[PATCH] ipa-sra: Improve debug info for removed parameters (PR 93385)

Martin Jambor mjambor@suse.cz
Thu Nov 4 16:55:20 GMT 2021


Hi,

On Wed, Nov 03 2021, Richard Biener wrote:
> On Mon, 1 Nov 2021, Martin Jambor wrote:
>
>> Hello,
>> 
>> I'd like to ping this patch.
>> 
>> Thanks,
>> 
>> Martin
>> 
>> 
>> On Wed, Oct 13 2021, Martin Jambor wrote:
>> > Hi,
>> >
>> > in spring I added code eliminating any statements using parameters
>> > removed by IPA passes (to fix PR 93385).  That patch fixed issues such
>> > as divisions by zero that such code could perform but it only reset
>> > all affected debug bind statements, this one updates them with
>> > expressions which can allow the debugger to print the removed value -
>> > see the added test-case for an example.
>> >
[...]
>> >
>> > Bootstrapped and tested on x86_64-linux, i686-linux and (long time
>> > ago) on aarch64-linux.  Also LTO-bootstrapped and on x86_64-linux.
>> >
>> > Perhaps it is good to go to trunk?
>
> I think the patch is OK for trunk.  It would be nice to common the

Thank you very much, I will commit the patch shortly after a rebase and
a final test.

>
> +      tree vexpr = make_node (DEBUG_EXPR_DECL);
> +      DECL_ARTIFICIAL (vexpr) = 1;
> +      TREE_TYPE (vexpr) = TREE_TYPE (val);
> +      SET_DECL_MODE (vexpr, TYPE_MODE (TREE_TYPE (val)));
>
> blob that exists all over the GCC code base with a new
> build_debug_expr_decl (tree type) (next to tree.c:build_decl).
>

That makes sense, I'll prepare a patch as a follow-up.

A minority of places in GCC which produce a DEBUG_DECL_EXPR however set
its mode like cfgexpand.c does:

    tree vexpr = make_node (DEBUG_EXPR_DECL);
    DECL_ARTIFICIAL (vexpr) = 1;
    TREE_TYPE (vexpr) = TREE_TYPE (value);
    if (DECL_P (value))
      mode = DECL_MODE (value);
    else
      mode = TYPE_MODE (TREE_TYPE (value));
    SET_DECL_MODE (vexpr, mode);

Should build_debug_expr_decl's parameter be perhaps more general,
allowing both DECLs, TYPEs and use its TREE_TYPE if it is neither)?

Or should I leave such places as they are and only convert those that
set the mode to TYPE_MODE (type)?

Thanks,

Martin


>> >
>> > gcc/ChangeLog:
>> >
>> > 2021-03-29  Martin Jambor  <mjambor@suse.cz>
>> >
>> > 	PR ipa/93385
>> > 	* ipa-param-manipulation.h (class ipa_param_body_adjustments): New
>> > 	members remap_with_debug_expressions, m_dead_ssa_debug_equiv,
>> > 	m_dead_stmt_debug_equiv and prepare_debug_expressions.  Added
>> > 	parameter to mark_dead_statements.
>> > 	* ipa-param-manipulation.c: Include tree-phinodes.h and cfgexpand.h.
>> > 	(ipa_param_body_adjustments::mark_dead_statements): New parameter
>> > 	debugstack, push into it all SSA names used in debug statements,
>> > 	produce m_dead_ssa_debug_equiv mapping for the removed param.
>> > 	(replace_with_mapped_expr): New function.
>> > 	(ipa_param_body_adjustments::remap_with_debug_expressions): Likewise.
>> > 	(ipa_param_body_adjustments::prepare_debug_expressions): Likewise.
>> > 	(ipa_param_body_adjustments::common_initialization): Gather and
>> > 	procecc SSA which will be removed but are in debug statements. Simplify.
>> > 	(ipa_param_body_adjustments::ipa_param_body_adjustments): Initialize
>> > 	new members.
>> > 	* tree-inline.c (remap_gimple_stmt): Create a debug bind when possible
>> > 	when avoiding a copy of an unnecessary statement.  Remap removed SSA
>> > 	names in existing debug statements.
>> > 	(tree_function_versioning): Do not create DEBUG_EXPR_DECL for removed
>> > 	parameters if we have already done so.
>> >
>> > gcc/testsuite/ChangeLog:
>> >
>> > 2021-03-29  Martin Jambor  <mjambor@suse.cz>
>> >
>> > 	PR ipa/93385
>> > 	* gcc.dg/guality/ipa-sra-1.c: New test.


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