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Add the new linker-flavor field to target json

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See https://github.com/rust-lang/rust/pull/40018
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Philipp Oppermann
2017-04-12 20:45:59 +02:00
parent 239e96e8f2
commit c202937302
2 changed files with 7 additions and 0 deletions
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6
blog/content/post/03-set-up-rust.md
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@@ -97,6 +97,7 @@ Rust allows us to define [custom targets] through a JSON configuration file. A m
{ {
"llvm-target": "x86_64-unknown-linux-gnu", "llvm-target": "x86_64-unknown-linux-gnu",
"data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128", "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
"linker-flavor": "gcc",
"target-endian": "little", "target-endian": "little",
"target-pointer-width": "64", "target-pointer-width": "64",
"arch": "x86_64", "arch": "x86_64",
@@ -113,6 +114,11 @@ The `llvm-target` field specifies the target triple that is passed to LLVM. [Tar
The `data-layout` field is also passed to LLVM and specifies how data should be laid out in memory. It consists of various specifications seperated by a `-` character. For example, the `e` means little endian and `S128` specifies that the stack should be 128 bits (= 16 byte) aligned. The format is described in detail in the [LLVM documentation][data layout] but there shouldn't be a reason to change this string. The `data-layout` field is also passed to LLVM and specifies how data should be laid out in memory. It consists of various specifications seperated by a `-` character. For example, the `e` means little endian and `S128` specifies that the stack should be 128 bits (= 16 byte) aligned. The format is described in detail in the [LLVM documentation][data layout] but there shouldn't be a reason to change this string.
The `linker-flavor` field was recently introduced in [#40018] with the intention to add support for the LLVM linker [LLD], which is platform independent. In the future, this might allow easy cross compilation without the need to install a gcc cross compiler for linking.
[#40018]: https://github.com/rust-lang/rust/pull/40018
[LLD]: https://lld.llvm.org/
The other fields are used for conditional compilation. This allows crate authors to use `cfg` variables to write special code for depending on the OS or the architecture. There isn't any up-to-date documentation about these fields but the [corresponding source code][target specification] is quite readable. The other fields are used for conditional compilation. This allows crate authors to use `cfg` variables to write special code for depending on the OS or the architecture. There isn't any up-to-date documentation about these fields but the [corresponding source code][target specification] is quite readable.
[data layout]: http://llvm.org/docs/LangRef.html#data-layout [data layout]: http://llvm.org/docs/LangRef.html#data-layout

1
x86_64-blog_os.json
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@@ -1,6 +1,7 @@
{ {
"llvm-target": "x86_64-unknown-linux-gnu", "llvm-target": "x86_64-unknown-linux-gnu",
"data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128", "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
"linker-flavor": "gcc",
"target-endian": "little", "target-endian": "little",
"target-pointer-width": "64", "target-pointer-width": "64",
"arch": "x86_64", "arch": "x86_64",