[all-commits] [llvm/llvm-project] dcf336: [lld][WebAssembly] Retain data segments referenced...

[Yuta Saito via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: dcf3368e33c3a01bd21b692d3be5dc1ecee587f4
      https://github.com/llvm/llvm-project/commit/dcf3368e33c3a01bd21b692d3be5dc1ecee587f4
  Author: Yuta Saito <kateinoigakukun at gmail.com>
  Date:   2022-06-04 (Sat, 04 Jun 2022)

  Changed paths:
    A lld/test/wasm/gc-sections-startstop.s
    M lld/wasm/MarkLive.cpp

  Log Message:
  -----------
  [lld][WebAssembly] Retain data segments referenced via __start/__stop

As well as ELF linker does, retain all data segments named X referenced
through `__start_X` or `__stop_X`.

For example, `FOO_MD` should not be stripped in the below case, but it's currently mis-stripped

```llvm
@FOO_MD  = global [4 x i8] c"bar\00", section "foo_md", align 1
@__start_foo_md = external constant i8*
@__stop_foo_md = external constant i8*
@llvm.used = appending global [1 x i8*] [i8* bitcast (i32 ()* @foo_md_size to i8*)], section "llvm.metadata"

define i32 @foo_md_size()  {
entry:
  ret i32 sub (
    i32 ptrtoint (i8** @__stop_foo_md to i32),
    i32 ptrtoint (i8** @__start_foo_md to i32)
  )
}
```

This fixes https://github.com/llvm/llvm-project/issues/55839

Reviewed By: sbc100

Differential Revision: https://reviews.llvm.org/D126950