From a3ee7d6102b9387554e78d0de0e5292885ccd5b5 Mon Sep 17 00:00:00 2001 From: jules Date: Fri, 15 Apr 2005 16:37:45 +0000 Subject: [PATCH] * bfd/bfd-in.h (bfd_elf32_arm_set_target_relocs): Update prototype. * bfd/bfd-in2.h: Regenerate. * bfd/elf32-arm.c (elf32_arm_link_hash_table): New field, 'use_blx'. (elf32_arm_link_hash_table_create): Initialise fix_v4bx, use_blx. (bfd_elf32_arm_set_target_relocs): Handle use_blx. (elf32_arm_final_link_relocate): Use Thumb BLX for R_ARM_THM_PC22 relocations if requested to. (allocate_dynrelocs): Don't count size of omitted Thumb stubs based on use_blx rather than symbian_p. (elf32_arm_finish_dynamic_symbol): Don't output Thumb PLT stubs if use_blx is in effect. (elf32_arm_symbian_link_hash_table_create): Enable use_blx by default for SymbianOS. * ld/ld.texinfo: Document --use-blx. * ld/emultempl/armelf.em (use_blx): New variable. (arm_elf_create_output_section_statements): Communicate value of use_blx to bfd. (PARSE_AND_LIST_PROLOGUE): Add OPTION_USE_BLX. (PARSE_AND_LIST_OPTIONS): Add --use-blx option. (PARSE_AND_LIST_ARGS_CASES): Add OPTION_USE_BLX case. --- bfd/ChangeLog | 16 ++++++++++++++++ bfd/bfd-in.h | 2 +- bfd/bfd-in2.h | 2 +- bfd/elf32-arm.c | 36 +++++++++++++++++++++++++++++------- ld/ChangeLog | 10 ++++++++++ ld/emultempl/armelf.em | 12 ++++++++++-- ld/ld.texinfo | 11 +++++++++++ 7 files changed, 78 insertions(+), 11 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index 35ac02d4b8..2ec46011a3 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,19 @@ +2004-04-15 Julian Brown + + * bfd-in.h (bfd_elf32_arm_set_target_relocs): Update prototype. + * bfd-in2.h: Regenerate. + * elf32-arm.c (elf32_arm_link_hash_table): New field, 'use_blx'. + (elf32_arm_link_hash_table_create): Initialise fix_v4bx, use_blx. + (bfd_elf32_arm_set_target_relocs): Handle use_blx. + (elf32_arm_final_link_relocate): Use Thumb BLX for R_ARM_THM_PC22 + relocations if requested to. + (allocate_dynrelocs): Don't count size of omitted Thumb stubs based on + use_blx rather than symbian_p. + (elf32_arm_finish_dynamic_symbol): Don't output Thumb PLT stubs if + use_blx is in effect. + (elf32_arm_symbian_link_hash_table_create): Enable use_blx by default + for SymbianOS. + 2005-04-15 Nick Clifton * coffgen.c (coff_print_symbol): Use fprintf_vma to print vma diff --git a/bfd/bfd-in.h b/bfd/bfd-in.h index a3dedb5732..90e123d998 100644 --- a/bfd/bfd-in.h +++ b/bfd/bfd-in.h @@ -816,7 +816,7 @@ extern bfd_boolean bfd_elf32_arm_process_before_allocation (bfd *, struct bfd_link_info *, int); void bfd_elf32_arm_set_target_relocs - (struct bfd_link_info *, int, char *, int); + (struct bfd_link_info *, int, char *, int, int); extern bfd_boolean bfd_elf32_arm_get_bfd_for_interworking (bfd *, struct bfd_link_info *); diff --git a/bfd/bfd-in2.h b/bfd/bfd-in2.h index bed224d34b..1e373f28fc 100644 --- a/bfd/bfd-in2.h +++ b/bfd/bfd-in2.h @@ -823,7 +823,7 @@ extern bfd_boolean bfd_elf32_arm_process_before_allocation (bfd *, struct bfd_link_info *, int); void bfd_elf32_arm_set_target_relocs - (struct bfd_link_info *, int, char *, int); + (struct bfd_link_info *, int, char *, int, int); extern bfd_boolean bfd_elf32_arm_get_bfd_for_interworking (bfd *, struct bfd_link_info *); diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c index a46713d661..ef317405c9 100644 --- a/bfd/elf32-arm.c +++ b/bfd/elf32-arm.c @@ -1324,6 +1324,9 @@ struct elf32_arm_link_hash_table /* Nonzero to fix BX instructions for ARMv4 targets. */ int fix_v4bx; + /* Nonzero if the ARM/Thumb BLX instructions are available for use. */ + int use_blx; + /* The number of bytes in the initial entry in the PLT. */ bfd_size_type plt_header_size; @@ -1559,6 +1562,8 @@ elf32_arm_link_hash_table_create (bfd *abfd) ret->plt_header_size = 20; ret->plt_entry_size = 12; #endif + ret->fix_v4bx = 0; + ret->use_blx = 0; ret->symbian_p = 0; ret->use_rel = 1; ret->sym_sec.abfd = NULL; @@ -2125,7 +2130,8 @@ void bfd_elf32_arm_set_target_relocs (struct bfd_link_info *link_info, int target1_is_rel, char * target2_type, - int fix_v4bx) + int fix_v4bx, + int use_blx) { struct elf32_arm_link_hash_table *globals; @@ -2144,6 +2150,7 @@ bfd_elf32_arm_set_target_relocs (struct bfd_link_info *link_info, target2_type); } globals->fix_v4bx = fix_v4bx; + globals->use_blx |= use_blx; } #endif @@ -2893,6 +2900,7 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, bfd_signed_vma reloc_signed_min = ~ reloc_signed_max; bfd_vma check; bfd_signed_vma signed_check; + bfd_boolean thumb_plt_call = FALSE; /* Need to refetch the addend and squish the two 11 bit pieces together. */ @@ -2942,8 +2950,19 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, value = (splt->output_section->vma + splt->output_offset + h->plt.offset); - /* Target the Thumb stub before the ARM PLT entry. */ - value -= 4; + if (globals->use_blx) + { + /* If the Thumb BLX instruction is available, convert the + BL to a BLX instruction to call the ARM-mode PLT entry. */ + if ((lower_insn & (0x3 << 11)) == 0x3 << 11) + { + lower_insn = (lower_insn & ~(0x3 << 11)) | 0x1 << 11; + thumb_plt_call = TRUE; + } + } + else + /* Target the Thumb stub before the ARM PLT entry. */ + value -= PLT_THUMB_STUB_SIZE; *unresolved_reloc_p = FALSE; } @@ -2967,8 +2986,9 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, overflow = TRUE; #ifndef OLD_ARM_ABI - if (r_type == R_ARM_THM_XPC22 - && ((lower_insn & 0x1800) == 0x0800)) + if ((r_type == R_ARM_THM_XPC22 + && ((lower_insn & 0x1800) == 0x0800)) + || thumb_plt_call) /* For a BLX instruction, make sure that the relocation is rounded up to a word boundary. This follows the semantics of the instruction which specifies that bit 1 of the target address will come from bit @@ -5059,7 +5079,7 @@ allocate_dynrelocs (struct elf_link_hash_entry *h, void * inf) /* If we will insert a Thumb trampoline before this PLT, leave room for it. */ - if (!htab->symbian_p && eh->plt_thumb_refcount > 0) + if (!htab->use_blx && eh->plt_thumb_refcount > 0) { h->plt.offset += PLT_THUMB_STUB_SIZE; s->size += PLT_THUMB_STUB_SIZE; @@ -5632,7 +5652,7 @@ elf32_arm_finish_dynamic_symbol (bfd * output_bfd, struct bfd_link_info * info, BFD_ASSERT ((got_displacement & 0xf0000000) == 0); - if (eh->plt_thumb_refcount > 0) + if (!htab->use_blx && eh->plt_thumb_refcount > 0) { bfd_put_16 (output_bfd, elf32_arm_plt_thumb_stub[0], splt->contents + h->plt.offset - 4); @@ -6505,6 +6525,8 @@ elf32_arm_symbian_link_hash_table_create (bfd *abfd) /* The PLT entries are each three instructions. */ htab->plt_entry_size = 4 * NUM_ELEM (elf32_arm_symbian_plt_entry); htab->symbian_p = 1; + /* Symbian uses armv5t or above, so use_blx is always true. */ + htab->use_blx = 1; htab->root.is_relocatable_executable = 1; } return ret; diff --git a/ld/ChangeLog b/ld/ChangeLog index 36fba51d10..3af8c71d65 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,13 @@ +2005-04-15 Julian Brown + + * ld.texinfo: Document --use-blx. + * emultempl/armelf.em (use_blx): New variable. + (arm_elf_create_output_section_statements): Communicate value of + use_blx to bfd. + (PARSE_AND_LIST_PROLOGUE): Add OPTION_USE_BLX. + (PARSE_AND_LIST_OPTIONS): Add --use-blx option. + (PARSE_AND_LIST_ARGS_CASES): Add OPTION_USE_BLX case. + 2005-04-14 Alan Modra * Makefile.am (NO_WERROR): Define. Use instead of -Wno-error. diff --git a/ld/emultempl/armelf.em b/ld/emultempl/armelf.em index 886cf8bd76..d3804001ff 100644 --- a/ld/emultempl/armelf.em +++ b/ld/emultempl/armelf.em @@ -32,6 +32,7 @@ static int byteswap_code = 0; static int target1_is_rel = 0${TARGET1_IS_REL}; static char *target2_type = "${TARGET2_TYPE}"; static int fix_v4bx = 0; +static int use_blx = 0; static void gld${EMULATION_NAME}_before_parse (void) @@ -192,7 +193,7 @@ static void arm_elf_create_output_section_statements (void) { bfd_elf32_arm_set_target_relocs (&link_info, target1_is_rel, target2_type, - fix_v4bx); + fix_v4bx, use_blx); } EOF @@ -206,7 +207,8 @@ PARSE_AND_LIST_PROLOGUE=' #define OPTION_TARGET1_REL 303 #define OPTION_TARGET1_ABS 304 #define OPTION_TARGET2 305 -#define OPTION_FIX_V4BX 306 +#define OPTION_FIX_V4BX 306 +#define OPTION_USE_BLX 307 ' PARSE_AND_LIST_SHORTOPTS=p @@ -219,6 +221,7 @@ PARSE_AND_LIST_LONGOPTS=' { "target1-abs", no_argument, NULL, OPTION_TARGET1_ABS}, { "target2", required_argument, NULL, OPTION_TARGET2}, { "fix-v4bx", no_argument, NULL, OPTION_FIX_V4BX}, + { "use-blx", no_argument, NULL, OPTION_USE_BLX}, ' PARSE_AND_LIST_OPTIONS=' @@ -228,6 +231,7 @@ PARSE_AND_LIST_OPTIONS=' fprintf (file, _(" --target1=abs Interpret R_ARM_TARGET1 as R_ARM_ABS32\n")); fprintf (file, _(" --target2= Specify definition of R_ARM_TARGET2\n")); fprintf (file, _(" --fix-v4bx Rewrite BX rn as MOV pc, rn for ARMv4\n")); + fprintf (file, _(" --use-blx Enable use of BLX instructions\n")); ' PARSE_AND_LIST_ARGS_CASES=' @@ -258,6 +262,10 @@ PARSE_AND_LIST_ARGS_CASES=' case OPTION_FIX_V4BX: fix_v4bx = 1; break; + + case OPTION_USE_BLX: + use_blx = 1; + break; ' # We have our own after_open and before_allocation functions, but they call diff --git a/ld/ld.texinfo b/ld/ld.texinfo index 99afaf2f4d..7860e25059 100644 --- a/ld/ld.texinfo +++ b/ld/ld.texinfo @@ -5262,6 +5262,17 @@ linker, which causes v4t @code{BX rM} instructions to be rewritten as In the former case, the switch should not be used, and @samp{R_ARM_V4BX} relocations are ignored. +@cindex USE_BLX +@kindex --use-blx +The @samp{--use-blx} switch enables the linker to use ARM/Thumb +BLX instructions (available on ARMv5t and above) in various +situations. Currently it is used to perform calls via the PLT from Thumb +code using BLX rather than using BX and a mode-switching stub before +each PLT entry. This should lead to such calls executing slightly faster. + +This option is enabled implicitly for SymbianOS, so there is no need to +specify it if you are using that target. + @ifclear GENERIC @lowersections @end ifclear -- 2.11.0