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author | Marc Glisse <marc.glisse@inria.fr> | 2017-11-21 19:23:56 +0100 |
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committer | Marc Glisse <glisse@gcc.gnu.org> | 2017-11-21 18:23:56 +0000 |
commit | 1af4ebf5985ef2aaac13862654044d84a3cd7ae4 (patch) | |
tree | 6136f270e536b46d7d9de96d28e38794684035dd /gcc/c/c-typeck.c | |
parent | ffb41aab7a9b8475e773b75fdebd194f4491c9db (diff) | |
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New POINTER_DIFF_EXPR
2017-11-21 Marc Glisse <marc.glisse@inria.fr>
gcc/c/
* c-fold.c (c_fully_fold_internal): Handle POINTER_DIFF_EXPR.
* c-typeck.c (pointer_diff): Use POINTER_DIFF_EXPR.
gcc/c-family/
* c-pretty-print.c (pp_c_additive_expression,
c_pretty_printer::expression): Handle POINTER_DIFF_EXPR.
gcc/cp/
* constexpr.c (cxx_eval_constant_expression,
potential_constant_expression_1): Handle POINTER_DIFF_EXPR.
* cp-gimplify.c (cp_fold): Likewise.
* error.c (dump_expr): Likewise.
* typeck.c (pointer_diff): Use POINTER_DIFF_EXPR.
gcc/
* doc/generic.texi: Document POINTER_DIFF_EXPR, update
POINTER_PLUS_EXPR.
* cfgexpand.c (expand_debug_expr): Handle POINTER_DIFF_EXPR.
* expr.c (expand_expr_real_2): Likewise.
* fold-const.c (const_binop, fold_addr_of_array_ref_difference,
fold_binary_loc): Likewise.
* match.pd (X-X, P+(Q-P), &D-P, (P+N)-P, P-(P+N), (P+M)-(P+N),
P-Q==0, -(A-B), X-Z<Y-Z, (X-Z)-(Y-Z), Z-X<Z-Y, (Z-X)-(Z-Y),
(A-B)+(C-A)): New transformations for POINTER_DIFF_EXPR, based on
MINUS_EXPR transformations.
* optabs-tree.c (optab_for_tree_code): Handle POINTER_DIFF_EXPR.
* tree-cfg.c (verify_expr, verify_gimple_assign_binary): Likewise.
* tree-inline.c (estimate_operator_cost): Likewise.
* tree-pretty-print.c (dump_generic_node, op_code_prio,
op_symbol_code): Likewise.
* tree-vect-stmts.c (vectorizable_operation): Likewise.
* vr-values.c (extract_range_from_binary_expr): Likewise.
* varasm.c (initializer_constant_valid_p_1): Likewise.
* tree.def: New tree code POINTER_DIFF_EXPR.
From-SVN: r255021
Diffstat (limited to 'gcc/c/c-typeck.c')
-rw-r--r-- | gcc/c/c-typeck.c | 25 |
1 files changed, 16 insertions, 9 deletions
diff --git a/gcc/c/c-typeck.c b/gcc/c/c-typeck.c index 8a09ea2..7f85c6b 100644 --- a/gcc/c/c-typeck.c +++ b/gcc/c/c-typeck.c @@ -3778,7 +3778,7 @@ parser_build_binary_op (location_t location, enum tree_code code, } /* Return a tree for the difference of pointers OP0 and OP1. - The resulting tree has type int. */ + The resulting tree has type ptrdiff_t. */ static tree pointer_diff (location_t loc, tree op0, tree op1) @@ -3810,7 +3810,7 @@ pointer_diff (location_t loc, tree op0, tree op1) op1 = convert (common_type, op1); } - /* Determine integer type to perform computations in. This will usually + /* Determine integer type result of the subtraction. This will usually be the same as the result type (ptrdiff_t), but may need to be a wider type if pointers for the address space are wider than ptrdiff_t. */ if (TYPE_PRECISION (restype) < TYPE_PRECISION (TREE_TYPE (op0))) @@ -3825,14 +3825,21 @@ pointer_diff (location_t loc, tree op0, tree op1) pedwarn (loc, OPT_Wpointer_arith, "pointer to a function used in subtraction"); - /* First do the subtraction as integers; - then drop through to build the divide operator. - Do not do default conversions on the minus operator - in case restype is a short type. */ + /* First do the subtraction, then build the divide operator + and only convert at the very end. + Do not do default conversions in case restype is a short type. */ + + /* POINTER_DIFF_EXPR requires a signed integer type of the same size as + pointers. If some platform cannot provide that, or has a larger + ptrdiff_type to support differences larger than half the address + space, cast the pointers to some larger integer type and do the + computations in that type. */ + if (TYPE_PRECISION (inttype) > TYPE_PRECISION (TREE_TYPE (op0))) + op0 = build_binary_op (loc, MINUS_EXPR, convert (inttype, op0), + convert (inttype, op1), false); + else + op0 = build2_loc (loc, POINTER_DIFF_EXPR, inttype, op0, op1); - op0 = build_binary_op (loc, - MINUS_EXPR, convert (inttype, op0), - convert (inttype, op1), false); /* This generates an error if op1 is pointer to incomplete type. */ if (!COMPLETE_OR_VOID_TYPE_P (TREE_TYPE (TREE_TYPE (orig_op1)))) error_at (loc, "arithmetic on pointer to an incomplete type"); |