This is actually fairly simple in the current code layout: Check if we should
compress just before writing out and everything else just works.
This removes the last case in which the object writer was creating a
fragment.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236267 91177308-0d34-0410-b5e6-96231b3b80d8
During ELF writing, there is no need to further relax the sections, so we
should not be creating fragments. This patch avoids doing so in all cases
but debug section compression (that is next).
Also, the ELF format is fairly simple to write. We can do a single pass over
the sections to write them out and compute the section header table.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236235 91177308-0d34-0410-b5e6-96231b3b80d8
Instead of accumulating the content in a fragment first, just write it
to the output stream.
Also put it first in the section table, so that we never have to worry
about its index being >= SHN_LORESERVE.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236145 91177308-0d34-0410-b5e6-96231b3b80d8
This matches other assemblers and is less unexpected (e.g. PR23227).
On ELF, I tried binutils gas v2.24 and nasm 2.10.09, and they both
agree on LShr. On COFF, I couldn't get my hands on an assembler yet,
so don't change the behavior. For now, don't change it on non-AArch64
Darwin either, as the other assembler is gas v1.38, which does an AShr.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235963 91177308-0d34-0410-b5e6-96231b3b80d8
Defaulting to AShr without consulting the target MCAsmInfo isn't OK.
Add a flag to fix that. Keep it off for now: target migrations will
follow in separate commits.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235951 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
When used, it is substituted with the number of .macro instantiations we've done up to that point in time.
So if this is the 1st time we've instantiated a .macro (any .macro, regardless of name), \@ will instantiate to 0, if it's the 2nd .macro instantiation, it will instantiate to 1 etc.
It can only be used inside a .macro definition, an .irp definition or an .irpc definition (those last 2 uses are undocumented).
Reviewers: echristo, rafael
Reviewed By: rafael
Subscribers: dsanders, llvm-commits
Differential Revision: http://reviews.llvm.org/D9197
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235862 91177308-0d34-0410-b5e6-96231b3b80d8
Currently symbol names are printed in quotes if it contains something
outside of the arbitrary set of characters that isAcceptableChar tests
for. On somem targets, it is never OK to print a symbol name in quotes
so allow targets to opt out of this behavior.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235670 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This directive is exactly the same as .asciz, except it's only used by MIPS.
It is used to store null terminated strings in object files.
Reviewers: rafael, dsanders, echristo
Reviewed By: dsanders, echristo
Subscribers: echristo, llvm-commits
Differential Revision: http://reviews.llvm.org/D7530
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235382 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
Bundle aligment requires that the functions always start at an aligned address.
Usually this is ensured by the compiler, but assembly code does not always
begin with a .align directive.
This change ensures that sections get the correct alignment if they contain
any instructions and bundling is enabled. (It also makes LLVM match the
behavior of GNU as).
Differential Revision: http://reviews.llvm.org/D9131
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235365 91177308-0d34-0410-b5e6-96231b3b80d8
We have to avoid converting a reference to a global into a reference to a local,
but it is fine to look past a local.
Patch by Vasileios Kalintiris.
I just moved the comment and added thet test.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235300 91177308-0d34-0410-b5e6-96231b3b80d8
Similar to r235222, but for the weak symbol case.
In an "ideal" assembler/object format an expression would always refer to the
final value and A-B would only be computed from a section in the same
comdat as A and B with A and B strong.
Unfortunately that is not the case with debug info on ELF, so we need an
heuristic. Since we need an heuristic, we may as well use the same one as
gas:
* call weak_sym : produces a relocation, even if in the same section.
* A - weak_sym and weak_sym -A: don't produce a relocation if we can
compute it.
This fixes pr23272 and changes the fix of pr22815 to match what gas does.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235227 91177308-0d34-0410-b5e6-96231b3b80d8
Part of pr23272.
A small annoyance with the assembly syntax we implement is that given an
expression there is no way to know if what is desired is the value of that
expression for the symbols in this file or for the final values of those
symbols in a link.
The first case is useful for use in sections that get discarded or ignored
if the section they are describing is discarded.
For axample, consider A-B where A and B are in the same comdat section.
We can compute the value of the difference in the section that is present in
the current .o and if that section survives to the final DSO the value will
still will be correct.
But the section is in a comdat. Another section from another object file
might be used istead. We know that that section will define A and B, but
we have no idea what the value of A-B might be.
In practice we have to assume that the intention is to compute the value
in the current section since otherwise the is no way to create something like
the debug aranges section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235222 91177308-0d34-0410-b5e6-96231b3b80d8
Linkers normally read all the relocations upfront to compute the references
between sections. Putting them together is a bit more cache friendly.
I benchmarked linking a Release+Asserts clang with gold on a vm. I tried all
4 combinations of --gc-sections/no --gc-section hot and cold cache.
I cleared the cache with
echo 3 > /proc/sys/vm/drop_caches
and warmed it up by running the link once before timing the subsequent ones.
With cold cache and --gc-sections the time goes from
1.86130781665 +- 0.01713126697463843 seconds
to
1.82370735105 +- 0.014127522318814516 seconds
With cold cache and no --gc-sections the time goes from
1.6087245435500002 +- 0.012999066825178644 seconds
to
1.5687122041500001 +- 0.013145850126026619 seconds
With hot cache and no --gc-sections the time goes from
0.926200939 ( +- 0.33% ) seconds
to
0.907200079 ( +- 0.31% ) seconds
With hot cache and gc sections the time goes from
1.183038049 ( +- 0.34% ) seconds
to
1.147355862 ( +- 0.39% ) seconds
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235165 91177308-0d34-0410-b5e6-96231b3b80d8
Now we don't have to do 2 synchronized passes to compute offsets and then
write the file.
This also includes a fix for the corner case of seeking in /dev/null. It
is not an error, but on some systems (Linux) the returned offset is
always 0. An error is signaled by returning -1. This is checked by
the existing tests now that "clang -o /dev/null ..." seeks.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234952 91177308-0d34-0410-b5e6-96231b3b80d8
