Commit Graph

7 Commits

Author SHA1 Message Date
Fangrui Song 73d01a80ce [ELF] Sort by input order within an input section description
According to
https://sourceware.org/binutils/docs/ld/Input-Section-Basics.html#Input-Section-Basics
for `*(.a .b)`, the order should match the input order:

* for `ld 1.o 2.o`, sections from 1.o precede sections from 2.o
* within a file, `.a` and `.b` appear in the section header table order

This patch implements the behavior. The interaction with `SORT*` and --sort-section is:

Matched sections are ordered by radix sort with the keys being `(SORT*, --sort-section, input order)`,
where `SORT*` (if present) is most significant.

> Note, multiple `SORT*` within an input section description has undocumented and
> confusing behaviors in GNU ld:
> https://sourceware.org/pipermail/binutils/2020-November/114083.html
> Therefore multiple `SORT*` is not the focus for this patch but
> this patch still strives to have an explainable behavior.

As an example, we partition `SORT(a.*) b.* c.* SORT(d.*)`, into
`SORT(a.*) | b.* c.* | SORT(d.*)` and perform sorting within groups. Sections
matched by patterns between two `SORT*` are sorted by input order.  If
--sort-alignment is given, they are sorted by --sort-alignment, breaking tie by
input order.

This patch also allows a section to be matched by multiple patterns, previously
duplicated sections could occupy more space in the output and had erroneous zero bytes.

The patch is in preparation for support for
`*(SORT_BY_INIT_PRIORITY(.init_array.* .ctors.*)) *(.init_array .ctors)`,
which will allow LLD to mix .ctors*/.init_array* like GNU ld (gold's --ctors-in-init-array)
PR44698 and PR48096

Reviewed By: grimar, psmith

Differential Revision: https://reviews.llvm.org/D91127
2020-11-12 08:53:11 -08:00
Fangrui Song 81cebfd008 [ELF][test] Change -o %t to -o /dev/null if the output is not needed 2020-02-12 21:54:50 -08:00
George Rimar 601e989879 [ELF] - Linkerscript: reimplement readSectionExcludes()
It is not only a bit more straightforward now, but also next 2 issues are solved:

* It just crashed on ".foo : { *(EXCLUDE_FILE (*file1.o)) }" before.
* It accepted multiple EXCLUDE_FILEs in a row.

Differential revision: https://reviews.llvm.org/D24726

llvm-svn: 282060
2016-09-21 08:53:21 +00:00
Rafael Espindola 1b87995f31 Make tests less dependent on the exact layout.
In most cases that means just not checking the address when we don't
need it.

For some tests it is easier to just set . to a known value.

llvm-svn: 281976
2016-09-20 15:08:24 +00:00
George Rimar 395281cfc3 Recommit r281721 "[ELF] - Linkerscript: implement EXCLUDE_FILE in the middle of a input section description."
With fix for 2 bots. Details about the fix performed is on a review page.

Initial commit message:
This is PR30387:

From PR description:
We fail to parse

SECTIONS
{
  foo :
  {
    *(sec0 EXCLUDE_FILE (zed1.o) sec1  EXCLUDE_FILE (zed2.o) sec2 )
  }
}
The semantics according to bfd are:

Include sec1 from every file but zed1.o
Include sec2 from every file but zed2.o
Include sec0 from every file

Patch implements the support.

Differential revision: https://reviews.llvm.org/D24650

llvm-svn: 281754
2016-09-16 17:42:10 +00:00
George Rimar ceae630c9b Reverted r281721 ("[ELF] - Linkerscript: implement EXCLUDE_FILE in the middle of a input section description.").
It broke build bot:
http://lab.llvm.org:8011/builders/lld-x86_64-darwin13/builds/27508

llvm-svn: 281723
2016-09-16 13:30:18 +00:00
George Rimar 4906c7f5c4 [ELF] - Linkerscript: implement EXCLUDE_FILE in the middle of a input section description.
This is PR30387:

From PR description:
We fail to parse

SECTIONS
{
  foo :
  {
    *(sec0 EXCLUDE_FILE (zed1.o) sec1  EXCLUDE_FILE (zed2.o) sec2 )
  }
}
The semantics according to bfd are:

Include sec1 from every file but zed1.o
Include sec2 from every file but zed2.o
Include sec0 from every file

Patch implements the support.

Differential revision: https://reviews.llvm.org/D24650

llvm-svn: 281721
2016-09-16 13:07:02 +00:00