If `Mask` and `Amt` are not constants and `binop1` and `binop2` are
the same we can transform to:
`(binop (lshift (binop X, Y), Amt), Mask)`
If `binop` is `add`, `lshift` must be `shl`.
If `Mask` and `Amt` are constants `C` and `C1` respectively.
We can transform to:
`(lshift1 (binop1 (binop2 X, (inv_lshift1 C, C1), Y)), C1)`
Saving an instruction IFF:
`lshift1` is same opcode as `lshift2`
Either `bitwise1` and/or `bitwise2` is `and`.
Proofs(1/2): https://alive2.llvm.org/ce/z/BjN-m_
Proofs(2/2): https://alive2.llvm.org/ce/z/bZn5QB
This is to help fix the regression caused in D151807
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D152568
The last use was removed by:
commit 934c82d31801e65aa3bbe99a0e64f903621c2e04
Author: Florian Hahn <flo@fhahn.com>
Date: Fri Feb 24 13:39:32 2023 +0100
Once I remove createInstructionCombiningPass, then:
InstructionCombiningPass::InstructionCombiningPass(unsigned MaxIterations)
becomes unused. Once I remove that:
InstructionCombiningPass::MaxIterations is always initialized with
InstCombineDefaultMaxIterations, so this patch does the constant
propagation and removes InstructionCombiningPass::MaxIterations as
well.
Differential Revision: https://reviews.llvm.org/D152641
We try to fold constant computeKnownBits() with context for return
instructions only. Otherwise, we rely on SimplifyDemandedBits() to
fold instructions with constant known bits.
The presence of this special fold for returns is dangerous, because
it makes our tests lie about what works and what doesn't. Tests are
usually written by returning the result we're interested in, but
will go through this separate code path that is not used for anything
else. This patch removes the special fold.
This primarily regresses patterns of the style "assume(x); return x".
The responsibility of handling such patterns lies with passes like
EarlyCSE/GVN anyway, which will do this reliably, and not just for
returns.
Differential Revision: https://reviews.llvm.org/D151099
We already do this during initial worklist population. Doing this
as part of primary combining allows us to remove instructions in
blocks that were rendered dead by condition folding within the
same instcombine iteration.
If the branch condition is undef, then behavior is undefined and
neither of the successors are live.
This is to ensure that optimization quality does not decrease
when a constant gets replaced with undef/poison in this context.
When sinking and users are dropped, add the using instructions
to the worklist, as they can likely be removed as well.
This should be NFC apart from worklist order effects.
This patch-set aims to simplify the existing RVV segment load/store
intrinsics to use a type that represents a tuple of vectors instead.
To achieve this, first we need to relax the current limitation for an
aggregate type to be a target of load/store/alloca when the aggregate
type contains homogeneous scalable vector types. Then to adjust the
prolog of an LLVM function during lowering to clang. Finally we
re-define the RVV segment load/store intrinsics to use the tuple types.
The pull request under the RVV intrinsic specification is
riscv-non-isa/rvv-intrinsic-doc#198
---
This is the 1st patch of the patch-set. This patch is originated from
D98169.
This patch allows aggregate type (StructType) that contains homogeneous
scalable vector types to be a target of load/store/alloca. The RFC of
this patch was posted in LLVM Discourse.
https://discourse.llvm.org/t/rfc-ir-permit-load-store-alloca-for-struct-of-the-same-scalable-vector-type/69527
The main changes in this patch are:
Extend `StructLayout::StructSize` from `uint64_t` to `TypeSize` to
accommodate an expression of scalable size.
Allow `StructType:isSized` to also return true for homogeneous
scalable vector types.
Let `Type::isScalableTy` return true when `Type` is `StructType`
and contains scalable vectors
Extra description is added in the LLVM Language Reference Manual on the
relaxation of this patch.
Authored-by: Hsiangkai Wang <kai.wang@sifive.com>
Co-Authored-by: eop Chen <eop.chen@sifive.com>
Reviewed By: craig.topper, nikic
Differential Revision: https://reviews.llvm.org/D146872
The bitcast was not being added to the worklist. I could switch
this to use the IRBuilder instead, but this bitcast is not relevant
with opaque pointers anyway, so just drop it entirely.
The last use of Descale was removed on Apr 6, 2023 in commit
db6b30b1831095c216378a9df215b7c0ae6b959f.
Differential Revision: https://reviews.llvm.org/D150045
D146349 Introduced the ability to use the information from the
`select` condition to deduce constants as we folded a binop into
select. I.e if the `select` cond was `icmp eq %A, 10`, then in the
true-arm of `select`, we would be able to replace usage of `A` with
`10`.
This is broken for vectors that contain `undef` elements. I.e with
`icmp eq %A, <10, undef>`, subsituting `<10, undef>` for `A` can
result in creating a more undefined result than we otherwise would
have.
We fix the issue with simply checking if the candidate constant for
substituting may contain `undef` elements and don't do it in that
case.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D149592
This patch reverts rGae739aefd7473517d3f08b5c8d08a66c7f469198 to address performance regressions reported by our [CI](https://github.com/dtcxzyw/llvm-ci/issues/137) after rG2ec1d0f427c7822540352c0c14d057e7bfe4f77b.
For example:
```
define ptr @const_gep_chain(ptr %p, i64 %a) {
%p1 = getelementptr inbounds i8, ptr %p, i64 %a
%p2 = getelementptr inbounds i8, ptr %p1, i64 1
%p3 = getelementptr inbounds i8, ptr %p2, i64 2
%p4 = getelementptr inbounds i8, ptr %p3, i64 3
ret ptr %p4
}
```
The last three GEPs will not be folded since rG2ec1d0f427c7822540352c0c14d057e7bfe4f77b.
I think it is appropriate to remove this code because there is no compile-time regression reported in our benchmarks.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D149240
Following the change in shufflevector semantics,
poison will be used to represent undefined elements in shufflevector masks.
Differential Revision: https://reviews.llvm.org/D149256
Since D146813, LICM will reassociate GEPs to expose hoisting
opportunities itself. Don't perform this transform in InstCombine,
where it is fragile because it depends on an optional LoopInfo
analysis.
Make the fold use the information present in the condition for deducing constants i.e:
```
%c = icmp eq i8 %x, 10
%s = select i1 %c, i8 3, i8 2
%r = mul i8 %x, %s
```
If we fold the `mul` into the select, on the true side we insert `10` for `%x` in the `mul`.
Reviewed By: nikic
Differential Revision: https://reviews.llvm.org/D146349
Remove C APIs for interacting with PassRegistry and pass
initialization. These are legacy PM concepts, and are no longer
relevant for the new pass manager.
Calls to these initialization functions can simply be dropped.
Differential Revision: https://reviews.llvm.org/D145043
No need to include CallGraphSCCPass.h from the IPO/Inliner.
Also removed the include of LegacyPassManager.h in a couple of files
that do not really depend on that header file.
Differential Revision: https://reviews.llvm.org/D148083
- As the address space cast may not be valid on a specific target,
`addrspacecast` is not handled when an `alloca` is able to be replaced
with the source of memcpy/memmove. This patch addresses that by
querying a target hook on whether that address space cast is valid.
For example, on most GPU targets, the cast from a global pointer to a
generic pointer is valid.
- If that cast is allowedd (by querying `isValidAddrSpaceCast`), the
replacement is enhanced to handle that `addrspacecast` as well.
Reviewed By: yaxunl
Differential Revision: https://reviews.llvm.org/D147025
Move this handling to a centralized place and extend it to handle
saturating add/sub intrinsics.
I originally wanted to make this fully generic rather than
whitelist based, because this is legal and likely profitable for all
speculatable intrinsics. The caveat is that for vector selects,
the intrinsic can't perform cross-lane operations like a shuffle
or reduction, which we don't really expose as a generic property
right now. So for now I'm just extending the list.
Now that we canonicalize to min/max intrinsics, we no longer need
to guard against this here.
In fact, it seems like the issue from PR46271 was the final push
for introducing the intrinsics in the first place...
Combine binary operator of two phi node if there is at least one
specific constant value in phi0 and phi1's incoming values for each
same incoming block and this specific constant value can be used
to do optimization for specific binary operator.
For example:
```
%phi0 = phi i32 [0, %bb0], [%i, %bb1]
%phi1 = phi i32 [%j, %bb0], [0, %bb1]
%add = add i32 %phi0, %phi1
==>
%add = phi i32 [%j, %bb0], [%i, %bb1]
```
Fixes: https://github.com/llvm/llvm-project/issues/61137
Differential Revision: https://reviews.llvm.org/D145223
This is the follow-up to D144199 and suggestion from D144045.
We make use of loop info explicit via InstCombine pass parameter
rather than semi-arbitrary via caching.
The only InstCombine transform that uses LoopInfo currently is a
GEP fold in visitGEPOfGEP(), so that shows up as a failure in the
dedicated test for the fold as well as several LoopVectorizer tests
that run extra passes.
I don't see any pass manager regression tests that actually check
for pass options, but this is intended to be NFC for the pass
pipeline behavior - we only try to use loop info where it would
have been used before via caching .
Differential Revision: https://reviews.llvm.org/D144274
Legacy passes are only supported for codegen, and I don't believe
it's possible to write backends using the C API, so we should drop
all of those. Reduces the number of places that need to be modified
when removing legacy passes.
Differential Revision: https://reviews.llvm.org/D144970
The reported compile-time regression has been address in
47f9109dff80a1abbe2705ee71dc0882b1d62274.
Additionally, this contains a change to immediately fold zext
with constant operand, even if it's used in a trunc. I'm not sure
if this is relevant for anything, but I noticed it as a behavioral
discrepancy when investigating this issue.
-----
InstCombine currently performs a constant folding attempt as part
of the main InstCombine loop, before visiting the instruction.
However, each visit method will also attempt to simplify the
instruction, which will in turn constant fold it. (Additionally,
we also constant fold instructions before the main InstCombine loop
and use a constant folding IR builder, so this is doubly redundant.)
There is one place where InstCombine visit methods currently don't
call into simplification, and that's casts. To be conservative,
I've added an explicit constant folding call there (though it has
no impact on tests).
This makes for a mild compile-time improvement and in particular
mitigates the compile-time regression from enabling load
simplification in be88b5814d9efce131dbc0c8e288907e2e6c89be.
Differential Revision: https://reviews.llvm.org/D144369
Increase compile time with ubsan ARM from 3 to 14 min single file.
I upload reproducer into D144369.
Also we have random timeouts on internal x86_64 builds.
Both bisected to this one.
This reverts commit 45a0b812fa13ec255cae91f974540a4d805a8d79.
Enabling assignment tracking without this patch, a significant amount of
additional compiler run time comes from the RemoveRedundantDbgInstrs call in
InstCombine. This patch reduces compiler run time by choosing better places to
call RemoveRedundantDbgInstrs.
In non-assignment-tracking builds, RemoveRedundantDbgInstrs is called by
InstCombine if LowerDbgDeclare makes a change (i.e. it is _sometimes_
called). In assignment tracking builds LowerDbgDeclare doesn't do anything. We
still need to clean up redundant intrinsics to avoid a large performance hit
due to the number of instructions, so the current approach is to have
InstCombine _always_ call RemoveRedundantDbgInstrs.
Instrumenting the compiler to run RemoveRedundantDbgInstrs after every pass and
dump the numbers and building CTMark/tramp3d-v4 indicates that SROA and
LoopVectorize give us a bigger bang (number removed) for buck (times pass is
run).
The compile time tracker reports that this patch reduces the number of
instructions retired building CTMark projects by an average of 1.1%.
Reviewed By: scott.linder
Differential Revision: https://reviews.llvm.org/D144483
With this patch freeze undef/poison will no longer be folded into a constant if it's used as a
vector operand in a shufflevector.
Differential Revision: https://reviews.llvm.org/D143593
InstCombine currently performs a constant folding attempt as part
of the main InstCombine loop, before visiting the instruction.
However, each visit method will also attempt to simplify the
instruction, which will in turn constant fold it. (Additionally,
we also constant fold instructions before the main InstCombine loop
and use a constant folding IR builder, so this is doubly redundant.)
There is one place where InstCombine visit methods currently don't
call into simplification, and that's casts. To be conservative,
I've added an explicit constant folding call there (though it has
no impact on tests).
This makes for a mild compile-time improvement and in particular
mitigates the compile-time regression from enabling load
simplification in be88b5814d9efce131dbc0c8e288907e2e6c89be.
Differential Revision: https://reviews.llvm.org/D144369
This is a cleanup/modernization patch requested in D144045 to make loop
analysis a proper optional parameter to the pass rather than a
semi-arbitrary value inherited via the pass pipeline.
It's a bit more complicated than the recent patch I started copying from
(D143980) because InstCombine already has an option for MaxIterations
(added with D71145).
I debated just deleting that option, but it was used by a pair of existing
tests, so I put it into a struct (code largely copied from SimplifyCFG's
implementation) to make the code more flexible for future options
enhancements.
I didn't alter the pass manager invocations of InstCombine in this patch
because the patch was already getting big, but that will be a small
follow-up as noted with the TODO comment.
Differential Revision: https://reviews.llvm.org/D144199
Computing EH-related information was only relevant for analysis passes so far. Lifting it to IR will allow the IR Verifier to calculate EH funclet coloring and validate funclet operand bundles in a follow-up step.
Reviewed By: rnk, compnerd
Differential Revision: https://reviews.llvm.org/D138122
Remove LLVM flag -experimental-assignment-tracking. Assignment tracking is
still enabled from Clang with the command line -Xclang
-fexperimental-assignment-tracking which tells Clang to ask LLVM to run the
pass declare-to-assign. That pass converts conventional debug intrinsics to
assignment tracking metadata. With this patch it now also sets a module flag
debug-info-assignment-tracking with the value `i1 true` (using the flag conflict
rule `Max` since enabling assignment tracking on IR that contains only
conventional debug intrinsics should cause no issues).
Update the docs and tests too.
Reviewed By: CarlosAlbertoEnciso
Differential Revision: https://reviews.llvm.org/D142027
In canCreateUndefOrPoison(), take not only poison-generating flags,
but also poison-generating metadata into account. The helpers are
written generically, but I believe the only case that can actually
matter is !range on calls -- !nonnull and !align are only valid on
loads, and those can create undef/poison anyway.
Unfortunately, this negatively impacts logical to bitwise and/or
conversion: For ctpop/ctlz/cttz we always attach !range metadata,
which will now block the transform, because it might introduce
poison. It would be possible to recover this regression by supporting
a ConsiderFlagsAndMetadata=false mode in impliesPoison() and clearing
flags/metadata on visited instructions.
Fixes https://github.com/llvm/llvm-project/issues/59888.
Differential Revision: https://reviews.llvm.org/D142115
Use deduction guides instead of helper functions.
The only non-automatic changes have been:
1. ArrayRef(some_uint8_pointer, 0) needs to be changed into ArrayRef(some_uint8_pointer, (size_t)0) to avoid an ambiguous call with ArrayRef((uint8_t*), (uint8_t*))
2. CVSymbol sym(makeArrayRef(symStorage)); needed to be rewritten as CVSymbol sym{ArrayRef(symStorage)}; otherwise the compiler is confused and thinks we have a (bad) function prototype. There was a few similar situation across the codebase.
3. ADL doesn't seem to work the same for deduction-guides and functions, so at some point the llvm namespace must be explicitly stated.
4. The "reference mode" of makeArrayRef(ArrayRef<T> &) that acts as no-op is not supported (a constructor cannot achieve that).
Per reviewers' comment, some useless makeArrayRef have been removed in the process.
This is a follow-up to https://reviews.llvm.org/D140896 that introduced
the deduction guides.
Differential Revision: https://reviews.llvm.org/D140955
This mirrors a similar shufflevector transformation so the same
effect is obtained for scalable vectors. The transformation is
only performed when it can be proven the number of resulting
reversals is not increased. By bubbling the reversals from operand
to result this should typically be the case and ideally leads to
back-back shuffles that can be elimitated entirely.
Differential Revision: https://reviews.llvm.org/D139342
The important bit here is that we gracefully handle other uses,
iff they can be adapted to inversion.
I'll note, the previous logic was actively bad,
it increased instruction count since it didn't actually ensure
that the inversions happened.
