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Revision tags: llvmorg-21-init, llvmorg-19.1.7, llvmorg-19.1.6, llvmorg-19.1.5, llvmorg-19.1.4, llvmorg-19.1.3, llvmorg-19.1.2, llvmorg-19.1.1
# e762d4da 19-Sep-2024 David Sherwood <david.sherwood@arm.com>

[LoopVectorize] Teach LoopVectorizationLegality about more early exits (#107004)

This patch is split off from PR #88385 and concerns only the code
related to the legality of vectorising early exit

[LoopVectorize] Teach LoopVectorizationLegality about more early exits (#107004)

This patch is split off from PR #88385 and concerns only the code
related to the legality of vectorising early exit loops. It is the first
step in adding support for vectorisation of a simple class of loops that
typically involves searching for something, i.e.

for (int i = 0; i < n; i++) {
if (p[i] == val)
return i;
}
return n;

or

for (int i = 0; i < n; i++) {
if (p1[i] != p2[i])
return i;
}
return n;

In this initial commit LoopVectorizationLegality will only consider
early exit loops legal for vectorising if they follow these criteria:

1. There are no stores in the loop.
2. The loop must have only one early exit like those shown in the above
example. I have referred to such exits as speculative early exits, to
distinguish from existing support for early exits where the
exit-not-taken count is known exactly at compile time.
3. The early exit block dominates the latch block.
4. The latch block must have an exact exit count.
5. There are no loads after the early exit block.
6. The loop must not contain reductions or recurrences. I don't see
anything fundamental blocking vectorisation of such loops, but I just
haven't done the work to support them yet.
7. We must be able to prove at compile-time that loops will not contain
faulting loads.

Tests have been added here:

Transforms/LoopVectorize/AArch64/simple_early_exit.ll

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Revision tags: llvmorg-19.1.0, llvmorg-19.1.0-rc4, llvmorg-19.1.0-rc3, llvmorg-19.1.0-rc2, llvmorg-19.1.0-rc1, llvmorg-20-init, llvmorg-18.1.8, llvmorg-18.1.7, llvmorg-18.1.6, llvmorg-18.1.5, llvmorg-18.1.4, llvmorg-18.1.3, llvmorg-18.1.2, llvmorg-18.1.1, llvmorg-18.1.0, llvmorg-18.1.0-rc4, llvmorg-18.1.0-rc3, llvmorg-18.1.0-rc2, llvmorg-18.1.0-rc1, llvmorg-19-init, llvmorg-17.0.6, llvmorg-17.0.5, llvmorg-17.0.4, llvmorg-17.0.3, llvmorg-17.0.2, llvmorg-17.0.1, llvmorg-17.0.0, llvmorg-17.0.0-rc4, llvmorg-17.0.0-rc3, llvmorg-17.0.0-rc2, llvmorg-17.0.0-rc1, llvmorg-18-init, llvmorg-16.0.6, llvmorg-16.0.5, llvmorg-16.0.4, llvmorg-16.0.3, llvmorg-16.0.2, llvmorg-16.0.1, llvmorg-16.0.0, llvmorg-16.0.0-rc4, llvmorg-16.0.0-rc3, llvmorg-16.0.0-rc2, llvmorg-16.0.0-rc1, llvmorg-17-init, llvmorg-15.0.7
# 7d757725 14-Dec-2022 Nikita Popov <npopov@redhat.com>

[LoopVectorize] Convert some tests to opaque pointers (NFC)


Revision tags: llvmorg-15.0.6, llvmorg-15.0.5, llvmorg-15.0.4, llvmorg-15.0.3, working, llvmorg-15.0.2, llvmorg-15.0.1, llvmorg-15.0.0, llvmorg-15.0.0-rc3, llvmorg-15.0.0-rc2, llvmorg-15.0.0-rc1, llvmorg-16-init, llvmorg-14.0.6, llvmorg-14.0.5, llvmorg-14.0.4, llvmorg-14.0.3
# 2e14900d 28-Apr-2022 Bjorn Pettersson <bjorn.a.pettersson@ericsson.com>

[test][NewPM] Use -passes=loop-vectorize instead of -loop-vectorize

Update a bunch of loop-vectorize regression tests to use the new PM
syntax (opt -passes=loop-vectorize) instead of the deprecated

[test][NewPM] Use -passes=loop-vectorize instead of -loop-vectorize

Update a bunch of loop-vectorize regression tests to use the new PM
syntax (opt -passes=loop-vectorize) instead of the deprecated legacy
PM syntax (opt -loop-vectorize).

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Revision tags: llvmorg-14.0.2, llvmorg-14.0.1, llvmorg-14.0.0, llvmorg-14.0.0-rc4, llvmorg-14.0.0-rc3, llvmorg-14.0.0-rc2, llvmorg-14.0.0-rc1, llvmorg-15-init, llvmorg-13.0.1, llvmorg-13.0.1-rc3, llvmorg-13.0.1-rc2, llvmorg-13.0.1-rc1, llvmorg-13.0.0, llvmorg-13.0.0-rc4, llvmorg-13.0.0-rc3, llvmorg-13.0.0-rc2, llvmorg-13.0.0-rc1, llvmorg-14-init
# 95346ba8 15-Jul-2021 Philip Reames <listmail@philipreames.com>

[LV] Enable vectorization of multiple exit loops w/computable exit counts

This change enables vectorization of multiple exit loops when the exit count is statically computable. That requirement - sh

[LV] Enable vectorization of multiple exit loops w/computable exit counts

This change enables vectorization of multiple exit loops when the exit count is statically computable. That requirement - shared with the rest of LV - in turn requires each exit to be analyzeable and to dominate the latch.

The majority of work to support this was done in a set of previous patches. In particular,, 72314466 avoids having multiple edges from the middle block to the exits, and 4b33b2387 which added support for non-latch single exit and multiple exits with a single exiting block. As a result, this change is basically just removing a bailout and adjusting some tests now that the prerequisite work is done and has stuck in tree for a bit.

Differential Revision: https://reviews.llvm.org/D105817

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Revision tags: llvmorg-12.0.1, llvmorg-12.0.1-rc4, llvmorg-12.0.1-rc3, llvmorg-12.0.1-rc2, llvmorg-12.0.1-rc1, llvmorg-12.0.0, llvmorg-12.0.0-rc5, llvmorg-12.0.0-rc4, llvmorg-12.0.0-rc3, llvmorg-12.0.0-rc2, llvmorg-11.1.0, llvmorg-11.1.0-rc3, llvmorg-12.0.0-rc1, llvmorg-13-init, llvmorg-11.1.0-rc2, llvmorg-11.1.0-rc1
# d9f306aa 30-Dec-2020 Florian Hahn <flo@fhahn.com>

[LV] Fix crash when generating remarks with multi-exit loops.

If DoExtraAnalysis is true (e.g. because remarks are enabled), we
continue with the analysis rather than exiting. Update code to
conditi

[LV] Fix crash when generating remarks with multi-exit loops.

If DoExtraAnalysis is true (e.g. because remarks are enabled), we
continue with the analysis rather than exiting. Update code to
conditionally check if the ExitBB has phis or not a single predecessor.
Otherwise a nullptr is dereferenced with DoExtraAnalysis.

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