Re: [PATCH 1/2] gdb/block: remove block_iterator::d::block, remove union

Andrew Burgess
2026-02-06T16:36:27Z

simon.marchi@polymtl.ca writes:

> From: Simon Marchi <simon.marchi@efficios.com>
>
> The block field is never used. The block is only used to grab a
> reference to the mdict, which is stored in the mdict_iterator.

Isn't there a contradiction between these two sentences? Either the
block is not used, or it's used to access the mdict?

Thanks,
Andrew

>
> Remove it and remove the union. Leave the compunit_symtab field, whose
> name unfortunately conflicts with the method.
>
> Change-Id: I09dbc42f937eaba6c70598acca8ff355c4e5bdb9
> ---
> gdb/block.c | 9 +++------
> gdb/block.h | 13 ++++++-------
> 2 files changed, 9 insertions(+), 13 deletions(-)
>
> diff --git a/gdb/block.c b/gdb/block.c
> index 64ca59d44a1d..5aa58545393b 100644
> --- a/gdb/block.c
> +++ b/gdb/block.c
> @@ -407,8 +407,6 @@ initialize_block_iterator (const struct block *block,
> which = STATIC_BLOCK;
> else
> {
> - iter->d.block = block;
> -
> /* A signal value meaning that we're iterating over a single
> block. */
> iter->which = FIRST_LOCAL_BLOCK;
> @@ -428,14 +426,13 @@ initialize_block_iterator (const struct block *block,
> directly. */
> if (cu->includes.empty ())
> {
> - iter->d.block = block;
> /* A signal value meaning that we're iterating over a single
> block. */
> iter->which = FIRST_LOCAL_BLOCK;
> }
> else
> {
> - iter->d.compunit_symtab = cu;
> + iter->compunit_symtab_ = cu;
> iter->which = which;
> }
> }
> @@ -446,9 +443,9 @@ compunit_symtab *
> block_iterator::compunit_symtab () const
> {
> if (this->idx == -1)
> - return this->d.compunit_symtab;
> + return this->compunit_symtab_;
>
> - auto &includes = this->d.compunit_symtab->includes;
> + auto &includes = this->compunit_symtab_->includes;
>
> if (this->idx < includes.size ())
> return includes[this->idx];
> diff --git a/gdb/block.h b/gdb/block.h
> index d9a8c4b6ff89..b84ca12c35a6 100644
> --- a/gdb/block.h
> +++ b/gdb/block.h
> @@ -557,14 +557,13 @@ struct block_iterator
> iterates. Return nullptr if the iteration is finished. */
> struct compunit_symtab *compunit_symtab () const;
>
> - /* If we're iterating over a single block, this holds the block.
> - Otherwise, it holds the canonical compunit. */
> + /* If iterating on a global or static blocks, iteration starts from the
> + top-level CU and then continues with the global or static blocks of all
> + the included CUs. This field holds the compunit of the current block.
>
> - union
> - {
> - struct compunit_symtab *compunit_symtab;
> - const struct block *block;
> - } d;
> + This field is not private because block_iterator must remain trivial,
> + but treat it as private. */
> + struct compunit_symtab *compunit_symtab_;
>
> /* If we're trying to match a name, this will be non-NULL. */
> const lookup_name_info *name;
>
> base-commit: 1d688bb5f48a0feddf3ca3c60af2e91f4147dc36
> --
> 2.52.0