402 lines
11 KiB
Markdown
402 lines
11 KiB
Markdown
# `compiler-builtins`
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[](https://ci.appveyor.com/project/rust-lang-libs/compiler-builtins)
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[](https://travis-ci.org/rust-lang-nursery/compiler-builtins)
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> [WIP] Porting `compiler-rt` intrinsics to Rust
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See [rust-lang/rust#35437][0].
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[0]: https://github.com/rust-lang/rust/issues/35437
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## When and how to use this crate?
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If you are working with a target that doesn't have binary releases of std
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available via rustup (this probably means you are building the core crate
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yourself) and need compiler-rt intrinsics (i.e. you are probably getting linker
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errors when building an executable: `undefined reference to __aeabi_memcpy`),
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you can use this crate to get those intrinsics and solve the linker errors. To
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do that, add this crate somewhere in the dependency graph of the crate you are
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building:
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``` toml
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# Cargo.toml
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[dependencies]
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compiler_builtins = { git = "https://github.com/rust-lang-nursery/compiler-builtins" }
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```
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``` rust
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extern crate compiler_builtins;
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// ...
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```
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If you still get an "undefined reference to $INTRINSIC" error after that change,
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that means that we haven't ported `$INTRINSIC` to Rust yet! Please open [an
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issue] with the name of the intrinsic and the LLVM triple (e.g.
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thumbv7m-none-eabi) of the target you are using. That way we can prioritize
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porting that particular intrinsic.
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If you've got a C compiler available for your target then while we implement
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this intrinsic you can temporarily enable a fallback to the actual compiler-rt
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implementation as well for unimplemented intrinsics:
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```toml
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[dependencies.compiler_builtins]
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git = "https://github.com/rust-lang-nursery/compiler-builtins"
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features = ["c"]
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```
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[an issue]: https://github.com/rust-lang-nursery/compiler-builtins/issues
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## Contributing
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1. Pick one or more intrinsics from the [pending list](#progress).
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2. Fork this repository.
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3. Port the intrinsic(s) and their corresponding [unit tests][1] from their
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[C implementation][2] to Rust.
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4. Implement a [test generator][3] to compare the behavior of the ported intrinsic(s)
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with their implementation on the testing host. Note that randomized compiler-builtin tests
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should be run using `cargo test --features gen-tests`.
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4. Send a Pull Request (PR).
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5. Once the PR passes our extensive [testing infrastructure][4], we'll merge it!
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6. Celebrate :tada:
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[1]: https://github.com/rust-lang/compiler-rt/tree/8598065bd965d9713bfafb6c1e766d63a7b17b89/test/builtins/Unit
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[2]: https://github.com/rust-lang/compiler-rt/tree/8598065bd965d9713bfafb6c1e766d63a7b17b89/lib/builtins
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[3]: https://github.com/rust-lang-nursery/compiler-builtins/blob/0ba07e49264a54cb5bbd4856fcea083bb3fbec15/build.rs#L180-L265
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[4]: https://travis-ci.org/rust-lang-nursery/compiler-builtins
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### Porting Reminders
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1. [Rust][5a] and [C][5b] have slightly different operator precedence. C evaluates comparisons (`== !=`) before bitwise operations (`& | ^`), while Rust evaluates the other way.
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2. C assumes wrapping operations everywhere. Rust panics on overflow when in debug mode. Consider using the [Wrapping][6] type or the explicit [wrapping_*][7] functions where applicable.
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3. Note [C implicit casts][8], especially integer promotion. Rust is much more explicit about casting, so be sure that any cast which affects the output is ported to the Rust implementation.
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4. Rust has [many functions][9] for integer or floating point manipulation in the standard library. Consider using one of these functions rather than porting a new one.
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[5a]: https://doc.rust-lang.org/reference/expressions.html#expression-precedence
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[5b]: http://en.cppreference.com/w/c/language/operator_precedence
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[6]: https://doc.rust-lang.org/core/num/struct.Wrapping.html
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[7]: https://doc.rust-lang.org/std/primitive.i32.html#method.wrapping_add
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[8]: http://en.cppreference.com/w/cpp/language/implicit_conversion
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[9]: https://doc.rust-lang.org/std/primitive.i32.html
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## Progress
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- [x] adddf3.c
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- [x] addsf3.c
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- [x] arm/adddf3vfp.S
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- [x] arm/addsf3vfp.S
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- [x] arm/aeabi_dcmp.S
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- [x] arm/aeabi_fcmp.S
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- [x] arm/aeabi_idivmod.S
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- [x] arm/aeabi_ldivmod.S
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- [x] arm/aeabi_memcpy.S
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- [x] arm/aeabi_memmove.S
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- [x] arm/aeabi_memset.S
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- [x] arm/aeabi_uidivmod.S
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- [x] arm/aeabi_uldivmod.S
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- [x] arm/divdf3vfp.S
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- [ ] arm/divmodsi4.S (generic version is done)
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- [x] arm/divsf3vfp.S
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- [ ] arm/divsi3.S (generic version is done)
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- [x] arm/eqdf2vfp.S
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- [x] arm/eqsf2vfp.S
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- [x] arm/extendsfdf2vfp.S
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- [ ] arm/fixdfsivfp.S
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- [ ] arm/fixsfsivfp.S
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- [ ] arm/fixunsdfsivfp.S
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- [ ] arm/fixunssfsivfp.S
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- [ ] arm/floatsidfvfp.S
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- [ ] arm/floatsisfvfp.S
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- [ ] arm/floatunssidfvfp.S
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- [ ] arm/floatunssisfvfp.S
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- [x] arm/gedf2vfp.S
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- [x] arm/gesf2vfp.S
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- [x] arm/gtdf2vfp.S
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- [x] arm/gtsf2vfp.S
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- [x] arm/ledf2vfp.S
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- [x] arm/lesf2vfp.S
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- [x] arm/ltdf2vfp.S
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- [x] arm/ltsf2vfp.S
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- [ ] arm/modsi3.S (generic version is done)
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- [x] arm/muldf3vfp.S
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- [x] arm/mulsf3vfp.S
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- [x] arm/nedf2vfp.S
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- [ ] arm/negdf2vfp.S
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- [ ] arm/negsf2vfp.S
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- [x] arm/nesf2vfp.S
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- [x] arm/softfloat-alias.list
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- [x] arm/subdf3vfp.S
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- [x] arm/subsf3vfp.S
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- [ ] arm/truncdfsf2vfp.S
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- [ ] arm/udivmodsi4.S (generic version is done)
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- [ ] arm/udivsi3.S (generic version is done)
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- [ ] arm/umodsi3.S (generic version is done)
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- [ ] arm/unorddf2vfp.S
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- [ ] arm/unordsf2vfp.S
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- [x] ashldi3.c
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- [x] ashrdi3.c
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- [x] comparedf2.c
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- [x] comparesf2.c
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- [x] divdf3.c
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- [x] divdi3.c
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- [x] divmoddi4.c
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- [x] divmodsi4.c
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- [x] divsf3.c
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- [x] divsi3.c
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- [ ] extendhfsf2.c
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- [x] extendsfdf2.c
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- [x] fixdfdi.c
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- [x] fixdfsi.c
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- [x] fixsfdi.c
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- [x] fixsfsi.c
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- [x] fixunsdfdi.c
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- [x] fixunsdfsi.c
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- [x] fixunssfdi.c
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- [x] fixunssfsi.c
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- [x] floatdidf.c
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- [x] floatdisf.c
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- [x] floatsidf.c
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- [x] floatsisf.c
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- [x] floatundidf.c
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- [x] floatundisf.c
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- [x] floatunsidf.c
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- [x] floatunsisf.c
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- [ ] i386/ashldi3.S
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- [ ] i386/ashrdi3.S
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- [x] i386/chkstk.S
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- [x] i386/chkstk2.S
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- [ ] i386/divdi3.S
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- [ ] i386/lshrdi3.S
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- [ ] i386/moddi3.S
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- [ ] i386/muldi3.S
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- [ ] i386/udivdi3.S
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- [ ] i386/umoddi3.S
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- [x] lshrdi3.c
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- [x] moddi3.c
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- [x] modsi3.c
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- [x] muldf3.c
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- [x] muldi3.c
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- [x] mulodi4.c
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- [x] mulosi4.c
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- [x] mulsf3.c
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- [x] powidf2.c
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- [x] powisf2.c
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- [x] subdf3.c
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- [x] subsf3.c
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- [ ] truncdfhf2.c
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- [ ] truncdfsf2.c
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- [ ] truncsfhf2.c
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- [x] udivdi3.c
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- [x] udivmoddi4.c
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- [x] udivmodsi4.c
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- [x] udivsi3.c
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- [x] umoddi3.c
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- [x] umodsi3.c
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- [x] x86_64/chkstk.S
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- [x] x86_64/chkstk2.S
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These builtins are needed to support 128-bit integers, which are in the process of being added to Rust.
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- [x] ashlti3.c
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- [x] ashrti3.c
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- [x] divti3.c
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- [x] fixdfti.c
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- [x] fixsfti.c
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- [x] fixunsdfti.c
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- [x] fixunssfti.c
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- [x] floattidf.c
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- [x] floattisf.c
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- [x] floatuntidf.c
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- [x] floatuntisf.c
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- [x] lshrti3.c
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- [x] modti3.c
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- [x] muloti4.c
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- [x] multi3.c
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- [x] udivmodti4.c
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- [x] udivti3.c
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- [x] umodti3.c
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## Unimplemented functions
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These builtins involve floating-point types ("`f128`", "`f80`" and complex numbers) that are not supported by Rust.
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- ~~addtf3.c~~
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- ~~comparetf2.c~~
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- ~~divdc3.c~~
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- ~~divsc3.c~~
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- ~~divtc3.c~~
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- ~~divtf3.c~~
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- ~~divxc3.c~~
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- ~~extenddftf2.c~~
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- ~~extendsftf2.c~~
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- ~~fixtfdi.c~~
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- ~~fixtfsi.c~~
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- ~~fixtfti.c~~
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- ~~fixunstfdi.c~~
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- ~~fixunstfsi.c~~
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- ~~fixunstfti.c~~
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- ~~fixunsxfdi.c~~
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- ~~fixunsxfsi.c~~
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- ~~fixunsxfti.c~~
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- ~~fixxfdi.c~~
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- ~~fixxfti.c~~
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- ~~floatditf.c~~
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- ~~floatdixf.c~~
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- ~~floatsitf.c~~
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- ~~floattixf.c~~
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- ~~floatunditf.c~~
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- ~~floatundixf.c~~
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- ~~floatunsitf.c~~
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- ~~floatuntixf.c~~
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- ~~i386/floatdixf.S~~
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- ~~i386/floatundixf.S~~
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- ~~muldc3.c~~
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- ~~mulsc3.c~~
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- ~~multc3.c~~
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- ~~multf3.c~~
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- ~~mulxc3.c~~
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- ~~powitf2.c~~
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- ~~powixf2.c~~
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- ~~ppc/divtc3.c~~
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- ~~ppc/fixtfdi.c~~
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- ~~ppc/fixunstfdi.c~~
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- ~~ppc/floatditf.c~~
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- ~~ppc/floatunditf.c~~
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- ~~ppc/gcc_qadd.c~~
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- ~~ppc/gcc_qdiv.c~~
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- ~~ppc/gcc_qmul.c~~
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- ~~ppc/gcc_qsub.c~~
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- ~~ppc/multc3.c~~
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- ~~subtf3.c~~
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- ~~trunctfdf2.c~~
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- ~~trunctfsf2.c~~
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- ~~x86_64/floatdixf.c~~
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- ~~x86_64/floatundixf.S~~
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These builtins are never called by LLVM.
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- ~~absvdi2.c~~
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- ~~absvsi2.c~~
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- ~~absvti2.c~~
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- ~~addvdi3.c~~
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- ~~addvsi3.c~~
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- ~~addvti3.c~~
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- ~~arm/aeabi_cdcmp.S~~
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- ~~arm/aeabi_cdcmpeq_check_nan.c~~
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- ~~arm/aeabi_cfcmp.S~~
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- ~~arm/aeabi_cfcmpeq_check_nan.c~~
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- ~~arm/aeabi_div0.c~~
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- ~~arm/aeabi_drsub.c~~
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- ~~arm/aeabi_frsub.c~~
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- ~~arm/aeabi_memcmp.S~~
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- ~~arm/bswapdi2.S~~
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- ~~arm/bswapsi2.S~~
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- ~~arm/clzdi2.S~~
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- ~~arm/clzsi2.S~~
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- ~~arm/comparesf2.S~~
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- ~~arm/restore_vfp_d8_d15_regs.S~~
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- ~~arm/save_vfp_d8_d15_regs.S~~
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- ~~arm/switch16.S~~
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- ~~arm/switch32.S~~
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- ~~arm/switch8.S~~
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- ~~arm/switchu8.S~~
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- ~~clzdi2.c~~
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- ~~clzsi2.c~~
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- ~~clzti2.c~~
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- ~~cmpdi2.c~~
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- ~~cmpti2.c~~
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- ~~ctzdi2.c~~
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- ~~ctzsi2.c~~
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- ~~ctzti2.c~~
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- ~~ffsdi2.c~~ - this is [called by gcc][jemalloc-fail] though!
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- ~~ffsti2.c~~
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- ~~mulvdi3.c~~
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- ~~mulvsi3.c~~
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- ~~mulvti3.c~~
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- ~~negdf2.c~~
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- ~~negdi2.c~~
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- ~~negsf2.c~~
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- ~~negti2.c~~
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- ~~negvdi2.c~~
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- ~~negvsi2.c~~
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- ~~negvti2.c~~
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- ~~paritydi2.c~~
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- ~~paritysi2.c~~
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- ~~parityti2.c~~
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- ~~popcountdi2.c~~
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- ~~popcountsi2.c~~
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- ~~popcountti2.c~~
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- ~~ppc/restFP.S~~
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- ~~ppc/saveFP.S~~
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- ~~subvdi3.c~~
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- ~~subvsi3.c~~
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- ~~subvti3.c~~
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- ~~ucmpdi2.c~~
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- ~~ucmpti2.c~~
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- ~~udivmodti4.c~~
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[jemalloc-fail]: https://travis-ci.org/rust-lang/rust/jobs/249772758
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Rust only exposes atomic types on platforms that support them, and therefore does not need to fall back to software implementations.
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- ~~arm/sync_fetch_and_add_4.S~~
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- ~~arm/sync_fetch_and_add_8.S~~
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- ~~arm/sync_fetch_and_and_4.S~~
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- ~~arm/sync_fetch_and_and_8.S~~
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- ~~arm/sync_fetch_and_max_4.S~~
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- ~~arm/sync_fetch_and_max_8.S~~
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- ~~arm/sync_fetch_and_min_4.S~~
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- ~~arm/sync_fetch_and_min_8.S~~
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- ~~arm/sync_fetch_and_nand_4.S~~
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- ~~arm/sync_fetch_and_nand_8.S~~
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- ~~arm/sync_fetch_and_or_4.S~~
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- ~~arm/sync_fetch_and_or_8.S~~
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- ~~arm/sync_fetch_and_sub_4.S~~
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- ~~arm/sync_fetch_and_sub_8.S~~
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- ~~arm/sync_fetch_and_umax_4.S~~
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- ~~arm/sync_fetch_and_umax_8.S~~
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- ~~arm/sync_fetch_and_umin_4.S~~
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- ~~arm/sync_fetch_and_umin_8.S~~
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- ~~arm/sync_fetch_and_xor_4.S~~
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- ~~arm/sync_fetch_and_xor_8.S~~
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- ~~arm/sync_synchronize.S~~
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- ~~atomic.c~~
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- ~~atomic_flag_clear.c~~
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- ~~atomic_flag_clear_explicit.c~~
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- ~~atomic_flag_test_and_set.c~~
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- ~~atomic_flag_test_and_set_explicit.c~~
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- ~~atomic_signal_fence.c~~
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- ~~atomic_thread_fence.c~~
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Miscellaneous functionality that is not used by Rust.
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- ~~apple_versioning.c~~
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- ~~clear_cache.c~~
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- ~~emutls.c~~
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- ~~enable_execute_stack.c~~
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- ~~eprintf.c~~
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- ~~gcc_personality_v0.c~~
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- ~~trampoline_setup.c~~
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Floating-point implementations of builtins that are only called from soft-float code. It would be better to simply use the generic soft-float versions in this case.
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- ~~i386/floatdidf.S~~
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- ~~i386/floatdisf.S~~
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- ~~i386/floatundidf.S~~
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- ~~i386/floatundisf.S~~
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- ~~x86_64/floatundidf.S~~
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- ~~x86_64/floatundisf.S~~
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- ~~x86_64/floatdidf.c~~
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- ~~x86_64/floatdisf.c~~
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## License
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The compiler-builtins crate is dual licensed under both the University of
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Illinois "BSD-Like" license and the MIT license. As a user of this code you may
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choose to use it under either license. As a contributor, you agree to allow
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your code to be used under both.
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Full text of the relevant licenses is in LICENSE.TXT.
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