2009-11-24 Martin Jambor <mjambor@suse.cz>

	PR tree-optimization/42154
	* tree-sra.c (struct access): Added comments.
	(sra_modify_expr): Build references to the old aggregate with
	build_ref_for_offset instead of reusing access->expr.
	(load_assign_lhs_subreplacements): Likewise.

	* testsuite/gcc.c-torture/execute/pr42154.c: New test.



git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@154493 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 26 insertions, 7 deletions

diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index fe82d9851be..52036851587 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -125,7 +125,9 @@ struct access
   HOST_WIDE_INT size;
   tree base;
 
-  /* Expression.  */
+  /* Expression.  It is context dependent so do not use it to create new
+     expressions to access the original aggregate.  See PR 42154 for a
+     testcase.  */
   tree expr;
   /* Type.  */
   tree type;
@@ -2113,10 +2115,17 @@ sra_modify_expr (tree *expr, gimple_stmt_iterator *gsi, bool write,
 	 gcc.c-torture/compile/20011217-1.c.  */
       if (!is_gimple_reg_type (type))
 	{
-	  gimple stmt;
+	  tree ref = access->base;
+	  bool ok;
+
+	  ok = build_ref_for_offset (&ref, TREE_TYPE (ref),
+				     access->offset, access->type, false);
+	  gcc_assert (ok);
+
 	  if (write)
 	    {
-	      tree ref = unshare_expr (access->expr);
+	      gimple stmt;
+
 	      if (access->grp_partial_lhs)
 		ref = force_gimple_operand_gsi (gsi, ref, true, NULL_TREE,
 						 false, GSI_NEW_STMT);
@@ -2125,10 +2134,12 @@ sra_modify_expr (tree *expr, gimple_stmt_iterator *gsi, bool write,
 	    }
 	  else
 	    {
+	      gimple stmt;
+
 	      if (access->grp_partial_lhs)
 		repl = force_gimple_operand_gsi (gsi, repl, true, NULL_TREE,
 						 true, GSI_SAME_STMT);
-	      stmt = gimple_build_assign (unshare_expr (access->expr), repl);
+	      stmt = gimple_build_assign (ref, repl);
 	      gsi_insert_before (gsi, stmt, GSI_SAME_STMT);
 	    }
 	}
@@ -2227,8 +2238,6 @@ load_assign_lhs_subreplacements (struct access *lacc, struct access *top_racc,
 	    }
 	  else
 	    {
-	      bool repl_found;
-
 	      /* No suitable access on the right hand side, need to load from
 		 the aggregate.  See if we have to update it first... */
 	      if (*refreshed == SRA_UDH_NONE)
@@ -2236,9 +2245,19 @@ load_assign_lhs_subreplacements (struct access *lacc, struct access *top_racc,
 								  lhs, old_gsi);
 
 	      if (*refreshed == SRA_UDH_LEFT)
-		rhs = unshare_expr (lacc->expr);
+		{
+		  bool repl_found;
+
+		  rhs = lacc->base;
+		  repl_found = build_ref_for_offset (&rhs, TREE_TYPE (rhs),
+						     lacc->offset, lacc->type,
+						     false);
+		  gcc_assert (repl_found);
+		}
 	      else
 		{
+		  bool repl_found;
+
 		  rhs = top_racc->base;
 		  repl_found = build_ref_for_offset (&rhs,
 						     TREE_TYPE (top_racc->base),