This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
This fixes https://github.com/llvm/llvm-project/issues/57616.
Type test lowering in ThinLTO modules relies on having type id
summaries set up for the referenced types, which provide the type
test resolution. If there is no summary, the type tests are lowered
to false. At the very least, a default type id summary gives the
type tests a resolution of Unknown, which is handled correctly (ignored
by the first invocation of LTT, and lowered to true by the second).
WPD sets up the type id summaries (with a default type test resolution)
as it is processing the type tests, but only does this for the patterns
handled by WPD, which is a type test directly feeding an assume. In the
case of type tests feeding an assume via a phi, the type id summary was
not being set up, leading to the type tests being lowered to false
incorrectly.
Fix this by adding the default type id summary entries for all type ids
used on globals during index-only WPD.
This is not an issue for hybrid (split-lto-unit) LTO, as in that case
the type test resolution is determined and set up during LTT, since the
type definitions are in the regular LTO split module, and exported via
the summary to the ThinLTO split module.
Differential Revision: https://reviews.llvm.org/D134012
Currently, FunctionModRefBehavior tracks whether the function reads
or writes memory (ModRefInfo) and which locations it can access
(argmem, inaccessiblemem and other). This patch changes it to track
ModRef information per-location instead.
To give two examples of why this is useful:
* D117095 highlights a weakness of ModRef modelling in the presence
of operand bundles. For a memcpy call with deopt operand bundle,
we want to say that it can read any memory, but only write argument
memory. This would allow them to be treated like any other calls.
However, we currently can't express this and have to say that it
can read or write any memory.
* D127383 would ideally be modelled as a separate threadid location,
where threadid Refs outside pre-split coroutines can be ignored
(like other accesses to constant memory). The current representation
does not allow modelling this precisely.
The patch as implemented is intended to be NFC, but there are some
obvious opportunities for improvements and simplification. To fully
capitalize on this we would also want to change the way we represent
memory attributes on functions, but that's a larger change, and I
think it makes sense to separate out the FunctionModRefBehavior
refactoring.
Differential Revision: https://reviews.llvm.org/D130896
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
Some cl::ZeroOrMore were added to avoid the `may only occur zero or one times!`
error. More were added due to cargo cult. Since the error has been removed,
cl::ZeroOrMore is unneeded.
Also remove cl::init(false) while touching the lines.
Add statistics to count overall devirtualized targets as well as the
various types of devirtualizations applied at callsites.
Differential Revision: https://reviews.llvm.org/D123152
Update FunctionAttrs to use FunctionModRefBehavior instead
MemoryAccessKind.
This allows for adding support for inferring argmemonly and others,
see D121415.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D121460
Extend -wholeprogramdevirt-check to support both the existing
trapping mode on an incorrect devirtualization, as well as a new
mode to fallback to an indirect call on a mismatch. The new mode is
The new mode is useful in cases where we want to enable
devirtualization but cannot fully guarantee whole program visibility
(e.g in the case where LTO has been disabled for a small set of objects
that could potentially override virtual methods without having a symbol
reference to anything in the base class including the vtable).
Remove !prof and !callees metadata (which are used by indirect call
promotion) from both the new direct call and the fallback indirect call
(so that we don't perform another round of promotion on the latter).
Also remove it from the direct call in the non-fallback cases, which
was an oversight, although it didn't seem to cause any issues. Add tests
for the metadata removal covering the various cases.
Differential Revision: https://reviews.llvm.org/D121419
Minor efficiency fix. There is no reason to perform the same set lookup
repeatedly in the inner loop as it is invariant there.
Differential Revision: https://reviews.llvm.org/D119474
In regular LTO, analyze IR and discard unreachable functions when finding virtual call targets.
Differential Revision: https://reviews.llvm.org/D116056
WPD currently assumes that there is a one to one correspondence between
type test assume sequences and virtual calls. However, with
-fstrict-vtable-pointers this may not be true. This ends up causing
crashes when we try to optimize a virtual call more than once (
applyUniformRetValOpt()/applyUniqueRetValOpt()/applyVirtualConstProp()/applySingleImplDevirt()).
applySingleImplDevirt() actually didn't previous crash because it would
replace the devirtualized call with the same direct call. Adding an
assert that the call is indirect causes the corresponding test to crash
with the rest of the patch.
This makes Chrome successfully build with -fstrict-vtable-pointers + WPD.
Reviewed By: tejohnson
Differential Revision: https://reviews.llvm.org/D104798
Problem:
On SystemZ we need to open text files in text mode. On Windows, files opened in text mode adds a CRLF '\r\n' which may not be desirable.
Solution:
This patch adds two new flags
- OF_CRLF which indicates that CRLF translation is used.
- OF_TextWithCRLF = OF_Text | OF_CRLF indicates that the file is text and uses CRLF translation.
Developers should now use either the OF_Text or OF_TextWithCRLF for text files and OF_None for binary files. If the developer doesn't want carriage returns on Windows, they should use OF_Text, if they do want carriage returns on Windows, they should use OF_TextWithCRLF.
So this is the behaviour per platform with my patch:
z/OS:
OF_None: open in binary mode
OF_Text : open in text mode
OF_TextWithCRLF: open in text mode
Windows:
OF_None: open file with no carriage return
OF_Text: open file with no carriage return
OF_TextWithCRLF: open file with carriage return
The Major change is in llvm/lib/Support/Windows/Path.inc to only set text mode if the OF_CRLF is set.
```
if (Flags & OF_CRLF)
CrtOpenFlags |= _O_TEXT;
```
These following files are the ones that still use OF_Text which I left unchanged. I modified all these except raw_ostream.cpp in recent patches so I know these were previously in Binary mode on Windows.
./llvm/lib/Support/raw_ostream.cpp
./llvm/lib/TableGen/Main.cpp
./llvm/tools/dsymutil/DwarfLinkerForBinary.cpp
./llvm/unittests/Support/Path.cpp
./clang/lib/StaticAnalyzer/Core/HTMLDiagnostics.cpp
./clang/lib/Frontend/CompilerInstance.cpp
./clang/lib/Driver/Driver.cpp
./clang/lib/Driver/ToolChains/Clang.cpp
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D99426
Using $ breaks demangling of the symbols. For example,
$ c++filt _Z3foov\$123
_Z3foov$123
This causes problems for developers who would like to see nice stack traces
etc., but also for automatic crash tracking systems which try to organize
crashes based on the stack traces.
Instead, use the period as suffix separator, since Itanium demanglers normally
ignore such suffixes:
$ c++filt _Z3foov.123
foo() [clone .123]
This is already done in some places; try to do it everywhere.
Differential revision: https://reviews.llvm.org/D97484
The fix in 3c4c205060 caused an assert in
the case of a pure virtual base class. In that case, the vTableFuncs
list on the summary will be empty, so we were hitting the new assert
that the linkage type was not available_externally.
In the case of pure virtual, we do not want to assert, and additionally
need to set VS so that we don't treat it conservatively and quit the
analysis of the type id early.
This exposed a pre-existing issue where we were not updating the vcall
visibility on pure virtual functions when whole program visibility was
specified. We were skipping updating the visibility on any global vars
that didn't have any vTableFuncs, which meant all pure virtual were not
updated, and the later analysis would block any devirtualization of
calls that had a type id used on those pure virtual vtables (see the
handling in the other code modified in this patch). Simply remove that
check. It will mean that we may update the vcall visibility on global
vars that aren't vtables, but that setting is ignored for any global
vars that didn't have type metadata anyway.
Added a new test case that asserted without removing the assert, and
that requires the other fixes in this patch (updateVCallVisibilityInIndex
and not skipping all vtables without virtual funcs) to get a successful
devirtualization with index-only WPD. I added cases to test hybrid and
regular LTO for completeness, although those already worked without the
fixes here.
With this final fix, a clang multistage bootstrap with WPD builds and
runs all tests successfully.
Differential Revision: https://reviews.llvm.org/D97126
This adds an internal option -wholeprogramdevirt-check which if enabled
will guard each devirtualization with a runtime check against the
expected target, and an invocation of a debug trap if the check fails.
This is useful for debugging WPD failures involving undefined behavior
(e.g. casting to another class type not in the inheritance chain).
Differential Revision: https://reviews.llvm.org/D95969
Adds a lld test for a case that the handling added for dynamically
exported symbols in 1487747e99 already
fixes. Because isExportDynamic returns true when the symbol is
SharedKind with default visibility, it will treat as dynamically
exported and block devirtualization when the definition of a vtable
comes from a shared library. This is desireable as it is dangerous to
devirtualize in that case, since there could be hidden overrides in the
shared library. Typically that happens when the shared library header
contains available externally definitions, which applications can
override. An example is std::error_category, which is overridden in LLVM
and causing failures after a self build with WPD enabled, because
libstdc++ contains hidden overrides of the virtual base class methods.
The regular LTO case in the new test already worked, but there are
2 fixes in this patch needed for the index-only case and the hybrid
LTO case. For the index-only case, WPD should not simply ignore
available externally vtables. A follow on fix will be made to clang to
emit type metadata for those vtables, which the new test is modeling.
For the hybrid case, we need to ensure when the module is split that any
llvm.*used globals are cloned to the regular LTO split module so
available externally vtable definitions are not prematurely deleted.
Another follow on fix will add the equivalent gold test, which requires
a small fix to the plugin to treat symbols in dynamic libraries the same
way lld already is.
Differential Revision: https://reviews.llvm.org/D96721
Identify dynamically exported symbols (--export-dynamic[-symbol=],
--dynamic-list=, or definitions needed to preempt shared objects) and
prevent their LTO visibility from being upgraded.
This helps avoid use of whole program devirtualization when there may
be overrides in dynamic libraries.
Differential Revision: https://reviews.llvm.org/D91583
1. Removed #include "...AliasAnalysis.h" in other headers and modules.
2. Cleaned up includes in AliasAnalysis.h.
Reviewed By: RKSimon
Differential Revision: https://reviews.llvm.org/D92489
Previously this option could be used to skip devirtualizations of the
given functions in regular LTO and in the ThinLTO indexing step. This
change allows them to be skipped in the backend as well, which is useful
when debugging WPD in a distributed ThinLTO backend.
Differential Revision: https://reviews.llvm.org/D91812
The legacy pass's default constructor sets UseCommandLine = true and
goes down a separate testing route. Match that in the NPM pass.
This fixes all tests in llvm/test/Transforms/WholeProgramDevirt under NPM.
Reviewed By: ychen
Differential Revision: https://reviews.llvm.org/D88588
There's a special case in hasAttribute for None when pImpl is null. If pImpl is not null we dispatch to pImpl->hasAttribute which will always return false for Attribute::None.
So if we just want to check for None its sufficient to just check that pImpl is null. Which can even be done inline.
This patch adds a helper for that case which I hope will speed up our getSubtargetImpl implementations.
Differential Revision: https://reviews.llvm.org/D86744
This restores commit 80d0a137a5, and the
follow on fix in 873c0d0786, with a new
fix for test failures after a 2-stage clang bootstrap, and a more robust
fix for the Chromium build failure that an earlier version partially
fixed. See also discussion on D75201.
Reviewers: evgeny777
Subscribers: mehdi_amini, Prazek, hiraditya, steven_wu, dexonsmith, arphaman, davidxl, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D73242
Summary:
In D52514 I had fixed a bug with WPD after indirect call promotion, by
checking that a type test being analyzed dominates potential virtual
calls. With that fix I included a small effiency enhancement to avoid
processing a devirt candidate multiple times (when there are multiple
type tests). This latter change wasn't in response to any measured
efficiency issues, it was merely theoretical. Unfortuantely, it turns
out to limit optimization opportunities after inlining.
Specifically, consider code that looks like:
class A {
virtual void foo();
};
class B : public A {
void foo();
}
void callee(A *a) {
a->foo(); // Call 1
}
void caller(B *b) {
b->foo(); // Call 2
callee(b);
}
After inlining callee into caller, because of the existing call to
b->foo() in caller there will be 2 type tests in caller for the vtable
pointer of b: the original type test against B from Call 2, and the
inlined type test against A from Call 1. If the code was compiled with
-fstrict-vtable-pointers, then after optimization WPD will see that
both type tests are associated with the inlined virtual Call 1.
With my earlier change to only process a virtual call against one type
test, we may only consider virtual Call 1 against the base class A type
test, which can't be devirtualized. With my change here to remove this
restriction, it also gets considered for the type test against the
derived class B type test, where it can be devirtualized.
Note that if caller didn't include it's own earlier virtual call
b->foo() we will not be able to devirtualize after inlining callee even
after this fix, since there would not be a type test against B in the
IR. As a future enhancement we can consider inserting type tests at call
sites that pass pointers to classes with virtual calls, to enable
context-sensitive devirtualization after inlining.
Reviewers: pcc, vitalybuka, evgeny777
Subscribers: Prazek, hiraditya, steven_wu, dexonsmith, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D79235
This method has been commented as deprecated for a while. Remove
it and replace all uses with the equivalent getCalledOperand().
I also made a few cleanups in here. For example, to removes use
of getElementType on a pointer when we could just use getFunctionType
from the call.
Differential Revision: https://reviews.llvm.org/D78882
Kazu Hirata