perf(levm): use unchecked swap #5439

iovoid · 2025-11-27T13:03:16Z

Motivation

Currently we check the validity of the swap for the purpose of returning EVM errors, but swap itself contains bounds checks too.

Description

Uses unsafe code to perform the swap.

github-actions · 2025-11-27T13:06:16Z

Lines of code report

Total lines added: 4
Total lines removed: 0
Total lines changed: 4

Detailed view

+-----------------------------------------+-------+------+
| File                                    | Lines | Diff |
+-----------------------------------------+-------+------+
| ethrex/crates/vm/levm/src/call_frame.rs | 348   | +4   |
+-----------------------------------------+-------+------+

github-actions · 2025-11-27T13:18:46Z

Benchmark Results Comparison

No significant difference was registered for any benchmark run.

Detailed Results

Benchmark Results: BubbleSort

Command	Mean [s]	Min [s]	Max [s]	Relative
`main_revm_BubbleSort`	3.010 ± 0.024	2.986	3.065	1.02 ± 0.01
`main_levm_BubbleSort`	3.118 ± 0.013	3.094	3.139	1.05 ± 0.01
`pr_revm_BubbleSort`	2.958 ± 0.016	2.941	2.986	1.00
`pr_levm_BubbleSort`	3.074 ± 0.007	3.066	3.089	1.04 ± 0.01

Benchmark Results: ERC20Approval

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_ERC20Approval`	968.7 ± 4.5	961.4	976.3	1.00 ± 0.01
`main_levm_ERC20Approval`	1117.1 ± 36.3	1089.6	1204.3	1.16 ± 0.04
`pr_revm_ERC20Approval`	964.4 ± 3.8	960.6	972.1	1.00
`pr_levm_ERC20Approval`	1096.6 ± 10.9	1083.4	1118.9	1.14 ± 0.01

Benchmark Results: ERC20Mint

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_ERC20Mint`	134.8 ± 0.6	133.6	135.5	1.02 ± 0.01
`main_levm_ERC20Mint`	165.6 ± 4.6	163.0	178.3	1.25 ± 0.03
`pr_revm_ERC20Mint`	132.6 ± 0.5	132.1	133.5	1.00
`pr_levm_ERC20Mint`	164.6 ± 2.6	162.1	169.0	1.24 ± 0.02

Benchmark Results: ERC20Transfer

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_ERC20Transfer`	234.5 ± 4.4	229.3	241.1	1.03 ± 0.02
`main_levm_ERC20Transfer`	281.8 ± 6.0	275.5	296.7	1.23 ± 0.03
`pr_revm_ERC20Transfer`	228.8 ± 0.8	227.2	229.9	1.00
`pr_levm_ERC20Transfer`	282.5 ± 8.7	275.9	305.9	1.23 ± 0.04

Benchmark Results: Factorial

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_Factorial`	229.6 ± 10.1	222.3	257.8	1.00
`main_levm_Factorial`	269.2 ± 2.6	266.4	274.5	1.17 ± 0.05
`pr_revm_Factorial`	229.8 ± 4.6	224.2	241.9	1.00 ± 0.05
`pr_levm_Factorial`	268.9 ± 4.7	266.0	281.8	1.17 ± 0.06

Benchmark Results: FactorialRecursive

Command	Mean [s]	Min [s]	Max [s]	Relative
`main_revm_FactorialRecursive`	1.676 ± 0.049	1.559	1.742	1.00
`main_levm_FactorialRecursive`	8.457 ± 0.064	8.383	8.608	5.05 ± 0.15
`pr_revm_FactorialRecursive`	1.697 ± 0.044	1.659	1.793	1.01 ± 0.04
`pr_levm_FactorialRecursive`	8.568 ± 0.106	8.433	8.738	5.11 ± 0.16

Benchmark Results: Fibonacci

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_Fibonacci`	207.8 ± 0.9	206.0	209.3	1.00 ± 0.01
`main_levm_Fibonacci`	263.6 ± 5.2	254.6	275.3	1.27 ± 0.03
`pr_revm_Fibonacci`	207.0 ± 0.5	206.4	207.8	1.00
`pr_levm_Fibonacci`	262.2 ± 2.8	257.0	266.7	1.27 ± 0.01

Benchmark Results: FibonacciRecursive

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_FibonacciRecursive`	880.6 ± 20.3	865.1	935.5	1.18 ± 0.03
`main_levm_FibonacciRecursive`	748.2 ± 10.6	736.7	775.3	1.00 ± 0.02
`pr_revm_FibonacciRecursive`	889.8 ± 7.7	882.0	908.4	1.19 ± 0.02
`pr_levm_FibonacciRecursive`	747.5 ± 9.9	727.7	762.3	1.00

Benchmark Results: ManyHashes

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_ManyHashes`	8.4 ± 0.1	8.4	8.7	1.01 ± 0.02
`main_levm_ManyHashes`	9.2 ± 0.1	9.0	9.3	1.10 ± 0.02
`pr_revm_ManyHashes`	8.4 ± 0.1	8.3	8.6	1.00
`pr_levm_ManyHashes`	9.0 ± 0.1	8.9	9.3	1.08 ± 0.02

Benchmark Results: MstoreBench

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_MstoreBench`	273.8 ± 12.0	266.1	306.1	1.12 ± 0.05
`main_levm_MstoreBench`	244.5 ± 2.1	241.0	247.3	1.00
`pr_revm_MstoreBench`	271.1 ± 2.3	269.0	275.1	1.11 ± 0.01
`pr_levm_MstoreBench`	245.7 ± 2.8	242.7	251.1	1.01 ± 0.01

Benchmark Results: Push

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_Push`	296.3 ± 3.8	293.6	303.6	1.01 ± 0.01
`main_levm_Push`	302.0 ± 0.8	300.6	303.3	1.03 ± 0.00
`pr_revm_Push`	293.5 ± 1.1	292.5	295.9	1.00
`pr_levm_Push`	308.3 ± 2.1	305.6	311.5	1.05 ± 0.01

Benchmark Results: SstoreBench_no_opt

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
`main_revm_SstoreBench_no_opt`	166.8 ± 3.4	160.8	171.1	1.84 ± 0.06
`main_levm_SstoreBench_no_opt`	90.6 ± 2.0	88.3	92.6	1.00
`pr_revm_SstoreBench_no_opt`	166.0 ± 3.0	161.2	169.3	1.83 ± 0.05
`pr_levm_SstoreBench_no_opt`	93.8 ± 9.6	87.9	118.0	1.03 ± 0.11

github-actions · 2025-11-27T14:02:40Z

Benchmark Block Execution Results Comparison Against Main

Command	Mean [s]	Min [s]	Max [s]	Relative
`base`	61.735 ± 0.267	61.141	62.183	1.02 ± 0.01
`head`	60.788 ± 0.368	60.314	61.477	1.00

iovoid · 2025-11-27T15:07:04Z

Assembly code for SWAP:

Base

.section ".text.ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap","ax",@progbits
	.p2align	4
.type	ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap,@function
ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap:
		// crates/vm/levm/src/opcode_handlers/exchange.rs:12
		pub fn op_swap<const N: usize>(&mut self) -> Result<OpcodeResult, VMError> {
	.cfi_startproc
	sub rsp, 40
	.cfi_def_cfa_offset 48
		// crates/vm/levm/src/call_frame.rs:373
		self.gas_remaining -= gas as i64;
	add qword ptr [rsi + 1048], -3
		// crates/vm/levm/src/call_frame.rs:375
		if self.gas_remaining < 0 {
	js .LBB480_4
		// crates/vm/levm/src/call_frame.rs:145
		let index = self.offset + N;
	mov rax, qword ptr [rsi + 816]
	lea rcx, [rax + 7]
		// crates/vm/levm/src/call_frame.rs:147
		if index >= self.values.len() {
	cmp rcx, 1023
	jbe .LBB480_2
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/result.rs:2087
		Err(e) => Err(From::from(e)),
	mov word ptr [rdi], 2583
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	mov rax, rdi
	add rsp, 40
	.cfi_def_cfa_offset 8
	ret
.LBB480_4:
	.cfi_def_cfa_offset 48
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/result.rs:2087
		Err(e) => Err(From::from(e)),
	mov word ptr [rdi], 5143
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	mov rax, rdi
	add rsp, 40
	.cfi_def_cfa_offset 8
	ret
.LBB480_2:
	.cfi_def_cfa_offset 48
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/slice/mod.rs:904
		let pa = &raw mut self[a];
	cmp rax, 1024
	jae .LBB480_3
		// crates/vm/levm/src/call_frame.rs:151
		self.values.swap(self.offset, index);
	mov rdx, qword ptr [rsi + 808]
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/slice/mod.rs:904
		let pa = &raw mut self[a];
	shl rax, 5
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/ptr/mod.rs:547
		unsafe { crate::intrinsics::copy_nonoverlapping(src, dst, count) }
	vmovups ymm0, ymmword ptr [rdx + rax]
	vmovups ymmword ptr [rsp], ymm0
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/slice/mod.rs:905
		let pb = &raw mut self[b];
	shl rcx, 5
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/ptr/mod.rs:638
		crate::intrinsics::copy(src, dst, count)
	vmovups ymm0, ymmword ptr [rdx + rcx]
	vmovups ymmword ptr [rdx + rax], ymm0
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/ptr/mod.rs:547
		unsafe { crate::intrinsics::copy_nonoverlapping(src, dst, count) }
	vmovups ymm0, ymmword ptr [rsp]
	vmovups ymmword ptr [rdx + rcx], ymm0
		// crates/vm/levm/src/opcode_handlers/exchange.rs:18
		Ok(OpcodeResult::Continue)
	mov word ptr [rdi], 25
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	mov rax, rdi
	add rsp, 40
	.cfi_def_cfa_offset 8
	vzeroupper
	ret
.LBB480_3:
	.cfi_def_cfa_offset 48
		// /rustc/1159e78c4747b02ef996e55082b704c09b970588/library/core/src/slice/mod.rs:904
		let pa = &raw mut self[a];
	lea rdx, [rip + .Lanon.6faccdc95a04ea1765da90a999bd6d7e.248]
	mov esi, 1024
	mov rdi, rax
	call qword ptr [rip + core::panicking::panic_bounds_check@GOTPCREL]

PR

.section ".text.ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap","ax",@progbits
	.p2align	4
.type	ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap,@function
ethrex_levm::opcode_handlers::exchange::<impl ethrex_levm::vm::VM>::op_swap:
		// crates/vm/levm/src/opcode_handlers/exchange.rs:12
		pub fn op_swap<const N: usize>(&mut self) -> Result<OpcodeResult, VMError> {
	.cfi_startproc
	mov rax, rdi
		// crates/vm/levm/src/call_frame.rs:382
		self.gas_remaining -= gas as i64;
	add qword ptr [rsi + 1048], -3
		// crates/vm/levm/src/call_frame.rs:384
		if self.gas_remaining < 0 {
	js .LBB480_5
		// crates/vm/levm/src/call_frame.rs:145
		let index = self.offset + N;
	mov rdx, qword ptr [rsi + 816]
	lea rcx, [rdx + 7]
		// crates/vm/levm/src/call_frame.rs:147
		if index >= self.values.len() {
	cmp rcx, 1023
	jbe .LBB480_2
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:2087
		Err(e) => Err(From::from(e)),
	mov word ptr [rax], 2583
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	ret
.LBB480_5:
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/result.rs:2087
		Err(e) => Err(From::from(e)),
	mov word ptr [rax], 5143
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	ret
.LBB480_2:
		// crates/vm/levm/src/call_frame.rs:156
		let base = self.values.as_mut_ptr();
	mov rsi, qword ptr [rsi + 808]
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mut_ptr.rs:1008
		unsafe { intrinsics::offset(self, count) }
	shl rdx, 5
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:547
		unsafe { crate::intrinsics::copy_nonoverlapping(src, dst, count) }
	vmovups ymm0, ymmword ptr [rsi + rdx]
	vmovups ymmword ptr [rsp - 40], ymm0
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mut_ptr.rs:1008
		unsafe { intrinsics::offset(self, count) }
	shl rcx, 5
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:638
		crate::intrinsics::copy(src, dst, count)
	vmovups ymm0, ymmword ptr [rsi + rcx]
	vmovups ymmword ptr [rsi + rdx], ymm0
		// ~/.rustup/toolchains/1.90.0-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:547
		unsafe { crate::intrinsics::copy_nonoverlapping(src, dst, count) }
	vmovups ymm0, ymmword ptr [rsp - 40]
	vmovups ymmword ptr [rsi + rcx], ymm0
		// crates/vm/levm/src/opcode_handlers/exchange.rs:18
		Ok(OpcodeResult::Continue)
	mov word ptr [rax], 25
		// crates/vm/levm/src/opcode_handlers/exchange.rs:19
		}
	vzeroupper
	ret

iovoid · 2025-11-27T15:10:19Z

The noteworthy difference being the absence of cmp rax, 1024 and the accompanying branch to LBB480_3 (which throws a panic due to the bounds check failure)

Oppen · 2025-11-28T19:30:51Z

CHANGELOG.md


+### 2025-11-27
+
+- Use unchecked swap for stack [#5439](https://github.com/lambdaclass/ethrex/pull/5439)


The entry is misleading, as this no longer uses unchecked swap but a hint for the compiler.

Oppen · 2025-11-28T19:31:12Z

crates/vm/levm/src/call_frame.rs

+        unsafe {
+            assert_unchecked(self.offset < STACK_LIMIT)
+        };


Let's add a comment explaining that this removes a bound check in the call to swap.

use unchecked swap

9a8fc7e

iovoid requested a review from a team as a code owner November 27, 2025 13:03

github-actions bot assigned iovoid Nov 27, 2025

github-actions bot added levm Lambda EVM implementation performance Block execution throughput and performance in general labels Nov 27, 2025

github-project-automation bot added this to ethrex_performance and ethrex_l1 Nov 27, 2025

github-project-automation bot moved this to Todo in ethrex_performance Nov 27, 2025

update perf changelog

8fef9d0

iovoid added 2 commits November 27, 2025 12:21

Merge branch 'main' into unchecked_swap

3b900a1

use assert instead of manually implementing swap

be5b553

edg-l approved these changes Nov 28, 2025

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Merge branch 'main' into unchecked_swap

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fmoletta approved these changes Nov 28, 2025

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github-project-automation bot moved this to In Review in ethrex_l1 Nov 28, 2025

Merge branch 'main' into unchecked_swap

38604ac

iovoid enabled auto-merge November 28, 2025 19:16

Oppen reviewed Nov 28, 2025

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Oppen approved these changes Nov 28, 2025

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iovoid added this pull request to the merge queue Nov 28, 2025

Merged via the queue into main with commit 80ea03f Nov 28, 2025
58 checks passed

iovoid deleted the unchecked_swap branch November 28, 2025 20:03

github-project-automation bot moved this from In Review to Done in ethrex_l1 Nov 28, 2025

github-project-automation bot moved this from Todo to Done in ethrex_performance Nov 28, 2025


		### 2025-11-27

		- Use unchecked swap for stack [#5439](https://github.com/lambdaclass/ethrex/pull/5439)

perf(levm): use unchecked swap #5439

perf(levm): use unchecked swap #5439

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Benchmark Results Comparison

Benchmark Results: BubbleSort

Benchmark Results: ERC20Approval

Benchmark Results: ERC20Mint

Benchmark Results: ERC20Transfer

Benchmark Results: Factorial

Benchmark Results: FactorialRecursive

Benchmark Results: Fibonacci

Benchmark Results: FibonacciRecursive

Benchmark Results: ManyHashes

Benchmark Results: MstoreBench

Benchmark Results: Push

Benchmark Results: SstoreBench_no_opt

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Benchmark Block Execution Results Comparison Against Main

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PR

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