This is reduced from a fuzzer test:
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14890
Usually, demanded elements should be able to simplify shuffle
mask elements that are pointing to undef elements of its source
operands, but that doesn't happen in the test case.
llvm-svn: 361533
This should be a valid exception to the general rule of not creating new shuffle masks in IR...
because we already do it. :)
Also, DAG combining/legalization will undo this by widening the shuffle back out if needed.
Explanation for how we already do this: SLP or vector source can create chains of insert/extract
as shown in 1 of the examples from PR16739:
https://godbolt.org/z/NlK7rAhttps://bugs.llvm.org/show_bug.cgi?id=16739
And we expect instcombine or DAGCombine to clean that up by creating relatively simple shuffles.
Differential Revision: https://reviews.llvm.org/D62024
llvm-svn: 361338
As discussed in D62024, we want to limit any potential IR
transforms of shuffles to cases where we know the SDAG
conversion would result in equivalent patterns for these
IR variants.
llvm-svn: 361317
As it's causing some bot failures (and per request from kbarton).
This reverts commit r358543/ab70da07286e618016e78247e4a24fcb84077fda.
llvm-svn: 358546
As discussed in D53037, this can lead to worse codegen, and we
don't generally expect the backend to be able to optimize
arbitrary shuffles. If there's only one use of the 1st shuffle,
that means it's getting removed, so that should always be
safe.
llvm-svn: 353235
When we have a shuffle that extends a source vector with undefs
and then do some binop on that, we must make sure that the extra
elements remain undef with that binop if we reverse the order of
the binop and shuffle.
'or' is probably the easiest example to show the bug because
'or C, undef --> -1' (not undef). But there are other
opcode/constant combinations where this is true as shown by
the 'shl' test.
llvm-svn: 348191
This is part of the missing IR-level folding noted in D52912.
This should be ok as a canonicalization because the new shuffle mask can't
be any more complicated than the existing shuffle mask. If there's some
target where the shorter vector shuffle is not legal, it should just end up
expanding to something like the pair of shuffles that we're starting with here.
Differential Revision: https://reviews.llvm.org/D53037
llvm-svn: 344476
We're a long way from D50992 and D51553, but this is where we have to start.
We weren't back-propagating undefs into binop constant values for anything but
add/sub/mul/and/or/xor.
This is likely because we have to be careful about not introducing UB/poison
with div/rem/shift. But I suspect we already are getting the poison part wrong
for add/sub/mul (although it may not be possible to expose the bug currently
because we use SimplifyDemandedVectorElts from a limited set of opcodes).
See the discussion/implementation from D48987 and D49047.
This patch just enables functionality for FP ops because those do not have
UB/poison potential.
llvm-svn: 343727
As noted in post-commit comments for D52548, the limitation on
increasing vector length can be applied by opcode.
As a first step, this patch only allows insertelement to be
widened because that has no logical downsides for IR and has
little risk of pessimizing codegen.
This may cause PR39132 to go into hiding during a full compile,
but that bug is not fixed.
llvm-svn: 343406
InstCombine would propagate shufflevector insts that had wider output vectors onto
predecessors, which would sometimes push undef's onto the divisor of a div/rem and
result in bad codegen.
I've fixed this by just banning propagating shufflevector back if the result of
the shufflevector is wider than the input vectors.
Patch by: @sheredom (Neil Henning)
Differential Revision: https://reviews.llvm.org/D52548
llvm-svn: 343329
These are the updated baseline tests for D52548 -
I'm putting the tests next to the tests where the transform
functions as expected, so we can see the intended/unintended
consequences.
Patch by: @sheredom (Neil Henning)
llvm-svn: 343328
If the fsub in this pattern was replaced by an actual fneg
instruction, we would need to add a fold to recognize that
because fneg would not be a binop.
llvm-svn: 343041
This lines up with the behavior of an existing transform where if both
operands of the binop are shuffled, we allow moving the binop before the
shuffle regardless of whether the shuffle changes the size of the vector.
llvm-svn: 340787
As discussed in D49047 / D48987, shift-by-undef produces poison,
so we can't use undef vector elements in that case..
Note that we need to extend this for poison-generating flags,
and there's a proposal to create poison from FMF in D47963,
llvm-svn: 336562
As noted in rL333782, we can be both better for optimization and
safer with this transform:
BinOp (shuffle V1, Mask), C --> shuffle (BinOp V1, NewC), Mask
The only potentially unsafe-to-speculate binops are integer div/rem.
All other binops are always safe (although I don't see a way to
assert that in code here).
For opcodes like shifts that can produce poison, it can't matter
here because we know the lanes with undef are dropped by the
subsequent shuffle.
Differential Revision: https://reviews.llvm.org/D47686
llvm-svn: 333962
As noted in the review thread for rL333782, we could have
made a bug harder to hit if we were simplifying instructions
before trying other folds.
The shuffle transform in question isn't ever a simplification;
it's just a canonicalization. So I've renamed that to make that
clearer.
This is NFCI at this point, but I've regenerated the test file
to show the cosmetic value naming difference of using
instcombine's RAUW vs. the builder.
Possible follow-ups:
1. Move reassociation folds after simplifies too.
2. Refactor common code; we shouldn't have so much repetition.
llvm-svn: 333820
As noted in the review thread for rL333782, we're lacking coverage
for this transform, so add tests for each binop opcode with constant
operand.
llvm-svn: 333818
This bug:
https://bugs.llvm.org/show_bug.cgi?id=37648
...was created with the enhancement to this transform with rL332479.
The urem test shows the disaster potential: any undef divisor lane makes
the whole op undef.
The test diffs show that vector demanded elements turns some of the potential,
but not all, unused binop operands back into undef already.
llvm-svn: 333782
The canonicalization was restricted to shuffle masks with
a 1-to-1 mapping to the constant vector, but that disqualifies
the common splat pattern. This is part of solving PR37463:
https://bugs.llvm.org/show_bug.cgi?id=37463
llvm-svn: 332479
InstCombine didn't realize that it needs to use DataLayout to determine
how wide pointers are. This lead to assertion failures.
This fixes PR23113.
llvm-svn: 234046
Essentially the same as the GEP change in r230786.
A similar migration script can be used to update test cases, though a few more
test case improvements/changes were required this time around: (r229269-r229278)
import fileinput
import sys
import re
pat = re.compile(r"((?:=|:|^)\s*load (?:atomic )?(?:volatile )?(.*?))(| addrspace\(\d+\) *)\*($| *(?:%|@|null|undef|blockaddress|getelementptr|addrspacecast|bitcast|inttoptr|\[\[[a-zA-Z]|\{\{).*$)")
for line in sys.stdin:
sys.stdout.write(re.sub(pat, r"\1, \2\3*\4", line))
Reviewers: rafael, dexonsmith, grosser
Differential Revision: http://reviews.llvm.org/D7649
llvm-svn: 230794
In transformation:
BinOp(shuffle(v1,undef), shuffle(v2,undef)) -> shuffle(BinOp(v1, v2),undef)
type of the undef argument must be same as type of BinOp.
llvm-svn: 208531
Do not apply transformation:
BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))
if operands v1 and v2 are of different size.
This change fixes PR19717, which was caused by r208488.
llvm-svn: 208518
This patch enables transformations:
BinOp(shuffle(v1), shuffle(v2)) -> shuffle(BinOp(v1, v2))
BinOp(shuffle(v1), const1) -> shuffle(BinOp, const2)
They allow to eliminate extra shuffles in some cases.
Differential Revision: http://reviews.llvm.org/D3525
llvm-svn: 208488
This update was done with the following bash script:
find test/Transforms -name "*.ll" | \
while read NAME; do
echo "$NAME"
if ! grep -q "^; *RUN: *llc" $NAME; then
TEMP=`mktemp -t temp`
cp $NAME $TEMP
sed -n "s/^define [^@]*@\([A-Za-z0-9_]*\)(.*$/\1/p" < $NAME | \
while read FUNC; do
sed -i '' "s/;\(.*\)\([A-Za-z0-9_]*\):\( *\)@$FUNC\([( ]*\)\$/;\1\2-LABEL:\3@$FUNC(/g" $TEMP
done
mv $TEMP $NAME
fi
done
llvm-svn: 186268
Sanjay Patel