| Issue |
143368
|
| Summary |
Missed deadcode elimination when using `phi`
|
| Labels |
new issue
|
| Assignees |
|
| Reporter |
GINN-Imp
|
The following reduced IR is derived from https://github.com/clap-rs/clap/blob/1036060f1319412d3d50d821a7b39a0a0122f0f7/clap_builder/src/parser/parser.rs#L49
Godbolt: https://godbolt.org/z/aedE1YjfK
alive2 proof: https://alive2.llvm.org/ce/z/Df2FFT
opt-O3 works as expected when `phi` is replaced with simpler instructions.
```llvm
define void @_ZN12clap_builder6parser6parser6Parser16get_matches_with17h7b0a6fdc0204a479E(i64 %0, ptr %p) personality ptr null {
%2 = xor i64 %0, 1
switch i64 %2, label %3 [
i64 0, label %common.ret
i64 3, label %4
]
common.ret:
ret void
3:
br label %4
4:
%.0 = phi i8 [ 0, %3 ], [ 1, %1 ]
%cond2 = icmp eq i64 %0, 1
br i1 %cond2, label %5, label %common.ret
5:
store i8 %.0, ptr %p, align 1
br label %common.ret
}
```
expected:
```llvm
define void @tgt(i64 %0, ptr %p) personality ptr null {
ret void
}
```
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