[mpich2-dev] [PATCH 1/1] Issue 4120: Fix attr alignment check from MPI_Aint to long alignment

[William Gropp]

This one is system-specific - some systems will require the MPI_Aint  
alignment.   This should probably be abstracted out and set based on  
the requirements of the system.

Bill

On Mar 21, 2008, at 10:14 AM, Jeff Parker wrote:

> In the mpi/attr code, there were checks to ensure the attribute was  
> aligned on a void*
> boundary.  This check anded the pointer with sizeof(MPI_Aint)-1.   
> In the case of an
> MPI_Aint being 8 bytes, this was forcing the attribute to be on an  
> 8-byte boundary, when
> in fact a 4-byte boundary would do.  Changed the and operation to  
> use sizeof(long)-1 instead.
>
> Signed-off-by: Jeff Parker <jjparker at us.ibm.com>
> ---
>  lib/mpi/mpich2/src/mpi/attr/attr_get.c      |    7 +++++--
>  lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c |    7 +++++--
>  lib/mpi/mpich2/src/mpi/attr/type_get_attr.c |    7 +++++--
>  lib/mpi/mpich2/src/mpi/attr/win_get_attr.c  |    9 ++++++---
>  4 files changed, 21 insertions(+), 9 deletions(-)
>
> diff --git a/lib/mpi/mpich2/src/mpi/attr/attr_get.c b/lib/mpi/ 
> mpich2/src/mpi/attr/attr_get.c
> index 095c979..cc39822 100644
> --- a/lib/mpi/mpich2/src/mpi/attr/attr_get.c
> +++ b/lib/mpi/mpich2/src/mpi/attr/attr_get.c
> @@ -93,8 +93,11 @@ int MPI_Attr_get(MPI_Comm comm, int keyval, void  
> *attr_value, int *flag)
>  	       int when the address of a pointer (or an address-sized int)
>  	       should have been used.  We can test for this specific
>  	       case.  Note that this code assumes sizeof(MPI_Aint) is
> -	       a power of 2. */
> -	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof 
> (MPI_Aint)-1)) {
> +	       a power of 2. Note that this formerly used MPI_Aint for the
> +               address sized int, but since this is configurable  
> and could
> +               be larger than a pointer, we use long for the  
> check, since
> +               long is expected to be the size of a pointer.*/
> +	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attr_value & (sizeof 
> (long)-1)) {
>  		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
>  	    }
>  #           endif
> diff --git a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c b/lib/mpi/ 
> mpich2/src/mpi/attr/comm_get_attr.c
> index ce5c836..b243968 100644
> --- a/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
> +++ b/lib/mpi/mpich2/src/mpi/attr/comm_get_attr.c
> @@ -85,8 +85,11 @@ int MPI_Comm_get_attr(MPI_Comm comm, int  
> comm_keyval, void *attribute_val, int *
>  	       int when the address of a pointer (or an address-sized int)
>  	       should have been used.  We can test for this specific
>  	       case.  Note that this code assumes sizeof(MPI_Aint) is
> -	       a power of 2. */
> -	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (MPI_Aint)-1)) {
> +	       a power of 2. Note that this formerly used MPI_Aint for the
> +               address sized int, but since this is configurable  
> and could
> +               be larger than a pointer, we use long for the  
> check, since
> +               long is expected to be the size of a pointer. */
> +	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (long)-1)) {
>  		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
>  	    }
>  #           endif
> diff --git a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c b/lib/mpi/ 
> mpich2/src/mpi/attr/type_get_attr.c
> index 7547bbb..7a41051 100644
> --- a/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
> +++ b/lib/mpi/mpich2/src/mpi/attr/type_get_attr.c
> @@ -87,8 +87,11 @@ int MPI_Type_get_attr(MPI_Datatype type, int  
> type_keyval, void *attribute_val,
>  	       int when the address of a pointer (or an address-sized int)
>  	       should have been used.  We can test for this specific
>  	       case.  Note that this code assumes sizeof(MPI_Aint) is
> -	       a power of 2. */
> -	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (MPI_Aint)-1)) {
> +	       a power of 2. Note that this formerly used MPI_Aint for the
> +               address sized int, but since this is configurable  
> and could
> +               be larger than a pointer, we use long for the  
> check, since
> +               long is expected to be the size of a pointer. */
> +	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (long)-1)) {
>  		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
>  	    }
>  #           endif
> diff --git a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c b/lib/mpi/ 
> mpich2/src/mpi/attr/win_get_attr.c
> index 5fbef66..921f018 100644
> --- a/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
> +++ b/lib/mpi/mpich2/src/mpi/attr/win_get_attr.c
> @@ -82,9 +82,12 @@ int MPI_Win_get_attr(MPI_Win win, int  
> win_keyval, void *attribute_val,
>              /* A common user error is to pass the address of a 4-byte
>  	       int when the address of a pointer (or an address-sized int)
>  	       should have been used.  We can test for this specific
> -	       case.  Note that this code assumes sizeof(MPI_Aint) is
> -	       a power of 2. */
> -	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (MPI_Aint)-1)) {
> +	       case.  Note that this code assumes sizeof(long) is
> +	       a power of 2. Note that this formerly used MPI_Aint for the
> +               address sized int, but since this is configurable  
> and could
> +               be larger than a pointer, we use long for the  
> check, since
> +               long is expected to be the size of a pointer. */
> +	    if (MPI_VOID_PTR_CAST_TO_MPI_AINT attribute_val & (sizeof 
> (long)-1)) {
>  		MPIU_ERR_SET(mpi_errno,MPI_ERR_ARG,"**attrnotptr");
>  	    }
>  #           endif
> -- 
> 1.5.3.7
>

William Gropp
Paul and Cynthia Saylor Professor of Computer Science
University of Illinois Urbana-Champaign


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