23683716461

Committed 28 Mar 2026 10:55AM UTC coverage: 95.115% (-0.3%) from 95.372%

Build # 23683716461

Build Type

push

github

Committed by

henrythasler

Commit Message

add breakpoint before calling a JIT function

Coverage Stats

10 of 13 new or added lines in 2 files covered. (76.92%)

954 of 1003 relevant lines covered (95.11%)

23.76 hits per line

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57.14

/src/runtime/debugger.rs

/// This function is used to trigger a breakpoint for debugging purposes.
///
/// It uses architecture-specific assembly instructions to cause a trap if the `QEMU_DEBUG` environment variable is set, allowing developers to inspect the state of the program at that point.
///
/// # Notes
/// - On x86_64, it uses the `int3` instruction, which is a software breakpoint interrupt.
/// - On aarch64, it uses the `brk #0` instruction, which is a breakpoint instruction that causes a trap to the debugger.
///
/// # Important
///
/// `set $pc = $pc + 4` must be used to skip the breakpoint instruction itself when resuming execution after hitting the breakpoint.
///
/// # Example
///
/// ```bash
/// QEMU_DEBUG=1 qemu-aarch64 -L /usr/aarch64-linux-gnu/ -g 1234 target/aarch64-unknown-linux-gnu/debug/tiny-wasm
/// ```
#[inline(always)]
pub fn set_breakpoint() {
    // check for environment variable to determine if we should trigger a breakpoint
    if std::env::var_os("QEMU_DEBUG").is_some() {
        #[cfg(target_arch = "x86_64")]
        unsafe {
            std::arch::asm!("int3");
        }

        #[cfg(target_arch = "aarch64")]
        unsafe {
            std::arch::asm!("brk #0");
        }
    }
}

1	/// This function is used to trigger a breakpoint for debugging purposes.
2	///
3	/// It uses architecture-specific assembly instructions to cause a trap if the `QEMU_DEBUG` environment variable is set, allowing developers to inspect the state of the program at that point.
4	///
5	/// # Notes
6	/// - On x86_64, it uses the `int3` instruction, which is a software breakpoint interrupt.
7	/// - On aarch64, it uses the `brk #0` instruction, which is a breakpoint instruction that causes a trap to the debugger.
8	///
9	/// # Important
10	///
11	/// `set $pc = $pc + 4` must be used to skip the breakpoint instruction itself when resuming execution after hitting the breakpoint.
12	///
13	/// # Example
14	///
15	/// ```bash
16	/// QEMU_DEBUG=1 qemu-aarch64 -L /usr/aarch64-linux-gnu/ -g 1234 target/aarch64-unknown-linux-gnu/debug/tiny-wasm
17	/// ```
18	#[inline(always)]
19	pub fn set_breakpoint() {	16✔
20	// check for environment variable to determine if we should trigger a breakpoint
21	if std::env::var_os("QEMU_DEBUG").is_some() {	16✔
22	#[cfg(target_arch = "x86_64")]
23	unsafe {
24	std::arch::asm!("int3");
25	}
26
27	#[cfg(target_arch = "aarch64")]
NEW 28	unsafe {	×
NEW 29	std::arch::asm!("brk #0");	×
NEW 30	}	×
31	}	16✔
32	}	16✔

henrythasler / rust-tiny-wasm / 23683716461

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