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inline asm jmp 'invalid operand for instruction' #48797
Description
Rust nightly version 2018-02-11 broke some inline assembly in code that previously worked.
Specifically, the jmp instruction on x86_64 doesn't work as it has before.
A minimum example to reproduce is that
fn foo(bytes: &[u8]) -> u32 {
let result: u32;
unsafe {
asm!(
"
1:
jmp 1b
"
: "={ax}"(result) // Output register
: "r"(bytes.as_ptr()), "r"(bytes.len()) // Input registers
: "rax" // Clobbered registers
: "intel", "volatile" // Options (intel syntax, don't optimize out)
);
}
result
}
now fails to compile with error:
error: <inline asm>:5:2: error: invalid operand for instruction jmp 1b
The code snippet above compiles with rust-nightly-x86_64-unknown-linux-gnu nightly 2018-02-10 and earlier, but returns an error on nightly 2018-02-11 and beyond. I tried looking through the commits that happened that day but couldn't find the exact source of the issue.
Activity
parched commentedon Mar 7, 2018
The will have been the upgrade to LLVM 6.
parched commentedon Mar 7, 2018
Try again once the LLVM 6 fixes are in, but I can't see an obvious fix for this.
paoloteti commentedon Mar 7, 2018
Your example compile without errors on
nightly 2018-03-05aasosaa commentedon Mar 7, 2018
No I tried 2018-03-05 and it failed with same error.
rust from
https://static.rust-lang.org/dist/2018-03-05/rust-nightly-x86_64-unknown-linux-gnu.tar.gzcommand:
paoloteti commentedon Mar 8, 2018
Yes sorry I was wrong, I mixed up open terminals. BTW this issue looks like: https://bugs.llvm.org/show_bug.cgi?id=36144.
So you can't use
1or0as local labels. Changing label to5: jmp 5bthe issue disappear.aasosaa commentedon Mar 8, 2018
Great, thanks for finding that! Fixes the issue.