If a section cannot be dead stripped, it is safe to use L symbols, since
the linker will keep all of it in the end.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@221431 91177308-0d34-0410-b5e6-96231b3b80d8
A problem with our old behavior becomes observable under x86-64 COFF
when we need a read-only GV which has an initializer which is referenced
using a relocation: we would mark the section as writable. Marking the
section as writable interferes with section merging.
This fixes PR21009.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218179 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit r217211.
Both the bfd ld and gold outputs were valid. They were using a Rela relocation,
so the value present in the relocated location was not used, which caused me
to misread the output.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217264 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This fixes a long standing issue where we would emit many little .text
sections and only one .pdata and .xdata section. Now we generate one
.pdata / .xdata pair per .text section and associate them correctly.
Fixes PR19667.
Reviewers: majnemer
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D5181
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On MachO, putting a symbol that doesn't start with a 'L' or 'l' in one of the
__TEXT,__literal* sections prevents the linker from merging the context of the
section.
Since private GVs are the ones the get mangled to start with 'L' or 'l', we now
only put those on the __TEXT,__literal* sections.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216682 91177308-0d34-0410-b5e6-96231b3b80d8
COFF lacks a feature that other object file formats support: mergeable
sections.
To work around this, MSVC sticks constant pool entries in special COMDAT
sections so that each constant is in it's own section. This permits
unused constants to be dropped and it also allows duplicate constants in
different translation units to get merged together.
This fixes PR20262.
Differential Revision: http://reviews.llvm.org/D4482
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This new IR facility allows us to represent the object-file semantic of
a COMDAT group.
COMDATs allow us to tie together sections and make the inclusion of one
dependent on another. This is required to implement features like MS
ABI VFTables and optimizing away certain kinds of initialization in C++.
This functionality is only representable in COFF and ELF, Mach-O has no
similar mechanism.
Differential Revision: http://reviews.llvm.org/D4178
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* Section association cannot use just the section name as many
sections can have the same name. With this patch, the comdat symbol in
an assoc section is interpreted to mean a symbol in the associated
section and the mapping is discovered from it.
* Comdat symbols were not being set correctly. Instead we were getting
whatever was output first for that section.
A consequence is that associative sections now must use .section to
set the association. Using .linkonce would not work since it is not
possible to change a sections comdat symbol (it is used to decide if
we should create a new section or reuse an existing one).
This includes r210298, which was reverted because it was asserting
on an associated section having the same comdat as the associated
section.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@210367 91177308-0d34-0410-b5e6-96231b3b80d8
For MIPS, we have to encode the personality routine with
an indirect pointer to absptr; otherwise, some link warning
warning will be raised, and the program might crash in some
early MIPS Android device.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@209907 91177308-0d34-0410-b5e6-96231b3b80d8
This allows us to put dynamic initializers for weak data into the same
comdat group as the data being initialized. This is necessary for MSVC
ABI compatibility. Once we have comdats for guard variables, we can use
the combination to help GlobalOpt fire more often for weak data with
guarded initialization on other platforms.
Reviewers: nlewycky
Differential Revision: http://reviews.llvm.org/D3499
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Summary:
Local common symbols were properly inserted into the .bss section.
However, putting external common symbols in the .bss section would give
them a strong definition.
Instead, encode them as undefined, external symbols who's symbol value
is equivalent to their size.
Reviewers: Bigcheese, rafael, rnk
CC: llvm-commits
Differential Revision: http://reviews.llvm.org/D3324
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This is a pretty straight forward translation for COFF, we just need to
stick the data in a COMDAT section marked as
IMAGE_COMDAT_SELECT_NODUPLICATES.
N.B. We must be careful to avoid sticking entities with private linkage
in COMDAT groups. COFF is pretty hostile to the renaming of entities so
we must be careful to disallow GlobalVariables with unstable names.
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This is a pretty straight forward translation for COFF, we just need to
stick the function in a COMDAT section marked as
IMAGE_COMDAT_SELECT_NODUPLICATES.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@204565 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
llvm/MC/MCSectionMachO.h and llvm/Support/MachO.h both had the same
definitions for the section flags. Instead, grab the definitions out of
support.
No functionality change.
Reviewers: grosbach, Bigcheese, rafael
Reviewed By: rafael
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D2998
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203211 91177308-0d34-0410-b5e6-96231b3b80d8
TargetLoweringBase is implemented in CodeGen, so before this patch we had
a dependency fom Target to CodeGen. This would show up as a link failure of
llvm-stress when building with -DBUILD_SHARED_LIBS=ON.
This fixes pr18900.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201711 91177308-0d34-0410-b5e6-96231b3b80d8
r201608 made llvm corretly handle private globals with MachO. r201622 fixed
a bug in it and r201624 and r201625 were changes for using private linkage,
assuming that llvm would do the right thing.
They all got reverted because r201608 introduced a crash in LTO. This patch
includes a fix for that. The issue was that TargetLoweringObjectFile now has
to be initialized before we can mangle names of private globals. This is
trivially true during the normal codegen pipeline (the asm printer does it),
but LTO has to do it manually.
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When outputting an object we check its section to find its name, but when
looking for the section with -ffunction-section we look for the symbol name.
Break the loop by requesting a name with the private prefix when constructing
the section name. This matches the behavior before r201608.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201622 91177308-0d34-0410-b5e6-96231b3b80d8
The IR
@foo = private constant i32 42
is valid, but before this patch we would produce an invalid MachO from it. It
was invalid because it would use an L label in a section where the liker needs
the labels in order to atomize it.
One way of fixing it would be to just reject this IR in the backend, but that
would not be very front end friendly.
What this patch does is use an 'l' prefix in sections that we know the linker
requires symbols for atomizing them. This allows frontends to just use
private and not worry about which sections they go to or how the linker handles
them.
One small issue with this strategy is that now a symbol name depends on the
section, which is not available before codegen. This is not a problem in
practice. The reason is that it only happens with private linkage, which will
be ignored by the non codegen users (llvm-nm and llvm-ar).
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These methods normally call each other and it is really annoying if the
arguments are in different order. The more common rule was that the arguments
specific to call are first (GV, Encoding, Suffix) and the auxiliary objects
(Mang, TM) come after. This patch changes the exceptions.
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It is never null and it is not used in casts, so there is no reason to use a
pointer. This matches how we pass TM.
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code to see if we're emitting a function into a non-default
text section. This is still a less-than-ideal solution, but more
contained than r199871 to determine whether or not we're emitting
code into an array of comdat sections.
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e.g. linkonce, to TargetMachine and set it when we've done so
for ELF targets currently. This involved making TargetMachine
non-const in a TLOF use and propagating that change around - I'm
open to other ideas.
This will be used in a future commit to handle emitting debug
information with ranges.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199871 91177308-0d34-0410-b5e6-96231b3b80d8
We currently error in clang with:
"error: thread-local storage is unsupported for the current target", but we
can start to get the llvm level ready.
When compiling
template<typename T>
struct foo {
static __declspec(thread) int bar;
};
template<typename T>
__declspec(therad) int foo<T>::bar;
template struct foo<int>;
msvc produces
SECTION HEADER #3
.tls$ name
0 physical address
0 virtual address
4 size of raw data
12F file pointer to raw data (0000012F to 00000132)
0 file pointer to relocation table
0 file pointer to line numbers
0 number of relocations
0 number of line numbers
C0301040 flags
Initialized Data
COMDAT; sym= "public: static int foo<int>::bar" (?bar@?$foo@H@@2HA)
4 byte align
Read Write
gcc produces a ".data$__emutls_v.<symbol>" for the testcase with
__declspec(thread) replaced with thread_local.
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With this patch we use simple names for COMDAT sections (like .text or .bss).
This matches the MSVC behavior.
When merging it is the COMDAT symbol that is used to decide if two sections
should be merged, so there is no point in building a fancy name.
This survived a bootstrap on mingw32.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195798 91177308-0d34-0410-b5e6-96231b3b80d8
This is the first step to fix pr17918.
It extends the .section directive a bit, inspired by what the ELF one looks
like. The problem with using linkonce is that given
.section foo
.linkonce....
.section foo
.linkonce
we would already have switched sections when getting to .linkonce. The cleanest
solution seems to be to add the comdat information in the .section itself.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@195148 91177308-0d34-0410-b5e6-96231b3b80d8
This reverts commit f1d9fe9d04ce93f6d5dcebbd2cb6a07414d7a029.
This was causing PR17964. We need to use thread data before regular data.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194960 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
We need to do two things:
- Initialize BSSSection in MCObjectFileInfo::InitCOFFMCObjectFileInfo
- Teach TargetLoweringObjectFileCOFF::SelectSectionForGlobal what to do
with it
This fixes PR16861.
Reviewers: rnk
Reviewed By: rnk
CC: llvm-commits
Differential Revision: http://llvm-reviews.chandlerc.com/D1361
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This reverts commit r77814.
We were sticking global constants in the .data section instead of in the
.rdata section when emitting for COFF.
This fixes PR16831.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187956 91177308-0d34-0410-b5e6-96231b3b80d8
Original commit message:
Stop emitting weak symbols into the "coal" sections.
The Mach-O linker has been able to support the weak-def bit on any symbol for
quite a while now. The compiler however continued to place these symbols into a
"coal" section, which required the linker to map them back to the base section
name.
Replace the sections like this:
__TEXT/__textcoal_nt instead use __TEXT/__text
__TEXT/__const_coal instead use __TEXT/__const
__DATA/__datacoal_nt instead use __DATA/__data
<rdar://problem/14265330>
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32-bit symbols have "_" as global prefix, but when forming the name of
COMDAT sections this prefix is ignored. The current behavior assumes that
this prefix is always present which is not the case for 64-bit and names
are truncated.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187356 91177308-0d34-0410-b5e6-96231b3b80d8
This patch broke `make check-asan` on Mac, causing ld warnings like the following one:
ld: warning: direct access in __GLOBAL__I_a to global weak symbol
___asan_mapping_scale means the weak symbol cannot be overridden at
runtime. This was likely caused by different translation units being
compiled with different visibility settings.
The resulting test binaries crashed with incorrect ASan warnings.
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