Import Lookup Table in Import Directory Table has the same contents
as Hint/Name Table. Symbol names imported from DLLs are pointed by
both Import Directory Table and Hint/Name Table. We had duplicate
strings there.
This patch eliminates that duplication to make the table smaller.
This should reduce binary size by the sum of lengths of imported
symbols.
llvm-svn: 233128
Visual C++ shows the "right shift by too large amount" warning if
`MipsELFReference` is instantiated for 32-bit target and `Elf_Rel_Impl::getType`
method has `unsigned char` return type. We can freely suppress the warning in
that case because MIPS 32-bit ABI does not pack multiple relocation types into
the single field `r_type` and the `MipsELFReference::_tag` should be always
zero in that case.
No functional changes.
llvm-svn: 233088
N64 ABI relocation record r_info field in fact consists of five subfields:
* r_sym - symbol index
* r_ssym - special symbol
* r_type3 - third relocation type
* r_type2 - second relocation type
* r_type - first relocation type
Up to three these relocations applied one by one. The first relocation
uses an addendum from the relocation record. Each subsequent relocation
takes as its addend the result of the previous operation. Only the final
operation actually modifies the location relocated. The first relocation
uses as a reference symbol specified by the `r_sym` field. The third
relocation assumes NULL symbol.
The patch represents these data using LLD model and takes in account
additional relocation types during a relocation calculation.
Additional relocations do not introduce any new relations between two
atoms and just specify operations need to be done during a relocation
calculation. The first relocation type (`r_type`) stored in the
`Reference::_kindValue`. The rest of relocations and `r_ssym` value are
stored in the new `Reference::_tag` field "as-is". I decided to do not
"decode" these data on the core LLD level to prevent pollution of the
core LLD model by very target specific data.
Also I have to override writing of relocation records in the `RelocationTable`
class to convert MIPS N64 ABI relocation information from the `Reference`
class back to the ELF relocation record.
http://reviews.llvm.org/D8533
llvm-svn: 233057
The aforementioned relocation generate a GOT entry with a
R_X86_64_TPOFF64. The new relocation is processed at startup
time by the loader. lld didn't generate the outstanding relocation,
now it does. This bug was found while trying to link ls(1) on FreeBSD.
Simplified repro:
#include <stdio.h>
#include <wchar.h>
#include <wctype.h>
int
main(void)
{
wchar_t wc = 98;
if (!iswprint(wc))
printf("blah\n");
else
printf("foo\n");
return (0);
}
which incorrectly outputs "blah" when linked with lld before this patch.
llvm-svn: 233051
separately
This change reduce difference between the trunk and upcoming patch and
simplify the future code review.
No functional changes.
llvm-svn: 232919
This changes improves performance of lld, when self-hosting lld, when compared
with the bfd linker. BFD linker on average takes 8 seconds in elapsed time.
lld takes 3 seconds elapased time average. Without this change, lld takes ~5
seconds average. The runtime comparisons were done on a release build and
measured by running linking thrice.
lld self-host without the change
----------------------------------
real 0m3.196s
user 0m4.580s
sys 0m0.832s
lld self-host with lld
-----------------------
user 0m3.024s
user 0m3.252s
sys 0m0.796s
time taken to build lld with bfd
--------------------------------
real 0m8.419s
user 0m7.748s
sys 0m0.632s
llvm-svn: 232460
I knew I cut corners when I wrote this. Turned out that it is
actually slow when a file being read has many symbols. This patch
is to stop doing linear search and instead do map lookup.
llvm-svn: 232436
The `eh_frame_ptr` field in the `.eh_frame_hdr` section contains an address
of the `.eh_frame` section. Using an absolute 32-bit format for encoding
of this field does not work for 64-bit targets. It is better to use a
relative format because it covers both 32-bit and 64-bit cases. Sure
this work if a distance between `.eh_frame_hdr` and `.eh_frame` sections
is less than 4 Gb but it is a rather correct assumption.
http://reviews.llvm.org/D8352
llvm-svn: 232414
Puts symbols defined in linker script expressions in a runtime file that is
added as input to the resolver, making the input object files see symbols
defined in linker scripts.
http://reviews.llvm.org/D8263
llvm-svn: 232409
This commit implements the behaviour of the SECTIONS linker script directive,
used to not only define a custom mapping between input and output sections, but
also order input sections in the output file. To do this, we modify
DefaultLayout with hooks at important places that allow us to re-order input
sections according to a custom order. We also add a hook in SegmentChunk to
allow us to calculate linker script expressions while assigning virtual
addresses to the input sections that live in a segment.
Not all SECTIONS constructs are currently supported, but only the ones that do
not use special sort orders. It adds two LIT test as practical examples of
which sections directives are currently supported.
In terms of high-level changes, it creates a new class "script::Sema" that owns
all linker script ASTs and the logic for linker script semantics as well.
ELFLinkingContext owns a single copy of Sema, which will be used throughout
the object file writing process (to layout sections as proposed by the linker
script).
Other high-level change is that the writer no longer uses a "const" copy of
the linking context. This happens because linker script expressions must be
calculated *while* calculating final virtual addresses, which is a very late
step in object file writing. While calculating these expressions, we need to
update the linker script symbol table (inside the semantics object), and, thus,
we are "modifying our context" as we prepare to write the file.
http://reviews.llvm.org/D8157
llvm-svn: 232402
The gotSymbol need not be a global static variable. Apart from this reason, This
variable was creating an issue with self hosting lld, as there seems to be an
issue running global initializers, when initializing the guard for this static
variable.
Program received signal SIGTRAP, Trace/breakpoint trap.
llvm-svn: 232341
Rui Ueyama