Commit Graph

10 Commits

Author SHA1 Message Date
Fangrui Song 962b29d716 ELFObjectWriter: Don't sort non-local symbols
As we don't sort local symbols, don't sort non-local symbols.  This makes
non-local symbols appear in their register order, which matches GNU as. The
register order is nice in that you can write tests with interleaved CHECK
prefixes, e.g.

```
// CHECK: something about foo
.globl foo
foo:
// CHECK: something about bar
.globl bar
bar:
```

With the lexicographical order, the user needs to place lexicographical smallest
symbol first or keep CHECK prefixes in one place.
2021-02-13 10:32:27 -08:00
Fangrui Song bb4a36ea28 [ELF] Propagate LMA offset to sections with neither AT() nor AT>
Fixes https://bugs.llvm.org/show_bug.cgi?id=45313
Also fixes linkerscript/{at4.s,overlay.test} LMA address issues exposed by
011b785505.
Related: D74297

This patch improves emulation of GNU ld's heuristics on the difference
between the LMA and the VMA:
https://sourceware.org/binutils/docs/ld/Output-Section-LMA.html#Output-Section-LMA

New test linkerscript/lma-offset.s (based on at4.s) demonstrates some behaviors.

Reviewed By: psmith

Differential Revision: https://reviews.llvm.org/D76995
2020-04-01 08:19:06 -07:00
Fangrui Song 011b785505 [ELF] Create readonly PT_LOAD in the presence of a SECTIONS command
This essentially drops the change by r288021 (discussed with Georgii Rymar
and Peter Smith and noted down in the release note of lld 10).

GNU ld>=2.31 enables -z separate-code by default for Linux x86. By
default (in the absence of a PHDRS command) a readonly PT_LOAD is
created, which is different from its traditional behavior.

Not emulating GNU ld's traditional behavior is good for us because it
improves code consistency (we create a readonly PT_LOAD in the absence
of a SECTIONS command).

Users can add --no-rosegment to restore the previous behavior (combined
readonly and read-executable sections in a single RX PT_LOAD).
2020-03-19 19:11:11 -07:00
George Rimar b3be390f94 [ELF] - (-Map file) Implement printing of LMA for assignments outside of section declarations.
This was a missing piece.
We started to print LMAs and information about assignments,
but did not do that for assignments outside of section declarations yet.
The patch implements it.

Differential revision: https://reviews.llvm.org/D45314

llvm-svn: 348468
2018-12-06 09:04:52 +00:00
Fangrui Song 68fa4e8c34 [ELF] Assign RF_EXEC rank even if --no-rosegment or SECTIONS command is used
Summary:
Currently when --no-rosegment is specified or a linker script with SECTIONS command is used,
.rodata (A) .text (AX) are assigned the same rank and .rodata may be placed after .text .
This increases the gap between .text and .bss and can cause pc-relative relocation overflow (e.g. gcc crtbegin.o crtbegin.S have R_X86_64_PC32 relocation from .text to .bss).

This patch makes SingleRoRx affect only segment layout, not section layout. As a consequence, .rodata will be placed before .text regardless of SingleRoRx.

Reviewers: espindola, ruiu, grimar, echristo, javed.absar

Subscribers: emaste, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D48405

llvm-svn: 335627
2018-06-26 17:04:47 +00:00
Fangrui Song 95851515d7 Add a CIE with length 0 unconditionally.
Summary: This is not technically required, but glibc unwind-dw2-fde.c classify_object_over_fdes expects there is a CIE record length 0 as a terminator.

Reviewers: ruiu, espindola

Subscribers: emaste, arichardson, llvm-commits

Differential Revision: https://reviews.llvm.org/D46566

llvm-svn: 331708
2018-05-08 01:19:16 +00:00
Rui Ueyama 4e150c4c88 Make "Size" column in the map file one characters shorter.
Previously, "size" column is 9 characters long which is too long
at least for 32-bit (because at maximum it needs 8 columns). This
patch make it one column shorter than before. That's also a reasonable
default for 64-bit.

llvm-svn: 329317
2018-04-05 17:20:18 +00:00
Rui Ueyama 16a130bc78 Fix column size in the map file.
Size can be narrow, but LMA should be the same width as VMA.

llvm-svn: 329312
2018-04-05 16:45:37 +00:00
George Rimar e88b76a989 [ELF] - Reveal more information in -Map file about assignments.
Currently, LLD print symbol assignment commands to the map file,
but it does not do that for assignments that are outside of the section
descriptions. Such assignments can affect the layout though.

The patch implements the following:

* Teaches LLD to print symbol assignments outside of section declaration.
* Teaches LLD to print PROVIDE/HIDDEN/PROVIDE hidden commands.

In case when symbol is not provided, nothing will be printed.

Differential revision: https://reviews.llvm.org/D44894

llvm-svn: 329272
2018-04-05 11:25:58 +00:00
George Rimar ee01b1d390 [ELF] - Print LMA in a -Map file.
Currently, LLD prints VA, but not LMA in a map file.
It seems can be useful to print both to reveal layout
details and patch implements it.

Differential revision: https://reviews.llvm.org/D44899

llvm-svn: 329271
2018-04-05 10:51:06 +00:00