| Summary: | nm print "c" for a common symbol with -flto and -fcommon | ||
|---|---|---|---|
| Product: | binutils | Reporter: | Martin Liska <mliska> |
| Component: | binutils | Assignee: | Alan Modra <amodra> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | laurent.stacul, nickc |
| Priority: | P2 | ||
| Version: | 2.34 | ||
| Target Milestone: | 2.35 | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | 2020-08-15 00:00:00 | |
Yes, I jumped the wrong way in handling .scommon and other small data common sections. I'll commit the following after some testing.
diff --git a/bfd/syms.c b/bfd/syms.c
index b9f73361e6..cb25af17fa 100644
--- a/bfd/syms.c
+++ b/bfd/syms.c
@@ -653,10 +653,10 @@ bfd_decode_symclass (asymbol *symbol)
if (symbol->section && bfd_is_com_section (symbol->section))
{
- if (symbol->section == bfd_com_section_ptr)
- return 'C';
- else
+ if (symbol->section->flags & SEC_SMALL_DATA)
return 'c';
+ else
+ return 'C';
}
if (bfd_is_und_section (symbol->section))
{
The master branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=4d1823674eedf267c7cafac2b923256db0b10ac8 commit 4d1823674eedf267c7cafac2b923256db0b10ac8 Author: Alan Modra <amodra@gmail.com> Date: Sat Aug 15 09:42:44 2020 +0930 PR26389, nm prints "c" for a common symbol with -flto and -fcommon git commit 49d9fd42acef chose to make nm print 'C' for the normal common section, and 'c' for other commons. This was an attempt to make common symbols in .scommon and other small common sections show a 'c' type without a section name comparison, but it failed for nm --plugin on lto objects where normal common symbols are stashed in a "plug" section. It's also wrong for large common symbols. So instead set SEC_SMALL_DATA on sections created for small commons, and key off that flag to show 'c' type. If your ELF target doesn't have an elf_backend_symbol_processing function, then you won't see 'c' for symbols in .scommon. Note that due to bfd_decode_symclass decoding common symbols without a chance for coff_section_type to treat .scommon specially, then having .scommon in the array of special sections handled by coff_section_type prior to 49d9fd42acef was entirely ineffective. That fact escaped me when writing 49d9fd42acef. Unless .scommon didn't have SEC_IS_COMMON set, which would be a little weird. PR 26389 * syms.c (bfd_decode_symclass): Choose 'c' for commons only when SEC_SMALL_DATA. * elf32-m32r.c (_bfd_m32r_elf_symbol_processing): Set SEC_SMALL_DATA on small common section. * elf32-score.c (s3_bfd_score_elf_symbol_processing): Likewise. * elf32-score7.c (s7_bfd_score_elf_symbol_processing): Likewise. * elf32-tic6x.c (elf32_tic6x_symbol_processing): Likewise. * elf32-v850.c (v850_elf_symbol_processing): Likewise. * elfxx-mips.c (_bfd_mips_elf_symbol_processing): Likewise. * ecoff.c (ecoff_set_symbol_info, ecoff_link_add_externals): Likewise. The binutils-2_35-branch branch has been updated by Alan Modra <amodra@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=6183270ab45614eef9f33f58a3e01fdd0b525c6b commit 6183270ab45614eef9f33f58a3e01fdd0b525c6b Author: Alan Modra <amodra@gmail.com> Date: Sat Aug 15 09:42:44 2020 +0930 PR26389, nm prints "c" for a common symbol with -flto and -fcommon git commit 49d9fd42acef chose to make nm print 'C' for the normal common section, and 'c' for other commons. This was an attempt to make common symbols in .scommon and other small common sections show a 'c' type without a section name comparison, but it failed for nm --plugin on lto objects where normal common symbols are stashed in a "plug" section. It's also wrong for large common symbols. So instead set SEC_SMALL_DATA on sections created for small commons, and key off that flag to show 'c' type. If your ELF target doesn't have an elf_backend_symbol_processing function, then you won't see 'c' for symbols in .scommon. Note that due to bfd_decode_symclass decoding common symbols without a chance for coff_section_type to treat .scommon specially, then having .scommon in the array of special sections handled by coff_section_type prior to 49d9fd42acef was entirely ineffective. That fact escaped me when writing 49d9fd42acef. Unless .scommon didn't have SEC_IS_COMMON set, which would be a little weird. PR 26389 * syms.c (bfd_decode_symclass): Choose 'c' for commons only when SEC_SMALL_DATA. * elf32-m32r.c (_bfd_m32r_elf_symbol_processing): Set SEC_SMALL_DATA on small common section. * elf32-score.c (s3_bfd_score_elf_symbol_processing): Likewise. * elf32-score7.c (s7_bfd_score_elf_symbol_processing): Likewise. * elf32-tic6x.c (elf32_tic6x_symbol_processing): Likewise. * elf32-v850.c (v850_elf_symbol_processing): Likewise. * elfxx-mips.c (_bfd_mips_elf_symbol_processing): Likewise. * ecoff.c (ecoff_set_symbol_info, ecoff_link_add_externals): Likewise. (cherry picked from commit 4d1823674eedf267c7cafac2b923256db0b10ac8) Fixed The master branch has been updated by H.J. Lu <hjl@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=246b9ea1983d59c8b0070746a904a6b3f8d62187 commit 246b9ea1983d59c8b0070746a904a6b3f8d62187 Author: H.J. Lu <hjl.tools@gmail.com> Date: Sun Aug 16 05:45:02 2020 -0700 ld: Add a PR binutils/26389 test PR binutils/26389 * testsuite/ld-plugin/lto.exp: Run PR binutils/26389 test. * testsuite/ld-plugin/pr26389.c: New file. * testsuite/ld-plugin/pr26389.d: Likewise. The binutils-2_35-branch branch has been updated by H.J. Lu <hjl@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=d79b7acb00900e23fdb58d535039ad2e9d026843 commit d79b7acb00900e23fdb58d535039ad2e9d026843 Author: H.J. Lu <hjl.tools@gmail.com> Date: Sun Aug 16 05:45:02 2020 -0700 ld: Add a PR binutils/26389 test PR binutils/26389 * testsuite/ld-plugin/lto.exp: Run PR binutils/26389 test. * testsuite/ld-plugin/pr26389.c: New file. * testsuite/ld-plugin/pr26389.d: Likewise. (cherry picked from commit 246b9ea1983d59c8b0070746a904a6b3f8d62187) Quick note - this PR was duplicated in 26662, where it was also noted that the 'c' type in nm's output is not documented. So I have checked in a small patch to update the documentation: https://sourceware.org/bugzilla/show_bug.cgi?id=26662 https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=a2ab58313a248e4848c69c8d11ff547539a3c46f |
Starting from Alan's 49d9fd42acefc1c0ee282b5808874a1074bf1ecd, the following changed: $ cat conf.c char nm_test_var; $ gcc -flto -fcommon -c conf.c $ ./binutils/nm-new conf.o 00000000 c nm_test_var while before the revision the following is printed: $ nm conf.o 00000000 C nm_test_var Note that the "c" value is not supported by libtool and so a configure detection fails for various packages. I think we want to print "C" for a common symbol from LTO plugin. So one needs something like: bfd/syms.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/bfd/syms.c b/bfd/syms.c index c1de8ebab1..baa22cfcd9 100644 --- a/bfd/syms.c +++ b/bfd/syms.c @@ -653,7 +653,9 @@ bfd_decode_symclass (asymbol *symbol) if (symbol->section && bfd_is_com_section (symbol->section)) { - if (symbol->section == bfd_com_section_ptr) + if (symbol->section == bfd_com_section_ptr + || (symbol->section->name + && strcmp (symbol->section->name, "plug") == 0)) return 'C'; else return 'c'; And, can you please document the "c" in manual page?