From 2949ed612849ff9f936c5fb2570f67cf8a5cc553 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Thu, 13 Apr 2017 12:15:36 -0700 Subject: [PATCH] Handle symbol defined in IR and referenced in DSO We need to make an IR symbol visible if it is defined in an IR object and referenced in a dynamic object. When --as-needed is used, since linker removes the IR symbol reference of the dynamic object if the dynamic object isn't needed in the first pass, the IR definition isn't visible to the dynamic object even if the dynamic object becomes needed in the second pass. Add dynamic_ref_after_ir_def to bfd_link_hash_entry to track IR symbol which is defined in an IR object and later referenced in a dynamic object. dynamic_ref_after_ir_def is preserved when restoring the symbol table for unneeded dynamic object. bfd/ PR ld/21382 * elflink.c (elf_link_add_object_symbols): Preserve re_def_dynamic_ref when restoring the symbol table for unneeded dynamic object. include/ PR ld/21382 * bfdlink.h (bfd_link_hash_entry): Add dynamic_ref_after_ir_def. ld/ PR ld/21382 * plugin.c (is_visible_from_outside): Symbol may be visible from outside if dynamic_ref_after_ir_def is set. (plugin_notice): Set dynamic_ref_after_ir_def if the symbol is defined in an IR object and referenced in a dynamic object. * testsuite/ld-plugin/lto.exp: Run PR ld/21382 tests. * testsuite/ld-plugin/pr21382a.c: New file. * testsuite/ld-plugin/pr21382b.c: Likewise. --- bfd/elflink.c | 6 ++++++ include/bfdlink.h | 4 ++++ ld/plugin.c | 23 +++++++++++++++++------ ld/testsuite/ld-plugin/lto.exp | 9 +++++++++ ld/testsuite/ld-plugin/pr21382a.c | 17 +++++++++++++++++ ld/testsuite/ld-plugin/pr21382b.c | 7 +++++++ 6 files changed, 60 insertions(+), 6 deletions(-) create mode 100644 ld/testsuite/ld-plugin/pr21382a.c create mode 100644 ld/testsuite/ld-plugin/pr21382b.c diff --git a/bfd/elflink.c b/bfd/elflink.c index 0add01b..972b6f8 100644 --- a/bfd/elflink.c +++ b/bfd/elflink.c @@ -4932,6 +4932,7 @@ error_free_dyn: struct elf_link_hash_entry *h; bfd_size_type size; unsigned int alignment_power; + unsigned int dynamic_ref_after_ir_def; for (p = htab->root.table.table[i]; p != NULL; p = p->next) { @@ -4953,6 +4954,10 @@ error_free_dyn: size = 0; alignment_power = 0; } + /* Preserve dynamic_ref_after_ir_def so that this symbol + will be exported when the dynamic lib becomes needed + in the second pass. */ + dynamic_ref_after_ir_def = h->root.dynamic_ref_after_ir_def; memcpy (p, old_ent, htab->root.table.entsize); old_ent = (char *) old_ent + htab->root.table.entsize; h = (struct elf_link_hash_entry *) p; @@ -4969,6 +4974,7 @@ error_free_dyn: if (alignment_power > h->root.u.c.p->alignment_power) h->root.u.c.p->alignment_power = alignment_power; } + h->root.dynamic_ref_after_ir_def = dynamic_ref_after_ir_def; } } diff --git a/include/bfdlink.h b/include/bfdlink.h index 18dea0c..cb4bad9 100644 --- a/include/bfdlink.h +++ b/include/bfdlink.h @@ -104,6 +104,10 @@ struct bfd_link_hash_entry IR object file. */ unsigned int non_ir_ref : 1; + /* Symbol is referenced in a dynamic object after it has been defined + in an IR object. */ + unsigned int dynamic_ref_after_ir_def : 1; + /* Symbol is a built-in define. These will be overridden by PROVIDE in a linker script. */ unsigned int linker_def : 1; diff --git a/ld/plugin.c b/ld/plugin.c index 03e2e69..164b5db 100644 --- a/ld/plugin.c +++ b/ld/plugin.c @@ -629,7 +629,9 @@ is_visible_from_outside (struct ld_plugin_symbol *lsym, if (bfd_link_relocatable (&link_info)) return TRUE; - if (link_info.export_dynamic || bfd_link_dll (&link_info)) + if (blhe->dynamic_ref_after_ir_def + || link_info.export_dynamic + || bfd_link_dll (&link_info)) { /* Check if symbol is hidden by version script. */ if (bfd_hide_sym_by_version (link_info.version_info, @@ -1316,12 +1318,21 @@ plugin_notice (struct bfd_link_info *info, /* If this is a ref, set non_ir_ref. */ else if (bfd_is_und_section (section)) { + if (h->type == bfd_link_hash_defweak + || h->type == bfd_link_hash_defined) + { + /* Check if the symbol is referenced in a dynamic object + after it has been defined in an IR object. */ + if ((abfd->flags & DYNAMIC) != 0 + && is_ir_dummy_bfd (h->u.def.section->owner)) + h->dynamic_ref_after_ir_def = TRUE; + } /* Replace the undefined dummy bfd with the real one. */ - if ((h->type == bfd_link_hash_undefined - || h->type == bfd_link_hash_undefweak) - && (h->u.undef.abfd == NULL - || (h->u.undef.abfd->flags & BFD_PLUGIN) != 0)) - h->u.undef.abfd = abfd; + else if ((h->type == bfd_link_hash_undefined + || h->type == bfd_link_hash_undefweak) + && (h->u.undef.abfd == NULL + || (h->u.undef.abfd->flags & BFD_PLUGIN) != 0)) + h->u.undef.abfd = abfd; h->non_ir_ref = TRUE; } diff --git a/ld/testsuite/ld-plugin/lto.exp b/ld/testsuite/ld-plugin/lto.exp index 80c084b..f0bc345 100644 --- a/ld/testsuite/ld-plugin/lto.exp +++ b/ld/testsuite/ld-plugin/lto.exp @@ -289,6 +289,12 @@ set lto_link_elf_tests [list \ [list "PR ld/14918" \ "-flto" "-flto" \ {pr14918.c} {{"readelf" {-d --wide} "pr14918.d"}} "pr14918.exe" "c"] \ + [list "Build pr21382a.o" \ + "" "-O2 -flto" \ + {pr21382a.c} {} "" "c"] \ + [list "Build pr21382.so" \ + "-shared" "-O2 -fpic" \ + {pr21382b.c} {} "pr21382.so" "c"] \ ] # Check final symbols in executables. @@ -387,6 +393,9 @@ set lto_run_elf_shared_tests [list \ [list "LTO 7" \ "-O2 -flto -fuse-linker-plugin tmpdir/lto-7b.o tmpdir/lto-7c.o tmpdir/lto-7a.o -Wl,--no-as-needed tmpdir/liblto-7.so" "" \ {dummy.c} "lto-7.exe" "lto-7.out" "" "c"] \ + [list "Run pr21382" \ + "-O2 -flto -fuse-linker-plugin -Wl,--as-needed tmpdir/pr21382a.o tmpdir/pr21382.so" "" \ + {dummy.c} "pr21382.exe" "pass.out" "" "c"] \ ] # LTO run-time tests for ELF diff --git a/ld/testsuite/ld-plugin/pr21382a.c b/ld/testsuite/ld-plugin/pr21382a.c new file mode 100644 index 0000000..09b9d75 --- /dev/null +++ b/ld/testsuite/ld-plugin/pr21382a.c @@ -0,0 +1,17 @@ +#include + +extern void y (void); + +void +x (void) +{ + printf ("PASS\n"); +} + + +int +main (void) +{ + y (); + return 0; +} diff --git a/ld/testsuite/ld-plugin/pr21382b.c b/ld/testsuite/ld-plugin/pr21382b.c new file mode 100644 index 0000000..c5b74a9 --- /dev/null +++ b/ld/testsuite/ld-plugin/pr21382b.c @@ -0,0 +1,7 @@ +extern void x (void); + +void +y (void) +{ + x (); +} -- 2.9.3