Patch from Rafael Auler!
When a shared lib has an undefined symbol that is defined in a regular object
(the program), the final executable must export this symbol in the dynamic
symbol table. However, in the current logic, lld only puts the symbol in the
dynamic symbol table if the symbol is weak. This patch fixes lld to put the
symbol in the dynamic symbol table regardless if it is weak or not.
This caused a problem in FreeBSD10, whose programs link against a crt1.o
that defines the symbol __progname, which is, in turn, undefined in libc.so.7
and will only be resolved in runtime.
http://reviews.llvm.org/D5424
llvm-svn: 218259
llvm\tools\lld\lib\readerwriter\macho\macholinkingcontext.cpp(647):
warning C4715: 'lld::MachOLinkingContext::exportSymbolNamed' :
not all control paths return a value
llvm\tools\lld\lib\readerwriter\macho\machonormalizedfilefromatoms.cpp(723):
warning C4715: '`anonymous namespace'::Util::getSymbolTableRegion' :
not all control paths return a value
While all enum values do appear in the switch, an uninitialized or corrupted
enum variable would not be caught without the default: case in the switch.
llvm-svn: 218197
Atoms are ordered in the output file by ordinal. File has file ordinal,
and atom has atom ordinal which is unique within the file.
No two atoms should have the same combination of ordinals.
However that contract was not satisifed for alias atoms. Alias atom
is defined by /alternatename:sym1=sym2. In this case sym1 is defined
as an alias for sym2. sym1 always got ordinal 0.
As a result LLD failed with an assertion failure.
This patch assigns ordinal to alias atoms.
llvm-svn: 218158
Cache the machine type value of the linking context. We need this in order to
calculate the virtual address of the atom when resolving function symbols.
Windows on ARM must check if the atom is a function and if so, set the Thumb bit
for the returned virtual address. Failure to do so will result in an abnormal
exit due to a trap caused by invalid instruction decoding. The same information
can be used to determine the relocation type that was previously being done via
is64 to select between x86 and x86_64.
llvm-svn: 218106
Accept /machine:arm as an argument. This is changed to support ARM NT.
Although there is no way to differentiate between ARM (Windows CE) and ARM NT
(Windows on ARM), since LLVM currently only supports Windows on ARM, simply take
/machine:arm to mean Windows on ARM.
llvm-svn: 218105
Rather than saving whether we are targeting 64-bit x86 (x86_64), simply convert
the single use of that information to the actual relocation type. This will
permit the selection of non-x86 relocation types (e.g. for WoA support).
Inline the access of the machine type field as it is relatively cheap (a couple
of pointer dereferences) rather than storing the relocation type as a member
variable.
llvm-svn: 218104
When we encounter an unknown machine type, we print out the machine type magic.
However, we would print out the magic in decimal rather than hex. Perform this
conversion to make it easier to identify what machine is unsupported.
llvm-svn: 218103
This patch fixes a forbidden use of Twine. It should only be used
as an intermediary value, but never stored.
This caused a bug in lld when running on Linux and compiled with
optimizations - it couldn't properly search libs.
Patch from Rafael Auler!
llvm-svn: 218083
I made LLD to report an error if /safeseh:no option is given on x64,
but it turned out MSVC link.exe doesn't report error on it.
Removing the check.
llvm-svn: 218077
The contents from section .CRT$XLA to .CRT$XLZ is an array of function
pointers. They are called by the runtime when a new thread is created
or (gracefully) terminated.
You can make your own initialization function to be called by that
mechanism. All you have to do is:
- Define a pointer to a function in a .CRT$XL* section using pragma
- Make an external reference to "__tls_used" symbol
That technique is used in many projects. This patch is to support that.
What this patch does is to set the relative virtual address of
"__tls_used" to the PECOFF directory table. __tls_used is actually a
struct containing pointers to a symbol in .CRT$XLA and another symbol
in .CRT$XLZ. The runtime looks at the directory table, gets the address
of the struct, and call the function pointers between XLA and XLZ.
llvm-svn: 218007
On darwin, the linker tools records which dylib (DSO) each undefined was found
in, and then at runtime, the loader (dyld) only looks in that one specific
dylib for each undefined symbol. Now that llvm-objdump can display that info
I can write test cases.
llvm-svn: 217898
The provided base must also be a multiple of the system's page size, which is a
reasonable enough demand.
Also check the other diagnostics more thoroughly.
llvm-svn: 217577
The existing system linkers on Darwin and Linux are called "ld". We'd like to
eventually drop in lld as "ld" and have it just work. But lld is a universal
linker that requires the first option to be -flavor to know which command line
mode to emulate (gnu or darwin).
This change tests if argv[0] is "ld" and if so, if the tool was built on MacOSX
then assume the darwin flavor otherwise the gnu flavor. There are two test
cases which copy lld to "ld" and then run it. One for darwin and one for linux.
llvm-svn: 217566
lld shouldn't directly use the COFF header nor should it use raw
coff_symbols. Instead, query the header properties from the
COFFObjectFile and use COFFSymbolRef to abstractly reference COFF
symbols.
This is just enough to get lld compiling with the changes to
llvm::object. Bigobj specific testing will come later.
Differential Revision: http://reviews.llvm.org/D5280
llvm-svn: 217497
Most of the changes are in the new file ArchHandler_arm64.cpp. But a few
things had to be fixed to support 16KB pages (instead of 4KB) which iOS arm64
requires. In addition the StubInfo struct had to be expanded because
arm64 uses two instruction (ADRP/LDR) to load a global which requires two
relocations. The other mach-o arches just needed one relocation.
llvm-svn: 217469
There is a bit (MH_PIE) in the flags field of the mach_header which tells
the kernel is a program was built position independent (for ASLR). The linker
automatically attempts to build programs PIE if they are built for a recent
OS version. But the -pie and -no_pie options override that default behavior.
llvm-svn: 217408
defined in a shared library.
Now LLD does not export a strong defined symbol if it coalesces away a
weak symbol defined in a shared library. This bug affects all ELF
architectures and leads to segfault:
% cat foo.c
extern int __attribute__((weak)) flag;
int foo() { return flag; }
% cat main.c
int flag = 1;
int foo();
int main() { return foo() == 1 ? 0 : -1; }
% clang -c -fPIC foo.c main.c
% lld -flavor gnu -target x86_64 -shared -o libfoo.so ... foo.o
% lld -flavor gnu -target x86_64 -o a.out ... main.o libfoo.so
% ./a.out
Segmentation fault
The problem is caused by the fact that we lose all information about
coalesced symbols after the `Resolver::resolve()` method is finished.
The patch solves the problem by overriding the
`LinkingContext::notifySymbolTableCoalesce()` method and saving names
of coalesced symbols. Later in the `buildDynamicSymbolTable()` routine
we use this information to export these symbols.
llvm-svn: 217363
When a file is not found, produce a proper error message. The previous error
message produced a file format error, which made me wonder for a while why
there is a file format error, but essentially the file was not found.
This fixes the problem by producing a proper error message.
llvm-svn: 217359
By default linker would not create a separate segment to hold read only data.
This option overrides that behavior by creating the a separate read only segment
for read only data.
llvm-svn: 217358
Moved code used only by isDataSymbol from find to isDataSymbol member
function. Also changed the return type of isDataSymbol because
previously "if (isDataSymbol(...))" meant "if it is *not* a data symbol"
which is opposite from what you'd expect.
llvm-svn: 217285
If we are creating a PE+ executable, we need to run cvtres with
/machine:x64 instead of /machine:x86. Otherwise the resulting executable
would be invalid.
llvm-svn: 217214
Mach-O has a "fat" (or "universal") variant where the same contents built for
different architectures are concatenated into one file with a table-of-contents
header at the start. But this leaves a dilemma for the linker - which
architecture to use.
Normally, the linker command line -arch is used to force which slice of any fat
files are used. The clang compiler always passes -arch to the linker when
invoking it. But some Makefiles invoke the linker directly and don’t specify
the -arch option. For those cases, the linker scans all input files in command
line order and finds the first non-fat object file. Whatever architecture it
is becomes the architecture for the link.
llvm-svn: 217189
Rui Ueyama