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doc/rustc: fill out target platform-support docs #1

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adamgreig
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Adds maintainers and other information for bare-metal MSP430, RISC-V RV32I/IMC/IMAC, and thumbv{6,7,8} targets.

  • thumbv7em-none-eabihf, thumbv7em-none-eabi now both point to thumbv7m-none-eabi as the relevant documentation is shared
  • similarly thumbv8m.main-none-eabi and thumbv8m.main-none-eabihf both point to thumbv8m.base-none-eabi
  • similarly riscv32i-unknown-none-elf, riscv32imc-unknown-none-elf both point to riscv32imac-unknown-none-elf
  • the riscv32im-unknown-none-elf file is left untouched for now as it already has a maintainer and is tier 3 (the rest are tier 2), but in the future a separate PR to upstream could promote it to tier 2 and merge its platform support file with the other three targets
  • most of these maintainers are rust-embedded working group teams, so represent a few developers

cc rust-embedded/wg#704

Adds maintainers and other information for bare-metal MSP430, RISC-V
RV32I/IMC/IMAC, and thumbv{6,7,8} targets.

Signed-off-by: Adam Greig <[email protected]>
@adamgreig
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Hi @davidtwco, just wanted to check if you'd seen the PR and had any feedback!

@davidtwco
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Hi @davidtwco, just wanted to check if you'd seen the PR and had any feedback!

👋 I have, just a bit behind - this looks good, and I'll incorporate it once I've got some time to look at the target tier work :)

@MabezDev
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I have a need for the imafc target, and I wasn't allowed to grandfather it in, so I've copied much of the work here into that PR: rust-lang#117874, just as an FYI

matthiaskrgr added a commit to matthiaskrgr/rust that referenced this pull request Dec 6, 2023
…-elf, r=davidtwco

`riscv32` platform support

This PR  adds the following RISCV targets to the tier 2 list of targets:

- riscv32imafc-unknown-none-elf
- riscv32im-unknown-none-elf

The rationale behind adding them directly to tier 2, is that the other bare metal targets already exist at tier 2, and these new targets are the same with an additional target feature enabled.

As well as the additional targets, this PR fills out the platform support document(s) that were previously missing.

~~The RISC-V bare metal targets don't currently have a platform support document, but this will change soon as the RISC-V team from the Rust-embedded working group will maintain these once davidtwco#1 is merged (and `@davidtwco's` upstream PR is merged after). For the time being you can cc myself or any other member of the RISC-V team: https://github.com/orgs/rust-embedded/teams/riscv.~~

> A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.)

RISC-V is an open specification, used and accessible to anyone including individuals.

> A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers.

This rust-embedded working group's [RISCV team](https://github.com/orgs/rust-embedded/teams/riscv) will maintain these targets.

> The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target.

I don't forsee this being an issue, the RISCV team will ensure we avoid undue burden for the general Rust community.

> The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent.

There are links to resources we maintain in the re wg org in the platform support document.

> The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar.

Documented in the platform support document.

> If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target.

New target features in RISCV can drastically change the capability of a CPU, hence the need for a separate target to support different variants. We aim to support any ratified RISCV extensions.

> Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target.

`core` is fully implemented.

> The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features.

RISCV is a well-established and well-maintained LLVM backend. To the best of my knowledge, the backend won't cause the generated code to have undefined behaviour.

> If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however.

The C calling convention is supported by RISCV.

> The target must build reliably in CI, for all components that Rust's CI considers mandatory.

For the last 4-5 years many of these RISCV targets have been building in CI without any known issues.

> The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems.

Not applicable, in the future we may wish to add qemu tests but this is out of scope for now.

> Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account.

To the best of my knowledge, this will not induce a burden on the current CI infra.

> Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools.

Cross-compilation is supported and documented in the platform support document.

> In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams.

There are no additional license issues to worry about.

> Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages.

The RISCV team agrees not to do this.

> The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion.

The RISCV team will fix any issues in a timely manner.
rust-timer added a commit to rust-lang-ci/rust that referenced this pull request Dec 6, 2023
Rollup merge of rust-lang#117874 - esp-rs:riscv3264imafc-unknown-none-elf, r=davidtwco

`riscv32` platform support

This PR  adds the following RISCV targets to the tier 2 list of targets:

- riscv32imafc-unknown-none-elf
- riscv32im-unknown-none-elf

The rationale behind adding them directly to tier 2, is that the other bare metal targets already exist at tier 2, and these new targets are the same with an additional target feature enabled.

As well as the additional targets, this PR fills out the platform support document(s) that were previously missing.

~~The RISC-V bare metal targets don't currently have a platform support document, but this will change soon as the RISC-V team from the Rust-embedded working group will maintain these once davidtwco#1 is merged (and `@davidtwco's` upstream PR is merged after). For the time being you can cc myself or any other member of the RISC-V team: https://github.com/orgs/rust-embedded/teams/riscv.~~

> A tier 2 target must have value to people other than its maintainers. (It may still be a niche target, but it must not be exclusively useful for an inherently closed group.)

RISC-V is an open specification, used and accessible to anyone including individuals.

> A tier 2 target must have a designated team of developers (the "target maintainers") available to consult on target-specific build-breaking issues, or if necessary to develop target-specific language or library implementation details. This team must have at least 2 developers.

This rust-embedded working group's [RISCV team](https://github.com/orgs/rust-embedded/teams/riscv) will maintain these targets.

> The target must not place undue burden on Rust developers not specifically concerned with that target. Rust developers are expected to not gratuitously break a tier 2 target, but are not expected to become experts in every tier 2 target, and are not expected to provide target-specific implementations for every tier 2 target.

I don't forsee this being an issue, the RISCV team will ensure we avoid undue burden for the general Rust community.

> The target must provide documentation for the Rust community explaining how to build for the target using cross-compilation, and explaining how to run tests for the target. If at all possible, this documentation should show how to run Rust programs and tests for the target using emulation, to allow anyone to do so. If the target cannot be feasibly emulated, the documentation should explain how to obtain and work with physical hardware, cloud systems, or equivalent.

There are links to resources we maintain in the re wg org in the platform support document.

> The target must document its baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar.

Documented in the platform support document.

> If introducing a new tier 2 or higher target that is identical to an existing Rust target except for the baseline expectations for the features or versions of CPUs, operating systems, libraries, runtime environments, and similar, then the proposed target must document to the satisfaction of the approving teams why the specific difference in baseline expectations provides sufficient value to justify a separate target.

New target features in RISCV can drastically change the capability of a CPU, hence the need for a separate target to support different variants. We aim to support any ratified RISCV extensions.

> Tier 2 targets must not leave any significant portions of core or the standard library unimplemented or stubbed out, unless they cannot possibly be supported on the target.

`core` is fully implemented.

> The code generation backend for the target should not have deficiencies that invalidate Rust safety properties, as evaluated by the Rust compiler team. (This requirement does not apply to arbitrary security enhancements or mitigations provided by code generation backends, only to those properties needed to ensure safe Rust code cannot cause undefined behavior or other unsoundness.) If this requirement does not hold, the target must clearly and prominently document any such limitations as part of the target's entry in the target tier list, and ideally also via a failing test in the testsuite. The Rust compiler team must be satisfied with the balance between these limitations and the difficulty of implementing the necessary features.

RISCV is a well-established and well-maintained LLVM backend. To the best of my knowledge, the backend won't cause the generated code to have undefined behaviour.

> If the target supports C code, and the target has an interoperable calling convention for C code, the Rust target must support that C calling convention for the platform via extern "C". The C calling convention does not need to be the default Rust calling convention for the target, however.

The C calling convention is supported by RISCV.

> The target must build reliably in CI, for all components that Rust's CI considers mandatory.

For the last 4-5 years many of these RISCV targets have been building in CI without any known issues.

> The approving teams may additionally require that a subset of tests pass in CI, such as enough to build a functional "hello world" program, ./x.py test --no-run, or equivalent "smoke tests". In particular, this requirement may apply if the target builds host tools, or if the tests in question provide substantial value via early detection of critical problems.

Not applicable, in the future we may wish to add qemu tests but this is out of scope for now.

> Building the target in CI must not take substantially longer than the current slowest target in CI, and should not substantially raise the maintenance burden of the CI infrastructure. This requirement is subjective, to be evaluated by the infrastructure team, and will take the community importance of the target into account.

To the best of my knowledge, this will not induce a burden on the current CI infra.

> Tier 2 targets should, if at all possible, support cross-compiling. Tier 2 targets should not require using the target as the host for builds, even if the target supports host tools.

Cross-compilation is supported and documented in the platform support document.

> In addition to the legal requirements for all targets (specified in the tier 3 requirements), because a tier 2 target typically involves the Rust project building and supplying various compiled binaries, incorporating the target and redistributing any resulting compiled binaries (e.g. built libraries, host tools if any) must not impose any onerous license requirements on any members of the Rust project, including infrastructure team members and those operating CI systems. This is a subjective requirement, to be evaluated by the approving teams.

There are no additional license issues to worry about.

> Tier 2 targets must not impose burden on the authors of pull requests, or other developers in the community, to ensure that tests pass for the target. In particular, do not post comments (automated or manual) on a PR that derail or suggest a block on the PR based on tests failing for the target. Do not send automated messages or notifications (via any medium, including via `@)` to a PR author or others involved with a PR regarding the PR breaking tests on a tier 2 target, unless they have opted into such messages.

The RISCV team agrees not to do this.

> The target maintainers should regularly run the testsuite for the target, and should fix any test failures in a reasonably timely fashion.

The RISCV team will fix any issues in a timely manner.
@adamgreig
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It looks like some of these changes are now obsoleted by either rust-lang#117874 (above, for risc-v) or rust-lang#119102 (for the thumb targets) and the upstream PR is closed (rust-lang#116004) so I'll close this too. Hopefully the other updates can make their way into rust-lang one way or another.

@adamgreig adamgreig closed this Feb 3, 2024
davidtwco pushed a commit that referenced this pull request Sep 13, 2024
better implementation of signed div_floor/ceil

Tracking issue for signed `div_floor`/`div_ceil`: rust-lang#88581.

This PR improves the implementation of those two functions by adding a better branchless algorithm. Side-by-side comparison of `i32::div_floor` on x86-64:

```asm
div_floor_new:                               div_floor_old:
        push    rax                                  push    rax
        test    esi, esi                             test    esi, esi
        je      .LBB0_3                              je      .LBB1_6
        mov     eax, esi                             mov     eax, esi
        not     eax                                  not     eax
        lea     ecx, [rdi - 2147483648]              lea     ecx, [rdi - 2147483648]
        or      ecx, eax                             or      ecx, eax
        je      .LBB0_2                              je      .LBB1_7
        mov     eax, edi                             mov     eax, edi
        cdq                                          cdq
        idiv    esi                                  idiv    esi
        xor     esi, edi                             test    edx, edx
        sar     esi, 31                              setg    cl
        test    edx, edx                             test    esi, esi
        cmove   esi, edx                             sets    dil
        add     eax, esi                             test    dil, cl
        pop     rcx                                  jne     .LBB1_4
        ret                                          test    edx, edx
.LBB0_3:                                             setns   cl
        lea     rdi, [rip + .L__unnamed_1]           test    esi, esi
        call    qword ptr [rip + panic...]          setle   dl
.LBB0_2:                                             or      dl, cl
        lea     rdi, [rip + .L__unnamed_1]           jne     .LBB1_5
        call    qword ptr [rip + panic...]   .LBB1_4:
                                                     dec     eax
                                             .LBB1_5:
                                                     pop     rcx
                                                     ret
                                             .LBB1_6:
                                                     lea     rdi, [rip + .L__unnamed_2]
                                                     call    qword ptr [rip + panic...]
                                             .LBB1_7:
                                                     lea     rdi, [rip + .L__unnamed_2]
                                                     call    qword ptr [rip + panic...]
```

And on Aarch64:

```asm
_div_floor_new:                                   _div_floor_old:
        stp     x29, x30, [sp, #-16]!                     stp     x29, x30, [sp, #-16]!
        mov     x29, sp                                   mov     x29, sp
        cbz     w1, LBB0_4                                cbz     w1, LBB1_9
        mov     w8, #-2147483648                          mov     x8, x0
        cmp     w0, w8                                    mov     w9, #-2147483648
        b.ne    LBB0_3                                    cmp     w0, w9
        cmn     w1, #1                                    b.ne    LBB1_3
        b.eq    LBB0_5                                    cmn     w1, #1
LBB0_3:                                                   b.eq    LBB1_10
        sdiv    w8, w0, w1                        LBB1_3:
        msub    w9, w8, w1, w0                            sdiv    w0, w8, w1
        eor     w10, w1, w0                               msub    w8, w0, w1, w8
        asr     w10, w10, rust-lang#31                             tbz     w1, rust-lang#31, LBB1_5
        cmp     w9, #0                                    cmp     w8, #0
        csel    w9, wzr, w10, eq                          b.gt    LBB1_7
        add     w0, w9, w8                        LBB1_5:
        ldp     x29, x30, [sp], rust-lang#16                       cmp     w1, #1
        ret                                               b.lt    LBB1_8
LBB0_4:                                                   tbz     w8, rust-lang#31, LBB1_8
        adrp    x0, l___unnamed_1@PAGE            LBB1_7:
        add     x0, x0, l___unnamed_1@PAGEOFF             sub     w0, w0, #1
        bl      panic...                          LBB1_8:
LBB0_5:                                                   ldp     x29, x30, [sp], rust-lang#16
        adrp    x0, l___unnamed_1@PAGE                    ret
        add     x0, x0, l___unnamed_1@PAGEOFF     LBB1_9:
        bl      panic...                                  adrp    x0, l___unnamed_2@PAGE
                                                          add     x0, x0, l___unnamed_2@PAGEOFF
                                                          bl      panic...
                                                  LBB1_10:
                                                          adrp    x0, l___unnamed_2@PAGE
                                                          add     x0, x0, l___unnamed_2@PAGEOFF
                                                          bl      panic...
```
davidtwco pushed a commit that referenced this pull request Oct 22, 2024
…raheemdev

Optimize `Box::default` and `Arc::default` to construct more types in place

Both the `Arc` and `Box` `Default` impls currently call `T::default()` before allocating, and then moving the resulting `T` into the allocation.

Most `Default` impls are trivial, which should in theory allow
LLVM to construct `T: Default` directly in the `Box` allocation when calling
`<Box<T>>::default()`.

However, the allocation may fail, which necessitates calling `T`'s destructor if it has one.
If the destructor is non-trivial, then LLVM has a hard time proving that it's
sound to elide, which makes it construct `T` on the stack first, and then copy it into the allocation.

Change both of these impls to allocate first, and then call `T::default` into the uninitialized allocation, so that LLVM doesn't have to prove that it's sound to elide the destructor/initial stack copy.

For example, given the following Rust code:

```rust
#[derive(Default, Clone)]
struct Foo {
    x: Vec<u8>,
    z: String,
    y: Vec<u8>,
}

#[no_mangle]
pub fn src() -> Box<Foo> {
    Box::default()
}
```

<details open>
<summary>Before this PR:</summary>

```llvm
`@__rust_no_alloc_shim_is_unstable` = external global i8

; drop_in_place() generated in case the allocation fails

; core::ptr::drop_in_place<playground::Foo>
; Function Attrs: nounwind nonlazybind uwtable
define internal fastcc void `@"_ZN4core3ptr36drop_in_place$LT$playground..Foo$GT$17hff376aece491233bE"(ptr` noalias nocapture noundef readonly align 8 dereferenceable(72) %_1) unnamed_addr #0 personality ptr `@rust_eh_personality` {
start:
  %_1.val = load i64, ptr %_1, align 8
  %0 = icmp eq i64 %_1.val, 0
  br i1 %0, label %bb6, label %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i"

"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i": ; preds = %start
  %1 = getelementptr inbounds i8, ptr %_1, i64 8
  %_1.val6 = load ptr, ptr %1, align 8, !nonnull !3, !noundef !3
  tail call void `@__rust_dealloc(ptr` noundef nonnull %_1.val6, i64 noundef %_1.val, i64 noundef 1) rust-lang#8
  br label %bb6

bb6:                                              ; preds = %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i", %start
  %2 = getelementptr inbounds i8, ptr %_1, i64 24
  %.val9 = load i64, ptr %2, align 8
  %3 = icmp eq i64 %.val9, 0
  br i1 %3, label %bb5, label %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i.i11"

"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i.i11": ; preds = %bb6
  %4 = getelementptr inbounds i8, ptr %_1, i64 32
  %.val10 = load ptr, ptr %4, align 8, !nonnull !3, !noundef !3
  tail call void `@__rust_dealloc(ptr` noundef nonnull %.val10, i64 noundef %.val9, i64 noundef 1) rust-lang#8
  br label %bb5

bb5:                                              ; preds = %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i.i11", %bb6
  %5 = getelementptr inbounds i8, ptr %_1, i64 48
  %.val4 = load i64, ptr %5, align 8
  %6 = icmp eq i64 %.val4, 0
  br i1 %6, label %"_ZN4core3ptr46drop_in_place$LT$alloc..vec..Vec$LT$u8$GT$$GT$17hb5ca95423e113cf7E.exit16", label %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i15"

"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i15": ; preds = %bb5
  %7 = getelementptr inbounds i8, ptr %_1, i64 56
  %.val5 = load ptr, ptr %7, align 8, !nonnull !3, !noundef !3
  tail call void `@__rust_dealloc(ptr` noundef nonnull %.val5, i64 noundef %.val4, i64 noundef 1) rust-lang#8
  br label %"_ZN4core3ptr46drop_in_place$LT$alloc..vec..Vec$LT$u8$GT$$GT$17hb5ca95423e113cf7E.exit16"

"_ZN4core3ptr46drop_in_place$LT$alloc..vec..Vec$LT$u8$GT$$GT$17hb5ca95423e113cf7E.exit16": ; preds = %bb5, %"_ZN63_$LT$alloc..alloc..Global$u20$as$u20$core..alloc..Allocator$GT$10deallocate17heaa87468709346b1E.exit.i.i.i4.i15"
  ret void
}

; Function Attrs: nonlazybind uwtable
define noalias noundef nonnull align 8 ptr `@src()` unnamed_addr #1 personality ptr `@rust_eh_personality` {
start:

; alloca to place `Foo` in.
  %_1 = alloca [72 x i8], align 8
  call void `@llvm.lifetime.start.p0(i64` 72, ptr nonnull %_1)
  store i64 0, ptr %_1, align 8
  %_2.sroa.4.0._1.sroa_idx = getelementptr inbounds i8, ptr %_1, i64 8
  store ptr inttoptr (i64 1 to ptr), ptr %_2.sroa.4.0._1.sroa_idx, align 8
  %_2.sroa.5.0._1.sroa_idx = getelementptr inbounds i8, ptr %_1, i64 16
  %_3.sroa.4.0..sroa_idx = getelementptr inbounds i8, ptr %_1, i64 32
  call void `@llvm.memset.p0.i64(ptr` noundef nonnull align 8 dereferenceable(16) %_2.sroa.5.0._1.sroa_idx, i8 0, i64 16, i1 false)
  store ptr inttoptr (i64 1 to ptr), ptr %_3.sroa.4.0..sroa_idx, align 8
  %_3.sroa.5.0..sroa_idx = getelementptr inbounds i8, ptr %_1, i64 40
  %_4.sroa.4.0..sroa_idx = getelementptr inbounds i8, ptr %_1, i64 56
  call void `@llvm.memset.p0.i64(ptr` noundef nonnull align 8 dereferenceable(16) %_3.sroa.5.0..sroa_idx, i8 0, i64 16, i1 false)
  store ptr inttoptr (i64 1 to ptr), ptr %_4.sroa.4.0..sroa_idx, align 8
  %_4.sroa.5.0..sroa_idx = getelementptr inbounds i8, ptr %_1, i64 64
  store i64 0, ptr %_4.sroa.5.0..sroa_idx, align 8
  %0 = load volatile i8, ptr `@__rust_no_alloc_shim_is_unstable,` align 1, !noalias !4
  %_0.i.i.i = tail call noalias noundef align 8 dereferenceable_or_null(72) ptr `@__rust_alloc(i64` noundef 72, i64 noundef 8) rust-lang#8, !noalias !4
  %1 = icmp eq ptr %_0.i.i.i, null
  br i1 %1, label %bb2.i, label %"_ZN5alloc5boxed12Box$LT$T$GT$3new17h0864de14f863a27aE.exit"

bb2.i:                                            ; preds = %start
; invoke alloc::alloc::handle_alloc_error
  invoke void `@_ZN5alloc5alloc18handle_alloc_error17h98142d0d8d74161bE(i64` noundef 8, i64 noundef 72) rust-lang#9
          to label %.noexc unwind label %cleanup.i

.noexc:                                           ; preds = %bb2.i
  unreachable

cleanup.i:                                        ; preds = %bb2.i
  %2 = landingpad { ptr, i32 }
          cleanup
; call core::ptr::drop_in_place<playground::Foo>
  call fastcc void `@"_ZN4core3ptr36drop_in_place$LT$playground..Foo$GT$17hff376aece491233bE"(ptr` noalias noundef nonnull align 8 dereferenceable(72) %_1) rust-lang#10
  resume { ptr, i32 } %2

"_ZN5alloc5boxed12Box$LT$T$GT$3new17h0864de14f863a27aE.exit": ; preds = %start

; Copy from stack to heap if allocation is successful
  call void `@llvm.memcpy.p0.p0.i64(ptr` noundef nonnull align 8 dereferenceable(72) %_0.i.i.i, ptr noundef nonnull align 8 dereferenceable(72) %_1, i64 72, i1 false)
  call void `@llvm.lifetime.end.p0(i64` 72, ptr nonnull %_1)
  ret ptr %_0.i.i.i
}

```
</details>

<details>
<summary>After this PR</summary>

```llvm
; Notice how there's no `drop_in_place()` generated as well

define noalias noundef nonnull align 8 ptr `@src()` unnamed_addr #0 personality ptr `@rust_eh_personality` {
start:
; no stack allocation

  %0 = load volatile i8, ptr `@__rust_no_alloc_shim_is_unstable,` align 1
  %_0.i.i.i.i.i = tail call noalias noundef align 8 dereferenceable_or_null(72) ptr `@__rust_alloc(i64` noundef 72, i64 noundef 8) rust-lang#5
  %1 = icmp eq ptr %_0.i.i.i.i.i, null
  br i1 %1, label %bb3.i, label %"_ZN5alloc5boxed16Box$LT$T$C$A$GT$13new_uninit_in17h80d6355ef4b73ea3E.exit"

bb3.i:                                            ; preds = %start
; call alloc::alloc::handle_alloc_error
  tail call void `@_ZN5alloc5alloc18handle_alloc_error17h98142d0d8d74161bE(i64` noundef 8, i64 noundef 72) rust-lang#6
  unreachable

"_ZN5alloc5boxed16Box$LT$T$C$A$GT$13new_uninit_in17h80d6355ef4b73ea3E.exit": ; preds = %start
; construct `Foo` directly into the allocation if successful

  store i64 0, ptr %_0.i.i.i.i.i, align 8
  %_8.sroa.4.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 8
  store ptr inttoptr (i64 1 to ptr), ptr %_8.sroa.4.0._1.sroa_idx, align 8
  %_8.sroa.5.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 16
  %_8.sroa.7.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 32
  tail call void `@llvm.memset.p0.i64(ptr` noundef nonnull align 8 dereferenceable(16) %_8.sroa.5.0._1.sroa_idx, i8 0, i64 16, i1 false)
  store ptr inttoptr (i64 1 to ptr), ptr %_8.sroa.7.0._1.sroa_idx, align 8
  %_8.sroa.8.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 40
  %_8.sroa.10.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 56
  tail call void `@llvm.memset.p0.i64(ptr` noundef nonnull align 8 dereferenceable(16) %_8.sroa.8.0._1.sroa_idx, i8 0, i64 16, i1 false)
  store ptr inttoptr (i64 1 to ptr), ptr %_8.sroa.10.0._1.sroa_idx, align 8
  %_8.sroa.11.0._1.sroa_idx = getelementptr inbounds i8, ptr %_0.i.i.i.i.i, i64 64
  store i64 0, ptr %_8.sroa.11.0._1.sroa_idx, align 8
  ret ptr %_0.i.i.i.i.i
}
```

</details>
davidtwco pushed a commit that referenced this pull request Oct 22, 2024
…Kobzol

shave 150ms off bootstrap

This starts `git` commands inside `GitInfo`and the submodule updates in parallel. Git should already perform internal locking in cases where it needs to serialize a modification.

```
OLD
Benchmark #1: ./x check core
  Time (mean ± σ):     608.7 ms ±   4.4 ms    [User: 368.3 ms, System: 455.1 ms]
  Range (min … max):   602.3 ms … 618.8 ms    10 runs

NEW
Benchmark #1: ./x check core
  Time (mean ± σ):     462.8 ms ±   2.6 ms    [User: 350.2 ms, System: 485.1 ms]
  Range (min … max):   457.5 ms … 465.6 ms    10 runs
```

This should help with the rust-analyzer setup which issues many individual `./x check` calls. There's more that could be done but these were the lowest-hanging fruits that I saw.
davidtwco pushed a commit that referenced this pull request Nov 4, 2024
The failure output is:
```
SplitVectorOperand Op #1: t51: i32 = llvm.wasm.alltrue TargetConstant:i32<12408>, t50

rustc-LLVM ERROR: Do not know how to split this operator's operand!
```
davidtwco pushed a commit that referenced this pull request Dec 12, 2024
we get these declarations

```
; opt level 0
declare x86_intrcc void @page_fault_handler(ptr byval([8 x i8]) align 8, i64) unnamed_addr #1
; opt level > 0
declare x86_intrcc void @page_fault_handler(ptr noalias nocapture noundef byval([8 x i8]) align 8 dereferenceable(8), i64 noundef) unnamed_addr #1
```

The space after `i64` in the original regex made the regex not match for
opt level 0. Removing the space fixes the issue.

```
declare x86_intrcc void @page_fault_handler(ptr {{.*}}, i64 {{.*}}){{.*}}#[[ATTRS:[0-9]+]]
```
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3 participants