Replace pattern-matching with existing SCEV and Loop APIs as a more
robust way of identifying the loop increment and trip count. Also
rename 'Limit' as 'TripCount' to be consistent with terminology.
Differential Revision: https://reviews.llvm.org/D106580
Make getLatchCmpInst non-static and use it in LoopFlatten as a more
robust way of identifying the compare.
Differential Revision: https://reviews.llvm.org/D106256
Replace code which identifies induction phi with helper function
getInductionVariable to improve robustness.
Differential Revision: https://reviews.llvm.org/D106045
This patch changes LoopFlattenPass from FunctionPass to LoopNestPass.
Utilize LoopNest and let function 'Flatten' generate information from it.
Reviewed By: Whitney
Differential Revision: https://reviews.llvm.org/D102904
This patch changes LoopFlattenPass from FunctionPass to LoopNestPass.
Utilize LoopNest and let function 'Flatten' generate information from it.
Reviewed By: Whitney
Differential Revision: https://reviews.llvm.org/D102904
This patch changes LoopFlattenPass from FunctionPass to LoopNestPass.
Utilize LoopNest and let function 'Flatten' generate information from it.
Reviewed By: Whitney
Differential Revision: https://reviews.llvm.org/D102904
The loop flattening pass requires loops to be in simplified form. If the
loops are not in simplified form, the pass cannot operate. This patch
simplifies all loops before flattening. As a result, all loops will be
simplified regardless of whether anything ends up being flattened.
This change was inspired by observing a certain loop that was not flatten
because the loops were not in simplified form. This loop is added as a
test to verify that it is now flattened.
Differential Revision: https://reviews.llvm.org/D102249
Change-Id: I45bcabe70fb99b0d89f0effafc82eb9e0585ec30
Removes CFGAnalyses from the preserved analyses set
returned by LoopFlattenPass::run().
Reviewed By: Dave Green, Ta-Wei Tu
Differential Revision: https://reviews.llvm.org/D99700
The `InductionPHI` is not necessarily the increment instruction, as
demonstrated in pr49571.ll.
This patch removes the assertion and instead bails out from the
`LoopFlatten` pass if that happens.
This fixes https://bugs.llvm.org/show_bug.cgi?id=49571
Reviewed By: SjoerdMeijer
Differential Revision: https://reviews.llvm.org/D99252
I disabled the widening in fa5cb4b because it run in an assert, which was
related to replacing values with different types. I forgot that an extend could
also be a zero-extend, which I have added now. This means that the approach now
is to create and insert a trunc value of the outerloop for each user, and use
that to replace IV values.
Differential Revision: https://reviews.llvm.org/D91690
Widen the IV to the widest available and legal integer type, which makes this
transformations always safe so that we can skip overflow checks.
Motivation is to let this pass trigger on 64-bit targets too, and this is the
last patch in a serie to achieve this: D90402 moves pass LoopFlatten to just
before IndVarSimplify so that IVs are not already widened, D90421 factors out
widening from IndVarSimplify into Utils/SimplifyIndVar so that we can also use
it in LoopFlatten.
Differential Revision: https://reviews.llvm.org/D90640
This converts LoopFlatten from a LoopPass to a FunctionPass so that we don't
run into problems of a loop pass deleting a (inner)loop.
Differential Revision: https://reviews.llvm.org/D90940
Introduce struct FlattenInfo to group some of the bookkeeping. Besides this
being a bit of a clean-up, it is a prep step for next additions (D90640). I
could take things a bit further, but thought this was a good first step also
not to make this change too large.
Differential Revision: https://reviews.llvm.org/D90408
This is a simple pass that flattens nested loops. The intention is to optimise
loop nests like this, which together access an array linearly:
for (int i = 0; i < N; ++i)
for (int j = 0; j < M; ++j)
f(A[i*M+j]);
into one loop:
for (int i = 0; i < (N*M); ++i)
f(A[i]);
It can also flatten loops where the induction variables are not used in the
loop. This can help with codesize and runtime, especially on simple cpus
without advanced branch prediction.
This is only worth flattening if the induction variables are only used in an
expression like i*M+j. If they had any other uses, we would have to insert a
div/mod to reconstruct the original values, so this wouldn't be profitable.
This partially fixes PR40581 as this pass triggers on one of the two cases. I
will follow up on this to learn LoopFlatten a few more (small) tricks. Please
note that LoopFlatten is not yet enabled by default.
Patch by Oliver Stannard, with minor tweaks from Dave Green and myself.
Differential Revision: https://reviews.llvm.org/D42365
