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
LTO objects might compiled with different `mbranch-protection` flags which will cause an error in the linker.
Such a setup is allowed in the normal build with this change that is possible.
Reviewed By: pcc
Differential Revision: https://reviews.llvm.org/D123493
This removes support for the legacy pass manager in llvm-lto and
llvm-lto2. In this case I've dropped the use-new-pm option entirely,
as I don't think this is considered part of the public interface.
This also makes -debug-pass-manager work with llvm-lto, because
that was needed to migrate some tests to NewPM.
Differential Revision: https://reviews.llvm.org/D123376
These tests are located in 'X86' subfolders which means that they should
be compiled for that target. As they did not have the target specified
explicitly, they in fact were compiled for a default target triple. Not
all targets support all required features for these tests; for example,
if NVPTX is used as a default triple, the tests fail. The patch makes the
tests run for 'x86_64', thus they pass regardless of the default target.
Differential Revision: https://reviews.llvm.org/D121998
There are two test issues:
- The test assumes the current directory is writeable, but it may not be. Use `%t.o`-like paths instead of implicit `a.out`.
- The `RUN llvm-nm` line is missing a colon, so the test was not being exercised.
This patch removes an incorrect behaviour in Constants.cpp, which would
replace dead constant references in metadata with an undef value. This
blanket replacement resulted in undef values being inserted into
metadata that would not accept them. The replacement was intended for
debug info metadata, but this is now instead handled in the RAUW
handler.
Differential Revision: https://reviews.llvm.org/D117300
The modified tests fail because 64-bit XCOFF object files are not currently supported on AIX. This patch disables these tests on 64-bit AIX for now.
This patch is similar to D111887 except the failures on this patch are on a 64-bit build.
Reviewed By: shchenz, #powerpc
Differential Revision: https://reviews.llvm.org/D113049
Many codegen pass require this pass with useful triple info. Legacy pass manager need to
add a TargetLibraryInfo with the module info before run passes. Or the TargetLibraryInfo
will be initialized too conservative.
Reviewed By: pengfei, aeubanks
Differential Revision: https://reviews.llvm.org/D115850
The `default_triple` requirement is redundant if the test specifies the triple, so this patch removes it.
Reviewed By: hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D115048
On AIX, this test generates an XCOFF file and hits "unknown binary format" assertion in llvm-nm. This patch specifies the triple to mitigate this issue.
Reviewed By: steven_wu
Differential Revision: https://reviews.llvm.org/D114683
Verify that the resolver exists, that it is a defined
Function, and that its return type matches the ifunc's
type. Add corresponding check to BitcodeReader, change
clang to emit the correct type, and fix tests to comply.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D112349
A constant complaint we get is that the __typeid__ symbols in the CFI
jump tables causes confusing stack traces in applications. Emit the more
readable cfi_jt aliases regardless of function export (LTO vs Thin LTO).
Reviewed By: pcc, tejohnson
Differential Revision: https://reviews.llvm.org/D107934
While both GlobalAlias and GlobalIFunc are GlobalIndirectSymbol, their
`getIndirectSymbol()` usage is quite different (GlobalIFunc's resolver
is an entity different from GlobalIFunc itself).
As discussed on https://lists.llvm.org/pipermail/llvm-dev/2020-September/144904.html
("[IR] Modelling of GlobalIFunc"), the name `getBaseObject` is confusing when
used with GlobalIFunc.
To resolve the confusion:
* Move GloalIndirectSymol::getBaseObject to GlobalAlias:: (GlobalIFunc should use `getResolver` instead)
* Change GlobalValue::getBaseObject not to inspect GlobalIFunc. Note: the function has 7 references.
* Add GlobalIFunc::getResolverFunction to peel off potential ConstantExpr indirection
(`strlen` in `test/LTO/Resolution/X86/ifunc.ll`)
Note: GlobalIFunc::getResolver (like GlobalAlias::getAliasee which does not peel
off ConstantExpr indirection) is kept to be used by ValueEnumerator.
Reviewed By: ibookstein
Differential Revision: https://reviews.llvm.org/D109792
Currently, the dead functions information getting from optimizations remarks does not contain debug location, but knowing where these dead functions locate could be useful for debugging or for detecting dead code.
Cause in `LTO::addRegularLTO()` we use `BitcodeModule::getLazyModule()` to read the bitcode module, when we pass Function F to `ore::NV()`, F is not materialized, so `F->getSubprogram()` returns nullptr, and there is no debug location information of dead functions in optimizations remarks.
This patch call `F->materialize()` before we pass Function F to `ore::NV()`, then debug location information will be emitted for dead functions in optimization remarks.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D109737
Clang diagnostics refer to identifier names in quotes.
This patch makes inline remarks conform to the convention.
New behavior:
```
% clang -O2 -Rpass=inline -Rpass-missed=inline -S a.c
a.c:4:25: remark: 'foo' inlined into 'bar' with (cost=-30, threshold=337) at callsite bar:0:25; [-Rpass=inline]
int bar(int a) { return foo(a); }
^
```
Reviewed By: hoy
Differential Revision: https://reviews.llvm.org/D107791
In PGO, a C++ external linkage function `foo` has a private counter
`__profc_foo` and a private `__profd_foo` in a `comdat nodeduplicate`.
A `__attribute__((weak))` function `foo` has a weak hidden counter `__profc_foo`
and a private `__profd_foo` in a `comdat nodeduplicate`.
In `ld.lld a.o b.o`, say a.o defines an external linkage `foo` and b.o
defines a weak `foo`. Currently we treat `comdat nodeduplicate` as `comdat any`,
ld.lld will incorrectly consider `b.o:__profc_foo` non-prevailing. In the worst
case when `b.o:__profd_foo` is retained and `b.o:__profc_foo` isn't, there will
be dangling reference causing an `undefined hidden symbol` error.
Add SelectionKind to `Comdat` in IRSymtab and let linkers ignore nodeduplicate comdat.
Differential Revision: https://reviews.llvm.org/D106228
LowerTypeTests pass adds functions with a non-canonical jump table
to cfiFunctionDecls instead of cfiFunctionDefs. As the jump table
is in the regular LTO object, these functions will also need to be
exported. This change fixes the non-canonical jump table case and
adds a test similar to the existing one for canonical jump tables.
Reviewed By: pcc
Differential Revision: https://reviews.llvm.org/D103120
Since d6de1e1a71406c75a4ea4d5a2fe84289f07ea3a1, no attributes is quivalent to
setting attribute to false.
This is a preliminary commit for https://reviews.llvm.org/D99080
This removes the need for the remaining doesNotMeet check and instead
directly checks if there are too many runtime checks for vectorization
in the planner.
A subsequent patch will adjust the logic used to decide whether to
vectorize with runtime to consider their cost more accurately.
Reviewed By: lebedev.ri
Differential Revision: https://reviews.llvm.org/D98634
This is the alternative approach to D96931.
In LTO, for each module with inlineasm block, prepend directive ".lto_discard <sym>, <sym>*" to the beginning of the inline
asm. ".lto_discard" is both a module inlineasm block marker and (optionally) provides a list of symbols to be discarded.
In MC while emitting for inlineasm, discard symbol binding & symbol
definitions according to ".lto_disard".
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D98762
In both ADCE and BDCE (via DemandedBits) we should not remove
instructions that are not guaranteed to return. This issue was
pointed out by fhahn in the recent llvm-dev thread.
Differential Revision: https://reviews.llvm.org/D96993
This version of the patch includes a fix for the cfi failures.
(undoes the revert commit 7db390cc7738a9ba0ed7d4ca59ab6ea2e69c47e9)
It also undoes reverts of follow-up patches that also needed reverting
originally:
* [LTO] Add option enable NewPM with LTOCodeGenerator.
(undoes revert commit 0a17664b47c153aa26a0d31b4835f26375440ec6)
* [LTOCodeGenerator] Use lto::Config for options (NFC)."
(undoes revert commit b0a8e41cfff717ff067bf63412d6edb0280608cd)
As we don't sort local symbols, don't sort non-local symbols. This makes
non-local symbols appear in their register order, which matches GNU as. The
register order is nice in that you can write tests with interleaved CHECK
prefixes, e.g.
```
// CHECK: something about foo
.globl foo
foo:
// CHECK: something about bar
.globl bar
bar:
```
With the lexicographical order, the user needs to place lexicographical smallest
symbol first or keep CHECK prefixes in one place.
