--emit=asm,link -C opt-level=1 causes "Instruction does not dominate all uses!"

[huonw]

fn main() {
    let mut v = 0;
    for i in 0..0 {
        v += i;
    }
    println!("{}", v)
}

Compiling with rustc --emit=asm,link -C opt-level=1 (with 1.1.0-nightly (da623844a 2015-04-25) (built 2015-04-26) gives:

Instruction does not dominate all uses!
  %1 = bitcast %"2.core::fmt::Arguments"* %0 to i64*
  %tmpcast = bitcast i64* %1 to %"2.core::ops::Range<i32>"*
LLVM ERROR: Broken function found, compilation aborted!

[apasel422]

Still ICEs with the given compilation command.

[arielb1]

cc @dotdash

[dotdash]

This is due to stack coloring / merging of stack slots. When preparing the asm for output, stack merging eliminates an alloca leading to non-SSA compliant IR, which is fine for this pass, but we're re-using the same IR again, and then the verifier rightfully complains.