From cd5b2babea487b0a71a14b593af98330efd8d73e Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Mon, 27 Nov 2017 18:43:03 +1030 Subject: [PATCH] Copying symbol type in ld script assignments There is a call to update_definedness between code that evaluates an assignment expression value and code that transfers symbol attributes. When script assignment expressions contain DEFINED, that can mean the wrong symbol type is copied. This patch tracks symbols read during expression evaluation, rather than examining the expression and re-evaluating conditionals. Not only does this simplify the code, it also means ld can now copy symbol types in more complex expressions. An unfortunate side effect of copying symbol type for more complex expressions affects mmix, which uses PROVIDE (Main = DEFINED (Main) ? Main : (DEFINED (_start) ? _start : _start.)); in a default script. So now _start or _start. symbol type may be copied, losing the function type specially set up for Main. This can be avoided by making bfd_copy_link_hash_symbol_type do nothing for mmix. bfd/ * elf64-mmix.c (bfd_elf64_bfd_copy_link_hash_symbol_type): Define. ld/ * ldexp.h (struct ldexp_control): Add "assign_src". * ldexp.c (fold_trinary): Save and restore assign_src around condition evaluation. (fold_name ): Set expld.assign_src. (try_copy_symbol_type): Delete. (exp_fold_tree_1): Set symbol type using expld.assign_src. --- bfd/ChangeLog | 4 ++++ bfd/elf64-mmix.c | 3 +++ ld/ChangeLog | 9 +++++++++ ld/ldexp.c | 51 ++++++++++++++++-------------------------------- ld/ldexp.h | 5 +++++ 5 files changed, 38 insertions(+), 34 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index abd7c96ac9c..dc3aa2f0d9d 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,7 @@ +2017-11-28 Alan Modra + + * elf64-mmix.c (bfd_elf64_bfd_copy_link_hash_symbol_type): Define. + 2017-11-28 H.J. Lu PR ld/22502 diff --git a/bfd/elf64-mmix.c b/bfd/elf64-mmix.c index c057d34904c..ae6afc20f1e 100644 --- a/bfd/elf64-mmix.c +++ b/bfd/elf64-mmix.c @@ -2908,6 +2908,9 @@ mmix_elf_relax_section (bfd *abfd, #define elf_backend_omit_section_dynsym \ ((bfd_boolean (*) (bfd *, struct bfd_link_info *, asection *)) bfd_true) +#define bfd_elf64_bfd_copy_link_hash_symbol_type \ + _bfd_generic_copy_link_hash_symbol_type + #define bfd_elf64_bfd_is_local_label_name \ mmix_elf_is_local_label_name diff --git a/ld/ChangeLog b/ld/ChangeLog index ed63236e5b0..058318dfaba 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,12 @@ +2017-11-28 Alan Modra + + * ldexp.h (struct ldexp_control): Add "assign_src". + * ldexp.c (fold_trinary): Save and restore assign_src around + condition evaluation. + (fold_name ): Set expld.assign_src. + (try_copy_symbol_type): Delete. + (exp_fold_tree_1): Set symbol type using expld.assign_src. + 2017-11-28 H.J. Lu PR ld/22502 diff --git a/ld/ldexp.c b/ld/ldexp.c index 83d9f8f2a7f..33ca289682c 100644 --- a/ld/ldexp.c +++ b/ld/ldexp.c @@ -673,7 +673,10 @@ fold_binary (etree_type *tree) static void fold_trinary (etree_type *tree) { + struct bfd_link_hash_entry *save = expld.assign_src; + exp_fold_tree_1 (tree->trinary.cond); + expld.assign_src = save; if (expld.result.valid_p) exp_fold_tree_1 (expld.result.value ? tree->trinary.lhs @@ -790,6 +793,10 @@ fold_name (etree_type *tree) if (h->u.undef.next == NULL && h != link_info.hash->undefs_tail) bfd_link_add_undef (link_info.hash, h); } + if (expld.assign_src == NULL) + expld.assign_src = h; + else + expld.assign_src = (struct bfd_link_hash_entry *) 0 - 1; } break; @@ -1001,19 +1008,6 @@ is_align_conditional (const etree_type *tree) return FALSE; } -/* Subroutine of exp_fold_tree_1 for copying a symbol type. */ - -static void -try_copy_symbol_type (struct bfd_link_hash_entry *h, etree_type *src) -{ - struct bfd_link_hash_entry *hsrc; - - hsrc = bfd_link_hash_lookup (link_info.hash, src->name.name, - FALSE, FALSE, TRUE); - if (hsrc != NULL) - bfd_copy_link_hash_symbol_type (link_info.output_bfd, h, hsrc); -} - static void exp_fold_tree_1 (etree_type *tree) { @@ -1162,6 +1156,7 @@ exp_fold_tree_1 (etree_type *tree) } expld.assign_name = tree->assign.dst; + expld.assign_src = NULL; exp_fold_tree_1 (tree->assign.src); /* expld.assign_name remaining equal to tree->assign.dst below indicates the evaluation of tree->assign.src did @@ -1209,27 +1204,15 @@ exp_fold_tree_1 (etree_type *tree) if (tree->type.node_class == etree_provide) tree->type.node_class = etree_provided; - /* Copy the symbol type if this is a simple assignment of - one symbol to another. Also, handle the case of a foldable - ternary conditional with names on either side. */ - if (tree->assign.src->type.node_class == etree_name) - try_copy_symbol_type (h, tree->assign.src); - else if (tree->assign.src->type.node_class == etree_trinary) - { - exp_fold_tree_1 (tree->assign.src->trinary.cond); - if (expld.result.valid_p) - { - if (expld.result.value - && tree->assign.src->trinary.lhs->type.node_class - == etree_name) - try_copy_symbol_type (h, tree->assign.src->trinary.lhs); - - if (!expld.result.value - && tree->assign.src->trinary.rhs->type.node_class - == etree_name) - try_copy_symbol_type (h, tree->assign.src->trinary.rhs); - } - } + /* Copy the symbol type if this is an expression only + referencing a single symbol. (If the expression + contains ternary conditions, ignoring symbols on + false branches.) */ + if (expld.result.valid_p + && expld.assign_src != NULL + && expld.assign_src != (struct bfd_link_hash_entry *) 0 - 1) + bfd_copy_link_hash_symbol_type (link_info.output_bfd, h, + expld.assign_src); } else if (expld.phase == lang_final_phase_enum) { diff --git a/ld/ldexp.h b/ld/ldexp.h index 5ff0fa0a1fc..189570aaf72 100644 --- a/ld/ldexp.h +++ b/ld/ldexp.h @@ -163,6 +163,11 @@ struct ldexp_control { does the false branch of a trinary expression. */ const char *assign_name; + /* If evaluating an assignment, the source if it is an expression + referencing single etree_name NAME, or a trinary expression where + the true branch references a single etree_name NAME. */ + struct bfd_link_hash_entry *assign_src; + /* Working results. */ etree_value_type result; bfd_vma dot; -- 2.30.2