This patch implements the enhancement proposed by
https://github.com/llvm/llvm-project/issues/59312.
Suppose we have following code
v0 = load %addr
br %LoadBB
LoadBB:
v1 = load %addr
...
PredBB:
...
br %cond, label %LoadBB, label %SuccBB
SuccBB:
v2 = load %addr
...
Instruction v1 in LoadBB is partially redundant, edge (PredBB, LoadBB) is a
critical edge. SuccBB is another successor of PredBB, it contains another load
v2 which is identical to v1. Current GVN splits the critical edge
(PredBB, LoadBB) and inserts a new load in it. A better method is move the load
of v2 into PredBB, then v1 can be changed to a PHI instruction.
If there are two or more similar predecessors, like the test case in the bug
entry, current GVN simply gives up because otherwise it needs to split multiple
critical edges. But we can move all loads in successor blocks into predecessors.
Differential Revision: https://reviews.llvm.org/D141712
Comparison between two AliasResults implicitly decayed to comparison
of AliasResult::Kind. As a result, MergeAliasResults() ended up
considering two PartialAlias results with different offsets as
equivalent.
Fix this by adding an operator== implementation. To stay
compatible with extensive use of comparisons between AliasResult
and AliasResult::Kind, add an overload for that as well, which
will ignore the offset. In the future, it would probably be a
good idea to remove these implicit decays to AliasResult::Kind
and add dedicated methods to check for specific AliasResult kinds.
Fixes https://github.com/llvm/llvm-project/issues/63019.
Note that this is very conservative since it will not even combine
convergent calls that appear in the same basic block, but EarlyCSE will
handle that case.
Differential Revision: https://reviews.llvm.org/D150974
This patch implements the enhancement proposed by
https://github.com/llvm/llvm-project/issues/59312.
Suppose we have following code
v0 = load %addr
br %LoadBB
LoadBB:
v1 = load %addr
...
PredBB:
...
br %cond, label %LoadBB, label %SuccBB
SuccBB:
v2 = load %addr
...
Instruction v1 in LoadBB is partially redundant, edge (PredBB, LoadBB) is a
critical edge. SuccBB is another successor of PredBB, it contains another load
v2 which is identical to v1. Current GVN splits the critical edge
(PredBB, LoadBB) and inserts a new load in it. A better method is move the load
of v2 into PredBB, then v1 can be changed to a PHI instruction.
If there are two or more similar predecessors, like the test case in the bug
entry, current GVN simply gives up because otherwise it needs to split multiple
critical edges. But we can move all loads in successor blocks into predecessors.
Differential Revision: https://reviews.llvm.org/D141712
Make MaterializeAdjustedValue() responsible for adjusting load
metadata in all cases, so it also covers the non-local case.
In conjunction with that, we no longer need to call
patchReplacementInstruction() for the local case, which would
unnecessarily drop metadata if the replacement value just happened
to be a load (without actual load CSE).
When reusing a load in a way that requires coercion (i.e. casts or
bit extraction) we currently fail to adjust metadata. Unfortunately,
none of our existing tooling for this is really suitable, because
combineMetadataForCSE() expects both loads to have the same type.
In this case we may work on loads of different types and possibly
offset memory location.
As such, what this patch does is to simply drop all metadata, with
the following exceptions:
* Metadata for which violation is known to always cause UB.
* If the load is !noundef, keep all metadata, as this will turn
poison-generating metadata into UB as well.
This fixes the miscompile that was exposed by D146629.
Differential Revision: https://reviews.llvm.org/D148129
I believe !dereferencable violation is immediate undefined behavior,
but this was not explicitly spelled out in LangRef. We already
assume that !dereferenceable is implicitly !noundef and cannot
return poison in isGuaranteedNotToBeUndefOrPoison().
The reason why we made dereferenceable implicitly noundef is that
the purpose of this metadata is to allow speculation, and that
would not be legal on a potential poison pointer.
Differential Revision: https://reviews.llvm.org/D148202
Per LangRef:
> If a load instruction tagged with the !invariant.load metadata
> is executed, the memory location referenced by the load has to
> contain the same value at all points in the program where the
> memory location is dereferenceable; otherwise, the behavior is
> undefined.
As invariant.load violation is immediate undefined behavior, it
is sufficient for it to be present on the dominating load (for
the case where K does not move).
Since D141386 has changed the return value of !range from IUB to poison,
metadata !range shouldn't be preserved even if K dominates J.
If this patch was accepted, I plan to adjust metadata !nonnull as well.
BTW, I found that metadata !noundef is not handled in combineMetadata,
is this intentional?
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D142687
Process cases when phi incoming in predecessor block has select
instruction, and this select address is unavailable, but there
are addresses translated from both sides of select instruction.
Differential Revision: https://reviews.llvm.org/D142705
SimplifyCFG currently drops !nontemporal metadata when sinking
common instructions. With this change, SimplifyCFG and similar
transforms will preserve !nontemporal metadata as long as it is
set on both original instructions.
Differential Revision: https://reviews.llvm.org/D144298
Handle !noundef metadata in comhineMetadata. The behavior of violating
!noundef metadata is undefined behavior. So if K dominates J, we can
preserve it uncontionally, otherwise, we preserve it if both K and J
have !noundef metadata been set.
This patch also makes !noundef metadata added in KnownIDs when doing
instruction combine for phi node or global value numbering for loads.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D142801
Don't count debug instructions when limit the number of checked instructions.
Otherwise the debug information may impact optimization like the test case
shows.
Differential Revision: https://reviews.llvm.org/D142787
This patch implements the enhancement proposed by
https://github.com/llvm/llvm-project/issues/59312.
Suppose we have following code
v0 = load %addr
br %LoadBB
LoadBB:
v1 = load %addr
...
PredBB:
...
br %cond, label %LoadBB, label %SuccBB
SuccBB:
v2 = load %addr
...
Instruction v1 in LoadBB is partially redundant, edge (PredBB, LoadBB) is a
critical edge. SuccBB is another successor of PredBB, it contains another load
v2 which is identical to v1. Current GVN splits the critical edge
(PredBB, LoadBB) and inserts a new load in it. A better method is move the load
of v2 into PredBB, then v1 can be changed to a PHI instruction.
If there are two or more similar predecessors, like the test case in the bug
entry, current GVN simply gives up because otherwise it needs to split multiple
critical edges. But we can move all loads in successor blocks into predecessors.
Differential Revision: https://reviews.llvm.org/D141712
Improve findDominatingLoad implementation:
1. Result is saved into gvn::AvailableValue struct
2. Search is done in extended BB (while there is a single predecessor or
limit is reached)
Differential Revision: https://reviews.llvm.org/D141680
IR is now always parsed in opaque pointer mode, unless
-opaque-pointers=0 is explicitly given. There is no automatic
detection of typed pointers anymore.
The -opaque-pointers=0 option is added to any remaining IR tests
that haven't been migrated yet.
Differential Revision: https://reviews.llvm.org/D141912
Add test cases when load is non-local for select dependency, but can be
found in extended BB (chain of blocks with single predecessor). Check
that type of found load is the same.
This patch extends Def memory dependency with support of select
instructions to consistently handle pointer-select conversion.
Differential Revision: https://reviews.llvm.org/D141619
This patch introduces new type of memory dependency - Select to
consistently handle it like Def/Clobber dependency.
Differential Revision: https://reviews.llvm.org/D141619
Intrinsics have historically been excluded from the call graph with an
exception of 3 special ones added at some point. This meant that passes
depending on the call graph needed to handle intrinsics explicitly as
the underlying assumption, namely that intrinsics can't call or modify
things, doesn't hold. We are slowly moving away from special handling of
intrinsics, or at least towards explicitly checking what intrinsics we
want to handle differently.
This patch:
- Includes most intrinsics in the call graph. Debug intrinsics are
still excluded.
- Removes the special handling of intrinsics in the GlobalsAA pass.
- Removes the `IntrinsicInst::isLeaf` method.
Properly
Fixes: https://github.com/llvm/llvm-project/issues/52706
See also:
https://discourse.llvm.org/t/intrinsics-are-not-special-stop-pretending-i-mean-it/67545
Differential Revision: https://reviews.llvm.org/D14119
This patch implements the enhancement proposed by
https://github.com/llvm/llvm-project/issues/59312.
Suppose we have following code
v0 = load %addr
br %LoadBB
LoadBB:
v1 = load %addr
...
PredBB:
...
br %cond, label %LoadBB, label %SuccBB
SuccBB:
v2 = load %addr
...
Instruction v1 in LoadBB is partially redundant, edge (PredBB, LoadBB) is a
critical edge. SuccBB is another successor of PredBB, it contains another load
v2 which is identical to v1. Current GVN splits the critical edge
(PredBB, LoadBB) and inserts a new load in it. A better method is move the load
of v2 into PredBB, then v1 can be changed to a PHI instruction.
If there are two or more similar predecessors, like the test case in the bug
entry, current GVN simply gives up because otherwise it needs to split multiple
critical edges. But we can move all loads in successor blocks into predecessors.
Differential Revision: https://reviews.llvm.org/D139582
This is a test case for D139582.
In this test case, %v4 and %v5 can be moved to predecessors, %v3 can be changed to a PHI instruction.
Differential Revision: https://reviews.llvm.org/D140234
Target-extension types represent types that need to be preserved through
optimization, but otherwise are not introspectable by target-independent
optimizations. This patch doesn't add any uses of these types by an existing
backend, it only provides basic infrastructure such that these types would work
correctly.
Reviewed By: nikic, barannikov88
Differential Revision: https://reviews.llvm.org/D135202
