Now that #149310 has restricted lifetime intrinsics to only work on
allocas, we can also drop the explicit size argument. Instead, the size
is implied by the alloca.
This removes the ability to only mark a prefix of an alloca alive/dead.
We never used that capability, so we should remove the need to handle
that possibility everywhere (though many key places, including stack
coloring, did not actually respect this).
This slightly relaxes the invariant established in #149310, by also
allowing the lifetime argument to be poison. This is to support the
typical pattern of RAUWing with poison when removing an instruction.
It's worth noting that this does not require any conservative
assumptions, lifetimes with poison arguments can simply be skipped.
Fixes https://github.com/llvm/llvm-project/issues/151119.
This was always undesirable, and after #149310 it is illegal and will
result in a verifier error.
Fix this by moving SimplifyCFG's check for this into
canReplaceOperandWithVariable(), so it's shared with GVNSink.
This is another prune of dead code -- we never generate debug intrinsics
nowadays, therefore there's no need for these codepaths to run.
---------
Co-authored-by: Nikita Popov <github@npopov.com>
At this stage I'm just opportunistically deleting any code using
debug-intrinsic types, largely adjacent to calls to findDbgUsers. I'll
get to deleting that in probably one or more two commits.
SROA and a few other facilities use generic-lambdas and some overloaded
functions to deal with both intrinsics and debug-records at the same time.
As part of stripping out intrinsic support, delete a swathe of this code
from things in the Utils directory.
This is a large diff, but is mostly about removing functions that were
duplicated during the migration to debug records. I've taken a few
opportunities to replace comments about "intrinsics" with "records",
and replace generic lambdas with plain lambdas (I believe this makes
it more readable).
All of this is chipping away at intrinsic-specific code until we get to
removing parts of findDbgUsers, which is the final boss -- we can't
remove that until almost everything else is gone.
`combineMetadata` helper currently drops `!nosanitize` metadata when
merging two instructions, even if both originally carried `!nosanitize`.
This is problematic because `!nosanitize` is a key mechanism used by
sanitizer (e.g., ASan) to suppress instrumentation. Removing it can lead
to unintended sanitizer behavior.
This patch adds `nosanitize` to the whitelist in combineMetadata,
preserving it only if both instructions carry `!nosanitize`; otherwise,
it is dropped. This patch also adds corresponding tests in a test file
and regenerates it.
---
### Details
**Example (see [Godbolt](https://godbolt.org/z/83P5eWczx) for
details**):
```llvm
%v1 = load i32, ptr %p, !nosanitize
%v2 = load i32, ptr %p, !nosanitize
```
When merged via `combineMetadata(%v1, %v2, ...)`, the resulting
instruction loses its `!nosanitize` metadata.
Tools such as UBSan and AFL rely on `nosanitize` to prevent unwanted
transformations or checks. However, the current implementation of
combineMetadata mistakenly drops !nosanitize. This may lead to
unintended behavior during optimization.
For example, under `-fsanitize=address,undefined -O2`, IR emitted by
UBSan may lose its `!nosanitize` metadata due to the incorrect metadata
merging in optimization. As a result, ASan could unexpectedly instrument
those instructions.
> Note: due to the current UBSan handlers having relatively
coarse-grained attributes, this specific case is difficult to reproduce
end-to-end from source code—UBSan currently inhibits such optimizations
(refer to #135135 for details).
Still, I believe it's necessary to fix this now, to support future
versions of UBSan that might allow such optimizations, and to support
third-party tools (such as AFL-based fuzzers) that rely on the presence
of !nosanitize.
Seeing how we can't generate any debug intrinsics any more: delete a
variety of codepaths where they're handled. For the most part these are
plain deletions, in others I've tweaked comments to remain coherent, or
added a type to (what was) type-generic-lambdas.
This isn't all the DbgInfoIntrinsic call sites but it's most of the
simple scenarios.
Co-authored-by: Nikita Popov <github@npopov.com>
These are identified by misc-include-cleaner. I've filtered out those
that break builds. Also, I'm staying away from llvm-config.h,
config.h, and Compiler.h, which likely cause platform- or
compiler-specific build failures.
Following the work in PR #107279, this patch applies the annotative
DebugLocs, which indicate that a particular instruction is intentionally
missing a location for a given reason, to existing sites in the compiler
where their conditions apply. This is NFC in ordinary LLVM builds (each
function `DebugLoc::getFoo()` is inlined as `DebugLoc()`), but marks the
instruction in coverage-tracking builds so that it will be ignored by
Debugify, allowing only real errors to be reported. From a developer
standpoint, it also communicates the intentionality and reason for a
missing DebugLoc.
Some notes for reviewers:
- The difference between `I->dropLocation()` and
`I->setDebugLoc(DebugLoc::getDropped())` is that the former _may_ decide
to keep some debug info alive, while the latter will always be empty; in
this patch, I always used the latter (even if the former could
technically be correct), because the former could result in some
(barely) different output, and I'd prefer to keep this patch purely NFC.
- I've generally documented the uses of `DebugLoc::getUnknown()`, with
the exception of the vectorizers - in summary, they are a huge cause of
dropped source locations, and I don't have the time or the domain
knowledge currently to solve that, so I've plastered it all over them as
a form of "fixme".
## Purpose
This patch is one in a series of code-mods that annotate LLVM’s public
interface for export. This patch annotates the `llvm/Transforms`
library. These annotations currently have no meaningful impact on the
LLVM build; however, they are a prerequisite to support an LLVM Windows
DLL (shared library) build.
## Background
This effort is tracked in #109483. Additional context is provided in
[this
discourse](https://discourse.llvm.org/t/psa-annotating-llvm-public-interface/85307),
and documentation for `LLVM_ABI` and related annotations is found in the
LLVM repo
[here](https://github.com/llvm/llvm-project/blob/main/llvm/docs/InterfaceExportAnnotations.rst).
The bulk of these changes were generated automatically using the
[Interface Definition Scanner (IDS)](https://github.com/compnerd/ids)
tool, followed formatting with `git clang-format`.
The following manual adjustments were also applied after running IDS on
Linux:
- Removed a redundant `operator<<` from Attributor.h. IDS only
auto-annotates the 1st declaration, and the 2nd declaration being
un-annotated resulted in an "inconsistent linkage" error on Windows when
building LLVM as a DLL.
- `#include` the `VirtualFileSystem.h` in PGOInstrumentation.h and
remove the local declaration of the `vfs::FileSystem` class. This is
required because exporting the `PGOInstrumentationUse` constructor
requires the class be fully defined because it is used by an argument.
- Add #include "llvm/Support/Compiler.h" to files where it was not
auto-added by IDS due to no pre-existing block of include statements.
- Add `LLVM_TEMPLATE_ABI` and `LLVM_EXPORT_TEMPLATE` to exported
instantiated templates.
## Validation
Local builds and tests to validate cross-platform compatibility. This
included llvm, clang, and lldb on the following configurations:
- Windows with MSVC
- Windows with Clang
- Linux with GCC
- Linux with Clang
- Darwin with Clang
Currently, GlobalObject has an "alignment" property... but it's
basically nonsense: alignment doesn't mean the same thing for variables
and functions, and it's completely meaningless for ifuncs.
This "removes" (actually marking protected) the methods from
GlobalObject, adds the relevant methods to Function and GlobalVariable,
and adjusts the code appropriately.
This should make future alignment-related cleanups easier.
Start removing debug intrinsics support -- starting with the flag that
controls production of their replacement, debug records. This patch
removes the command-line-flag and with it the ability to switch back to
intrinsics. The module / function / block level "IsNewDbgInfoFormat"
flags get hardcoded to true, I'll to incrementally remove things that
depend on those flags.
Having a finite Depth (or recursion limit) for computeKnownBits is very
limiting, but is currently a load-bearing necessity, as all KnownBits
are recomputed on each call and there is no caching. As a prerequisite
for an effort to remove the recursion limit altogether, either using a
clever caching technique, or writing a easily-invalidable KnownBits
analysis, make the Depth argument in APIs in ValueTracking uniformly the
last argument with a default value. This would aid in removing the
argument when the time comes, as many callers that currently pass 0
explicitly are now updated to omit the argument altogether.
Move parts of the logic used by Reassociate to OverflowTracking
(mergeFlags & applyFlags) and move the definition to Local.h.
For now it just moves the NUW/NSW handling, as this matches the uses in
LICM. I'll look into the FP math handling separately, as it looks like
there's a difference between Reassociate (takes all flags from I, while
LICM takes the intersection of the flags on both instructions).
PR: https://github.com/llvm/llvm-project/pull/140403
Fixes#138345. Before this patch, gvn-sink would try to sink inline
assembly statements. Other GVN passes avoid them (see
b4fac94181/llvm/lib/Transforms/Scalar/GVN.cpp (L2932)
Similarly, gvn-sink should skip these instructions, since they are not
safe to move. To do this, we update the early exit in
canReplaceOperandWithVariable, since it should have caught this case.
It's more efficient to also skip numbering in GVNSink if the instruction
is InlineAsm, but that should be infrequent.
The test added is reduced from a failure when compiling Fuchsia with
gvn-sink.
An existing transformation replaces invoke instructions with a call to
the invoked function and a branch to the destination; when this happens,
we propagate the invoke's source location to the call but not to the
branch. This patch updates this behaviour to propagate to the branch as
well.
Found using https://github.com/llvm/llvm-project/pull/107279.
Preserve branch weight metadata when merging instructions if one of the
instructions is missing metadata. This is similar in behaviour to what
we do today for other types of metadata such as mmra, memprof and
callsite metadata.
Also add a legality check when merging prof metadata based on
instruction type. Without this check GVN PRE optimizations result in
prof metadata on phi nodes which break the module verifier.
Build failure caught by
https://lab.llvm.org/buildbot/#/builders/113/builds/6621
```
!9185 = !{!"branch_weights", i32 3912, i32 802}
Wrong number of operands
!9185 = !{!"branch_weights", i32 3912, i32 802}
fatal error: error in backend: Broken module found, compilation aborted!
```
Reverts #134200 with additional changes.
Preserve branch weight metadata when merging instructions if one of the
instructions is missing metadata. This is similar in behaviour to what
we do today for other types of metadata such as mmra, memprof and
callsite metadata.
After #124287 updated several functions to return iterators rather than
Instruction *, it was no longer straightforward to pass their result to
DIBuilder. This commit updates DIBuilder methods to accept an
InsertPosition instead, so that they can be called with an iterator
(preferred), or with a deprecation warning an Instruction *, or a
BasicBlock *. This commit also updates the existing calls to the
DIBuilder methods to pass in iterators.
As a special exception, DIBuilder::insertDeclare() keeps a separate
overload accepting a BasicBlock *InsertAtEnd. This is because despite
the name, this method does not insert at the end of the block, therefore
this cannot be handled implicitly by using InsertPosition.
After #124287 updated several functions to return iterators rather than
Instruction *, it was no longer straightforward to pass their result to
DIBuilder. This commit updates DIBuilder methods to accept an
InsertPosition instead, so that they can be called with an iterator
(preferred), or with a deprecation warning an Instruction *, or a
BasicBlock *. This commit also updates the existing calls to the
DIBuilder methods to pass in iterators.
As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and similar feed into
instruction insertion positions. Call-sites where that's necessary were
updated a year ago; but to ensure some type safety however, we'd like to
have all calls to getFirstNonPHI use the iterator-returning version.
This patch changes a bunch of call-sites calling getFirstNonPHI to use
getFirstNonPHIIt, which returns an iterator. All these call sites are
where it's obviously safe to fetch the iterator then dereference it. A
follow-up patch will contain less-obviously-safe changes.
We'll eventually deprecate and remove the instruction-pointer
getFirstNonPHI, but not before adding concise documentation of what
considerations are needed (very few).
---------
Co-authored-by: Stephen Tozer <Melamoto@gmail.com>
As part of the "RemoveDIs" project, BasicBlock::iterator now carries a
debug-info bit that's needed when getFirstNonPHI and similar feed into
instruction insertion positions. Call-sites where that's necessary were
updated a year ago; but to ensure some type safety however, we'd like to
have all calls to moveBefore use iterators.
This patch adds a (guaranteed dereferenceable) iterator-taking
moveBefore, and changes a bunch of call-sites where it's obviously safe
to change to use it by just calling getIterator() on an instruction
pointer. A follow-up patch will contain less-obviously-safe changes.
We'll eventually deprecate and remove the instruction-pointer
insertBefore, but not before adding concise documentation of what
considerations are needed (very few).
This moves combineAAMetadata() into Local and implements it via a new
AAOnly flag, which will intersect only AA metadata and keep other known
metadata.
The existing KnownIDs list is dropped, because it is redundant with the
switch in combineMetadata(), which already drops unknown metadata.
I tried a few variants of this, and ultimately went with the AAOnly flag
because this way we make an explicit choice for each metadata kind
supported by combineMetadata(), and ignoring the flag gives you
conservatively correct behavior.
I checked that the memcpy tests still pass if we adjust the logic for
MD_memprof/MD_callsite to drop the metadata instead of arbitrarily
picking one.
Fixes https://github.com/llvm/llvm-project/issues/121495.
This patch fixes a couple of places where memprof-related metadata
(!memprof and !callsite) were being dropped, and one place where PGO
metadata (!prof) was being dropped.
All were due to instances of combineMetadata() being invoked. That
function drops all metadata not in the list provided by the client, and
also drops any not in its switch statement.
Memprof metadata needed a case in the combineMetadata switch statement.
For now we simply keep the metadata of the instruction being kept, which
doesn't retain all the profile information when two calls with
memprof metadata are being combined, but at least retains some.
For the memprof metadata being dropped during call CSE, add memprof and
callsite metadata to the list of known ids in combineMetadataForCSE.
Neither memprof nor regular prof metadata were in the list of known ids
for the callsite in MemCpyOptimizer, which was added to combine AA
metadata after optimization of byval arguments fed by memcpy
instructions, and similar types of optimizations of memcpy uses.
There is one other callsite of combineMetadata, but it is only invoked
on load instructions, which do not carry these types of metadata.
This PR is motivated by a mismatch we discovered between compilation
results with vs. without `-g3`. We noticed this when compiling SPEC2017
testcases. The specific instance we saw is fixed in this PR by modifying
a guard (see below), but it is likely similar instances exist elsewhere
in the codebase.
The specific case fixed in this PR manifests itself in the `SimplifyCFG`
pass doing different things depending on whether DebugInfo is generated
or not. At the end of this comment, there is reduced example code that
shows the behavior in question.
The differing behavior has two root causes:
1. Commit https://github.com/llvm/llvm-project/commit/c07e19b adds loop
metadata including debug locations to loops that otherwise would not
have loop metadata
2. Commit https://github.com/llvm/llvm-project/commit/ac28efa6c100 adds
a guard to a simplification action in `SImplifyCFG` that prevents it
from simplifying away loop metadata
So, the change in 2. does not consider that when compiling with debug
symbols, loops that otherwise would not have metadata that needs
preserving, now have debug locations in their loop metadata. Thus, with
`-g3`, `SimplifyCFG` behaves differently than without it.
The larger issue is that while debug info is not supposed to influence
the final compilation result, commits like 1. blur the line between what
is and is not debug info, and not all optimization passes account for
this.
This PR does not address that and rather just modifies this particular
guard in order to restore equivalent behavior between debug and
non-debug builds in this one instance.
---
Here is a reduced version of a file from `f526.blender_r` that showcases
the behavior in question:
```C
struct LinkNode;
typedef struct LinkNode {
struct LinkNode *next;
void *link;
} LinkNode;
void do_projectpaint_thread_ph_v_state() {
int *ps = do_projectpaint_thread_ph_v_state;
LinkNode *node;
while (do_projectpaint_thread_ph_v_state)
for (node = ps; node; node = node->next)
;
}
```
Compiling this with and without DebugInfo, and then disassembling the
results, leads to different outcomes (tested on SystemZ and X86). The
reason for this is that the `SimplifyCFG` pass does different things in
either case.
Preserve !alias.scope, !noalias and !mem.parallel_loop_access metadata
on the replacement instruction, if it does not move. In that case, the
program would be UB, if the aliasing property encoded in the metadata
does not hold. This makes use of the clarification re aliasing metadata
implying UB if the property does not hold: #116220
Same as #115868, but for !alias.scope, !noalias and
!mem.parallel_loop_access.
PR: https://github.com/llvm/llvm-project/pull/117716
This should act like range.
Previously ConstantRangeList assumed a 64-bit range. Now query from the
actual entries. This also means that the empty range has no bitwidth, so
move asserts to avoid checking the bitwidth of empty ranges.
