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[codegen] Test and document codegen for SplitAt and Split #3111

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Merged
jswrenn merged 1 commit into from
Mar 17, 2026
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Merged

[codegen] Test and document codegen for SplitAt and Split #3111

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2 changes: 1 addition & 1 deletion benches/formats/coco_dynamic_padding.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ pub enum C0C0 {
_XC0C0 = 0xC0C0,
}

#[derive(FromBytes, KnownLayout, Immutable)]
#[derive(FromBytes, KnownLayout, Immutable, SplitAt)]
#[repr(C, align(4))]
pub struct Packet<Magic> {
magic_number: Magic,
Expand Down
2 changes: 1 addition & 1 deletion benches/formats/coco_dynamic_size.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@ pub enum C0C0 {

macro_rules! define_packet {
($name: ident, $trait: ident, $leading_field: ty) => {
#[derive($trait, KnownLayout, Immutable, IntoBytes)]
#[derive($trait, KnownLayout, Immutable, IntoBytes, SplitAt)]
#[repr(C, align(2))]
pub struct $name {
magic_number: $leading_field,
Expand Down
12 changes: 12 additions & 0 deletions benches/split_at_dynamic_padding.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
use zerocopy::*;

#[path = "formats/coco_dynamic_padding.rs"]
mod format;

#[unsafe(no_mangle)]
fn bench_split_at_dynamic_padding(
source: &format::CocoPacket,
len: usize,
) -> Option<Split<&format::CocoPacket>> {
source.split_at(len)
}
12 changes: 12 additions & 0 deletions benches/split_at_dynamic_padding.x86-64
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
bench_split_at_dynamic_padding:
mov rax, rdi
cmp rcx, rdx
jbe .LBB5_2
xor esi, esi
mov qword ptr [rax], rsi
ret
.LBB5_2:
mov qword ptr [rax + 8], rdx
mov qword ptr [rax + 16], rcx
mov qword ptr [rax], rsi
ret
59 changes: 59 additions & 0 deletions benches/split_at_dynamic_padding.x86-64.mca
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Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
Iterations: 100
Instructions: 1000
Total Cycles: 404
Total uOps: 1000

Dispatch Width: 4
uOps Per Cycle: 2.48
IPC: 2.48
Block RThroughput: 4.0


Instruction Info:
[1]: #uOps
[2]: Latency
[3]: RThroughput
[4]: MayLoad
[5]: MayStore
[6]: HasSideEffects (U)

[1] [2] [3] [4] [5] [6] Instructions:
1 1 0.33 mov rax, rdi
1 1 0.33 cmp rcx, rdx
1 1 1.00 jbe .LBB5_2
1 0 0.25 xor esi, esi
1 1 1.00 * mov qword ptr [rax], rsi
1 1 1.00 U ret
1 1 1.00 * mov qword ptr [rax + 8], rdx
1 1 1.00 * mov qword ptr [rax + 16], rcx
1 1 1.00 * mov qword ptr [rax], rsi
1 1 1.00 U ret


Resources:
[0] - SBDivider
[1] - SBFPDivider
[2] - SBPort0
[3] - SBPort1
[4] - SBPort4
[5] - SBPort5
[6.0] - SBPort23
[6.1] - SBPort23


Resource pressure per iteration:
[0] [1] [2] [3] [4] [5] [6.0] [6.1]
- - 0.99 1.00 4.00 3.01 2.00 2.00

Resource pressure by instruction:
[0] [1] [2] [3] [4] [5] [6.0] [6.1] Instructions:
- - 0.99 - - 0.01 - - mov rax, rdi
- - - 1.00 - - - - cmp rcx, rdx
- - - - - 1.00 - - jbe .LBB5_2
- - - - - - - - xor esi, esi
- - - - 1.00 - - 1.00 mov qword ptr [rax], rsi
- - - - - 1.00 - - ret
- - - - 1.00 - 1.00 - mov qword ptr [rax + 8], rdx
- - - - 1.00 - - 1.00 mov qword ptr [rax + 16], rcx
- - - - 1.00 - 1.00 - mov qword ptr [rax], rsi
- - - - - 1.00 - - ret
12 changes: 12 additions & 0 deletions benches/split_at_dynamic_size.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
use zerocopy::*;

#[path = "formats/coco_dynamic_size.rs"]
mod format;

#[unsafe(no_mangle)]
fn bench_split_at_dynamic_size(
source: &format::CocoPacket,
len: usize,
) -> Option<Split<&format::CocoPacket>> {
source.split_at(len)
}
12 changes: 12 additions & 0 deletions benches/split_at_dynamic_size.x86-64
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
bench_split_at_dynamic_size:
mov rax, rdi
cmp rcx, rdx
jbe .LBB5_2
xor esi, esi
mov qword ptr [rax], rsi
ret
.LBB5_2:
mov qword ptr [rax + 8], rdx
mov qword ptr [rax + 16], rcx
mov qword ptr [rax], rsi
ret
59 changes: 59 additions & 0 deletions benches/split_at_dynamic_size.x86-64.mca
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Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,59 @@
Iterations: 100
Instructions: 1000
Total Cycles: 404
Total uOps: 1000

Dispatch Width: 4
uOps Per Cycle: 2.48
IPC: 2.48
Block RThroughput: 4.0


Instruction Info:
[1]: #uOps
[2]: Latency
[3]: RThroughput
[4]: MayLoad
[5]: MayStore
[6]: HasSideEffects (U)

[1] [2] [3] [4] [5] [6] Instructions:
1 1 0.33 mov rax, rdi
1 1 0.33 cmp rcx, rdx
1 1 1.00 jbe .LBB5_2
1 0 0.25 xor esi, esi
1 1 1.00 * mov qword ptr [rax], rsi
1 1 1.00 U ret
1 1 1.00 * mov qword ptr [rax + 8], rdx
1 1 1.00 * mov qword ptr [rax + 16], rcx
1 1 1.00 * mov qword ptr [rax], rsi
1 1 1.00 U ret


Resources:
[0] - SBDivider
[1] - SBFPDivider
[2] - SBPort0
[3] - SBPort1
[4] - SBPort4
[5] - SBPort5
[6.0] - SBPort23
[6.1] - SBPort23


Resource pressure per iteration:
[0] [1] [2] [3] [4] [5] [6.0] [6.1]
- - 0.99 1.00 4.00 3.01 2.00 2.00

Resource pressure by instruction:
[0] [1] [2] [3] [4] [5] [6.0] [6.1] Instructions:
- - 0.99 - - 0.01 - - mov rax, rdi
- - - 1.00 - - - - cmp rcx, rdx
- - - - - 1.00 - - jbe .LBB5_2
- - - - - - - - xor esi, esi
- - - - 1.00 - - 1.00 mov qword ptr [rax], rsi
- - - - - 1.00 - - ret
- - - - 1.00 - 1.00 - mov qword ptr [rax + 8], rdx
- - - - 1.00 - - 1.00 mov qword ptr [rax + 16], rcx
- - - - 1.00 - 1.00 - mov qword ptr [rax], rsi
- - - - - 1.00 - - ret
12 changes: 12 additions & 0 deletions benches/split_at_unchecked_dynamic_padding.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
use zerocopy::*;

#[path = "formats/coco_dynamic_padding.rs"]
mod format;

#[unsafe(no_mangle)]
unsafe fn bench_split_at_unchecked_dynamic_padding(
source: &format::CocoPacket,
len: usize,
) -> Split<&format::CocoPacket> {
unsafe { source.split_at_unchecked(len) }
}
6 changes: 6 additions & 0 deletions benches/split_at_unchecked_dynamic_padding.x86-64
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
bench_split_at_unchecked_dynamic_padding:
mov rax, rdi
mov qword ptr [rdi], rsi
mov qword ptr [rdi + 8], rdx
mov qword ptr [rdi + 16], rcx
ret
49 changes: 49 additions & 0 deletions benches/split_at_unchecked_dynamic_padding.x86-64.mca
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Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
Iterations: 100
Instructions: 500
Total Cycles: 303
Total uOps: 500

Dispatch Width: 4
uOps Per Cycle: 1.65
IPC: 1.65
Block RThroughput: 3.0


Instruction Info:
[1]: #uOps
[2]: Latency
[3]: RThroughput
[4]: MayLoad
[5]: MayStore
[6]: HasSideEffects (U)

[1] [2] [3] [4] [5] [6] Instructions:
1 1 0.33 mov rax, rdi
1 1 1.00 * mov qword ptr [rdi], rsi
1 1 1.00 * mov qword ptr [rdi + 8], rdx
1 1 1.00 * mov qword ptr [rdi + 16], rcx
1 1 1.00 U ret


Resources:
[0] - SBDivider
[1] - SBFPDivider
[2] - SBPort0
[3] - SBPort1
[4] - SBPort4
[5] - SBPort5
[6.0] - SBPort23
[6.1] - SBPort23


Resource pressure per iteration:
[0] [1] [2] [3] [4] [5] [6.0] [6.1]
- - 0.49 0.50 3.00 1.01 1.50 1.50

Resource pressure by instruction:
[0] [1] [2] [3] [4] [5] [6.0] [6.1] Instructions:
- - 0.49 0.50 - 0.01 - - mov rax, rdi
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi], rsi
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi + 8], rdx
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi + 16], rcx
- - - - - 1.00 - - ret
12 changes: 12 additions & 0 deletions benches/split_at_unchecked_dynamic_size.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,12 @@
use zerocopy::*;

#[path = "formats/coco_dynamic_size.rs"]
mod format;

#[unsafe(no_mangle)]
unsafe fn bench_split_at_unchecked_dynamic_size(
source: &format::CocoPacket,
len: usize,
) -> Split<&format::CocoPacket> {
unsafe { source.split_at_unchecked(len) }
}
6 changes: 6 additions & 0 deletions benches/split_at_unchecked_dynamic_size.x86-64
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Original file line number Diff line number Diff line change
@@ -0,0 +1,6 @@
bench_split_at_unchecked_dynamic_size:
mov rax, rdi
mov qword ptr [rdi], rsi
mov qword ptr [rdi + 8], rdx
mov qword ptr [rdi + 16], rcx
ret
49 changes: 49 additions & 0 deletions benches/split_at_unchecked_dynamic_size.x86-64.mca
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
Iterations: 100
Instructions: 500
Total Cycles: 303
Total uOps: 500

Dispatch Width: 4
uOps Per Cycle: 1.65
IPC: 1.65
Block RThroughput: 3.0


Instruction Info:
[1]: #uOps
[2]: Latency
[3]: RThroughput
[4]: MayLoad
[5]: MayStore
[6]: HasSideEffects (U)

[1] [2] [3] [4] [5] [6] Instructions:
1 1 0.33 mov rax, rdi
1 1 1.00 * mov qword ptr [rdi], rsi
1 1 1.00 * mov qword ptr [rdi + 8], rdx
1 1 1.00 * mov qword ptr [rdi + 16], rcx
1 1 1.00 U ret


Resources:
[0] - SBDivider
[1] - SBFPDivider
[2] - SBPort0
[3] - SBPort1
[4] - SBPort4
[5] - SBPort5
[6.0] - SBPort23
[6.1] - SBPort23


Resource pressure per iteration:
[0] [1] [2] [3] [4] [5] [6.0] [6.1]
- - 0.49 0.50 3.00 1.01 1.50 1.50

Resource pressure by instruction:
[0] [1] [2] [3] [4] [5] [6.0] [6.1] Instructions:
- - 0.49 0.50 - 0.01 - - mov rax, rdi
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi], rsi
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi + 8], rdx
- - - - 1.00 - 0.50 0.50 mov qword ptr [rdi + 16], rcx
- - - - - 1.00 - - ret
11 changes: 11 additions & 0 deletions benches/split_via_immutable_dynamic_padding.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,11 @@
use zerocopy::*;

#[path = "formats/coco_dynamic_padding.rs"]
mod format;

#[unsafe(no_mangle)]
fn bench_split_via_immutable_dynamic_padding(
split: Split<&format::CocoPacket>,
) -> (&format::CocoPacket, &[[u8; 3]]) {
split.via_immutable()
}
14 changes: 14 additions & 0 deletions benches/split_via_immutable_dynamic_padding.x86-64
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Original file line number Diff line number Diff line change
@@ -0,0 +1,14 @@
bench_split_via_immutable_dynamic_padding:
mov rax, rdi
mov rcx, qword ptr [rsi]
mov rdx, qword ptr [rsi + 8]
mov rsi, qword ptr [rsi + 16]
lea rdi, [rsi + 2*rsi]
add rdi, rcx
add rdi, 9
sub rdx, rsi
mov qword ptr [rax], rcx
mov qword ptr [rax + 8], rsi
mov qword ptr [rax + 16], rdi
mov qword ptr [rax + 24], rdx
ret
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