[all-commits] [llvm/llvm-project] 6baaad: [Bitcode] Include indirect users of BlockAddresses...

[Wende Tan via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 6baaad740a5abb4bfcff022a8114abb4eea66a2d
      https://github.com/llvm/llvm-project/commit/6baaad740a5abb4bfcff022a8114abb4eea66a2d
  Author: Wende Tan <twd2.me at gmail.com>
  Date:   2022-05-10 (Tue, 10 May 2022)

  Changed paths:
    M llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
    A llvm/test/Bitcode/blockaddress-aggregate-users.ll
    A llvm/test/Bitcode/blockaddress-expr-users.ll
    A llvm/test/Bitcode/blockaddress-globalvalue-users.ll
    A llvm/test/Bitcode/blockaddress-nested-users.ll

  Log Message:
  -----------
  [Bitcode] Include indirect users of BlockAddresses in bitcode

The original fix (commit 23ec5782c3cc) 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: 23ec5782c3cc ("[Bitcode] materialize Functions early when BlockAddress taken")

Reviewed By: nickdesaulniers

Differential Revision: https://reviews.llvm.org/D124878