From 451a61b609b10448c63de5509ec9e7e3978f1dc3 Mon Sep 17 00:00:00 2001 From: rth Date: Wed, 21 Oct 2015 20:31:26 +0000 Subject: [PATCH] Change default of non-overlapping address space conversion The current default of making all undefined coversions being set to null is not useful. It has caused all users to lie and say that spaces are subsets when they are not, just so that they can override the conversion. * expr.c (expand_expr_real_2): Use convert_modes on disjoint address spaces. git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@229142 138bc75d-0d04-0410-961f-82ee72b054a4 --- gcc/ChangeLog | 5 +++++ gcc/expr.c | 30 ++++++++++++++++++------------ 2 files changed, 23 insertions(+), 12 deletions(-) diff --git a/gcc/ChangeLog b/gcc/ChangeLog index 8271924..ec60f84 100644 --- a/gcc/ChangeLog +++ b/gcc/ChangeLog @@ -1,3 +1,8 @@ +2015-10-21 Richard Henderson + + * expr.c (expand_expr_real_2): Use convert_modes on disjoint + address spaces. + 2015-10-21 Richard Sandiford * builtins.c (fold_builtin_cabs): Delete. diff --git a/gcc/expr.c b/gcc/expr.c index adde00d..da68870 100644 --- a/gcc/expr.c +++ b/gcc/expr.c @@ -8171,34 +8171,40 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode, case ADDR_SPACE_CONVERT_EXPR: { tree treeop0_type = TREE_TYPE (treeop0); - addr_space_t as_to; - addr_space_t as_from; gcc_assert (POINTER_TYPE_P (type)); gcc_assert (POINTER_TYPE_P (treeop0_type)); - as_to = TYPE_ADDR_SPACE (TREE_TYPE (type)); - as_from = TYPE_ADDR_SPACE (TREE_TYPE (treeop0_type)); + addr_space_t as_to = TYPE_ADDR_SPACE (TREE_TYPE (type)); + addr_space_t as_from = TYPE_ADDR_SPACE (TREE_TYPE (treeop0_type)); /* Conversions between pointers to the same address space should have been implemented via CONVERT_EXPR / NOP_EXPR. */ gcc_assert (as_to != as_from); + op0 = expand_expr (treeop0, NULL_RTX, VOIDmode, modifier); + /* Ask target code to handle conversion between pointers to overlapping address spaces. */ if (targetm.addr_space.subset_p (as_to, as_from) || targetm.addr_space.subset_p (as_from, as_to)) { - op0 = expand_expr (treeop0, NULL_RTX, VOIDmode, modifier); op0 = targetm.addr_space.convert (op0, treeop0_type, type); - gcc_assert (op0); - return op0; } - - /* For disjoint address spaces, converting anything but - a null pointer invokes undefined behaviour. We simply - always return a null pointer here. */ - return CONST0_RTX (mode); + else + { + /* For disjoint address spaces, converting anything but a null + pointer invokes undefined behaviour. We truncate or extend the + value as if we'd converted via integers, which handles 0 as + required, and all others as the programmer likely expects. */ +#ifndef POINTERS_EXTEND_UNSIGNED + const int POINTERS_EXTEND_UNSIGNED = 1; +#endif + op0 = convert_modes (mode, TYPE_MODE (treeop0_type), + op0, POINTERS_EXTEND_UNSIGNED); + } + gcc_assert (op0); + return op0; } case POINTER_PLUS_EXPR: -- 2.7.4