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diff -Nur gcc-4.8.2.orig/gcc/tree-ssa-forwprop.c gcc-4.8.2/gcc/tree-ssa-forwprop.c
--- gcc-4.8.2.orig/gcc/tree-ssa-forwprop.c 2013-02-25 16:31:31.000000000 +0100
+++ gcc-4.8.2/gcc/tree-ssa-forwprop.c 2014-03-22 19:37:04.797991879 +0100
@@ -688,6 +688,130 @@
recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
}
+ /* DEF_RHS contains the address of the 0th element in an array.
+ USE_STMT uses type of DEF_RHS to compute the address of an
+ arbitrary element within the array. The (variable) byte offset
+ of the element is contained in OFFSET.
+
+ We walk back through the use-def chains of OFFSET to verify that
+ it is indeed computing the offset of an element within the array
+ and extract the index corresponding to the given byte offset.
+
+ We then try to fold the entire address expression into a form
+ &array[index].
+
+ If we are successful, we replace the right hand side of USE_STMT
+ with the new address computation. */
+
+ static bool
+ forward_propagate_addr_into_variable_array_index (tree offset,
+ tree def_rhs,
+ gimple_stmt_iterator *use_stmt_gsi)
+ {
+ tree index, tunit;
+ gimple offset_def, use_stmt = gsi_stmt (*use_stmt_gsi);
+ tree new_rhs, tmp;
+
+ if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
+ tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)));
+ else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (def_rhs, 0))) == ARRAY_TYPE)
+ tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))));
+ else
+ return false;
+ if (!host_integerp (tunit, 1))
+ return false;
+
+ /* Get the offset's defining statement. */
+ offset_def = SSA_NAME_DEF_STMT (offset);
+
+ /* Try to find an expression for a proper index. This is either a
+ multiplication expression by the element size or just the ssa name we came
+ along in case the element size is one. In that case, however, we do not
+ allow multiplications because they can be computing index to a higher
+ level dimension (PR 37861). */
+ if (integer_onep (tunit))
+ {
+ if (is_gimple_assign (offset_def)
+ && gimple_assign_rhs_code (offset_def) == MULT_EXPR)
+ return false;
+
+ index = offset;
+ }
+ else
+ {
+ /* The statement which defines OFFSET before type conversion
+ must be a simple GIMPLE_ASSIGN. */
+ if (!is_gimple_assign (offset_def))
+ return false;
+
+ /* The RHS of the statement which defines OFFSET must be a
+ multiplication of an object by the size of the array elements.
+ This implicitly verifies that the size of the array elements
+ is constant. */
+ if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
+ && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
+ && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), tunit))
+ {
+ /* The first operand to the MULT_EXPR is the desired index. */
+ index = gimple_assign_rhs1 (offset_def);
+ }
+ /* If we have idx * tunit + CST * tunit re-associate that. */
+ else if ((gimple_assign_rhs_code (offset_def) == PLUS_EXPR
+ || gimple_assign_rhs_code (offset_def) == MINUS_EXPR)
+ && TREE_CODE (gimple_assign_rhs1 (offset_def)) == SSA_NAME
+ && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
+ && (tmp = div_if_zero_remainder (EXACT_DIV_EXPR,
+ gimple_assign_rhs2 (offset_def),
+ tunit)) != NULL_TREE)
+ {
+ gimple offset_def2 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (offset_def));
+ if (is_gimple_assign (offset_def2)
+ && gimple_assign_rhs_code (offset_def2) == MULT_EXPR
+ && TREE_CODE (gimple_assign_rhs2 (offset_def2)) == INTEGER_CST
+ && tree_int_cst_equal (gimple_assign_rhs2 (offset_def2), tunit))
+ {
+ index = fold_build2 (gimple_assign_rhs_code (offset_def),
+ TREE_TYPE (offset),
+ gimple_assign_rhs1 (offset_def2), tmp);
+ }
+ else
+ return false;
+ }
+ else
+ return false;
+ }
+
+ /* Replace the pointer addition with array indexing. */
+ index = force_gimple_operand_gsi (use_stmt_gsi, index, true, NULL_TREE,
+ true, GSI_SAME_STMT);
+ if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
+ {
+ new_rhs = unshare_expr (def_rhs);
+ TREE_OPERAND (TREE_OPERAND (new_rhs, 0), 1) = index;
+ }
+ else
+ {
+ new_rhs = build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))),
+ unshare_expr (TREE_OPERAND (def_rhs, 0)),
+ index, integer_zero_node, NULL_TREE);
+ new_rhs = build_fold_addr_expr (new_rhs);
+ if (!useless_type_conversion_p (TREE_TYPE (gimple_assign_lhs (use_stmt)),
+ TREE_TYPE (new_rhs)))
+ {
+ new_rhs = force_gimple_operand_gsi (use_stmt_gsi, new_rhs, true,
+ NULL_TREE, true, GSI_SAME_STMT);
+ new_rhs = fold_convert (TREE_TYPE (gimple_assign_lhs (use_stmt)),
+ new_rhs);
+ }
+ }
+ gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
+ fold_stmt (use_stmt_gsi);
+ tidy_after_forward_propagate_addr (gsi_stmt (*use_stmt_gsi));
+ return true;
+ }
+
+
+
/* NAME is a SSA_NAME representing DEF_RHS which is of the form
ADDR_EXPR <whatever>.
@@ -977,6 +1101,19 @@
tidy_after_forward_propagate_addr (use_stmt);
return true;
}
+ /* Try to optimize &x[0] p+ OFFSET where OFFSET is defined by
+ converting a multiplication of an index by the size of the
+ array elements, then the result is converted into the proper
+ type for the arithmetic. */
+ if (TREE_CODE (rhs2) == SSA_NAME
+ && (TREE_CODE (array_ref) != ARRAY_REF
+ || integer_zerop (TREE_OPERAND (array_ref, 1)))
+ && useless_type_conversion_p (TREE_TYPE (name), TREE_TYPE (def_rhs))
+ /* Avoid problems with IVopts creating PLUS_EXPRs with a
+ different type than their operands. */
+ && useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
+ return forward_propagate_addr_into_variable_array_index (rhs2, def_rhs,
+ use_stmt_gsi);
return false;
}
|
