psamolysov added a comment.
I tried to triage a bit. The test
`lldb\test\API\functionalities\unused-inlined-parameters\TestUnusedInlinedParameters.py`
compiles the code in `main.c` with `-O1` and generates the following IR for
the `@f` function:
; Function Attrs: alwaysinline nounwind uwtable
define dso_local void @f(ptr nocapture noundef readnone %unused1, i32 noundef
%used, i32 noundef %unused2) local_unnamed_addr #1 {
entry:
tail call void @use(i32 noundef %used)
ret void
}
With the reverted patch, the IR looks like the follow:
; Function Attrs: alwaysinline nounwind uwtable
define dso_local void @f(ptr nocapture readnone %unused1, i32 noundef %used,
i32 %unused2) local_unnamed_addr #1 {
entry:
tail call void @use(i32 noundef %used)
ret void
}
So, as we can see, the attribute `readnone` is present for the first unused
argument for which an additional piece of the DWARF code is generated in both
IRs but the `noundef` attribute is omitted in the second case (so, this
attribute is introduces by some changes in the patch and this is "documented"
by the changes in the `llvm/test/Transforms/InstCombine/unused-nonnull.ll`
test).
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D128830/new/
https://reviews.llvm.org/D128830
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