On Wed, May 09, 2018 at 11:01:18AM -0400, Jason Merrill wrote: > On Wed, May 9, 2018 at 10:47 AM, Jakub Jelinek <[email protected]> wrote: > > On Wed, May 09, 2018 at 10:40:26AM -0400, Jason Merrill wrote: > >> On Wed, May 9, 2018 at 4:55 AM, Jakub Jelinek <[email protected]> wrote: > >> > On Tue, May 08, 2018 at 11:28:18PM -0400, Jason Merrill wrote: > >> >> Maybe add a type parameter that defaults to size_type_node... > >> >> > >> >> > + ret = fold_convert_loc (loc, TREE_TYPE (expr), > >> >> > + fold_offsetof_1 (TREE_TYPE (expr), > >> >> > op0)); > >> >> > >> >> ...and then this can be > >> >> > >> >> fold_offsetof (op0, TREE_TYPE (exp0)) > >> > > >> > Like this then? > >> > > >> > + ret = fold_convert_loc (loc, TREE_TYPE (expr), > >> > + fold_offsetof (op0, TREE_TYPE (expr))); > >> > >> I was thinking that we then wouldn't need the fold_convert at the call > >> sites anymore, either. > > > > The patch only converts to non-pointer types, I'm not sure if it is > > desirable to do the same with pointer types (and most of the other callers > > don't use convert, but fold_convert which is significantly different, the > > former is emitting diagnostics, the latter is just an conversion + > > optimization). > > Is there a reason we can't use fold_convert for the non-pointer case, > too? I don't think we're interested in diagnostics from this > particular call.
This patch instead uses convert everywhere. Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? 2018-05-09 Jakub Jelinek <[email protected]> PR c++/85662 * c-common.h (fold_offsetof_1): Removed. (fold_offsetof): Add TYPE argument defaulted to size_type_node and CTX argument defaulted to ERROR_MARK. * c-common.c (fold_offsetof_1): Renamed to ... (fold_offsetof): ... this. Remove wrapper function. Add TYPE argument, convert the pointer constant to TYPE and use size_binop with PLUS_EXPR instead of fold_build_pointer_plus if type is not a pointer type. Adjust recursive calls. * c-fold.c (c_fully_fold_internal): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (expr) as TYPE to it and drop the fold_convert_loc. * c-typeck.c (build_unary_op): Use fold_offsetof rather than fold_offsetof_1, pass argtype as TYPE to it and drop the fold_convert_loc. * cp-gimplify.c (cp_fold): Use fold_offsetof rather than fold_offsetof_1, pass TREE_TYPE (x) as TYPE to it and drop the fold_convert. * g++.dg/ext/offsetof2.C: New test. --- gcc/c-family/c-common.h.jj 2018-05-09 20:12:25.845258371 +0200 +++ gcc/c-family/c-common.h 2018-05-09 20:20:02.265649121 +0200 @@ -1033,8 +1033,8 @@ extern bool c_dump_tree (void *, tree); extern void verify_sequence_points (tree); -extern tree fold_offsetof_1 (tree, tree_code ctx = ERROR_MARK); -extern tree fold_offsetof (tree); +extern tree fold_offsetof (tree, tree = size_type_node, + tree_code ctx = ERROR_MARK); extern int complete_array_type (tree *, tree, bool); --- gcc/c-family/c-common.c.jj 2018-05-09 20:12:25.763258297 +0200 +++ gcc/c-family/c-common.c 2018-05-09 20:21:23.770718896 +0200 @@ -6168,10 +6168,11 @@ c_common_to_target_charset (HOST_WIDE_IN /* Fold an offsetof-like expression. EXPR is a nested sequence of component references with an INDIRECT_REF of a constant at the bottom; much like the - traditional rendering of offsetof as a macro. Return the folded result. */ + traditional rendering of offsetof as a macro. TYPE is the desired type of + the whole expression. Return the folded result. */ tree -fold_offsetof_1 (tree expr, enum tree_code ctx) +fold_offsetof (tree expr, tree type, enum tree_code ctx) { tree base, off, t; tree_code code = TREE_CODE (expr); @@ -6196,10 +6197,10 @@ fold_offsetof_1 (tree expr, enum tree_co error ("cannot apply %<offsetof%> to a non constant address"); return error_mark_node; } - return TREE_OPERAND (expr, 0); + return convert (type, TREE_OPERAND (expr, 0)); case COMPONENT_REF: - base = fold_offsetof_1 (TREE_OPERAND (expr, 0), code); + base = fold_offsetof (TREE_OPERAND (expr, 0), type, code); if (base == error_mark_node) return base; @@ -6216,7 +6217,7 @@ fold_offsetof_1 (tree expr, enum tree_co break; case ARRAY_REF: - base = fold_offsetof_1 (TREE_OPERAND (expr, 0), code); + base = fold_offsetof (TREE_OPERAND (expr, 0), type, code); if (base == error_mark_node) return base; @@ -6273,23 +6274,16 @@ fold_offsetof_1 (tree expr, enum tree_co /* Handle static members of volatile structs. */ t = TREE_OPERAND (expr, 1); gcc_checking_assert (VAR_P (get_base_address (t))); - return fold_offsetof_1 (t); + return fold_offsetof (t, type); default: gcc_unreachable (); } + if (!POINTER_TYPE_P (type)) + return size_binop (PLUS_EXPR, base, convert (type, off)); return fold_build_pointer_plus (base, off); } - -/* Likewise, but convert it to the return type of offsetof. */ - -tree -fold_offsetof (tree expr) -{ - return convert (size_type_node, fold_offsetof_1 (expr)); -} - /* *PTYPE is an incomplete array. Complete it with a domain based on INITIAL_VALUE. If INITIAL_VALUE is not present, use 1 if DO_DEFAULT --- gcc/c/c-fold.c.jj 2018-05-09 20:12:25.496258072 +0200 +++ gcc/c/c-fold.c 2018-05-09 20:21:53.673744504 +0200 @@ -473,7 +473,7 @@ c_fully_fold_internal (tree expr, bool i && (op1 = get_base_address (op0)) != NULL_TREE && INDIRECT_REF_P (op1) && TREE_CONSTANT (TREE_OPERAND (op1, 0))) - ret = fold_convert_loc (loc, TREE_TYPE (expr), fold_offsetof_1 (op0)); + ret = fold_offsetof (op0, TREE_TYPE (expr)); else if (op0 != orig_op0 || in_init) ret = in_init ? fold_build1_initializer_loc (loc, code, TREE_TYPE (expr), op0) --- gcc/c/c-typeck.c.jj 2018-05-09 20:12:25.529258100 +0200 +++ gcc/c/c-typeck.c 2018-05-09 20:22:10.592758986 +0200 @@ -4676,7 +4676,7 @@ build_unary_op (location_t location, enu if (val && INDIRECT_REF_P (val) && TREE_CONSTANT (TREE_OPERAND (val, 0))) { - ret = fold_convert_loc (location, argtype, fold_offsetof_1 (arg)); + ret = fold_offsetof (arg, argtype); goto return_build_unary_op; } --- gcc/cp/cp-gimplify.c.jj 2018-05-09 20:12:25.881258402 +0200 +++ gcc/cp/cp-gimplify.c 2018-05-09 20:22:35.639780430 +0200 @@ -2232,7 +2232,7 @@ cp_fold (tree x) val = TREE_OPERAND (val, 0); STRIP_NOPS (val); if (TREE_CODE (val) == INTEGER_CST) - return fold_convert (TREE_TYPE (x), fold_offsetof_1 (op0)); + return fold_offsetof (op0, TREE_TYPE (x)); } } goto finish_unary; --- gcc/testsuite/g++.dg/ext/offsetof2.C.jj 2018-05-09 20:20:02.272649127 +0200 +++ gcc/testsuite/g++.dg/ext/offsetof2.C 2018-05-09 20:20:02.272649127 +0200 @@ -0,0 +1,6 @@ +// PR c++/85662 +// { dg-do compile { target c++11 } } + +struct S { unsigned long x[31]; }; +struct T { bool b; S f; }; +static_assert (__builtin_offsetof (T, f.x[31 - 1]) == __builtin_offsetof (T, f.x[30]), ""); Jakub
