sign-return-address and similar module attributes should be propagated to
the function level before got merged because module flags may contradict and
this information is not recoverable.
Generated code will match with the normal linking flow.
Refactored version of (#80640).
Run the attribute copy only during IRMove.
`sign-return-address` and similar module attributes should be propagated
to the function level before modules got merged because module flags may
contradict and this information is not recoverable.
Generated code will match with the normal linking flow.
Turns out I was using DbgMarker::getDbgValueRange rather than the helper
utility in Instruction::getDbgValueRange, which checks for null-ness.
Original commit message follows.
[DebugInfo][RemoveDIs] Convert debug-info modes when loading bitcode (#78967)
As part of eliminating debug-intrinsics in LLVM, we'll shortly be
pushing the conversion from "old" dbg.value mode to "new" DPValue mode
out from when the pass manager runs, to when modules are loaded. This
patch adds that conversion process and some (temporary) options to
llvm-lto{,2} to help test it.
Specifically: now whenever we load a bitcode module, consider a flag of
whether to "upgrade" it into the new debug-info mode, and if we're
lazily materializing functions then do that lazily too. Doing this
exposes an error in the IRLinker/materializer handling of DPValues,
where we need to transfer the debug-info format flag correctly, and in
ValueMapper we need to remap the Values that DPValues point at.
I've added some test coverage in the modified tests; these will be
exercised by our llvm-new-debug-iterators buildbot.
This upgrading of debug-info won't be happening for the llvm18 release,
instead we'll turn it on after the branch date, thenbe push the boundary
of where "new" debug-info starts and ends down into the existing
debug-info upgrade path over the course of the next release.
As part of eliminating debug-intrinsics in LLVM, we'll shortly be
pushing the conversion from "old" dbg.value mode to "new" DPValue mode
out from when the pass manager runs, to when modules are loaded. This
patch adds that conversion process and some (temporary) options to
llvm-lto{,2} to help test it.
Specifically: now whenever we load a bitcode module, consider a flag of
whether to "upgrade" it into the new debug-info mode, and if we're
lazily materializing functions then do that lazily too. Doing this
exposes an error in the IRLinker/materializer handling of DPValues,
where we need to transfer the debug-info format flag correctly, and in
ValueMapper we need to remap the Values that DPValues point at.
I've added some test coverage in the modified tests; these will be
exercised by our llvm-new-debug-iterators buildbot.
This upgrading of debug-info won't be happening for the llvm18 release,
instead we'll turn it on after the branch date, thenbe push the boundary
of where "new" debug-info starts and ends down into the existing
debug-info upgrade path over the course of the next release.
The commit 3ab6209a3f93bdbeec8e9b9fcc00a9a4980915ff had the undesired
effect of retaining every `__imp_` symbol, even if it isn't referenced
in any way. Add a testcase to observe this behaviour, to serve as
a reference point if this behaviour were to be improved later.
Port the testcase from b963c0b658cc54b370832df4f5a3d63fd69da334 from
the llvm/LTO testsuite into LLD as a preparation for changing that fix;
the moved testcase has a comment for one case which doesn't work
currently.
The testcase is ported mostly as is, but with symbol mangling
simplified, rewriting function names from MSVC C++ mangling to plain
C, and unnecessary debug info is removed.
Add a case of a dllimported data symbol, in addition to the existing
call of a dllimported function.
Also extend the testcase to test combinations of both regular
object files and LTO objects. Leave out one combination which currently
fails, with a comment.
llvm/test/LTO/ARM/ssp-static-reloc.ll is more about using the static
relocation model with "PIC Level" and unrelated to the LTO infrastructure.
Move the test. Update stack_guard_remat.ll to clearly test "PIC Level"
with the relevant relocation models.
This allows us to not have to pass -mllvm flags to set the large data
threshold for (in-LLD/not-distributed) ThinLTO.
Follows https://reviews.llvm.org/D52322, which did the same for the code
model.
Since the large data threshold is tied to the code model and we disallow
mixing different code models, do the same for the large data threshold.
This is a pre-commit test of accessing the variable __stack_chk_guard
when the static relocation model is imposed on a module compiled with
pic enabled. It confirms issue
[#64999](https://github.com/llvm/llvm-project/issues/64999).
The intent is to update this test with the fix for the aforementioned
issue.
This changes the definition if isSectionBitcode to only be valid for the
.llvm.lto section, since this API is only called from LTO, and the
.llvmbc section was not intended to be used for LTO. This allows the
gold plugin to keep its existing behavior without introducing any
significant changes.
Reviewed By: MaskRay, nikic
Differential Revision: https://reviews.llvm.org/D152973
This reverts commit 421e4026111315d002879b1e7a0cf3aacd00f488.
One of the test needs a requires line, but we've also seen some issues
for downstream projects that may need coordination, so I'm reverting
this for until we can address those issues. see
https://reviews.llvm.org/D152973#4520240 for context.
This changes the definition if `isSectionBitcode` to only be valid for the
`.llvm.lto` section, since this API is only called from LTO, and the
`.llvmbc` section was not intended to be used for LTO. This allows the
gold plugin to keep its existing behavior without introducing any
significant changes.
Depends on D146778
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D152973
The test migration to opaque pointers has finished, so we can finally
drop typed pointer support from LLVM \o/
This removes the ability to disable typed pointers, as well as the
-opaque-pointers option, but otherwise doesn't yet touch any API
surface. I'll leave deprecation/removal of compatibility APIs to
future changes.
This also drops a few tests: These are either testing errors that
only occur with typed pointers, or type linking behavior that, to
the best of my knowledge, only applies to typed pointers.
Note that this will break some tests in the experimental SPIRV
backend, because the maintainers have failed to update their tests
in a reasonable time-frame, despite multiple warnings. In accordance
with our experimental target policy, this is not a blocking concern.
This issue is tracked at https://github.com/llvm/llvm-project/issues/60133.
Differential Revision: https://reviews.llvm.org/D155079
Here's a high level summary of the changes in this patch. For more
information on rational, see the RFC.
(https://discourse.llvm.org/t/rfc-a-unified-lto-bitcode-frontend/61774).
- Add config parameter to LTO backend, specifying which LTO mode is
desired when using unified LTO.
- Add unified LTO flag to the summary index for efficiency. Unified
LTO modules can be detected without parsing the module.
- Make sure that the ModuleID is generated by incorporating more types
of symbols.
Differential Revision: https://reviews.llvm.org/D123803
D63932 added a module flag to indicate that we are executing the regular
LTO post merge pipeline, so that GlobalDCE could perform more aggressive
optimization for Dead Virtual Function Elimination. This caused issues
trying to reuse bitcode that had already been through the LTO pipeline
(see context in D139816).
Instead support this by passing down a parameter flag to the
GlobalDCEPass constructor, which is the more usual way for indicating
this information.
Most test changes are to remove incidental uses of this flag. Of the 2
real uses, llvm/test/LTO/ARM/lto-linking-metadata.ll is now obsolete and
removed in this patch, and the virtual-functions-visibility-post-lto.ll
test is updated to use the regular LTO default pipeline where this
parameter is set to true.
Differential Revision: https://reviews.llvm.org/D153655
This is a follow-up to b71edfaa4ec3c998aadb35255ce2f60bba2940b0
since I forgot the lit.local.cfg files in that one.
Reformatting is done with `black`.
If you end up having problems merging this commit because you
have made changes to a python file, the best way to handle that
is to run git checkout --ours <yourfile> and then reformat it
with black.
If you run into any problems, post to discourse about it and
we will try to help.
RFC Thread below:
https://discourse.llvm.org/t/rfc-document-and-standardize-python-code-style
Reviewed By: barannikov88, kwk
Differential Revision: https://reviews.llvm.org/D150762
Adds an LTO option to indicate that whether we are linking with an
allocator that supports hot/cold operator new interfaces. If not,
at the start of the LTO backends any existing memprof hot/cold
attributes are removed from the IR, and we also remove memprof metadata
so that post-LTO inlining doesn't add any new attributes.
This is done via setting a new flag in the module summary index. It is
important to communicate via the index to the LTO backends so that
distributed ThinLTO handles this correctly, as they are invoked by
separate clang processes and the combined index is how we communicate
information from the LTO link. Specifically, for distributed ThinLTO the
LTO related processes look like:
```
# Thin link:
$ lld --thinlto-index-only obj1.o ... objN.o -llib ...
# ThinLTO backends:
$ clang -x ir obj1.o -fthinlto-index=obj1.o.thinlto.bc -c -O2
...
$ clang -x ir objN.o -fthinlto-index=objN.o.thinlto.bc -c -O2
```
It is during the thin link (lld --thinlto-index-only) that we have
visibility into linker dependences and want to be able to pass the new
option via -Wl,-supports-hot-cold-new. This will be recorded in the
summary indexes created for the distributed backend processes
(*.thinlto.bc) and queried from there, so that we don't need to know
during those individual clang backends what allocation library was
linked. Since in-process ThinLTO and regular LTO also use a combined
index, for consistency we query the flag out of the index in all LTO
backends.
Additionally, when the LTO option is disabled, exit early from the
MemProfContextDisambiguation handling performed during LTO, as this is
unnecessary.
Depends on D149117 and D149192.
Differential Revision: https://reviews.llvm.org/D149215
Internal testing showed that the change made in commit 62fcfc5a needed
more test coverage. Specifically, the imported function shouldn't be
externally visibile and the whole test needed to be run in regular LTO
mode.
Differential Revision: https://reviews.llvm.org/D148950
Auto-upgrade can be expensive, especially UpgradeDebugInfo() since it runs the verifier.
With this patch, we can specify that the imported bitcode is built with the same revision of LLVM, meaning there's no need to run any auto-upgrading. For now, limit this to just debug info since projects like Rust want to support multiple versions of LLVM at the same time (at compiler build time, not at Rust source code build time) and run a subset of the autoupgrade functionality for simplicity.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D143229
IR is now always parsed in opaque pointer mode, unless
-opaque-pointers=0 is explicitly given. There is no automatic
detection of typed pointers anymore.
The -opaque-pointers=0 option is added to any remaining IR tests
that haven't been migrated yet.
Differential Revision: https://reviews.llvm.org/D141912
MC and lld/ELF defaults were flipped in 2016. For Clang: CMake
ENABLE_X86_RELAX_RELOCATIONS defaults to on in 2020. It makes sense for
the TargetOptions default to be true now.
R_X86_64_GOTPCRELX/R_X86_64_REX_GOTPCRELX require GNU ld newer than 2015-10
(subsumed by the current requirement of -fbinutils-version=).
This should fix `rustc -Z plt=no` PIC relocatable files with GNU ld.
(See https://github.com/rust-lang/rust/pull/106380)
Over the past day or so, i've took a large swing at our tests,
and reduced the number of tests that were still using the old syntax
from ~1800 to just 200.
Left to handle: (as it is seen in this patch)
* Transforms/LSR
* Transforms/CGP
* Transforms/TypePromotion
* Transforms/HardwareLoops
* Analysis/*
* some misc.
I think this is the right point to start actively refusing
to honor the old syntax, except for the old tests,
to prevent the old syntax from creeping back in.
Thus, let's add temporary default-off flag,
and if it is not passed refuse to accept old syntax.
The tests that still need porting are annotated with this flag.
Reviewed By: aeubanks
Differential Revision: https://reviews.llvm.org/D139647
For a local linkage GlobalObject in a non-prevailing COMDAT, it remains defined while its
leader has been made available_externally. This violates the COMDAT rule that
its members must be retained or discarded as a unit.
To fix this, update the regular LTO change D34803 to track local linkage
GlobalValues, and port the code to ThinLTO (GlobalAliases are not handled.)
This fixes two problems.
(a) `__cxx_global_var_init` in a non-prevailing COMDAT group used to
linger around (unreferenced, hence benign), and is now correctly discarded.
```
int foo();
inline int v = foo();
```
(b) Fix https://github.com/llvm/llvm-project/issues/58215:
as a size optimization, we place private `__profd_` in a COMDAT with a
`__profc_` key. When FuncImport.cpp makes `__profc_` available_externally due to
a non-prevailing COMDAT, `__profd_` incorrectly remains private. This change
makes the `__profd_` available_externally.
```
cat > c.h <<'eof'
extern void bar();
inline __attribute__((noinline)) void foo() {}
eof
cat > m1.cc <<'eof'
#include "c.h"
int main() {
bar();
foo();
}
eof
cat > m2.cc <<'eof'
#include "c.h"
__attribute__((noinline)) void bar() {
foo();
}
eof
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto=thin -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
```
If a GlobalAlias references a GlobalValue which is just changed to
available_externally, change the GlobalAlias as well (e.g. C5/D5 comdats due to
cc1 -mconstructor-aliases). The GlobalAlias may be referenced by other
available_externally functions, so it cannot easily be removed.
Depends on D137441: we use available_externally to mark a GlobalAlias in a
non-prevailing COMDAT, similar to how we handle GlobalVariable/Function.
GlobalAlias may refer to a ConstantExpr, not changing GlobalAlias to
GlobalVariable gives flexibility for future extensions (the use case is niche.
For simplicity we don't handle it yet). In addition, available_externally
GlobalAlias is the most straightforward implementation and retains the aliasee
information to help optimizers.
See windows-vftable.ll: Windows vftable uses an alias pointing to a
private constant where the alias is the COMDAT leader. The COMDAT use case
is skeptical and ThinLTO does not discard the alias in the non-prevailing COMDAT.
This patch retains the behavior.
See new tests ctor-dtor-alias2.ll: depending on whether the complete object
destructor emitted, when ctor/dtor aliases are used, we may see D0/D2 COMDATs in
one TU and D0/D1/D2 in a D5 COMDAT in another TU.
Allow such a mix-and-match with `if (GO->getComdat()->getName() == GO->getName()) NonPrevailingComdats.insert(GO->getComdat());`
GlobalAlias handling in ThinLTO is still weird, but this patch should hopefully
improve the situation for at least all cases I can think of.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D135427
For a local linkage GlobalObject in a non-prevailing COMDAT, it remains defined while its
leader has been made available_externally. This violates the COMDAT rule that
its members must be retained or discarded as a unit.
To fix this, update the regular LTO change D34803 to track local linkage
GlobalValues, and port the code to ThinLTO (GlobalAliases are not handled.)
This fixes two problems.
(a) `__cxx_global_var_init` in a non-prevailing COMDAT group used to
linger around (unreferenced, hence benign), and is now correctly discarded.
```
int foo();
inline int v = foo();
```
(b) Fix https://github.com/llvm/llvm-project/issues/58215:
as a size optimization, we place private `__profd_` in a COMDAT with a
`__profc_` key. When FuncImport.cpp makes `__profc_` available_externally due to
a non-prevailing COMDAT, `__profd_` incorrectly remains private. This change
makes the `__profd_` available_externally.
```
cat > c.h <<'eof'
extern void bar();
inline __attribute__((noinline)) void foo() {}
eof
cat > m1.cc <<'eof'
#include "c.h"
int main() {
bar();
foo();
}
eof
cat > m2.cc <<'eof'
#include "c.h"
__attribute__((noinline)) void bar() {
foo();
}
eof
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto=thin -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
```
If a GlobalAlias references a GlobalValue which is just changed to
available_externally, change the GlobalAlias as well (e.g. C5/D5 comdats due to
cc1 -mconstructor-aliases). The GlobalAlias may be referenced by other
available_externally functions, so it cannot easily be removed.
Depends on D137441: we use available_externally to mark a GlobalAlias in a
non-prevailing COMDAT, similar to how we handle GlobalVariable/Function.
GlobalAlias may refer to a ConstantExpr, not changing GlobalAlias to
GlobalVariable gives flexibility for future extensions (the use case is niche.
For simplicity we don't handle it yet). In addition, available_externally
GlobalAlias is the most straightforward implementation and retains the aliasee
information to help optimizers.
See windows-vftable.ll: Windows vftable uses an alias pointing to a
private constant where the alias is the COMDAT leader. The COMDAT use case
is skeptical and ThinLTO does not discard the alias in the non-prevailing COMDAT.
This patch retains the behavior.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D135427
This reverts commit 89ddcff1d2d6e9f4de78f3a563a8b1987bf7ea8f.
Reason: This breaks bootstrapping builds of LLVM on Windows using
ThinLTO; see https://crbug.com/1382839
For a local linkage GlobalObject in a non-prevailing COMDAT, it remains defined while its
leader has been made available_externally. This violates the COMDAT rule that
its members must be retained or discarded as a unit.
To fix this, update the regular LTO change D34803 to track local linkage
GlobalValues, and port the code to ThinLTO (GlobalAliases are not handled.)
This fixes two problems.
(a) `__cxx_global_var_init` in a non-prevailing COMDAT group used to
linger around (unreferenced, hence benign), and is now correctly discarded.
```
int foo();
inline int v = foo();
```
(b) Fix https://github.com/llvm/llvm-project/issues/58215:
as a size optimization, we place private `__profd_` in a COMDAT with a
`__profc_` key. When FuncImport.cpp makes `__profc_` available_externally due to
a non-prevailing COMDAT, `__profd_` incorrectly remains private. This change
makes the `__profd_` available_externally.
```
cat > c.h <<'eof'
extern void bar();
inline __attribute__((noinline)) void foo() {}
eof
cat > m1.cc <<'eof'
#include "c.h"
int main() {
bar();
foo();
}
eof
cat > m2.cc <<'eof'
#include "c.h"
__attribute__((noinline)) void bar() {
foo();
}
eof
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto=thin -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
```
If a GlobalAlias references a GlobalValue which is just changed to
available_externally, change the GlobalAlias as well (e.g. C5/D5 comdats due to
cc1 -mconstructor-aliases). The GlobalAlias may be referenced by other
available_externally functions, so it cannot easily be removed.
Depends on D137441: we use available_externally to mark a GlobalAlias in a
non-prevailing COMDAT, similar to how we handle GlobalVariable/Function.
GlobalAlias may refer to a ConstantExpr, not changing GlobalAlias to
GlobalVariable gives flexibility for future extensions (the use case is niche.
For simplicity we don't handle it yet). In addition, available_externally
GlobalAlias is the most straightforward implementation and retains the aliasee
information to help optimizers.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D135427
This prepares for an upcoming change to make --print-imm-hex the default
behavior of llvm-objdump. These tests were updated in a semi-automatic
fashion.
See D136972 for details.
This reverts commit 8ef3fd8d59ba0100bc6e83350ab1e978536aa531.
I mentioned that GlobalAlias was not handled. It turns out GlobalAlias has to be handled in the same patch (as opposed to in a follow-up),
as otherwise clang codegen of C5/D5 constructor/destructor would regress (https://reviews.llvm.org/D135427#3869003).
Because of LLVM mangling escape sequence (through '\01' prefix), it is possible
for a single symbols two have two different IR representations.
For instance, consider @symbol and @"\01_symbol". On OSX, because of the system
mangling rules, these two IR names point are converted in the same final symbol
upon linkage.
LTO doesn't model this behavior, which may result in symbols being incorrectly
internalized (if all reference use the escaping sequence while the definition
doesn't).
The proper approach is probably to use the mangled name to compute GUID to
avoid the dual representation, but we can also avoid discarding symbols that are
bound to two different IR names. This is an approximation, but it's less
intrusive on the codebase.
Fix#57864
Differential Revision: https://reviews.llvm.org/D135710
For a local linkage GlobalObject in a non-prevailing COMDAT, it remains defined while its
leader has been made available_externally. This violates the COMDAT rule that
its members must be retained or discarded as a unit.
To fix this, update the regular LTO change D34803 to track local linkage
GlobalValues, and port the code to ThinLTO (GlobalAliases are not handled.)
This fixes two problems.
(a) `__cxx_global_var_init` in a non-prevailing COMDAT group used to
linger around (unreferenced, hence benign), and is now correctly discarded.
```
int foo();
inline int v = foo();
```
(b) Fix https://github.com/llvm/llvm-project/issues/58215:
as a size optimization, we place private `__profd_` in a COMDAT with a
`__profc_` key. When FuncImport.cpp makes `__profc_` available_externally due to
a non-prevailing COMDAT, `__profd_` incorrectly remains private. This change
makes the `__profd_` available_externally.
```
cat > c.h <<'eof'
extern void bar();
inline __attribute__((noinline)) void foo() {}
eof
cat > m1.cc <<'eof'
int main() {
bar();
foo();
}
eof
cat > m2.cc <<'eof'
__attribute__((noinline)) void bar() {
foo();
}
eof
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto=thin -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
```
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D135427
This reverts commit 4fbe33593c8132fdc48647c06f4d1455bfff1c88. It causes linking errors, with details provided internally. (Hopefully the author/reviewers will be able to upstream the internal repro).
See the updated linkonce_resolution_comdat.ll. For a local linkage GV in a
non-prevailing COMDAT, it remains defined while its leader has been made
available_externally. This violates the COMDAT rule that its members must be
retained or discarded as a unit.
To fix this, update the regular LTO change D34803 to track local linkage
GlobalValues, and port the code to ThinLTO (GlobalAliases are not handled.)
Fix https://github.com/llvm/llvm-project/issues/58215:
as a size optimization, we place private `__profd_` in a COMDAT with a
`__profc_` key. When FuncImport.cpp makes `__profc_` available_externally due to
a non-prevailing COMDAT, `__profd_` incorrectly remains private. This change
makes the `__profd_` available_externally.
```
cat > c.h <<'eof'
extern void bar();
inline __attribute__((noinline)) void foo() {}
eof
cat > m1.cc <<'eof'
#include "c.h"
int main() {
bar();
foo();
}
eof
cat > m2.cc <<'eof'
#include "c.h"
__attribute__((noinline)) void bar() {
foo();
}
eof
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
# one _Z3foov
clang -O2 -fprofile-generate=./t m1.cc m2.cc -flto=thin -fuse-ld=lld -o t_gen
rm -fr t && ./t_gen && llvm-profdata show -function=foo t/default_*.profraw
# one _Z3foov
```
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D135427
This patch changes legacy LTO to set data-sections by default. The user can
explicitly unset data-sections. The reason for this patch is to match the
behaviour of lld and gold plugin. Both lld and gold plugin have data-sections on
by default.
This patch also fixes the forwarding of the clang options -fno-data-sections and
-fno-function-sections to libLTO. Now, when -fno-data/function-sections are
specified in clang, -data/function-sections=0 will be passed to libLTO to
explicitly unset data/function-sections.
Reviewed By: w2yehia, MaskRay
Differential Revision: https://reviews.llvm.org/D129401
This patch changes legacy LTO to set data-sections by default. The user can
explicitly unset data-sections. The reason for this patch is to match the
behaviour of lld and gold plugin. Both lld and gold plugin have data-sections on
by default.
This patch also fixes the forwarding of the clang options -fno-data-sections and
-fno-function-sections to libLTO. Now, when -fno-data/function-sections are
specified in clang, -data/function-sections=0 will be passed to libLTO to
explicitly unset data/function-sections.
Reviewed By: w2yehia, MaskRay
Differential Revision: https://reviews.llvm.org/D129401
Turning on opaque pointers has uncovered an issue with WPD where we currently pattern match away `assume(type.test)` in WPD so that a later LTT doesn't resolve the type test to undef and introduce an `assume(false)`. The pattern matching can fail in cases where we transform two `assume(type.test)`s into `assume(phi(type.test.1, type.test.2))`.
Currently we create `assume(type.test)` for all virtual calls that might be devirtualized. This is to support `-Wl,--lto-whole-program-visibility`.
To prevent this, all virtual calls that may not be in the same LTO module instead use a new `llvm.public.type.test` intrinsic in place of the `llvm.type.test`. Then when we know if `-Wl,--lto-whole-program-visibility` is passed or not, we can either replace all `llvm.public.type.test` with `llvm.type.test`, or replace all `llvm.public.type.test` with `true`. This prevents WPD from trying to pattern match away `assume(type.test)` for public virtual calls when failing the pattern matching will result in miscompiles.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D128955
LTO code may end up mixing bitcode files from various sources varying in
their use of opaque pointer types. The current strategy to decide
between opaque / typed pointers upon the first bitcode file loaded does
not work here, since we could be loading a non-opaque bitcode file first
and would then be unable to load any files with opaque pointer types
later.
So for LTO this:
- Adds an `lto::Config::OpaquePointer` option and enforces an upfront
decision between the two modes.
- Adds `-opaque-pointers`/`-no-opaque-pointers` options to the gold
plugin; disabled by default.
- `--opaque-pointers`/`--no-opaque-pointers` options with
`-plugin-opt=-opaque-pointers`/`-plugin-opt=-no-opaque-pointers`
aliases to lld; disabled by default.
- Adds an `-lto-opaque-pointers` option to the `llvm-lto2` tool.
- Changes the clang driver to pass `-plugin-opt=-opaque-pointers` to
the linker in LTO modes when clang was configured with opaque
pointers enabled by default.
This fixes https://github.com/llvm/llvm-project/issues/55377
Differential Revision: https://reviews.llvm.org/D125847
