The original fix (commit 23ec5782c3) of
https://github.com/llvm/llvm-project/issues/52787 only adds `Function`s
that have `Instruction`s that directly use `BlockAddress`es into the
bitcode (`FUNC_CODE_BLOCKADDR_USERS`).
However, in either @rickyz's original reproducing code:
```
void f(long);
__attribute__((noinline)) static void fun(long x) {
f(x + 1);
}
void repro(void) {
fun(({
label:
(long)&&label;
}));
}
```
```
...
define dso_local void @repro() #0 {
entry:
br label %label
label: ; preds = %entry
tail call fastcc void @fun()
ret void
}
define internal fastcc void @fun() unnamed_addr #1 {
entry:
tail call void @f(i64 add (i64 ptrtoint (i8* blockaddress(@repro, %label) to i64), i64 1)) #3
ret void
}
...
```
or the xfs and overlayfs in the Linux kernel, `BlockAddress`es (e.g.,
`i8* blockaddress(@repro, %label)`) may first compose `ConstantExpr`s
(e.g., `i64 ptrtoint (i8* blockaddress(@repro, %label) to i64)`) and
then used by `Instruction`s. This case is not handled by the original
fix.
This patch adds *indirect* users of `BlockAddress`es, i.e., the
`Instruction`s using some `Constant`s which further use the
`BlockAddress`es, into the bitcode as well, by doing depth-first
searches.
Fixes: https://github.com/llvm/llvm-project/issues/52787
Fixes: 23ec5782c3 ("[Bitcode] materialize Functions early when BlockAddress taken")
Reviewed By: nickdesaulniers
Differential Revision: https://reviews.llvm.org/D124878
Wende Tan