_val_compare_and_swap_1
< 00000000 T __sync_val_compare_and_swap_2
< 00000000 T __sync_val_compare_and_swap_4
359c322
< 00000000 T _ZN17compiler_builtins3int3mul5UMulo4mulo17h6ebe8a25f3a18c0dE.llvm.698921072623391490
---
> 00000000 T _ZN17compiler_builtins3int3mul5UMulo4mulo17h6ebe8a25f3a18c0dE.llvm.9884457542086207240
400,402c363,365
< 00000000 T _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.10435582529288110963
< 00000000 T _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.10435582529288110963
< 00000000 T _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.10435582529288110963
---
> 00000000 T _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.13684769725188279451
> 00000000 T _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.13684769725188279451
> 00000000 T _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.13684769725188279451
1030c993
<          U _ZN17compiler_builtins3int3mul5UMulo4mulo17h6ebe8a25f3a18c0dE.llvm.698921072623391490
---
>          U _ZN17compiler_builtins3int3mul5UMulo4mulo17h6ebe8a25f3a18c0dE.llvm.9884457542086207240
1054,1060c1017,1023
<          U _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.10435582529288110963
<          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.10435582529288110963
---
>          U _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub6AddSub3add17hced610ae232a945dE.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub6AddSub3add17hde9f87aeaaf8b5c1E.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.13684769725188279451
>          U _ZN17compiler_builtins3int6addsub7UAddSub4usub17ha046c9d21f420f34E.llvm.13684769725188279451

The only significant changes seem to be the __sync_* family functions getting removed (whose _4 suffixed variants are already defined) as we want. I'm not sure why the name mangling of some other functions change, but I guess that's okay?

[Amanieu]

The stuff after a . in the symbol name is specific to LLVM internals, it's normal for it to vary with minor changes in codegen.