/ALTERNATENAME is a rarely-used, undocumented command line option that is
needed to link LLD for release build. It seems that the option is for defining
an weak alias; /alternatename:foo=bar defines weak symbol "foo" for "bar".
If "foo" is defined in an input file, it'll be linked normally and the command
line option will have no effect. If it's not defined, "foo" will be handled
as an alias for "bar".

This patch implements the parser for the option. The actual weak alias handling
will be implemented in a separate patch.

llvm-svn: 196743

llvm-svn: 196741

llvm-svn: 196716

Because compare() and its heper functions no longer have to be members of
LayoutPass class, we can remove it from the class. No functionality change.

llvm-svn: 196715

The comparator used in the layout pass has many calls of map::find(). Because
std::sort runs the comparator N*log2(N) times, the maps are looked up with the
same key again and again. The map lookup is not a very fast operation. It made
the pass slow.

This patch eliminates the duplicate map lookups using decorate-sort-undecorate
idiom. The pass used to take 1.1 seconds when linking LLD with LLD on Windows,
but it now takes only 0.3 seconds. Overall performance gain in that case is from
6.1 seconds to 5.2 seconds.

Differential Revision: http://llvm-reviews.chandlerc.com/D2358

llvm-svn: 196714

GroupedSectionsPass was a complicated pass. That pass's job was to reorder
atoms by section name, so that the atoms with the same section prefix will be
emitted consecutively to the executable. The pass added layout edges to atoms,
and let the layout pass to actually reorder them.

This patch simplifies the design by making GroupedSectionPass to directly
reorder atoms, rather than adding layout edges. This resembles ELF's
ArrayOrderPass.

This patch improves the performance of LLD; it used to take 7.1 seconds to
link LLD with LLD on my Macbook Pro, but it now takes 6.1 seconds.

llvm-svn: 196628

llvm-svn: 196564

llvm-svn: 196563

llvm-svn: 196562

llvm-svn: 196505

Currently we do not de-duplicate library files specified by /defaultlib option.
As a result, the same files are added multiple times to the input graph. In
particular, some popular files, such as kernel32.lib or oldnames.lib, are added
more than 10 times during linking of LLD. That makes the linker slower, as it
needs to parse the same file again and again.

This patch solves the issue by de-duplicating. The same file will be added only
once to the input graph. This patch improved the LLD linking time from 10.5
seconds to 7.7 seconds on my 4-core Core i7 Macbook Pro.

llvm-svn: 196504

Because ArrayRef has implicit conversion from C arrays, we don't need
makeArrayRef.

llvm-svn: 196475

llvm-svn: 196465

Emitting idata atoms to their own section would make debugging easier.
The Windows loader do not really care about whether the DLL import table is
in .rdata or its own .idata section, so there is no change in functionality.

llvm-svn: 196458

llvm-svn: 196366

If /functionpadmin is specified, the linker is supposed to make room at the
beginning of each function, so that self-modifying program would easily
hotpatch existing functions. Since I'm not sure if this feature is really used,
I'll make LLD to ignore the option for now.

llvm-svn: 196363

llvm-svn: 196332

These relocations are used in .debug section.

llvm-svn: 196262

llvm-svn: 196200

llvm-svn: 196196

llvm-svn: 196185

llvm-svn: 196092

This reverts commit r195852 because LLD seems to create broken executables
with that patch when compiled with MSVC 2013.

llvm-svn: 196078

llvm-svn: 196056

llvm-svn: 196055

llvm-svn: 196054

No change in functionality.

llvm-svn: 196053

/DEBUG option is to make the linker to emit debug information to the resulting
executable. It's not for enable debugging of the linker itself.

llvm-svn: 196040

This is a patch to let the PECOFF writer to use the information passed
by the parser for /section option. The implementation of /section should
now be complete.

llvm-svn: 195893

/MERGE option is a bit complicated for many reasons. Firstly, it takes both
positive and negative arguments. That means we have to have one of three
distinctive values (set, clear or unchange) for each permission bit. In this
patch we represent the three values using two bitmasks.

Secondly, the permissions specified by the parameter is bitwise or-ed with the
default permissions of a section. There is an exception for that rule; if one
of READ, WRITE or EXECUTE bit is specified, unspecified bits need to be
cleared. (So if you specify only WRITE for example, the resulting section will
not have WRITE nor EXECUTE bits.)

Lastly, multiple /merge options are allowed.

llvm-svn: 195882

This patch is to improve the readability of the tests before making a change
to /merge option.

llvm-svn: 195863

/MERGE:foo=bar command line option merges section foo to section bar. If
section bar does not exist, foo is just renamed as bar.

llvm-svn: 195856

llvm-svn: 195855

llvm-svn: 195854

llvm-svn: 195853

Atom ordinals are the indeces in a file. Currently the PECOFF reader assigns
ordinals for each section, so it's (incorrectly) assigning duplicate ordinals.

llvm-svn: 195852

llvm-svn: 195801

Instead of having multiple SectionChunks for each section (.text, .data,
.rdata and .bss), we could have one chunk writer that can emit any sections.
This patch does that -- removing all section-sepcific chunk writers and
replace them with one "generic" writer.

This change should simplify the code because it eliminates similar-but-
slightly-different classes.

It also fixes an issue in the previous design. Before this patch, we could
emit only limited set of sections (i.e. .text, .data, .rdata and .bss). With
this patch, we can emit any sections.

llvm-svn: 195797

This reverts accidental commit r195794.

llvm-svn: 195795

llvm-svn: 195794