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
The gold binary is not required to build the plugin. All that is
needed is for LLVM_BINUTILS_INCDIR to point to the directory
containing plugin-api.h.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235918 91177308-0d34-0410-b5e6-96231b3b80d8
The current implementations could exhibit some behavior differences:
raw_fd_ostream: Whatever the underlying fd does with seek+write. In a normal
file, the write position would be back to the old offset.
raw_svector_ostream: The write position is always the end of the stream, so
after pwrite the write position would be the new end. This matches what OS_X
(all BSD?) do with a pwrite in a O_APPEND fd.
Given that we don't need that feature and don't use O_APPEND a lot in LLVM,
just disallow it.
I am open to suggestions on renaming pwrite to something else, but this fixes
the issue for now.
Thanks to Yaron Keren for reporting it.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235303 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
Many of these predate llvm-readobj. With elf-dump we had to match
a relocation to symbol number and symbol number to symbol name or
section number.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235015 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
Original message.
Have one raw_fd_ostream constructor forward to the other.
This fixes some odd behaviour differences between the two. In particular,
the version that takes a FD no longer unconditionally sets stdout to binary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234734 91177308-0d34-0410-b5e6-96231b3b80d8
This fixes some odd behavior differences between the two. In particular,
the version that takes a FD no longer unconditionally sets stdout to binary.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234615 91177308-0d34-0410-b5e6-96231b3b80d8
formatted_raw_ostream is a wrapper over another stream to add column and line
number tracking.
It is used only for asm printing.
This patch moves the its creation down to where we know we are printing
assembly. This has the following advantages:
* Simpler lifetime management: std::unique_ptr
* We don't compute column and line number of object files :-)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234535 91177308-0d34-0410-b5e6-96231b3b80d8
Using this instead of
namespace llvm {
func...
}
Has the advantage that the build fails with a compiler error if it gets out
of sync with the .h file.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234515 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Add classof implementations to the raw_ostream classes."
Revert "Use the cast machinery to remove dummy uses of formatted_raw_ostream."
The underlying issue can be fixed without classof.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234495 91177308-0d34-0410-b5e6-96231b3b80d8
If we know we are producing an object, we don't need to wrap the stream
in a formatted_raw_ostream anymore.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234461 91177308-0d34-0410-b5e6-96231b3b80d8
One could make the argument for writing it immediately after the ELF header,
but writing it in the middle of the sections like we were doing just makes
it harder for no reason.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234400 91177308-0d34-0410-b5e6-96231b3b80d8
This also moves it earlier so that it they are produced before we print
an end symbol for the data section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234315 91177308-0d34-0410-b5e6-96231b3b80d8
Fast isel used to zero extends immediates to 64 bits. This normally goes
unnoticed because the value is truncated to 32 bits for output.
Two cases were it is noticed:
* We fail to use smaller encodings.
* If the original constant was smaller than i32.
In the tests using i1 constants, codegen would change to use -1, which is fine
(and matches what regular isel does) since only the lowest bit is then used.
Instead, this patch then changes the ir to use i8 constants, which looks more
like what clang produces.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234249 91177308-0d34-0410-b5e6-96231b3b80d8
H.J. Lu noted that all .section options are separated by a comma.
This patch changes the syntax of unique to require one.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234174 91177308-0d34-0410-b5e6-96231b3b80d8
As pr19627 points out, every use of AliasedSymbol is likely a bug.
The main use was to avoid the oddity of a variable showing up as undefined. That
was fixed in r233995, which made these calls nops.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234169 91177308-0d34-0410-b5e6-96231b3b80d8
Before when deciding if we needed a relocation in A-B, we wore only checking
if A was weak.
This fixes the asymmetry.
The "InSet" argument should probably be renamed to "ForValue", since InSet is
very MachO specific, but doing so in this patch would make it hard to read.
This fixes PR22815.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234165 91177308-0d34-0410-b5e6-96231b3b80d8
Unfortunately, on ELF there is not used attribute on the .o files,
so there is no easy way to keep the dump function alive.
If we are not gcing, we may as well produce non gcable files and
avoid the cost.
Linking a debug clang now takes 18.856225992 seconds, before it
took 21.206897447.
I will try avoiding --gc-sections -O3 on a followup patch.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234159 91177308-0d34-0410-b5e6-96231b3b80d8
The case values are not a tidy enum we can fully cover. They even ovelap
over the various extension.
Just use a default:
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234140 91177308-0d34-0410-b5e6-96231b3b80d8
Just store the section in MCSectionELF. This avoids multiple hash lookups.
This will also be used by ARM_EXIDX.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234139 91177308-0d34-0410-b5e6-96231b3b80d8
This allows the compiler/assembly programmer to switch back to a
section. This in turn fixes the bootstrap failure on powerpc (tested
on gcc110) without changing the ppc codegen at all.
I will try to cleanup the various getELFSection overloads in a followup patch.
Just using a default argument now would lead to ambiguities.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234099 91177308-0d34-0410-b5e6-96231b3b80d8
Rafael Espindola