This CL places .dynsym and .dynstr at the beginning of SHF_ALLOC
sections. We do this to mitigate the possibility that huge .dynsym and
.dynstr sections placed between ro-data and text sections cause
relocation overflow.
Differential Revision: https://reviews.llvm.org/D45788
llvm-svn: 332374
The --keep-unique <symbol> option is taken from gold. The intention is that
<symbol> will be prevented from being folded by ICF. Although not
specifically mentioned in the documentation <symbol> only matches
global symbols, with a warning if the symbol is not found.
The implementation finds the Section defining <symbol> and removes it from
the set of sections considered for ICF.
Differential Revision: https://reviews.llvm.org/D46755
llvm-svn: 332332
This allows producing pdb debug info. This is an LLD specific option
since GCC and GNU binutils doesn't support the PDB file format.
Differential Revision: https://reviews.llvm.org/D46796
llvm-svn: 332327
Since we a no longer using this function for the wasm start
section we don't actually care what its signature is.
Differential Revision: https://reviews.llvm.org/D46594
llvm-svn: 332308
The relocation R_PPC64_REL64 should return R_PC for getRelExpr since it
computes S + A - P.
Differential Revision: https://reviews.llvm.org/D46766
llvm-svn: 332259
The relocation R_PPC64_REL32 should return R_PC for getRelExpr since it
computes S + A - P.
Differential Revision: https://reviews.llvm.org/D46586
llvm-svn: 332252
If a symbol with an undefined version in a DSO is not going to be
exported into the dynamic symbol table then do not give an error message
for the missing version. This can happen with the --exclude-libs option
which implicitly gives all symbols in a static library the local version.
This matches the behavior of ld.gold and is exploited by the Bionic
dynamic linker on Arm.
Differential Revision: https://reviews.llvm.org/D43126
llvm-svn: 332224
This is needed to avoid merging two functions with identical
instructions but different xdata. It also reduces binary size by
deduplicating identical pdata sections.
Fixes PR35337.
Differential Revision: https://reviews.llvm.org/D46672
llvm-svn: 332169
We discovered (crbug.com/838449#c24) that string tail merging can
negatively affect compressed binary size, so provide a flag to turn
it off for users who care more about compressed size than uncompressed
size.
Differential Revision: https://reviews.llvm.org/D46780
llvm-svn: 332149
Both R_PPC_CALL and R_PPC_CALL_PLT Exprs map to the R_PPC64_REL24 relocation
which has the form Sym + addend - P.
Differential Revision: https://reviews.llvm.org/D46654
llvm-svn: 332127
Summary:
Suppose we visit symbols in this order:
1. weak definition of foo in a lazy object
2. reference of foo
3 (optional). definition of foo
bfd/gold allows 123 but not 12.
Current --warn-backrefs implementation will report both cases as a backward reference. With this change, both 123 (intended) and 12 (unintended) are allowed. The usage of weak definitions usually imply there are also global definitions, so the trade-off is justified.
Reviewers: ruiu, espindola
Subscribers: emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D46624
llvm-svn: 332061
The previous CL changes the order of output sections, which causes address changes in test cases.
Review: https://reviews.llvm.org/D46730
llvm-svn: 332054
This CL is to mitigate R_X86_64_PC32 relocation overflow problems for huge binaries that has near 4G allocated sections.
By examining those binaries, there're 2 issues contributes to the problem:
1). huge ".dynsym" and ".dynstr" stands in the way between .rodata and .text
2). _init_array_start/end are placed at 0 if no ".init_array" presents, this causes .text relocation against them become more prone to overflow.
This CL addresses 1st problem (the 2nd will be addressed in another CL.) by assigning a smaller sortrank to .dynsym and .dynstr thus they no longer stand in between.
llvm-svn: 332038
Merging data segments produces smaller code sizes because each segment
has some boilerplate. Therefore, merging data segments is generally the
right approach, especially with wasm where binaries are typically
delivered over the network.
However, when analyzing wasm binaries, it can be helpful to get a
conservative picture of which functions are using which data
segments[0]. Perhaps there is a large data segment that you didn't
expect to be included in the wasm, introduced by some library you're
using, and you'd like to know which library it was. In this scenario,
merging data segments only makes the analysis worse.
Alternatively, perhaps you will remove some dead functions by-hand[1]
that can't be statically proven dead by the compiler or lld, and
removing these functions might make some data garbage collect-able, and
you'd like to run `--gc-sections` again so that this now-unused data can
be collected. If the segments were originally merged, then a single use
of the merged data segment will entrench all of the data.
[0] https://github.com/rustwasm/twiggy
[1] https://github.com/fitzgen/wasm-snip
Patch by Nick Fitzgerald!
Differential Revision: https://reviews.llvm.org/D46417
llvm-svn: 332013
A non-alloc note section should not have a PT_NOTE program header.
Found while linking ghc (Haskell compiler) with lld on FreeBSD.
ghc emits a .debug-ghc-link-info note section (as the name suggests, it
contains link information) as a SHT_NOTE section without SHF_ALLOC set.
For this case ld.bfd does not emit a PT_NOTE segment for the
.debug-ghc-link-info section. lld previously emitted a PT_NOTE with
p_vaddr = 0 and FreeBSD's rtld segfaulted when trying to parse a note at
address 0.
llvm.org/pr37361
Differential Revision: https://reviews.llvm.org/D46623
llvm-svn: 331973
Reviewed by: ruiu, grimar, espindola
Differential Revision: https://reviews.llvm.org/D44562
Summary:
r331971 changes the debug line parser interface to report LLVM errors in an
interface that different executables can use, rather than always being printed
directly as warnings to stderr. This change allows LLD to make use of the new
interface and call its own warning methods to report problems.
llvm-svn: 331972
Previously this was only supported when specified on the command line
or in directives.
Differential Revision: https://reviews.llvm.org/D46244
llvm-svn: 331900
Adds support for .glink resolver stubs from the example implementation in the V2
ABI (Section 4.2.5.3. Procedure Linkage Table). The stubs are written to the
PltSection, and the sections are renamed to match the PPC64 ABI:
.got.plt --> .plt Type = SHT_NOBITS
.plt --> .glink
And adds the DT_PPC64_GLINK dynamic tag to the dynamic section when the plt is
not empty.
Differential Revision: https://reviews.llvm.org/D45642
llvm-svn: 331840
Separate output sections for selected text section prefixes to enable TLB optimizations and for readablilty.
Differential Revision: https://reviews.llvm.org/D45841
llvm-svn: 331823
Instead of writing empty index for file, this patch tracks the state of files in ObjectToIndexFileState. If the files are not indexed , only then we emit the empty files
Differential Revision: https://reviews.llvm.org/D46480
llvm-svn: 331803
Some MIPS relocations depend on "gp" value. By default, this value has
0x7ff0 offset from a .got section. But relocatable files produced by a
compiler or a linker might redefine this default value and we have to
use it for a calculation of the relocation result. When we generate EXE
or DSO it's trivial. Generating a relocatable output is more difficult
case because the linker does calculate relocations in this case and
cannot store individual "gp" values used by each input object file.
As a workaround we add the "gp" value to the relocation addend.
This fixes https://llvm.org/pr31149
Differential revision: https://reviews.llvm.org/D45972
llvm-svn: 331772
In the recognise test convert some ST1 multiple structure to ST1 single
structure to test the isST1SingleOpcode() function.
Differential Revision: https://reviews.llvm.org/D46263
llvm-svn: 331752
Add two test cases to improve the code coverage of ThunkSection creation
when there are no existing ThunkSections in range. There are two test
cases, one where a new section can be created and another to trigger the
"InputSection too large for range extension thunk" error message. A recent
code coverage report showed that this section of code wasn't covered by a
test case.
Differential Revision: https://reviews.llvm.org/D46261
llvm-svn: 331751
Summary: This is not technically required, but glibc unwind-dw2-fde.c classify_object_over_fdes expects there is a CIE record length 0 as a terminator.
Reviewers: ruiu, espindola
Subscribers: emaste, arichardson, llvm-commits
Differential Revision: https://reviews.llvm.org/D46566
llvm-svn: 331708
Our promise is that as long as there's no fatal error (i.e. broken
file is given to the linker), our main function returns to the caller.
So we can't use exit() in the regular code path.
Differential Revision: https://reviews.llvm.org/D46442
llvm-svn: 331690
On PowerPC calls to functions through the plt must be done through a call stub
that is responsible for:
1) Saving the toc pointer to the stack.
2) Loading the target functions address from the plt into both r12 and the
count register.
3) Indirectly branching to the target function.
Previously we have been emitting these call stubs to the .plt section, however
the .plt section should be reserved for the lazy symbol resolution stubs. This
patch moves the call stubs to the text section by moving the implementation from
writePlt to the thunk framework.
Differential Revision: https://reviews.llvm.org/D46204
llvm-svn: 331607
Specifically add support for custom sections that contain
relocations, and for the two new relocation types needed
by DWARF sections.
See: https://reviews.llvm.org/D44184
Patch by Yury Delendik!
Differential Revision: https://reviews.llvm.org/D44184
llvm-svn: 331566
The current support for V1 ABI in LLD is incomplete.
This patch removes V1 ABI support and changes the default behavior to V2 ABI,
issuing an error when using the V1 ABI. It also updates the testcases to V2
and removes any V1 specific tests.
Differential Revision: https://reviews.llvm.org/D46316
llvm-svn: 331529
Android AOSP has started specifying -m aarch64_elf64_le_vec as supported
by gold and BFD. This is a simple change to add the emulation so that LLD
doesn't immediately error when used as a linker in an AOSP build.
Differential Revision: https://reviews.llvm.org/D46429
llvm-svn: 331521
Implement the following relocations for AArch64:
R_AARCH64_TLSLE_LDST8_TPREL_LO12_NC
R_AARCH64_TLSLE_LDST16_TPREL_LO12_NC
R_AARCH64_TLSLE_LDST32_TPREL_LO12_NC
R_AARCH64_TLSLE_LDST64_TPREL_LO12_NC
R_AARCH64_TLSLE_LDST128_TPREL_LO12_NC
These are specified in ELF for the 64-bit Arm Architecture.
Fixes pr36727
Differential Revision: https://reviews.llvm.org/D46255
llvm-svn: 331511
Now only IMAGE_REL_ARM64_ABSOLUTE and IMAGE_REL_ARM64_TOKEN
are unhandled.
Also add range checks for the existing BRANCH26 relocation.
Differential Revision: https://reviews.llvm.org/D46354
llvm-svn: 331505
PPC64 V2 ABI describes two entry points to a function. The global entry point
sets up the TOC base pointer. When calling a local function, the call should
branch to the local entry point rather than the global entry point.
Section 3.4.1 describes using the 3 most significant bits of the st_other
field to find out how many instructions there are between the local and global
entry point. This patch adds the correct offset required to branch to the local
entry point of a function.
Differential Revision: https://reviews.llvm.org/D45729
llvm-svn: 331046
This is slightly simpler to read IMHO. Now if a symbol has a position
in the file, it is Defined.
The main motivation is that with this a SharedSymbol doesn't need a
section, which reduces the size of SymbolUnion.
With this the peak allocation when linking chromium goes from 568.1 to
564.2 MB.
llvm-svn: 330966
It returns a different Expr only in the case of creating a function
symbol pointing to its plt entry. We can just add a call to
addPltEntry to avoid that and return void.
With this patch further simplifications of how we handle copy
relocations are possible.
llvm-svn: 330960
Currently, LLD supports ASSERT as a separate command.
We support two forms now.
Assign expression-form: . = ASSERT(0x100)
(old GNU ld required it and some scripts in the wild are still using
something like . = ASSERT((_end - _text <= (512 * 1024 * 1024)), "kernel image bigger than KERNEL_IMAGE_SIZE");
Nowadays above is not a mandatory form and command-like form is commonly used:
ASSERT(<expr>, "text);
The return value of the ASSERT is Dot. That was implemented in D30171.
It looks like (2) is just a short version of (1) then.
GNU ld does *not* list ASSERT as a SECTIONS command:
https://sourceware.org/binutils/docs/ld/SECTIONS.html#SECTIONS
Given above we probably can change ASSERT to be an assignment to Dot.
That makes the rest of the code much simpler. Patch do that.
Differential revision: https://reviews.llvm.org/D45434
llvm-svn: 330814
The fix is to copy Used when replacing the symbol.
Original message:
Do not keep shared symbols created from garbage-collected eliminated DSOs.
If all references to a DSO happen to be weak, and if the DSO is
specified with --as-needed, the DSO is not added to DT_NEEDED.
If that happens, we also need to eliminate shared symbols created
from the DSO. Otherwise, they become dangling references that point
to non-exsitent DSO.
Fixes https://bugs.llvm.org/show_bug.cgi?id=36991
Differential Revision: https://reviews.llvm.org/D45536
llvm-svn: 330788
The PPC64 V2 ABI restores the toc base by loading from an offset of 24 from r1.
This patch fixes the offset and updates the testcases from V1 to V2. It also
issues an error when a nop is missing after a call to an external function.
Differential Revision: https://reviews.llvm.org/D45892
llvm-svn: 330600
This is what link.exe does and lets us avoid needing to worry about
merging output characteristics while adding input sections to output
sections.
With this change we can't process /merge in the same way as before
because sections with different output characteristics can still
be merged into one another. So this change moves the processing of
/merge to just before we assign addresses. In the case where there
are multiple output sections with the same name, link.exe only merges
the first section with the source name into the first section with
the target name, and we do the same.
At the same time I also implemented transitive merging (which means
that /merge:.c=.b /merge:.b=.a merges both .c and .b into .a).
This isn't quite enough though because link.exe has a special case for
.CRT in 32-bit mode: it processes sections whose output characteristics
are DATA | R | W as though the output characteristics were DATA | R
(so that they get merged into things like constructor lists in the
expected way). Chromium has a few such sections, and it turns out
that those sections were causing the problem that resulted in r318699
(merge .xdata into .rdata) being reverted: because of the previous
permission merging semantics, the .CRT sections were causing the entire
.rdata section to become writable, which caused the SEH runtime to
crash because it apparently requires .xdata to be read-only. This
change also implements the same special case.
This should unblock being able to merge .xdata into .rdata by default,
as well as .bss into .data, both of which will be done in followups.
Differential Revision: https://reviews.llvm.org/D45801
llvm-svn: 330479
Part of the DBI stream is a list of variable length structures
describing each module that contributes to the final executable.
One member of this structure is a section contribution entry that
describes the first section contribution in the output file for
the given module.
We have been leaving this structure unpopulated until now, so with
this patch it is now filled out correctly.
Differential Revision: https://reviews.llvm.org/D45832
llvm-svn: 330457
Enables cleaning up confusion between which name variables are mangled
and which are unmangled, and --print-gc-sections then excersises and
tests that.
Differential Revision: https://reviews.llvm.org/D44440
llvm-svn: 330449
Relocation addends can be negative so should be written as
signed LEBs. This bug meant that writing value between 64
and 128 would be incorrectly interpreted as negative by the
object file readers.
Differential Revision: https://reviews.llvm.org/D45825
llvm-svn: 330374
Summary:
DLLs and executables with no exception handlers need to be marked with
IMAGE_DLL_CHARACTERISTICS_NO_SEH, even if they have a load config.
Discovered here when building Chromium with LLD on Windows:
https://crbug.com/833951
Reviewers: ruiu, mstorsjo
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D45778
llvm-svn: 330300
Summary:
This change does three things:
- Try to find the file and line number of an undefined symbol
reference by reading codeview debug info.
- Try to find the name of the function or global variable with the
undefined symbol reference by searching the object file's symbol
table.
- Prints the information in the same style as the ELF linker.
Differential Revision: https://reviews.llvm.org/D45467
llvm-svn: 330235
In this reland I removed an unnecessary use of /debug in the test
delayimports32.test and used the /pdbaltpath flag in the test
pdb-publics-import.test, both of which avoid embedding absolute PDB
paths in executables which could affect later RVAs.
Original commit message:
> COFF: Merge .idata, .didat and .edata into .rdata by default.
>
> This saves a little space and matches what link.exe does.
>
> Tested using the chromium Windows trybots:
> https://chromium-review.googlesource.com/c/chromium/src/+/1014784
Differential Revision: https://reviews.llvm.org/D45737
llvm-svn: 330233
I needed to revert r330223 because we were embedding an absolute PDB
path in the .rdata section, which ended up being laid out before the
.idata section and affecting its RVAs. This flag will let us control
the embedded path.
Differential Revision: https://reviews.llvm.org/D45747
llvm-svn: 330232
Martin Storsjo