gas: add --reloc-section-sym={all,internal,none} option for ELF

When generating relocations for non-ifunc local symbols that satisfies
several conditions, GAS converts them to reference the section symbol
(STT_SECTION) instead, folding the original symbol's offset into the
addend.  This allows the original local symbol to be omitted from
.symtab, but the STT_SECTION symbol itself must be present, so the
conversion saves .symtab entries only when a section has more than one
local symbol referenced by relocations.

Add --reloc-section-sym to control this conversion:

- all (default): convert all eligible local symbols
- internal: only convert compiler-generated locals (.L prefix)
- none: never convert; keep all symbols as-is in relocations

This is useful for debugging and for tools that benefit from preserved
symbol names.

PR gas/33885

diff --git a/gas/NEWS b/gas/NEWS
index 60ab138384e21b6e092654be6e28a88c20fa532a..38928ab83ff51d84f1284d9a48c97852b6f4c64f 100644 (file)
--- a/gas/NEWS
+++ b/gas/NEWS
@@ -1,5 +1,9 @@
 -*- text -*-
 
+* New command line option --reloc-section-sym=[all|internal|none]
+  controls whether relocations referencing local binding symbols are adjusted
+  to use section symbols.
+
 * The aarch64 extensions TME and MPAMv2_VID have never been implemented in any
   products.  Arm has withdrawn them from the architecture.  The assembler will
   now warn if instructions or system registers from either extension are

diff --git a/gas/as.c b/gas/as.c
index f33f6ec85cd7414b2c91096a0f34dd41a8b2c07d..b652e81286c89ee0274a3bcf02cf4cf1c6284bca 100644 (file)
--- a/gas/as.c
+++ b/gas/as.c
@@ -326,6 +326,10 @@ Options:\n\
           DEFAULT_SFRAME ? "yes" : "no");
   fprintf (stream, _("\
   --gsframe-<N>           generate SFrame version <N> information. 3 == <N>\n"));
+  fprintf (stream, _("\
+  --reloc-section-sym=[all|internal|none]\n\
+                          adjust eligible relocations to use section symbols\n\
+                          (default: all)\n"));
 # if defined (TARGET_USE_SCFI) && defined (TARGET_USE_GINSN)
   fprintf (stream, _("\
   --scfi=experimental     Synthesize DWARF CFI for hand-written asm\n\
@@ -523,7 +527,8 @@ parse_args (int * pargc, char *** pargv)
       OPTION_SFRAME_3,
       OPTION_SCFI,
       OPTION_INFO,
-      OPTION_NOINFO
+      OPTION_NOINFO,
+      OPTION_RELOC_SECTION_SYM
     /* When you add options here, check that they do
        not collide with OPTION_MD_BASE.  See as.h.  */
     };
@@ -556,6 +561,7 @@ parse_args (int * pargc, char *** pargv)
     ,{"generate-missing-build-notes", required_argument, NULL, OPTION_ELF_BUILD_NOTES}
     ,{"gsframe", optional_argument, NULL, OPTION_SFRAME}
     ,{"gsframe-3", no_argument, NULL, OPTION_SFRAME_3}
+    ,{"reloc-section-sym", required_argument, NULL, OPTION_RELOC_SECTION_SYM}
 # if defined (TARGET_USE_SCFI) && defined (TARGET_USE_GINSN)
     ,{"scfi", required_argument, NULL, OPTION_SCFI}
 # endif
@@ -1043,6 +1049,18 @@ This program has absolutely no warranty.\n"));
          flag_sectname_subst = 1;
          break;
 
+       case OPTION_RELOC_SECTION_SYM:
+         if (strcasecmp (optarg, "all") == 0)
+           flag_reloc_section_sym = reloc_section_sym_all;
+         else if (strcasecmp (optarg, "internal") == 0)
+           flag_reloc_section_sym = reloc_section_sym_internal;
+         else if (strcasecmp (optarg, "none") == 0)
+           flag_reloc_section_sym = reloc_section_sym_none;
+         else
+           as_fatal (_("Invalid --reloc-section-sym= option: `%s'"),
+                     optarg);
+         break;
+
        case OPTION_ELF_BUILD_NOTES:
          if (strcasecmp (optarg, "no") == 0)
            flag_generate_build_notes = false;

diff --git a/gas/as.h b/gas/as.h
index 94bc816be1e7dbd1ad919feead7daadc87a6a0ba..2fe0a48a225a1b9f57457288adada916e64473b9 100644 (file)
--- a/gas/as.h
+++ b/gas/as.h
@@ -405,6 +405,16 @@ enum multibyte_input_handling
 };
 COMMON enum multibyte_input_handling multibyte_handling;
 
+/* Controls whether relocations referencing local symbols are converted
+   to use section symbols.  */
+enum reloc_section_sym_type
+{
+  reloc_section_sym_all = 0,
+  reloc_section_sym_internal,
+  reloc_section_sym_none
+};
+COMMON enum reloc_section_sym_type flag_reloc_section_sym;
+
 /* TRUE if we should produce a listing.  */
 extern int listing;
 

diff --git a/gas/doc/as.texi b/gas/doc/as.texi
index 3c4d20bd7d4e12ed0d2219dd2f3e066b5fb99106..5d7772d62d3bca0cf5078e8e6e3773c8613e6f94 100644 (file)
--- a/gas/doc/as.texi
+++ b/gas/doc/as.texi
@@ -257,6 +257,7 @@ gcc(1), ld(1), and the Info entries for @file{binutils} and @file{ld}.
  [@b{--multibyte-handling=[allow|warn|warn-sym-only]}]
  [@b{--no-pad-sections}]
  [@b{-o} @var{objfile}] [@b{-R}]
+ [@b{--reloc-section-sym=[all|internal|none]}]
  [@b{--scfi=experimental}]
  [@b{--sectname-subst}]
  [@b{--size-check=[error|warning]}]
@@ -956,6 +957,16 @@ Ignored.  Supported for compatibility with tools that pass the same option to
 both the assembler and the linker.
 
 @ifset ELF
+@item --reloc-section-sym=all
+@itemx --reloc-section-sym=internal
+@itemx --reloc-section-sym=none
+Control whether relocations referencing local binding symbols are adjusted to
+use section symbols instead.  With @code{all} (the default), relocations
+against all eligible local binding symbols are converted.  With
+@code{internal}, only relocations against internal labels (symbols matching the
+@code{.L} prefix) are converted.  With @code{none}, no such conversions are
+performed.
+
 @item --scfi=experimental
 This option controls whether the assembler should synthesize CFI for
 hand-written input.  If the input already contains some synthesizable CFI

diff --git a/gas/testsuite/gas/elf/elf.exp b/gas/testsuite/gas/elf/elf.exp
index 2232e2d58d9986146b52bf36684d9be3ef70e588..5580c494c543871db1d0b51e04377adf90f7ef6e 100644 (file)
--- a/gas/testsuite/gas/elf/elf.exp
+++ b/gas/testsuite/gas/elf/elf.exp
@@ -188,15 +188,18 @@ if { [is_elf_format] } then {
        rx-*-* { }
        loongarch*-*-* { }
        default {
-           # The next test can fail if the target does not convert fixups
+           # The following tests can fail if the target does not convert fixups
            # against ordinary symbols into relocations against section symbols.
-           # This is usually revealed by the error message:
-           #  symbol `sym' required but not present
            setup_xfail "m681*-*-*" "m68hc*-*-*" "xgate-*-*" "vax-*-*" "avr-*-*"
            run_dump_test redef
            run_dump_test equ-reloc
+           setup_xfail "m681*-*-*" "m68hc*-*-*" "xgate-*-*" "vax-*-*" "avr-*-*"
+           run_dump_test "reloc-section-sym-all"
+           setup_xfail "m681*-*-*" "m68hc*-*-*" "xgate-*-*" "avr-*-*"
+           run_dump_test "reloc-section-sym-internal"
        }
     }
+    run_dump_test "reloc-section-sym-none"
     run_dump_test "pseudo"
     run_dump_test "text-prev" $dump_opts
     run_dump_test "text-subsect" $dump_opts

diff --git a/gas/testsuite/gas/elf/reloc-section-sym-all.d b/gas/testsuite/gas/elf/reloc-section-sym-all.d
new file mode 100644 (file)
index 0000000..b4da309
--- /dev/null
+++ b/gas/testsuite/gas/elf/reloc-section-sym-all.d
@@ -0,0 +1,12 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=all
+#objdump: -rsj .data
+#name: reloc-section-sym=all
+
+.*: +file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0*0 [^ ]+ +\.bss.*
+0*4 [^ ]+ +\.bss.*
+#pass

diff --git a/gas/testsuite/gas/elf/reloc-section-sym-internal.d b/gas/testsuite/gas/elf/reloc-section-sym-internal.d
new file mode 100644 (file)
index 0000000..0c0f464
--- /dev/null
+++ b/gas/testsuite/gas/elf/reloc-section-sym-internal.d
@@ -0,0 +1,12 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=internal
+#objdump: -rsj .data
+#name: reloc-section-sym=internal
+
+.*: +file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0*0 [^ ]+ +local.*
+0*4 [^ ]+ +\.bss.*
+#pass

diff --git a/gas/testsuite/gas/elf/reloc-section-sym-none.d b/gas/testsuite/gas/elf/reloc-section-sym-none.d
new file mode 100644 (file)
index 0000000..557728b
--- /dev/null
+++ b/gas/testsuite/gas/elf/reloc-section-sym-none.d
@@ -0,0 +1,12 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=none
+#objdump: -rsj .data
+#name: reloc-section-sym=none
+
+.*: +file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0*0 [^ ]+ +local.*
+0*4 [^ ]+ +\.Ltemp.*
+#pass

diff --git a/gas/testsuite/gas/elf/reloc-section-sym.s b/gas/testsuite/gas/elf/reloc-section-sym.s
new file mode 100644 (file)
index 0000000..37f1258
--- /dev/null
+++ b/gas/testsuite/gas/elf/reloc-section-sym.s
@@ -0,0 +1,9 @@
+       .section .bss
+local:
+       .zero 1
+.Ltemp:
+       .zero 1
+
+       .data
+       .long local + 16
+       .long .Ltemp + 16

diff --git a/gas/testsuite/gas/i386/reloc-section-sym-all.d b/gas/testsuite/gas/i386/reloc-section-sym-all.d
new file mode 100644 (file)
index 0000000..2c8fd57
--- /dev/null
+++ b/gas/testsuite/gas/i386/reloc-section-sym-all.d
@@ -0,0 +1,23 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=all
+#objdump: -rsj .data -j .text1
+#name: reloc-section-sym=all
+
+.*:     file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0+0 R_X86_64_64 +\.text\+0x0+11
+0+8 R_X86_64_64 +\.text\+0x0+12
+
+
+RELOCATION RECORDS FOR \[\.text1\]:
+OFFSET +TYPE +VALUE
+0+1 R_X86_64_PC32 +\.text-0x0+3
+0+6 R_X86_64_PC32 +\.text-0x0+2
+
+
+Contents of section \.data:
+ 0000 00000000 00000000 00000000 00000000  \.+
+Contents of section \.text1:
+ 0000 e8000000 00e80000 0000 +.*

diff --git a/gas/testsuite/gas/i386/reloc-section-sym-internal.d b/gas/testsuite/gas/i386/reloc-section-sym-internal.d
new file mode 100644 (file)
index 0000000..2387fab
--- /dev/null
+++ b/gas/testsuite/gas/i386/reloc-section-sym-internal.d
@@ -0,0 +1,23 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=internal
+#objdump: -rsj .data -j .text1
+#name: reloc-section-sym=internal
+
+.*:     file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0+0 R_X86_64_64 +named_local\+0x0+10
+0+8 R_X86_64_64 +\.text\+0x0+12
+
+
+RELOCATION RECORDS FOR \[\.text1\]:
+OFFSET +TYPE +VALUE
+0+1 R_X86_64_PC32 +named_local-0x0+4
+0+6 R_X86_64_PC32 +\.text-0x0+2
+
+
+Contents of section \.data:
+ 0000 00000000 00000000 00000000 00000000  \.+
+Contents of section \.text1:
+ 0000 e8000000 00e80000 0000 +.*

diff --git a/gas/testsuite/gas/i386/reloc-section-sym-none.d b/gas/testsuite/gas/i386/reloc-section-sym-none.d
new file mode 100644 (file)
index 0000000..8f7fe3f
--- /dev/null
+++ b/gas/testsuite/gas/i386/reloc-section-sym-none.d
@@ -0,0 +1,23 @@
+#source: reloc-section-sym.s
+#as: --reloc-section-sym=none
+#objdump: -rsj .data -j .text1
+#name: reloc-section-sym=none
+
+.*:     file format .*
+
+RELOCATION RECORDS FOR \[\.data\]:
+OFFSET +TYPE +VALUE
+0+0 R_X86_64_64 +named_local\+0x0+10
+0+8 R_X86_64_64 +\.Ltemp\+0x0+10
+
+
+RELOCATION RECORDS FOR \[\.text1\]:
+OFFSET +TYPE +VALUE
+0+1 R_X86_64_PC32 +named_local-0x0+4
+0+6 R_X86_64_PC32 +\.Ltemp-0x0+4
+
+
+Contents of section \.data:
+ 0000 00000000 00000000 00000000 00000000  \.+
+Contents of section \.text1:
+ 0000 e8000000 00e80000 0000 +.*

diff --git a/gas/testsuite/gas/i386/reloc-section-sym.s b/gas/testsuite/gas/i386/reloc-section-sym.s
new file mode 100644 (file)
index 0000000..dcb25d3
--- /dev/null
+++ b/gas/testsuite/gas/i386/reloc-section-sym.s
@@ -0,0 +1,14 @@
+       .text
+       nop
+named_local:
+       .byte 0
+.Ltemp:
+       nop
+
+.section .text1,"ax"
+       call named_local
+       call .Ltemp
+
+.data
+       .quad named_local + 16
+       .quad .Ltemp + 16

diff --git a/gas/testsuite/gas/i386/x86-64.exp b/gas/testsuite/gas/i386/x86-64.exp
index 8ddf05481a5a1ebc36a31764718ad90cd7038384..3e5ffd8d13f6bc3f843a1abed869df642ba06b93 100644 (file)
--- a/gas/testsuite/gas/i386/x86-64.exp
+++ b/gas/testsuite/gas/i386/x86-64.exp
@@ -775,6 +775,10 @@ if [is_elf_format] then {
        run_dump_test "x86-64-align-branch-3"
     }
     run_dump_test ehinterp
+
+    run_dump_test "reloc-section-sym-all"
+    run_dump_test "reloc-section-sym-internal"
+    run_dump_test "reloc-section-sym-none"
 }
 run_dump_test pr27198
 run_dump_test pr29483

diff --git a/gas/write.c b/gas/write.c
index 9514c3df42e9f90ecf28825cef767cf30de79c95..cd02d8c7fb837ab314535a589e30f17f0a55498f 100644 (file)
--- a/gas/write.c
+++ b/gas/write.c
@@ -909,6 +909,14 @@ adjust_reloc_syms (bfd *abfd ATTRIBUTE_UNUSED,
        if ((symsec->flags & SEC_THREAD_LOCAL) != 0)
          continue;
 
+       /* With --reloc-section-sym=none, skip adjustment.
+          With --reloc-section-sym=internal, only adjust relocs against
+          internal labels (e.g. .L prefix symbols in ELF).  */
+       if (flag_reloc_section_sym == reloc_section_sym_none
+           || (flag_reloc_section_sym == reloc_section_sym_internal
+               && !bfd_is_local_label (stdoutput, symbol_get_bfdsym (sym))))
+         continue;
+
        val = S_GET_VALUE (sym);
 
 #if defined(TC_AARCH64) && defined(OBJ_COFF)