When forgetting multiple SCEVs, rather than doing this one by one, we can
instead use mass updates. We plan to make them more efficient than they
are now, potentially improving compile time.
Differential Revision: https://reviews.llvm.org/D111602
Reviewed By: reames
This patch changes signature of forgetMemoizedResults to be able to work with
multiple SCEVs. Usage will come in follow-ups. We also plan to optimize it in the
future to work faster than individual invalidation updates. Should not change
behavior in any sense.
Split-off from D111602.
Differential Revision: https://reviews.llvm.org/D112293
Reviewed By: reames
This removes duplication and makes nesting more clear.
It also reduces the amount of changes necessary for exposing future options.
Differential revision: https://reviews.llvm.org/D112344
Follow-up from D112295, suggested by Nikita: we can avoid tracking
users of SCEVConstants because dropping their cached info is unlikely
to give any new prospects for fact inference, and it should not introduce
any correctness problems.
This patch introduces API that keeps track of SCEVs users of
another SCEVs, required to handle invalidations of users along
with operands that comes in follow-up patches.
Differential Revision: https://reviews.llvm.org/D112295
Reviewed By: reames
This allows to clear an OpPassManager and populated it again with a new
pipeline, while preserving all the other options (including instrumentations).
Differential Revision: https://reviews.llvm.org/D112393
Add a new preparation pattern in PPCLoopInstFormPrep pass to reduce register
pressure.
Reviewed By: jsji
Differential Revision: https://reviews.llvm.org/D108750
GNU ld doesn't support `--no-pic-executable`.
`-p` has been removed from likely the only use case (Linux kernel) for over 2.5 years: https://git.kernel.org/linus/091bb549f7722723b284f63ac665e2aedcf9dec9
`--no-add-needed` was the pre-binutils-2.23 spelling for `--no-copy-dt-needed-entries`.
The legacy alias is irrelevant in 2021.
This extends `optimizeCompareInstr` to continue the backwards search
when it reached the beginning of a basic block. If there is a single
predecessor block then we can just continue the search in that block and
mark the EFLAGS register as live-in.
Differential Revision: https://reviews.llvm.org/D110862
This changes the first part of `optimizeCompareInstr` being split into a
loop with a forward scan for cases that re-use zero flags from a
producer in case of compare with zero and a backward scan for finding an
instruction equivalent to a compare.
The code now uses a single backward scan searching for the next
instructions that reads or writes EFLAGS.
Also:
- Add comments giving examples for the 3 cases handled.
- Check `MI` which contains the result of the zero-compare cases,
instead of re-checking `IsCmpZero`.
- Tweak coding style in some loops.
- Add new MIR based tests that test the optimization in isolation.
This also removes a check for flag readers in situations like this:
```
= SUB32rr %0, %1, implicit-def $eflags
... we no longer stop when there are $eflag users here
CMP32rr %0, %1 ; will be removed
...
```
Differential Revision: https://reviews.llvm.org/D110857
The LangRef clearly states that branching on a undef or poison value is immediate undefined behavior, but historically, we have not been consistent about implementing that interpretation in the optimizer. Historically, we used (in some cases) a more relaxed model which essentially looked for provable UB along both paths which was control dependent on the condition. However, we've never been 100% consistent here. For instance SCEV uses the strong model for increments which form AddRecs (and only addrecs).
At the moment, the last big blocker for finally making this switch is enabling the fix landed in D106041. Loop unswitching (in it's classic form) is incorrect as it creates many "branch on poisons" when unswitching conditions originally unreachable within the loop.
This change adds a flag to value tracking which allows to easily test the optimization potential of treating branch on poison as immediate UB. It's intended to help ease work on getting us finally through this transition and avoid multiple independent rediscovers of the same issues.
Differential Revision: https://reviews.llvm.org/D112026
Fixes a crash observed by oss-fuzz in 39934. Issue at hand is that code expects a pattern match on m_Mul to imply the operand is a mul instruction, however mul constexprs are also valid here.
This is msan/dfsan data which does not need waste cache
of other sanitizers.
Depends on D111614.
Differential Revision: https://reviews.llvm.org/D111615
This patch fixes a bug in implementation `mergeSymbolIds` where symbol
identifiers were not unique after merging them. Asserts for checking uniqueness
before and after the merge are also added. The asserts checking uniqueness
after the merge fail without the fix on existing test cases.
Reviewed By: arjunp
Differential Revision: https://reviews.llvm.org/D111958
As this API is now internally offset-based, we can accept a starting
offset and remove the need to create a temporary bitcast+gep
sequence to perform an offset load. The API now mirrors the
ConstantFoldLoadFromConst() API.
The test was removed temporarily in a539a847c9 to aid switching the RPC API in use in the LLJITWithRemoteDebugging example.
Reviewed By: lhames
Differential Revision: https://reviews.llvm.org/D110649
The functionality of this method is already covered by
computeExitCountExhaustively() in a more general fashion. It was
added at a time when exhaustive exit count calculation did not
support constant folding loads yet. I double checked that dropping
this code causes no binary changes in test-suite.
Differential Revision: https://reviews.llvm.org/D112343
This removes duplication and makes nesting more clear.
It also reduces the amount of changes necessary for exposing future options.
Differential revision: https://reviews.llvm.org/D112344
This patch adds a polynomial approximation that matches the
approximation in Eigen.
Note that the approximation only applies to vectorized inputs;
the scalar rsqrt is left unmodified.
The approximation is protected with a flag since it emits an AVX2
intrinsic (generated via the X86Vector). This is the only reasonably
clean way that I could find to generate the exact approximation that
I wanted (i.e. an identical one to Eigen's).
I considered two alternatives:
1. Introduce a Rsqrt intrinsic in LLVM, which doesn't exist yet.
I believe this is because there is no definition of Rsqrt that
all backends could agree on, since hardware instructions that
implement it have widely varying degrees of precision.
This is something that the standard could mandate, but Rsqrt is
not part of IEEE754, so I don't think this option is feasible.
2. Emit fdiv(1.0, sqrt) with fast math flags to allow reciprocal
transformations. Although portable, this doesn't allow us
to generate exactly the code we want; it is the LLVM backend,
and not MLIR, who controls what code is generated based on the
target CPU.
Reviewed By: ezhulenev
Differential Revision: https://reviews.llvm.org/D112192
The `clang` target used in the line below is only generated with `LLVM_ENABLE_PROJECTS=clang`.
Without this change, running `ninja clang` will fail with:
```
ninja: error: unknown target 'clang', did you mean 'clean'?
```
Reviewed By: xgupta
Differential Revision: https://reviews.llvm.org/D112257
Max Kazantsev