llvm-svn: 303226

Summary:
Previously, the garbage collector (enabled by default or by explicitly
passing /opt:ref) did not kill dllimported symbols. As a result,
dllimported symbols could be added to resulting executables' dllimport
list even if no one was actually using them.

This patch implements dllexported symbol garbage collection. Just like
COMDAT sections, dllimported symbols now have Live bits to manage their
liveness, and MarkLive marks reachable dllimported symbols.

Fixes https://bugs.llvm.org/show_bug.cgi?id=32950

Reviewers: pcc

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D33264

llvm-svn: 303225

llvm-svn: 303164

llvm-svn: 303155

Follow up for r303150.

llvm-svn: 303153

SymbolTableBaseSection was introduced.

Detemplation of SymbolTableSection should allow to detemplate more things.

Differential revision: https://reviews.llvm.org/D33124

llvm-svn: 303150

Switch to llvm::to_integer() everywhere in LLD instead of 
StringRef::getAsInteger() because API of latter is confusing. 
It returns true on error and false otherwise what makes reading 
the code incomfortable.

Differential revision: https://reviews.llvm.org/D33187

llvm-svn: 303149

llvm-svn: 303135

They are too slow otherwise. We track the issue in pr32942.

llvm-svn: 303097

We should only ever expect this function to return a regular
InputSection; I would not expect a function definition to be in a
MergeInputSection or EhInputSection. We were previously crashing
in writeTo if this function returned a section that was not an
InputSection because we do not set OutSec for such sections.

This can happen in practice if a function is defined in an empty
section which shares its offset-in-file with a MergeInputSection,
as in the provided test case.

A better fix for this bug would be to fix the
DWARFUnit::collectAddressRanges() interface to provide section
information (see D33183), but this at least fixes the crash.

Differential Revision: https://reviews.llvm.org/D33176

llvm-svn: 303089

Fixes PR33032.

Differential Revision: https://reviews.llvm.org/D33175

llvm-svn: 303088

This reorganisation prevents us from cluttering up the top-level lib directory
with more driver libraries such as llvm-dlltool (see D29892).

llvm-svn: 302995

llvm-svn: 302921

We used to place orphans by just using compareSectionsNonScript.

Then we noticed that since linker scripts can use another order, we
should first try match the section to a given PT_LOAD. But there is
nothing special about PT_LOAD. The same issue can show up for
PT_GNU_RELRO for example.

In general, we have to search for the most similar section and put the
orphan next to it. Most similar being defined as how long they follow
the same code path in compareSecitonsNonScript.

That is what this patch does. We now compute a rank for each output
section, with a bit for each branch in what was
compareSectionsNonScript.

With this findOrphanPos is now fully general and orphan placement can
be optimized by placing every section with the same rank at once.

The included testcase is a variation of many-sections.s that uses
allocatable sections to avoid the fast path in the existing
code. Without threads it goes form 46 seconds to 0.9 seconds.

llvm-svn: 302903

This reverts changes introduced in r302414 "[ELF] - Set DF_STATIC_TLS flag for i386 target."

Because DF_STATIC_TLS does not look to be used by glibc or anything else.

llvm-svn: 302884

Both gold and bfd restrict that one:

ld.bfd: test.o: relocation R_X86_64_TPOFF32 against `var' can not be 
used when making a shared object; recompile with -fPIC
ld.gold: error: test.o: unsupported reloc 23 against global symbol var

What looks reasonable because it is 32 bit one. Patch do the same.

Differential revision: https://reviews.llvm.org/D33100

llvm-svn: 302881

llvm-svn: 302849

llvm-svn: 302848

llvm-svn: 302847

llvm-svn: 302846

This is a bit hackish, but allows for a lot of followup cleanups.

llvm-svn: 302845

llvm-svn: 302843

llvm-svn: 302832

llvm-svn: 302828

llvm-svn: 302826

Testcase itself depends on .text section location, which was orphan earlier.

Suggested by Rafael Espíndola

llvm-svn: 302792

Differential Revision: https://reviews.llvm.org/D33024

llvm-svn: 302748

llvm-svn: 302719

So that it is clear that the function is a wrapper for for_each_n.

llvm-svn: 302718

This improves many-sections.s with a linker script from 22s to 0.9s.

llvm-svn: 302708

We now always use getCmd. I will optimize it in a followup commit.

llvm-svn: 302706

llvm-svn: 302697

Previously we were not printing out the type of the incompatible section
which made it difficult to determine what the problem was.

The error message format has been change to the following:

  error: section type mismatch for .shstrtab
  >>> <internal>:(.shstrtab): SHT_STRTAB
  >>> output section .shstrtab: Unknown

Patch by Alexander Richardson.

Differential Revision: https://reviews.llvm.org/D32488

llvm-svn: 302694

llvm-svn: 302690

This behavior differs from the semantics implemented by GNU linkers
which only define this symbol iff ELF headers are in the memory
mapped segment.

Differential Revision: https://reviews.llvm.org/D33019

llvm-svn: 302687

We used to inherit from it, but don't need it anymore.

llvm-svn: 302675

llvm-svn: 302672

llvm-svn: 302671

This is PR32664.

Issue was revealed by linux kernel script which was:

SECTIONS {
 . = (0xffffffff80000000 + ALIGN(0x1000000, 0x200000));
 phys_startup_64 = ABSOLUTE(startup_64 - 0xffffffff80000000);

 .text : AT(ADDR(.text) - 0xffffffff80000000) {
.....
  *(.head.text)
Where startup_64 is in .head.text.

At the place of assignment to phys_startup_64 we can not calculate absolute value for startup_64
because .text section has no VA assigned. Two patches were prepared earlier to address this: D32173 and D32174.

And in comments for D32173 was suggested not try to support this case, but error out.

Differential revision: https://reviews.llvm.org/D32793

llvm-svn: 302668

When compiling LLD using GCC 7 it reports warnings like:
"warning: this statement may fall through [-Wimplicit-fallthrough=]"

LLVM has LLVM_FALLTHROUGH macro which can be used to avoid such warnings.
Together with D33036 this patch fixes them.

Differential revision: https://reviews.llvm.org/D32907

llvm-svn: 302666