Currently if there's any memory access that AccessAnalysis couldn't
analyze then all of the runtime pointer check results are discarded.
This patch makes this able to be controlled with the AllowPartial
option, which makes it so we generate the runtime check information
for those pointers that we could analyze, as transformations may still
be able to make use of the partial information.
Of the transformations that use LoopAccessAnalysis, only
LoopVersioningLICM changes behaviour as a result of this change. This is
because the others either:
* Check canVectorizeMemory, which will return false when we have partial
pointer information as analyzeLoop() will return false.
* Examine the dependencies returned by getDepChecker(), which will be
empty as we exit analyzeLoop if we have partial pointer information
before calling areDepsSafe(), which is what fills in the dependency
information.
UpdateTestChecks has a make_analyzer_generalizer to replace pointer
addressess from the debug output of LAA with a pattern, which is an
acceptable solution when there is one RUN line. However, when there are
multiple RUN lines with a common pattern, UTC fails to recognize common
output due to mismatched pointer addresses. Instead of hacking UTC scrub
the output before comparing the outputs from the different RUN lines,
fix the issue once and for all by making LAA not output unstable pointer
addresses in the first place.
The removal of the now-dead make_analyzer_generalizer is left as a
non-trivial exercise for a follow-up.
getPtrStride returns 0 when the PtrScev is loop-invariant, and this is
not an erroneous value: it returns std::nullopt to communicate that it
was not able to find a valid pointer stride. In analyzeLoop, we call
getPtrStride with a value_or(0) conflating the zero return value with
std::nullopt. Fix this, handling loop-invariant loads correctly.
update_analyze_test_checks.py is an invaluable tool in updating tests.
Unfortunately, it only supports output from the CostModel,
ScalarEvolution, and LoopVectorize analyses. Many LoopAccessAnalysis
tests use hand-crafted CHECK lines, and it is moreover tedious to
generate these CHECK lines, as the output fom the analysis is not
stable, and requires the test-writer to hand-craft FileCheck matches.
Alleviate this pain, and support output from:
$ opt -passes='print<loop-accesses>'
This patch includes several non-trivial changes including:
- Preserving whitespace at the beginning of the line, so that the LAA
output can be properly indented.
- Regexes matching the unstable output, which is basically a pointer
address hex.
- Separating is_analyze from preserve_names clearly, as the former was
formerly used as an overload for the latter.
To demonstate the utility of this patch, several tests in
LoopAccessAnalysis have been auto-generated by
update_analyze_test_checks.py.
This updates the naming for the LAA printing pass to be in line with
most other analysis printing passes.
The old name has come up as confusing multiple times already, e.g. in
D131924.
Adds new optimization remarks when vectorization fails.
More specifically, new remarks are added for following 4 cases:
- Backward dependency
- Backward dependency that prevents Store-to-load forwarding
- Forward dependency that prevents Store-to-load forwarding
- Unknown dependency
It is important to note that only one of the sources
of failures (to vectorize) is reported by the remarks.
This source of failure may not be first in program order.
A regression test has been added to test the following cases:
a) Loop can be vectorized: No optimization remark is emitted
b) Loop can not be vectorized: In this case an optimization
remark will be emitted for one source of failure.
Reviewed By: sdesmalen, david-arm
Differential Revision: https://reviews.llvm.org/D108371
SCEV does not look through non-header PHIs inside the loop. Such phis
can be analyzed by adding separate accesses for each incoming pointer
value.
This results in 2 more loops vectorized in SPEC2000/186.crafty and
avoids regressions when sinking instructions before vectorizing.
Fixes PR50296, PR50288.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D102266
Only tests in llvm/test/Analysis.
-analyze is legacy PM-specific.
This only touches files with `-passes`.
I looked through everything and made sure that everything had a new PM equivalent.
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D109040
This reverts commit 1ed7f8ede564c3b11da4fdca30c36ccbff422576.
This change can cause loop-distribute to crash in some cases. Revert
until I have more time to wrap up a fix.
See PR50296, PR5028 and D102266.
SCEV does not look through non-header PHIs inside the loop. Such phis
can be analyzed by adding separate accesses for each incoming pointer
value.
This results in 2 more loops vectorized in SPEC2000/186.crafty and
avoids regressions when sinking instructions before vectorizing.
Reviewed By: Meinersbur
Differential Revision: https://reviews.llvm.org/D101286
