We can add multiple undefined atoms having the same name to the symbol table.
If such atoms are added, the symbol table compares their canBeNull attributes,
and select one having a stronger constraint. If their canBeNulls are the same,
the choice is arbitrary. Currently it choose the existing one.

This patch changes the preference, so that the symbol table choose the new one
if the new atom has a greater canBeNull or a fallback atom. This shouldn't
change the behavior except the case described below.

A new undefined atom may have a new fallback atom attribute. By choosing the new
atom, we can update the fallback atom during Core Linking. PE/COFF actually need
that. For example, _lseek is an alias for __lseek on Windows. One of an object
file in OLDNAMES.LIB has an undefined atom for _lseek with the fallback to
__lseek. When the linker tries to resolve _read, it supposed to read the file
from OLDNAMES.LIB and use the new fallback from the file. Currently LLD cannot
handle such case because duplicate undefined atoms with the same attributes are
ignored.

Differential Revision: http://llvm-reviews.chandlerc.com/D2161

llvm-svn: 194777

llvm-svn: 194768

Writing arguments after the redirection of input ("< somefile") seems a bit
strange. Changes the order.

llvm-svn: 194727

llvm-svn: 194723

llvm-svn: 194550

llvm-svn: 194292

llvm-svn: 194280

llvm-svn: 194278

This patch adds support for converting normalized mach-o to and from binary
mach-o. It also changes WriterMachO (which previously directly wrote a 
mach-o binary given a set of Atoms) to instead do it in two steps. The first 
step uses normalizedFromAtoms() to convert Atoms to normalized mach-o, and the
second step uses writeBinary() which to generate the mach-o binary file.  

llvm-svn: 194167

Errors in .drectve section were silently ignored. This patch fixes the issue.

llvm-svn: 194110

llvm-svn: 194003

llvm-svn: 193982

This patch should fix the test when it runs on Windows, by allowing drive
letter separator (colon) in the path. Now all LLD ELF tests passed on MSVC
2012 32-bit. Hooray!

llvm-svn: 193978

llvm-svn: 193974

llvm-svn: 193913

llvm-svn: 193911

These tests assume that the created objects are for x86_64. These tests
failed on non-x86_64 environments, such as 32 bit Windows.

llvm-svn: 193910

On Windows, neither "(" nor ")" are shell special characters, so -\( is passed
as-is to LLD. Because of that this test was failing on Windows.

llvm-svn: 193905

This patch adds "-target x86_64" to the command line. Without this option,
a 32 bit object file would be created on 32 bit machine, resulting in test
failure.

llvm-svn: 193904

llvm-svn: 193662

llvm-svn: 193586

Enable this for the following flavors

a) core
b) gnu
c) darwin

Its disabled for the flavor PECOFF. Convenient markers are added with FIXME
comments in the Driver that would be removed and code removed from each flavor.

llvm-svn: 193585

__ImageBase is an absolute symbol whose address is the same as the image base
address. What we did before this patch was to create __ImageBase symbol as a
symbol whose *contents* (not location) is the image base address, which is
clearly wrong.

llvm-svn: 193565

llvm-svn: 193483

llvm-svn: 193481

llvm-svn: 193451

llvm-svn: 193385

This renames the GOTPLTPass to RelocationPass and refactors it to better
represent the different types of relocations.

llvm-svn: 193379

llvm-svn: 193375

llvm-svn: 193369

The patch have completely broken COFF port and disabled many tests.
This also reverts r193302 (comment fix).

llvm-svn: 193362

Disable tests to be run with REQUIRES: disable. Note disable is not added to the
config by the test runner Mkaefiles, so essentially disables the test.

Code changes would be required to fix these tests :-

test/darwin/hello-world.objtxt
test/elf/check.test
test/elf/phdr.test
test/elf/ppc.test
test/elf/undef-from-main-dso.test
test/elf/X86_64/note-sections-ro_plus_rw.test
test/pecoff/alignment.test
test/pecoff/base-reloc.test
test/pecoff/bss-section.test
test/pecoff/drectve.test
test/pecoff/dynamic.test
test/pecoff/dynamicbase.test
test/pecoff/entry.test
test/pecoff/hello.test
test/pecoff/imagebase.test
test/pecoff/importlib.test
test/pecoff/lib.test
test/pecoff/multi.test
test/pecoff/reloc.test
test/pecoff/weak-external.test

llvm-svn: 193300

Because it depends on "-mllvm -debug" flag, the test fails in Release build.

llvm-svn: 193271

llvm-svn: 193259

llvm-svn: 193207

llvm-svn: 193121

This patch fixes a bug in r190608. The results of a comparison function
passed to std::sort must be transitive, which is, if a < b and b < c, and if
a != b, a < c must be also true. CompareAtoms::compare did not actually
guarantee the transitivity. As a result the sort results were sometimes just
wrong.

Consider there are three atoms, X, Y, and Z, whose file ordinals are 1, 2, 3,
respectively. Z has a property "layout-after X". In this case, all the
following conditionals become true:

  X < Y because X's ordinal is less than Y's
  Y < Z because Y's ordinal is less than Z's
  Z < X because of the layout-after relationship

This is not of course transitive. The reason why this happened is because
we used follow-on relationships for comparison if two atoms falls in the same
follow-on chain, but we used each atom's properties if they did not. This patch
fixes the issue by using follow-on root atoms for comparison to get consistent
results.

Differential Revision: http://llvm-reviews.chandlerc.com/D1980

llvm-svn: 193029

We should dead-strip atoms only if they are created for COMDAT symbols. If we
remove non-COMDAT atoms from a binary, it will no longer be guaranteed that
the binary will work correctly.

In COFF, you can manipulate the order of section contents in the resulting
binary by section name. For example, if you have four sections
.data$unique_prefix_{a,b,c,d}, it's guaranteed that the contents of A, B, C,
and D will be consecutive in the resulting .data section in that order.
Thus, you can access B's and C's contents by incrementing a pointer pointing
to A until it reached to D. That's why we cannot dead-strip B or C even if
no one is directly referencing to them.

Some object files in the standard library actually use that technique.

llvm-svn: 193017

llvm-svn: 192939

Dead-strip root symbols can be undefined atoms, but should not really be
nonexistent, because dead-strip root symbols should be added to initial
undefined atoms at startup. Whenever you look up its name in the symbol
table, some type of atom will always exist.

llvm-svn: 192831