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Add additional meta data to improve crate experience #118

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merged 1 commit into from
Oct 26, 2018
Merged

Add additional meta data to improve crate experience #118

merged 1 commit into from
Oct 26, 2018

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Nicoretti
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* Add readme setting, so README.md is shown on https://crates.io/
@Nicoretti Nicoretti requested a review from a team as a code owner October 26, 2018 13:47
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Good catch, thanks!

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bors r+

bors bot added a commit that referenced this pull request Oct 26, 2018
118: Add additional meta data to improve crate experience r=therealprof a=Nicoretti

* Add readme setting, so README.md is shown on https://crates.io/

Co-authored-by: Nicola Coretti <[email protected]>
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bors bot commented Oct 26, 2018

Build failed

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bors retry

bors bot added a commit that referenced this pull request Oct 26, 2018
118: Add additional meta data to improve crate experience r=therealprof a=Nicoretti

* Add readme setting, so README.md is shown on https://crates.io/

Co-authored-by: Nicola Coretti <[email protected]>
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bors bot commented Oct 26, 2018

Build succeeded

@bors bors bot merged commit ecea4a9 into rust-embedded:master Oct 26, 2018
adamgreig pushed a commit that referenced this pull request Jan 12, 2022
118: [RFC] Keep `.stack_sizes` r=japaric a=japaric

PR [rust-lang/rust#51946] will add a `-Z emit-stack-sizes` to `rustc` that can
be used to (make LLVM) emit stack usage metadata. Most linkers will discard this
metadata by default, however.

[rust-lang/rust#51946]: rust-lang/rust#51946

This PR / RFC proposes that we modify our linker script to keep this metadata
and place in an output `.stack_sizes` section (the canonical section name that
LLVM uses for this metadata).

This `.stack_sizes` section will be marked as `(INFO)` meaning that it won't be
loaded into the Flash or RAM of the target device.

The advantage of doing this is that tools that parse this information will work
out of the box. See examples at the bottom.

Not doing this means that users will have to mess with linker scripts and tweak
the linking process to be able to access the stack usage metadata. See [this
example] to get an idea of the required steps to keep the metadata information.

[this example]: https://github.com/japaric/stack-sizes#example-usage

# Examples

Using the [`cargo stack-sizes`] subcommand to build a project and print its
stack usage information. Assumes that this PR has been merged.

[`cargo stack-sizes`]: https://github.com/japaric/stack-sizes

``` console
$ cargo stack-sizes --bin app -v
RUSTC=stack-sizes-rustc "cargo" "rustc" "--bin" "app" "--"
    Finished dev [unoptimized + debuginfo] target(s) in 0.01s
"stack-sizes" "target/thumbv7m-none-eabi/debug/app"
address         stack   name
0x00000416      112     <cortex_m_rt::ExceptionFrame as core::fmt::Debug>::fmt::h4362577979112554
0x0000059e      96      <<cortex_m_rt::ExceptionFrame as core::fmt::Debug>::fmt::Hex as core::fmt::Debug>::fmt::hd24e21694d63c2ec
0x0000069c      72      core::fmt::Arguments::new_v1_formatted::hc22bfa5fcec35f0e
0x00000758      48      r0::init_data::hdc91f9605f364aeb
0x00000710      40      r0::zero_bss::h24ed73bae17eec88
0x000007d8      24      core::ptr::<impl *mut T>::offset::h940561014e707589
0x000007fc      24      core::ptr::<impl *const T>::offset::h6847f0bc0fe1f0b5
0x00000820      24      core::ptr::read::ha83613479c1b8688
0x00000858      24      core::sync::atomic::compiler_fence::h89dd3725007a5019
0x00002cb0      24      core::sync::atomic::compiler_fence::h4e6eb311378b7447
0x00000668      16      UserHardFault_
0x000007be      16      core::ptr::write_volatile::h92be4be56d39953d
0x00000840      16      core::ptr::write::h1bff45e7fbd786f1
0x00002c92      16      rust_begin_unwind
0x00000404      8       main
0x0000061c      8       Reset
0x00000684      8       SysTick
0x000006fc      8       core::ptr::drop_in_place::h96b0344554e68fcb
0x0000089c      8       core::mem::uninitialized::hea41370061be039b
0x000008aa      8       core::mem::zeroed::h87926bff0ea7d7b3
0x00000400      0       app::main::hb1f6f4352b7a35e2
0x0000069a      0       __pre_init
```

``` console
$ cargo stack-sizes --bin app --release -v
RUSTC=stack-sizes-rustc "cargo" "rustc" "--bin" "app" "--release" "--"
    Finished release [optimized + debuginfo] target(s) in 0.01s
"stack-sizes" "target/thumbv7m-none-eabi/release/app"
address         stack   name
0x00000400      0       main
0x00000402      0       Reset
0x00000616      0       UserHardFault_
0x00000618      0       SysTick
0x0000061a      0       __pre_init
```

---

r? @rust-embedded/cortex-m does this seem like a reasonable addition? Or do you think keeping .stack_sizes should *not* be done in this crate?

Co-authored-by: Jorge Aparicio <[email protected]>
adamgreig pushed a commit that referenced this pull request Jan 12, 2022
this undoes PR #118

I found a problem with keeping this section. Turns out that the input
`.stack_sizes` sections contain references to all functions compiled with `-Z
emit-stack-sizes` (the section contains the addresses of all those functions
after all) so keeping those section prevents the linker from removing *any* of
those functions. This is not a problem today because `-Z emit-stack-sizes` is
*opt-in* and only used to analyze a program.

However, I am proposing a rust-lang/rust PR to build the `compiler-builtins`
crate with `-Z emit-stack-sizes`. That change will cause *all* the functions in
that crate to be kept in binaries that link to `cortex-m-rt`, regardless of
whether the crate author uses `-Z emit-stack-sizes` or not, leading a increase
in binary size of about 14 KB (`.text` section).

To prevent issues with that rust-lang/rust PR I propose we undo PR #118. On the
bright side, the tools that were depending on this (`cargo-stack-sizes` and
`cargo-call-stack`) no longer do so in their latest releases so nothing is lost
on the tooling front with this change.
adamgreig pushed a commit that referenced this pull request Jan 12, 2022
186: do not KEEP the .stack_sizes section r=therealprof a=japaric

this undoes PR #118

I found a problem with keeping this section. Turns out that the input
`.stack_sizes` sections contain references to all functions compiled with `-Z
emit-stack-sizes` (the section contains the addresses of all those functions
after all) so keeping those section prevents the linker from removing *any* of
those functions. This is not a problem today because `-Z emit-stack-sizes` is
*opt-in* and only used to analyze a program.

However, I am proposing a rust-lang/rust PR to build the `compiler-builtins`
crate with `-Z emit-stack-sizes`. That change will cause *all* the functions in
that crate to be kept in binaries that link to `cortex-m-rt`, regardless of
whether the crate author uses `-Z emit-stack-sizes` or not, leading a increase
in binary size of about 14 KB (`.text` section).

To prevent issues with that rust-lang/rust PR I propose we undo PR #118. On the
bright side, the tools that were depending on this (`cargo-stack-sizes` and
`cargo-call-stack`) no longer do so in their latest releases so nothing is lost
on the tooling front with this change.

r? @rust-embedded/cortex-m

Co-authored-by: Jorge Aparicio <[email protected]>
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2 participants