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dayanruben
pushed a commit
that referenced
this pull request
Jul 15, 2025
Use zero for initialized Once state
By re-labeling which integer represents which internal state for `Once` we can ensure that the initialized state is the all-zero state. This is beneficial because some CPU architectures (such as Arm) have specialized instructions to specifically branch on non-zero, and checking for the initialized state is by far the most important operation.
As an example, take this:
```rust
use std::sync::atomic::{AtomicU32, Ordering};
const INIT: u32 = 3;
#[inline(never)]
#[cold]
pub fn slow(state: &AtomicU32) {
state.store(INIT, Ordering::Release);
}
pub fn ensure_init(state: &AtomicU32) {
if state.load(Ordering::Acquire) != INIT {
slow(state)
}
}
```
If `INIT` is 3 (as is currently the state for `Once`), we see the following assembly on `aarch64-apple-darwin`:
```asm
example::ensure_init::h332061368366e313:
ldapr w8, [x0]
cmp w8, #3
b.ne LBB1_2
ret
LBB1_2:
b example::slow::ha042bd6a4f33724e
```
By changing the `INIT` state to zero we get the following:
```asm
example::ensure_init::h332061368366e313:
ldapr w8, [x0]
cbnz w8, LBB1_2
ret
LBB1_2:
b example::slow::ha042bd6a4f33724e
```
So this PR saves 1 instruction every time a `LazyLock` gets accessed on platforms such as these.
dayanruben
pushed a commit
that referenced
this pull request
Jul 18, 2025
…-lines-debuginfo, r=wesleywiser tests: Test line debuginfo for linebreaked function parameters Closes rust-lang#45010 which just [E-needs-test](rust-lang#45010 (comment)). To verify that this is actually a regression test, do this, which is a simplified and adapted version of what compiletest does for 1.39 and then 1.88: ```sh for toolchain in 1.39 1.88; do echo -e "\nWith $toolchain:" rustc +$toolchain "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--emit" "llvm-ir" "-o" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "-g" "-Copt-level=0" "build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--check-prefix=CHECK" "--dump-input-context" "100" && echo OK || echo FAIL done ``` which gives ``` With 1.39: FAIL With 1.88: OK ``` <details> <summary>Click to expand full output</summary> ``` $ for toolchain in 1.39 1.88; do echo -e "\nWith $toolchain:" rustc +$toolchain "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--emit" "llvm-ir" "-o" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "-g" "-Copt-level=0" "build/x86_64-unknown-linux-gnu/ci-llvm/bin/FileCheck" "--input-file" "/tmp/fn-parameters-on-different-lines-debuginfo.ll" "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" "--check-prefix=CHECK" "--dump-input-context" "100" && echo OK || echo FAIL done With 1.39: tests/codegen/fn-parameters-on-different-lines-debuginfo.rs:16:16: error: CHECK-SAME: expected string not found in input // CHECK-SAME: line: 10 ^ /tmp/fn-parameters-on-different-lines-debuginfo.ll:69:42: note: scanning from here !10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9) ^ /tmp/fn-parameters-on-different-lines-debuginfo.ll:69:64: note: possible intended match here !10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9) ^ Input file: /tmp/fn-parameters-on-different-lines-debuginfo.ll Check file: tests/codegen/fn-parameters-on-different-lines-debuginfo.rs -dump-input=help explains the following input dump. Input was: <<<<<< 1: ; ModuleID = 'fn_parameters_on_different_lines_debuginfo.3a1fbbbh-cgu.0' 2: source_filename = "fn_parameters_on_different_lines_debuginfo.3a1fbbbh-cgu.0" 3: target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128" 4: target triple = "x86_64-unknown-linux-gnu" 5: 6: ``@str.0`` = internal constant [59 x i8] c"tests/codegen/fn-parameters-on-different-lines-debuginfo.rs" 7: ``@str.1`` = internal constant [28 x i8] c"attempt to add with overflow" 8: ``@panic_loc.2`` = private unnamed_addr constant { { [0 x i8]*, i64 }, { [0 x i8]*, i64 }, i32, i32 } { { [0 x i8]*, i64 } { [0 x i8]* bitcast ([28 x i8]* ``@str.1`` to [0 x i8]*), i64 28 }, { [0 x i8]*, i64 } { [0 x i8]* bitcast ([59 x i8]* ``@str.0`` to [0 x i8]*), i64 59 }, i32 13, i32 3 }, align 8 9: ``@__rustc_debug_gdb_scripts_section__`` = linkonce_odr unnamed_addr constant [34 x i8] c"\01gdb_load_rust_pretty_printers.py\00", section ".debug_gdb_scripts", align 1 10: 11: ; fn_parameters_on_different_lines_debuginfo::foo 12: ; Function Attrs: nonlazybind uwtable 13: define i32 ``@_ZN42fn_parameters_on_different_lines_debuginfo3foo17ha98e7c29f4ed8d60E(i32,`` i32) unnamed_addr #0 !dbg !5 { 14: start: 15: %y = alloca i32, align 4 16: %x = alloca i32, align 4 17: store i32 %0, i32* %x, align 4 18: call void ``@llvm.dbg.declare(metadata`` i32* %x, metadata !10, metadata !DIExpression()), !dbg !11 19: store i32 %1, i32* %y, align 4 20: call void ``@llvm.dbg.declare(metadata`` i32* %y, metadata !12, metadata !DIExpression()), !dbg !11 21: %2 = load i32, i32* %x, align 4, !dbg !13 22: %3 = load i32, i32* %y, align 4, !dbg !14 23: %4 = call { i32, i1 } ``@llvm.sadd.with.overflow.i32(i32`` %2, i32 %3), !dbg !13 24: %5 = extractvalue { i32, i1 } %4, 0, !dbg !13 25: %6 = extractvalue { i32, i1 } %4, 1, !dbg !13 26: %7 = call i1 ``@llvm.expect.i1(i1`` %6, i1 false), !dbg !13 27: br i1 %7, label %panic, label %bb1, !dbg !13 28: 29: bb1: ; preds = %start 30: ret i32 %5, !dbg !15 31: 32: panic: ; preds = %start 33: ; call core::panicking::panic 34: call void ``@_ZN4core9panicking5panic17h2f49f09cf859b728E({`` [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }* noalias readonly align 8 dereferenceable(40) bitcast ({ { [0 x i8]*, i64 }, { [0 x i8]*, i64 }, i32, i32 }* ``@panic_loc.2`` to { [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }*)), !dbg !13 35: unreachable, !dbg !13 36: } 37: 38: ; Function Attrs: nounwind readnone speculatable 39: declare void ``@llvm.dbg.declare(metadata,`` metadata, metadata) #1 40: 41: ; Function Attrs: nounwind readnone speculatable 42: declare { i32, i1 } ``@llvm.sadd.with.overflow.i32(i32,`` i32) #1 43: 44: ; Function Attrs: nounwind readnone 45: declare i1 ``@llvm.expect.i1(i1,`` i1) #2 46: 47: ; core::panicking::panic 48: ; Function Attrs: cold noinline noreturn nonlazybind uwtable 49: declare void ``@_ZN4core9panicking5panic17h2f49f09cf859b728E({`` [0 x i64], { [0 x i8]*, i64 }, [0 x i64], { [0 x i8]*, i64 }, [0 x i32], i32, [0 x i32], i32, [0 x i32] }* noalias readonly align 8 dereferenceable(40)) unnamed_addr #3 50: 51: attributes #0 = { nonlazybind uwtable "probe-stack"="__rust_probestack" "target-cpu"="x86-64" } 52: attributes #1 = { nounwind readnone speculatable } 53: attributes #2 = { nounwind readnone } 54: attributes #3 = { cold noinline noreturn nonlazybind uwtable "probe-stack"="__rust_probestack" "target-cpu"="x86-64" } 55: 56: !llvm.module.flags = !{!0, !1} 57: !llvm.dbg.cu = !{!2} 58: 59: !0 = !{i32 2, !"RtLibUseGOT", i32 1} 60: !1 = !{i32 2, !"Debug Info Version", i32 3} 61: !2 = distinct !DICompileUnit(language: DW_LANG_Rust, file: !3, producer: "clang LLVM (rustc version 1.39.0 (4560ea7 2019-11-04))", isOptimized: false, runtimeVersion: 0, emissionKind: FullDebug, enums: !4) 62: !3 = !DIFile(filename: "tests/codegen/fn-parameters-on-different-lines-debuginfo.rs", directory: "/home/martin/src/rust") 63: !4 = !{} 64: !5 = distinct !DISubprogram(name: "foo", linkageName: "_ZN42fn_parameters_on_different_lines_debuginfo3foo17ha98e7c29f4ed8d60E", scope: !6, file: !3, line: 9, type: !7, scopeLine: 9, flags: DIFlagPrototyped, spFlags: DISPFlagDefinition, unit: !2, templateParams: !4, retainedNodes: !4) 65: !6 = !DINamespace(name: "fn_parameters_on_different_lines_debuginfo", scope: null) 66: !7 = !DISubroutineType(types: !8) 67: !8 = !{!9, !9, !9} 68: !9 = !DIBasicType(name: "i32", size: 32, encoding: DW_ATE_signed) 69: !10 = !DILocalVariable(name: "x", arg: 1, scope: !5, file: !3, line: 1, type: !9) same:16'0 X~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ error: no match found same:16'1 ? possible intended match 70: !11 = !DILocation(line: 1, scope: !5) same:16'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 71: !12 = !DILocalVariable(name: "y", arg: 2, scope: !5, file: !3, line: 1, type: !9) same:16'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 72: !13 = !DILocation(line: 13, column: 2, scope: !5) same:16'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 73: !14 = !DILocation(line: 13, column: 6, scope: !5) same:16'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 74: !15 = !DILocation(line: 13, column: 9, scope: !5) same:16'0 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >>>>>> FAIL With 1.88: OK ``` <details>
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This PR initializes JetBrains Junie 🚀 by adding essential configuration files.
Includes:
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