[PATCH] Fix PR38884

[PATCH] Fix PR38884

[Richard Guenther]

This handles the case of CSEing part of an SSA name that is stored
to memory and defined with a composition like COMPLEX_EXPR or
CONSTRUCTOR.  This fixes the remaining pieces of PR38884 and
PR38885.

Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.

Richard.

2011-10-06  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/38884
	* tree-ssa-sccvn.c (vn_reference_lookup_3): Handle partial
	reads from aggregate SSA names.

	* gcc.dg/tree-ssa/ssa-fre-34.c: New testcase.
	* gcc.dg/tree-ssa/ssa-fre-35.c: Likewise.

Index: gcc/tree-ssa-sccvn.c
===================================================================
*** gcc/tree-ssa-sccvn.c	(revision 179556)
--- gcc/tree-ssa-sccvn.c	(working copy)
*************** vn_reference_lookup_3 (ao_ref *ref, tree
*** 1489,1495 ****
  	}
      }
  
!   /* 4) For aggregate copies translate the reference through them if
       the copy kills ref.  */
    else if (vn_walk_kind == VN_WALKREWRITE
  	   && gimple_assign_single_p (def_stmt)
--- 1489,1554 ----
  	}
      }
  
!   /* 4) Assignment from an SSA name which definition we may be able
!      to access pieces from.  */
!   else if (ref->size == maxsize
! 	   && is_gimple_reg_type (vr->type)
! 	   && gimple_assign_single_p (def_stmt)
! 	   && TREE_CODE (gimple_assign_rhs1 (def_stmt)) == SSA_NAME)
!     {
!       tree rhs1 = gimple_assign_rhs1 (def_stmt);
!       gimple def_stmt2 = SSA_NAME_DEF_STMT (rhs1);
!       if (is_gimple_assign (def_stmt2)
! 	  && (gimple_assign_rhs_code (def_stmt2) == COMPLEX_EXPR
! 	      || gimple_assign_rhs_code (def_stmt2) == CONSTRUCTOR)
! 	  && types_compatible_p (vr->type, TREE_TYPE (TREE_TYPE (rhs1))))
! 	{
! 	  tree base2;
! 	  HOST_WIDE_INT offset2, size2, maxsize2, off;
! 	  base2 = get_ref_base_and_extent (gimple_assign_lhs (def_stmt),
! 					   &offset2, &size2, &maxsize2);
! 	  off = offset - offset2;
! 	  if (maxsize2 != -1
! 	      && maxsize2 == size2
! 	      && operand_equal_p (base, base2, 0)
! 	      && offset2 <= offset
! 	      && offset2 + size2 >= offset + maxsize)
! 	    {
! 	      tree val = NULL_TREE;
! 	      HOST_WIDE_INT elsz
! 		= TREE_INT_CST_LOW (TYPE_SIZE (TREE_TYPE (TREE_TYPE (rhs1))));
! 	      if (gimple_assign_rhs_code (def_stmt2) == COMPLEX_EXPR)
! 		{
! 		  if (off == 0)
! 		    val = gimple_assign_rhs1 (def_stmt2);
! 		  else if (off == elsz)
! 		    val = gimple_assign_rhs2 (def_stmt2);
! 		}
! 	      else if (gimple_assign_rhs_code (def_stmt2) == CONSTRUCTOR
! 		       && off % elsz == 0)
! 		{
! 		  tree ctor = gimple_assign_rhs1 (def_stmt2);
! 		  unsigned i = off / elsz;
! 		  if (i < CONSTRUCTOR_NELTS (ctor))
! 		    {
! 		      constructor_elt *elt = CONSTRUCTOR_ELT (ctor, i);
! 		      if (compare_tree_int (elt->index, i) == 0)
! 			val = elt->value;
! 		    }
! 		}
! 	      if (val)
! 		{
! 		  unsigned int value_id = get_or_alloc_constant_value_id (val);
! 		  return vn_reference_insert_pieces
! 		           (vuse, vr->set, vr->type,
! 			    VEC_copy (vn_reference_op_s, heap, vr->operands),
! 			    val, value_id);
! 		}
! 	    }
! 	}
!     }
! 
!   /* 5) For aggregate copies translate the reference through them if
       the copy kills ref.  */
    else if (vn_walk_kind == VN_WALKREWRITE
  	   && gimple_assign_single_p (def_stmt)
*************** vn_reference_lookup_3 (ao_ref *ref, tree
*** 1587,1593 ****
        return NULL;
      }
  
!   /* 5) For memcpy copies translate the reference through them if
       the copy kills ref.  */
    else if (vn_walk_kind == VN_WALKREWRITE
  	   && is_gimple_reg_type (vr->type)
--- 1646,1652 ----
        return NULL;
      }
  
!   /* 6) For memcpy copies translate the reference through them if
       the copy kills ref.  */
    else if (vn_walk_kind == VN_WALKREWRITE
  	   && is_gimple_reg_type (vr->type)
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-34.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-34.c	(revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-34.c	(revision 0)
***************
*** 0 ****
--- 1,18 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fdump-tree-fre1-details" } */
+ 
+ #define vector __attribute__((vector_size(16) ))
+ 
+ struct {
+     float i;
+     vector float global_res;
+ } s;
+ float foo(float f)
+ {
+   vector float res = (vector float){0.0f,f,0.0f,1.0f};
+   s.global_res = res;
+   return *((float*)&s.global_res + 1);
+ }
+ 
+ /* { dg-final { scan-tree-dump "Replaced BIT_FIELD_REF.*with f" "fre1" } } */
+ /* { dg-final { cleanup-tree-dump "fre1" } } */
Index: gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-35.c
===================================================================
*** gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-35.c	(revision 0)
--- gcc/testsuite/gcc.dg/tree-ssa/ssa-fre-35.c	(revision 0)
***************
*** 0 ****
--- 1,17 ----
+ /* { dg-do compile } */
+ /* { dg-options "-O -fdump-tree-fre1-details" } */
+ 
+ struct s { _Complex float i; };
+ void g(struct s *);
+ 
+ float a1 (float dd)
+ {
+   struct s sv;
+   sv.i = dd;
+   float d = __real__ sv.i;
+   g(&sv);
+   return d;
+ }
+ 
+ /* { dg-final { scan-tree-dump "Replaced REALPART_EXPR.*with dd" "fre1" } } */
+ /* { dg-final { cleanup-tree-dump "fre1" } } */

Re: [PATCH] Fix PR38884

[H.J. Lu]

On Thu, Oct 6, 2011 at 1:36 AM, Richard Guenther <rguenther@suse.de> wrote:
>
> This handles the case of CSEing part of an SSA name that is stored
> to memory and defined with a composition like COMPLEX_EXPR or
> CONSTRUCTOR.  This fixes the remaining pieces of PR38884 and
> PR38885.
>
> Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk.
>
> Richard.
>
> 2011-10-06  Richard Guenther  <rguenther@suse.de>
>
>        PR tree-optimization/38884
>        * tree-ssa-sccvn.c (vn_reference_lookup_3): Handle partial
>        reads from aggregate SSA names.
>

This caused:

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53144

-- 
H.J.