[PATCH] sra: Avoid verification failure (PR 93516)

[Richard Biener]

On Fri, 14 Feb 2020, Martin Jambor wrote:

> Hi,
> 
> get_ref_base_and_extent can return different sizes for COMPONENT_REFs
> and DECLs of the same type, with the latter including (more?)  padding.
> When in the IL there is an assignment between such a COMPONENT_REF and a
> DECL, SRA will try to propagate the access from the former as a child of
> the latter, creating an artificial reference that does not match the
> access's declared size, which triggers a verifier assert.

"both" use DECL_SIZE, but those can differ dependent on alignment
for example.

> Fixed by teaching the propagation functions about this special situation
> so that they don't do it.  The condition is the same that
> build_user_friendly_ref_for_offset uses so the artificial reference
> causing the verifier is guaranteed not to be created.
> 
> Bootstrapped and tested on x86_64-linux.  OK for trunk?

OK.

Thanks,
Richard.

> Thanks,
> 
> Martin
> 
> 
> 2020-02-10  Martin Jambor  <mjambor@suse.cz>
> 	PR tree-optimization/93516
> 	* tree-sra.c (propagate_subaccesses_from_rhs): Do not create
> 	access of the same type as the parent.
> 	(propagate_subaccesses_from_lhs): Likewise.
> 
> 	gcc/testsuite/
> 	* g++.dg/tree-ssa/pr93516.C: New test.
> ---
>  gcc/ChangeLog                           |  7 ++++++
>  gcc/testsuite/ChangeLog                 |  5 ++++
>  gcc/testsuite/g++.dg/tree-ssa/pr93516.C | 24 +++++++++++++++++++
>  gcc/tree-sra.c                          | 31 +++++++++++++++++++------
>  4 files changed, 60 insertions(+), 7 deletions(-)
>  create mode 100644 gcc/testsuite/g++.dg/tree-ssa/pr93516.C
> 
> diff --git a/gcc/ChangeLog b/gcc/ChangeLog
> index fa3cbb895e9..daba335cf79 100644
> --- a/gcc/ChangeLog
> +++ b/gcc/ChangeLog
> @@ -1,3 +1,10 @@
> +2020-02-10  Martin Jambor  <mjambor@suse.cz>
> +
> +	PR tree-optimization/93516
> +	* tree-sra.c (propagate_subaccesses_from_rhs): Do not create
> +	access of the same type as the parent.
> +	(propagate_subaccesses_from_lhs): Likewise.
> +
>  2020-02-10  Feng Xue  <fxue@os.amperecomputing.com>
>  
>  	PR ipa/93203
> diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
> index 0ede9604611..eada2ebed63 100644
> --- a/gcc/testsuite/ChangeLog
> +++ b/gcc/testsuite/ChangeLog
> @@ -1,3 +1,8 @@
> +2020-02-10  Martin Jambor  <mjambor@suse.cz>
> +
> +	PR tree-optimization/93516
> +	* g++.dg/tree-ssa/pr93516.C: New test.
> +
>  2020-02-10  Feng Xue  <fxue@os.amperecomputing.com>
>  
>  	PR ipa/93203
> diff --git a/gcc/testsuite/g++.dg/tree-ssa/pr93516.C b/gcc/testsuite/g++.dg/tree-ssa/pr93516.C
> new file mode 100644
> index 00000000000..2bba37c1386
> --- /dev/null
> +++ b/gcc/testsuite/g++.dg/tree-ssa/pr93516.C
> @@ -0,0 +1,24 @@
> +// { dg-do compile }
> +// { dg-options "-O2" } */
> +
> +struct b;
> +struct c {
> +  b *operator->();
> +};
> +class e {
> +  void *f;
> +  int d;
> +
> +public:
> +  template <typename a> a g() { return *static_cast<a *>(this); }
> +};
> +struct h : e {};
> +struct b {
> +  void i(e);
> +  e j();
> +};
> +void m() {
> +  c k;
> +  h l = k->j().g<h>();
> +  k->i(l);
> +}
> diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
> index ea8594db193..a3bcd5f3e03 100644
> --- a/gcc/tree-sra.c
> +++ b/gcc/tree-sra.c
> @@ -2785,9 +2785,17 @@ propagate_subaccesses_from_rhs (struct access *lacc, struct access *racc)
>  	}
>  
>        rchild->grp_hint = 1;
> -      new_acc = create_artificial_child_access (lacc, rchild, norm_offset,
> -						false, (lacc->grp_write
> -							|| rchild->grp_write));
> +      /* Because get_ref_base_and_extent always includes padding in size for
> +	 accesses to DECLs but not necessarily for COMPONENT_REFs of the same
> +	 type, we might be actually attempting to here to create a child of the
> +	 same type as the parent.  */
> +      if (!types_compatible_p (lacc->type, rchild->type))
> +	new_acc = create_artificial_child_access (lacc, rchild, norm_offset,
> +						  false,
> +						  (lacc->grp_write
> +						   || rchild->grp_write));
> +      else
> +	new_acc = lacc;
>        gcc_checking_assert (new_acc);
>        if (racc->first_child)
>  	propagate_subaccesses_from_rhs (new_acc, rchild);
> @@ -2834,10 +2842,19 @@ propagate_subaccesses_from_lhs (struct access *lacc, struct access *racc)
>  	  continue;
>  	}
>  
> -      struct access *new_acc
> -	=  create_artificial_child_access (racc, lchild, norm_offset,
> -					   true, false);
> -      propagate_subaccesses_from_lhs (lchild, new_acc);
> +      /* Because get_ref_base_and_extent always includes padding in size for
> +	 accesses to DECLs but not necessarily for COMPONENT_REFs of the same
> +	 type, we might be actually attempting to here to create a child of the
> +	 same type as the parent.  */
> +      if (!types_compatible_p (racc->type, lchild->type))
> +	{
> +	  struct access *new_acc
> +	    = create_artificial_child_access (racc, lchild, norm_offset,
> +					      true, false);
> +	  propagate_subaccesses_from_lhs (lchild, new_acc);
> +	}
> +      else
> +	propagate_subaccesses_from_lhs (lchild, racc);
>        ret = true;
>      }
>    return ret;
> 

-- 
Richard Biener <rguenther@suse.de>
SUSE Software Solutions Germany GmbH, Maxfeldstrasse 5, 90409 Nuernberg,
Germany; GF: Felix Imendörffer; HRB 36809 (AG Nuernberg)