Commit Graph

336 Commits

Author SHA1 Message Date
Evgeniy Brevnov da41214d65 Add support for atomic memory copy lowering
Currently, the utility supports lowering of non atomic memory transfer routines only. This patch adds support for atomic version of memcopy. This may be useful for targets not supporting atomic memcopy.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D118443
2022-04-08 10:41:31 +07:00
Evgeniy Brevnov acfc785c0e Preserve aliasing info during memory intrinsics lowering
By specification, source and destination of llvm.memcpy.* must either be equal or non-overlapping. This semantics is hard or impossible to figure out once lowered. This patch explicitly marks loads from source and stores to destination as not aliasing if source and destination is known to be not equal.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D118441
2022-04-06 11:33:54 +07:00
Evgeniy Brevnov 4661a65f4b New regression test against expandMemCpyAsLoop utility
Unit test for functionality going to be added by D118441

Differential Revision: https://reviews.llvm.org/D118440
2022-04-05 17:37:34 +07:00
Evgeniy Brevnov 970ae8376e An attempt to fix problem with building
Transforms/Utils/MemTransferLowerTest
2022-04-05 14:12:00 +07:00
Simon Pilgrim 7120c67c04 Revert rG5adc94bb8a23eb819f6ca80e722f5b0e6e41401d "New regression test against expandMemCpyAsLoop utility"
This was causing link errors on buildbots (and locally)
2022-04-05 08:11:21 +01:00
Evgeniy Brevnov 5adc94bb8a New regression test against expandMemCpyAsLoop utility
Unit test for functionality going to be added by D118441

Differential Revision: https://reviews.llvm.org/D118440
2022-04-05 13:28:13 +07:00
Djordje Todorovic 73777b4c35 [Debugify] Optimize debugify original mode
Before we start addressing the issue with having
a lot of false positives when using debugify in
the original mode, we have made a few patches that
should speed up the execution of the testing
utility Passes.

For example, when testing a large project
(let's say LLVM project itself), we can face
a lot of potential DI issues. Usually, we use
-verify-each-debuginfo-preserve (that is very
similar to -debugify-each) -- it collects
DI metadata before each Pass, and after the Pass
it checks if the Pass preserved the DI metadata.
However, we can speed up this process, since we
don't need to collect DI metadata before each
Pass -- we could use the DI metadata that are
collected after the previous Pass from
the pipeline as an input for the next Pass.

This patch speeds up the utility for ~2x.

Differential Revision: https://reviews.llvm.org/D115622
2022-03-22 12:14:00 +01:00
serge-sans-paille a494ae43be Cleanup includes: TransformsUtils
Estimation on the impact on preprocessor output:
before: 1065307662
after:  1064800684

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D120741
2022-03-01 21:00:07 +01:00
serge-sans-paille 71c3a5519d Cleanup includes: LLVMAnalysis
Number of lines output by preprocessor:
before: 1065940348
after:  1065307662

Discourse thread: https://discourse.llvm.org/t/include-what-you-use-include-cleanup
Differential Revision: https://reviews.llvm.org/D120659
2022-03-01 18:01:54 +01:00
Matthias Braun 6a383369f9 PGOInstrumentation, GCOVProfiling: Split indirectbr critical edges regardless of PHIs
The `SplitIndirectBrCriticalEdges` function was originally designed for
`CodeGenPrepare` and skipped splitting of edges when the destination
block didn't contain any `PHI` instructions. This only makes sense when
reducing COPYs like `CodeGenPrepare`. In the case of
`PGOInstrumentation` or `GCOVProfiling` it would result in missed
counters and wrong result in functions with computed goto.

Differential Revision: https://reviews.llvm.org/D120096
2022-02-23 16:27:37 -08:00
Matthias Braun d7a307320e Simplify/cleanup BasicBlockUtilsTest
Cleanup BasicBolckUtilsTest using C++ raw string literals, remove
duplicated block functions and smaller style changes.

Differential Revision: https://reviews.llvm.org/D120095
2022-02-23 16:27:37 -08:00
Bill Wendling c1b9672534 [NFC] Add #include for constants 2022-02-23 01:23:45 -08:00
serge-sans-paille e188aae406 Cleanup header dependencies in LLVMCore
Based on the output of include-what-you-use.

This is a big chunk of changes. It is very likely to break downstream code
unless they took a lot of care in avoiding hidden ehader dependencies, something
the LLVM codebase doesn't do that well :-/

I've tried to summarize the biggest change below:

- llvm/include/llvm-c/Core.h: no longer includes llvm-c/ErrorHandling.h
- llvm/IR/DIBuilder.h no longer includes llvm/IR/DebugInfo.h
- llvm/IR/IRBuilder.h no longer includes llvm/IR/IntrinsicInst.h
- llvm/IR/LLVMRemarkStreamer.h no longer includes llvm/Support/ToolOutputFile.h
- llvm/IR/LegacyPassManager.h no longer include llvm/Pass.h
- llvm/IR/Type.h no longer includes llvm/ADT/SmallPtrSet.h
- llvm/IR/PassManager.h no longer includes llvm/Pass.h nor llvm/Support/Debug.h

And the usual count of preprocessed lines:
$ clang++ -E  -Iinclude -I../llvm/include ../llvm/lib/IR/*.cpp -std=c++14 -fno-rtti -fno-exceptions | wc -l
before: 6400831
after:  6189948

200k lines less to process is no that bad ;-)

Discourse thread on the topic: https://llvm.discourse.group/t/include-what-you-use-include-cleanup

Differential Revision: https://reviews.llvm.org/D118652
2022-02-02 06:54:20 +01:00
Giorgis Georgakoudis 95b981ca2a [CodeExtractor] Enable partial aggregate arguments
Summary:
Enable CodeExtractor to construct output functions that partially
aggregate inputs/outputs in their argument list. A use case is the
OMPIRBuilder to create outlined functions for parallel regions that
aggregate in a struct the payload variables for the region while passing
as scalars thread and bound identifiers.

Differential Revision: https://reviews.llvm.org/D96854
2022-01-25 20:50:34 -05:00
Stephen Tozer 32417b3203 [DebugInfo] ValueMapper impl for DIArgList respects IgnoreMissingLocals
This patch fixes an issue in which SSA value reference within a
DIArgList would be unnecessarily dropped by llvm-link, even when
invoking on a single file (which should be a no-op). The reason for the
difference is that the ValueMapper does not refer to the
RF_IgnoreMissingLocals flag for LocalAsMetadata contained within a
DIArgList; this flag is used for direct LocalAsMetadata uses to preserve
SSA references even when the ValueMapper does not have an explicit
mapping for the referenced SSA value, which appears to always be the
case when using llvm-link in this manner.

Differential Revision: https://reviews.llvm.org/D114355
2022-01-17 17:17:32 +00:00
Arthur Eubanks 512534bc16 [Cloning] Clone metadata on function declarations
Previously we missed cloning metadata on function declarations because
we don't call CloneFunctionInto() on declarations in CloneModule().

Reviewed By: dexonsmith

Differential Revision: https://reviews.llvm.org/D113812
2021-12-01 15:40:05 -08:00
Congzhe Cao c42772752a [CodeMoverUtils] Enhance isSafeToMoveBefore() when control flow equivalence is satisfied
With improved analysis in determining CFG equivalence that does
not require strict dominance and post-dominance conditions, we
now relax  isSafeToMoveBefore() such that an instruction I can
be moved before InsertPoint even if they do not strictly dominate
each other, as long as they follow the same control flow path.

For example,  we can move Instruction 0 before Instruction 1,
and vice versa.

```
if (cond1)
   // Instruction 0: %add = add i32 1, 2
if (cond1)
   // Instruction 1: %add2 = add i32 2, 1
```

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D110456
2021-09-27 18:37:36 -04:00
Congzhe Cao 751be2a064 [CodeMoverUtils] Enhance isSafeToMoveBefore() when moving BBs
When moving an entire basic block BB before InsertPoint, currently
we check for all instructions whether the operands dominates
InsertPoint, however, this can be improved such that even an
operand does not dominate InsertPoint, as long as it appears as
a previous instruction in the same BB, it is safe to move.

Reviewed By: Whitney

Differential Revision: https://reviews.llvm.org/D110378
2021-09-24 05:48:15 -04:00
Andrew Litteken 144cd22bae [CodeExtractor] Creating exit stubs based off original order branch instructions.
Previously the CodeExtractor created exit stubs, and the subsequent return value of the outlined function based on the order of out-of-region blocks after splitting any phi nodes, and collecting the blocks to be outlined. This could cause differences in order if there was a difference of exit block phi nodes between the two regions. This patch moves the collection of the output target blocks to be before this occurs, so that the assignment of target block to output value will be the same, regardless of the contents of the output block.

Reviewers: paquette, roelofs

Differential Revision: https://reviews.llvm.org/D108657
2021-09-08 15:15:15 -07:00
Andrew Litteken 9d2c859ebb [CodeExtractor] Making the arguments outlined easier to access from the outside
The Code Extractor does not provide an easy mechanism for determining the
inputs and outputs after extraction has occurred, this patch gives the
ability to pass in empty SetVectors to be filled with the inputs and
outputs if they need to be analyzed.

Added Tests:
- InputOutputMonitoring in unittests/Transforms/Utils/CodeExtractorTests.cpp

Reviewers: paquette

Differential Revision: https://reviews.llvm.org/D106991
2021-08-26 09:47:53 -07:00
Arthur Eubanks 7557d6c896 [NFC] Cleanup calls to CallBase::getAttribute() 2021-08-18 09:39:33 -07:00
Sander de Smalen 84a4caeb84 [InstSimplify] Don't assume parent function when simplifying llvm.vscale.
D106850 introduced a simplification for llvm.vscale by looking at the
surrounding function's vscale_range attributes. The call that's being
simplified may not yet have been inserted into the IR. This happens for
example during function cloning.

This patch fixes the issue by checking if the instruction is in a
parent basic block.
2021-07-29 20:08:08 +01:00
Johannes Doerfert 25a3130d89 [Local] Do not introduce a new `llvm.trap` before `unreachable`
This is the second attempt to remove the `llvm.trap` insertion after
https://reviews.llvm.org/rGe14e7bc4b889dfaffb7180d176a03311df2d4ae6
reverted the first one. It is not clear what the exact issue was back
then and it might already be gone by now, it has been >5 years after
all.

Replaces D106299.

Differential Revision: https://reviews.llvm.org/D106308
2021-07-26 23:33:36 -05:00
Arthur Eubanks 4e6013250d [NFC][OpaquePtr] Use GlobalValue::getValueType() more
Instead of getType()->getElementType().
2021-07-09 09:55:41 -07:00
Eli Friedman 8a567e5f22 [ScalarEvolution] Fix pointer/int type handling converting select/phi to min/max.
The old version of this code would blindly perform arithmetic without
paying attention to whether the types involved were pointers or
integers.  This could lead to weird expressions like negating a pointer.

Explicitly handle simple cases involving pointers, like "x < y ? x : y".
In all other cases, coerce the operands of the comparison to integer
types.  This avoids the weird cases, while handling most of the
interesting cases.

Differential Revision: https://reviews.llvm.org/D103660
2021-06-17 14:05:12 -07:00
Djordje Todorovic b9076d119a Recommit: "[Debugify][Original DI] Test dbg var loc preservation""
[Debugify][Original DI] Test dbg var loc preservation

    This is an improvement of [0]. This adds checking of
    original llvm.dbg.values()/declares() instructions in
    optimizations.

    We have picked a real issue that has been found with
    this (actually, picked one variable location missing
    from [1] and resolved the issue), and the result is
    the fix for that -- D100844.

    Before applying the D100844, using the options from [0]
    (but with this patch applied) on the compilation of GDB 7.11,
    the final HTML report for the debug-info issues can be found
    at [1] (please scroll down, and look for
    "Summary of Variable Location Bugs"). After applying
    the D100844, the numbers has improved a bit -- please take
    a look into [2].

    [0] https://llvm.org/docs/HowToUpdateDebugInfo.html#\
        test-original-debug-info-preservation-in-optimizations
    [1] https://djolertrk.github.io/di-check-before-adce-fix/
    [2] https://djolertrk.github.io/di-check-after-adce-fix/

    Differential Revision: https://reviews.llvm.org/D100845

The Unit test was failing because the pass from the test that
modifies the IR, in its runOnFunction() didn't return 'true',
so the expensive-check configuration triggered an assertion.
2021-05-21 02:04:29 -07:00
Djordje Todorovic 0ae3c1d4d7 Revert "[Debugify][Original DI] Test dbg var loc preservation"
This reverts commit 76f375f3d9.

This will be pushed again, after investigating a test failure:
https://lab.llvm.org/buildbot/#/builders/16/builds/11254
2021-05-20 07:11:35 -07:00
Djordje Todorovic 76f375f3d9 [Debugify][Original DI] Test dbg var loc preservation
This is an improvement of [0]. This adds checking of
original llvm.dbg.values()/declares() instructions in
optimizations.

We have picked a real issue that has been found with
this (actually, picked one variable location missing
from [1] and resolved the issue), and the result is
the fix for that -- D100844.

Before applying the D100844, using the options from [0]
(but with this patch applied) on the compilation of GDB 7.11,
the final HTML report for the debug-info issues can be found
at [1] (please scroll down, and look for
"Summary of Variable Location Bugs"). After applying
the D100844, the numbers has improved a bit -- please take
a look into [2].

[0] https://llvm.org/docs/HowToUpdateDebugInfo.html\
[1] https://djolertrk.github.io/di-check-before-adce-fix/
[2] https://djolertrk.github.io/di-check-after-adce-fix/

Differential Revision: https://reviews.llvm.org/D100845
2021-05-20 06:42:02 -07:00
Reshabh Sharma ed51156084 [ModuleUtils] NFC: Add unit tests for appendToUsedList
This patch adds initial unit tests for appendToUsedList
in the ModuleUtils. It specifically tests changes from
https://reviews.llvm.org/D101363 which intent to allow
insertion of globals in non-zero address spaces into the
llvm used lists.

Reviewed by: dblaikie

Differential Revision: https://reviews.llvm.org/D101746
2021-05-04 12:05:50 +05:30
Nico Weber ba7a92c01e [Support] Don't include VirtualFileSystem.h in CommandLine.h
CommandLine.h is indirectly included in ~50% of TUs when building
clang, and VirtualFileSystem.h is large.

(Already remarked by jhenderson on D70769.)

No behavior change.

Differential Revision: https://reviews.llvm.org/D100957
2021-04-21 10:19:01 -04:00
Sidharth Baveja d81d9e8b86 [SplitEdge] Update SplitCriticalEdge to return a nullptr only when the edge is not critical
Summary:
The function SplitCriticalEdge (called by SplitEdge) can return a nullptr in
cases where the edge is a critical. SplitEdge uses SplitCriticalEdge assuming it
can always split all critical edges, which is an incorrect assumption.

The three cases where the function SplitCriticalEdge will return a nullptr is:
1. DestBB is an exception block
2. Options.IgnoreUnreachableDests is set to true and
isa(DestBB->getFirstNonPHIOrDbgOrLifetime()) is not equal to a nullptr
3. LoopSimplify form must be preserved (Options.PreserveLoopSimplify is true)
and it cannot be maintained for a loop due to indirect branches

For each of these situations they are handled in the following way:
1. Modified the function ehAwareSplitEdge originally from
llvm/lib/Transforms/Coroutines/CoroFrame.cpp to handle the cases when the DestBB
is an exception block. This function is called directly in SplitEdge.
SplitEdge does not call SplitCriticalEdge in this case
2. Options.IgnoreUnreachableDests is set to false by default, so this situation
does not apply.
3. Return a nullptr in this situation since the SplitCriticalEdge also returned
nullptr. Nothing we can do in this case.

Reviewed By: asbirlea

Differential Revision:https://reviews.llvm.org/D94619
2021-04-06 21:24:40 +00:00
Matt Arsenault 9a0c9402fa Reapply "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 07e46367ba.
2021-03-29 08:55:30 -04:00
Oliver Stannard 07e46367ba Revert "Reapply "OpaquePtr: Turn inalloca into a type attribute""
Reverting because test 'Bindings/Go/go.test' is failing on most
buildbots.

This reverts commit fc9df30991.
2021-03-29 11:32:22 +01:00
Matt Arsenault fc9df30991 Reapply "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 20d5c42e0e.
2021-03-28 13:35:21 -04:00
Nico Weber 20d5c42e0e Revert "OpaquePtr: Turn inalloca into a type attribute"
This reverts commit 4fefed6563.
Broke check-clang everywhere.
2021-03-28 13:02:52 -04:00
Matt Arsenault 4fefed6563 OpaquePtr: Turn inalloca into a type attribute
I think byval/sret and the others are close to being able to rip out
the code to support the missing type case. A lot of this code is
shared with inalloca, so catch this up to the others so that can
happen.
2021-03-28 11:12:23 -04:00
Roman Lebedev 78b8ce40ef
Reland [SCEV] Improve modelling for (null) pointer constants
This reverts commit 329aeb5db4,
and relands commit 61f006ac65.

This is a continuation of D89456.

As it was suggested there, now that SCEV models `PtrToInt`,
we can try to improve SCEV's pointer handling.
In particular, i believe, i will need this in the future
to further fix `SCEVAddExpr`operation type handling.

This removes special handling of `ConstantPointerNull`
from `ScalarEvolution::createSCEV()`, and add constant folding
into `ScalarEvolution::getPtrToIntExpr()`.
This way, `null` constants stay as such in SCEV's,
but gracefully become zero integers when asked.

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D98147
2021-03-13 16:05:34 +03:00
Roman Lebedev 329aeb5db4
Temporairly evert "[SCEV] Improve modelling for (null) pointer constants"
This appears to have broken ubsan bot:
https://lab.llvm.org/buildbot/#/builders/85/builds/3062
https://reviews.llvm.org/D98147#2623549

It looks like LSR needs some kind of a change around insertion point handling.
Reverting until i have a fix.

This reverts commit 61f006ac65.
2021-03-13 09:10:28 +03:00
Roman Lebedev 61f006ac65
[SCEV] Improve modelling for (null) pointer constants
This is a continuation of D89456.

As it was suggested there, now that SCEV models `PtrToInt`,
we can try to improve SCEV's pointer handling.
In particular, i believe, i will need this in the future
to further fix `SCEVAddExpr`operation type handling.

This removes special handling of `ConstantPointerNull`
from `ScalarEvolution::createSCEV()`, and add constant folding
into `ScalarEvolution::getPtrToIntExpr()`.
This way, `null` constants stay as such in SCEV's,
but gracefully become zero integers when asked.

Reviewed By: Meinersbur

Differential Revision: https://reviews.llvm.org/D98147
2021-03-12 22:11:58 +03:00
Stephen Tozer 57a0e0d4c2 Fix 2: [DebugInfo] Support DIArgList in DbgVariableIntrinsic
Changes to function calls in LocalTest resulted in comparisons between
unsigned values and signed literals; the latter have been updated to be
unsigned to prevent this warning.
2021-03-08 15:43:39 +00:00
gbtozers e5d958c456 [DebugInfo] Support DIArgList in DbgVariableIntrinsic
This patch updates DbgVariableIntrinsics to support use of a DIArgList for the
location operand, resulting in a significant change to its interface. This patch
does not update all IR passes to support multiple location operands in a
dbg.value; the only change is to update the DbgVariableIntrinsic interface and
its uses. All code outside of the intrinsic classes assumes that an intrinsic
will always have exactly one location operand; they will still support
DIArgLists, but only if they contain exactly one Value.

Among other changes, the setOperand and setArgOperand functions in
DbgVariableIntrinsic have been made private. This is to prevent code from
setting the operands of these intrinsics directly, which could easily result in
incorrect/invalid operands being set. This does not prevent these functions from
being called on a debug intrinsic at all, as they can still be called on any
CallInst pointer; it is assumed that any code directly setting the operands on a
generic call instruction is doing so safely. The intention for making these
functions private is to prevent DIArgLists from being overwritten by code that's
naively trying to replace one of the Values it points to, and also to fail fast
if a DbgVariableIntrinsic is updated to use a DIArgList without a valid
corresponding DIExpression.
2021-03-08 14:36:13 +00:00
Djordje Todorovic 1a2b3536ef Reland "[Debugify] Make the debugify aware of the original (-g) Debug Info"
As discussed on the RFC [0], I am sharing the set of patches that
    enables checking of original Debug Info metadata preservation in
    optimizations. The proof-of-concept/proposal can be found at [1].

    The implementation from the [1] was full of duplicated code,
    so this set of patches tries to merge this approach into the existing
    debugify utility.

    For example, the utility pass in the original-debuginfo-check
    mode could be invoked as follows:

      $ opt -verify-debuginfo-preserve -pass-to-test sample.ll

    Since this is very initial stage of the implementation,
    there is a space for improvements such as:
      - Add support for the new pass manager
      - Add support for metadata other than DILocations and DISubprograms

    [0] https://groups.google.com/forum/#!msg/llvm-dev/QOyF-38YPlE/G213uiuwCAAJ
    [1] https://github.com/djolertrk/llvm-di-checker

    Differential Revision: https://reviews.llvm.org/D82545

The test that was failing is now forced to use the old PM.
2021-02-18 23:29:22 -08:00
Djordje Todorovic c1e23894fc Revert "[Debugify] Make the debugify aware of the original (-g) Debug Info"
This reverts rG8ee7c7e02953.
One test is failing, I'll reland this as soon as possible.
2021-02-18 02:04:27 -08:00
Djordje Todorovic 8ee7c7e029 [Debugify] Make the debugify aware of the original (-g) Debug Info
As discussed on the RFC [0], I am sharing the set of patches that
enables checking of original Debug Info metadata preservation in
optimizations. The proof-of-concept/proposal can be found at [1].

The implementation from the [1] was full of duplicated code,
so this set of patches tries to merge this approach into the existing
debugify utility.

For example, the utility pass in the original-debuginfo-check
mode could be invoked as follows:

  $ opt -verify-debuginfo-preserve -pass-to-test sample.ll

Since this is very initial stage of the implementation,
there is a space for improvements such as:
  - Add support for the new pass manager
  - Add support for metadata other than DILocations and DISubprograms

[0] https://groups.google.com/forum/#!msg/llvm-dev/QOyF-38YPlE/G213uiuwCAAJ
[1] https://github.com/djolertrk/llvm-di-checker

Differential Revision: https://reviews.llvm.org/D82545
2021-02-18 01:52:16 -08:00
Duncan P. N. Exon Smith 22a52dfddc TransformUtils: Fix metadata handling in CloneModule (and improve CloneFunctionInto)
This commit fixes how metadata is handled in CloneModule to be sound,
and improves how it's handled in CloneFunctionInto (although the latter
is still awkward when called within a module).

Ruiling Song pointed out in PR48841 that CloneModule was changed to
unsoundly use the RF_ReuseAndMutateDistinctMDs flag (renamed in
fa35c1f80f for clarity). This flag papered
over a crash caused by other various changes made to CloneFunctionInto
over the past few years that made it unsound to use cloning between
different modules.

(This commit partially addresses PR48841, fixing the repro from
preprocessed source but not textual IR. MDNodeMapper::mapDistinctNode
became unsound in df763188c9 and this
commit does not address that regression.)

RF_ReuseAndMutateDistinctMDs is designed for the IRMover to use,
avoiding unnecessary clones of all referenced metadata when linking
between modules (with IRMover, the source module is discarded after
linking). It never makes sense to use when you're not discarding the
source. This commit drops its incorrect use in CloneModule.

Sadly, the right thing to do with metadata when cloning a function is
complicated, and this patch doesn't totally fix it.

The first problem is that there are two different types of referenceable
metadata and it's not obvious what to with one of them when remapping.

- `!0 = !{!1}` is metadata's version of a constant. Programatically it's
  called "uniqued" (probably a better term would be "constant") because,
  like `ConstantArray`, it's stored in uniquing tables. Once it's
  constructed, it's illegal to change its arguments.
- `!0 = distinct !{!1}` is a bit closer to a global variable. It's legal
  to change the operands after construction.

What should be done with distinct metadata when cloning functions within
the same module?

- Should new, cloned nodes be created?
- Should all references point to the same, old nodes?

The answer depends on whether that metadata is effectively owned by a
function.

And that's the second problem. Referenceable metadata's ownership model
is not clear or explicit. Technically, it's all stored on an
LLVMContext. However, any metadata that is `distinct`, that transitively
references a `distinct` node, or that transitively references a
GlobalValue is specific to a Module and is effectively owned by it. More
specifically, some metadata is effectively owned by a specific Function
within a module.

Effectively function-local metadata was introduced somewhere around
c10d0e5ccd, which made it illegal for two
functions to share a DISubprogram attachment.

When cloning a function within a module, you need to clone the
function-local debug info and suppress cloning of global debug info (the
status quo suppresses cloning some global debug info but not all). When
cloning a function to a new/different module, you need to clone all of
the debug info.

Here's what I think we should do (eventually? soon? not this patch
though):
- Distinguish explicitly (somehow) between pure constant metadata owned
  by the LLVMContext, global metadata owned by the Module, and local
  metadata owned by a GlobalValue (such as a function).
- Update CloneFunctionInto to trigger cloning of all "local" metadata
  (only), perhaps by adding a bit to RemapFlag. Alternatively, split
  out a separate function CloneFunctionMetadataInto to prime the
  metadata map that callers are updated to call ahead of time as
  appropriate.

Here's the somewhat more isolated fix in this patch:
- Converted the `ModuleLevelChanges` parameter to `CloneFunctionInto` to
  an enum called `CloneFunctionChangeType` that is one of
  LocalChangesOnly, GlobalChanges, DifferentModule, and ClonedModule.
- The code maintaining the "functions uniquely own subprograms"
  invariant is now only active in the first two cases, where a function
  is being cloned within a single module. That's necessary because this
  code inhibits cloning of (some) "global" metadata that's effectively
  owned by the module.
- The code maintaining the "all compile units must be explicitly
  referenced by !llvm.dbg.cu" invariant is now only active in the
  DifferentModule case, where a function is being cloned into a new
  module in isolation.
- CoroSplit.cpp's call to CloneFunctionInto in CoroCloner::create
  uses LocalChangeOnly, since fa635d730f
  only set `ModuleLevelChanges` to trigger cloning of local metadata.
- CloneModule drops its unsound use of RF_ReuseAndMutateDistinctMDs
  and special handling of !llvm.dbg.cu.
- Fixed some outdated header docs and left a couple of FIXMEs.

Differential Revision: https://reviews.llvm.org/D96531
2021-02-15 11:56:00 -08:00
Duncan P. N. Exon Smith fa35c1f80f ValueMapper: Rename RF_MoveDistinctMDs => RF_ReuseAndMutateDistinctMDs, NFC
Rename the `RF_MoveDistinctMDs` flag passed into `MapValue` and
`MapMetadata` to `RF_ReuseAndMutateDistinctMDs` in order to more
precisely describe its effect and clarify the header documentation.

Found this while helping to investigate PR48841, which pointed out an
unsound use of the flag in `CloneModule()`. For now I've just added a
FIXME there, but I'm hopeful that the new (more precise) name will
prevent other similar errors.
2021-02-10 16:53:21 -08:00
Roman Lebedev 5fe0798dee
[Utils] LocalTest: fix SimplifyCFGWithNullAC test to work with `-simplifycfg-require-and-preserve-domtree=1` 2021-01-02 01:01:18 +03:00
Whitney Tsang 2a814cd9e1 Ensure SplitEdge to return the new block between the two given blocks
This PR implements the function splitBasicBlockBefore to address an
issue
that occurred during SplitEdge(BB, Succ, ...), inside splitBlockBefore.
The issue occurs in SplitEdge when the Succ has a single predecessor
and the edge between the BB and Succ is not critical. This produces
the result ‘BB->Succ->New’. The new function splitBasicBlockBefore
was added to splitBlockBefore to handle the issue and now produces
the correct result ‘BB->New->Succ’.

Below is an example of splitting the block bb1 at its first instruction.

/// Original IR
bb0:
	br bb1
bb1:
        %0 = mul i32 1, 2
	br bb2
bb2:
/// IR after splitEdge(bb0, bb1) using splitBasicBlock
bb0:
	br bb1
bb1:
	br bb1.split
bb1.split:
        %0 = mul i32 1, 2
	br bb2
bb2:
/// IR after splitEdge(bb0, bb1) using splitBasicBlockBefore
bb0:
	br bb1.split
bb1.split
	br bb1
bb1:
        %0 = mul i32 1, 2
	br bb2
bb2:

Differential Revision: https://reviews.llvm.org/D92200
2020-12-18 17:37:17 +00:00
Bangtian Liu 511cfe9441 Revert "Ensure SplitEdge to return the new block between the two given blocks"
This reverts commit d20e0c3444.
2020-12-17 21:00:37 +00:00
Bangtian Liu d20e0c3444 Ensure SplitEdge to return the new block between the two given blocks
This PR implements the function splitBasicBlockBefore to address an
issue
that occurred during SplitEdge(BB, Succ, ...), inside splitBlockBefore.
The issue occurs in SplitEdge when the Succ has a single predecessor
and the edge between the BB and Succ is not critical. This produces
the result ‘BB->Succ->New’. The new function splitBasicBlockBefore
was added to splitBlockBefore to handle the issue and now produces
the correct result ‘BB->New->Succ’.

Below is an example of splitting the block bb1 at its first instruction.

/// Original IR
bb0:
	br bb1
bb1:
        %0 = mul i32 1, 2
	br bb2
bb2:
/// IR after splitEdge(bb0, bb1) using splitBasicBlock
bb0:
	br bb1
bb1:
	br bb1.split
bb1.split:
        %0 = mul i32 1, 2
	br bb2
bb2:
/// IR after splitEdge(bb0, bb1) using splitBasicBlockBefore
bb0:
	br bb1.split
bb1.split
	br bb1
bb1:
        %0 = mul i32 1, 2
	br bb2
bb2:

Differential Revision: https://reviews.llvm.org/D92200
2020-12-17 16:00:15 +00:00