Summary:
I don't have a direct motivational case for this,
but it would be good to have this for completeness/symmetry.
This pattern is basically the motivational pattern from
https://bugs.llvm.org/show_bug.cgi?id=43251
but with different predicate that requires that the offset is non-zero.
The completeness bit comes from the fact that a similar pattern (offset != zero)
will be needed for https://bugs.llvm.org/show_bug.cgi?id=43259,
so it'd seem to be good to not overlook very similar patterns..
Proofs: https://rise4fun.com/Alive/21b
Also, there is something odd with `isKnownNonZero()`, if the non-zero
knowledge was specified as an assumption, it didn't pick it up (PR43267)
With this, i see no other missing folds for
https://bugs.llvm.org/show_bug.cgi?id=43251
Reviewers: spatel, nikic, xbolva00
Reviewed By: spatel
Subscribers: hiraditya, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D67412
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@372257 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This is rather unconventional..
As the comment there says, we don't have much folds for xor-of-icmps,
we try to turn them into an and-of-icmps, for which we have plenty of folds.
But if the ICmp we need to invert is not single-use - we give up.
As discussed in https://reviews.llvm.org/D65148#1603922,
we may have a non-canonical CLAMP pattern, with bit match and
select-of-threshold that we'll potentially clamp.
As it can be seen in `canonicalize-clamp-with-select-of-constant-threshold-pattern.ll`,
out of all 8 variations of the pattern, only two are **not** canonicalized into
the variant with and+icmp instead of bit math.
The reason is because the ICmp we need to invert is not single-use - we give up.
We indeed can't perform this fold at will, the general rule is that
we should not increase instruction count in InstCombine,
But we wouldn't end up increasing instruction count if we can adapt every other
user to the inverted value. This way the `not` we create **will** get folded,
and in the end the instruction count did not increase.
For that, of course, we need to look at the users of a Value,
which is again rather unconventional for InstCombine :S
Thus i'm proposing to be a little bit more insistive in `foldXorOfICmps()`.
The alternatives would be to not create that `not`, but add duplicate code to
manually invert all users; or to add some even less general combine to handle
some more specific pattern[s].
Reviewers: spatel, nikic, RKSimon, craig.topper
Reviewed By: spatel
Subscribers: hiraditya, jdoerfert, dmgreen, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D65530
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@368685 91177308-0d34-0410-b5e6-96231b3b80d8
We can treat icmp eq X, MIN_UINT as icmp ule X, MIN_UINT and allow
it to merge with icmp ugt X, C. Similar for the other constants.
We can do simliar for icmp ne X, (U)INT_MIN/MAX in foldAndOfICmps. And we already handled UINT_MIN there.
Fixes PR42691.
Differential Revision: https://reviews.llvm.org/D65017
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366945 91177308-0d34-0410-b5e6-96231b3b80d8
For equality, the function called getTrue/getFalse with the VT
of the comparison input. But getTrue/getFalse need the boolean VT.
So if this code ever executed, it would assert.
I believe these cases are removed by InstSimplify so we don't get here.
So this patch just fixes up an assert to exclude the equality
possibility and removes the broken code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366649 91177308-0d34-0410-b5e6-96231b3b80d8
AddOne/SubOne create new Constant objects. That seems heavy for
comparing ConstantInts which wrap APInts. Just do the math on
on the APInts and compare them.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@366648 91177308-0d34-0410-b5e6-96231b3b80d8
This is the Demorgan'd 'not' of the pattern handled in:
D63660 / rL364153
This is another intermediate IR step towards solving PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314
We can test if a value is not a power-of-2 using ctpop(X) > 1,
so combining that with an is-zero check of the input is the
same as testing if not exactly 1 bit is set:
(X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364246 91177308-0d34-0410-b5e6-96231b3b80d8
We have a similar match for patterns ending in a truncate. This
should be ok for all targets because the default expansion would
still likely be better from replacing 2 'and' ops with 1.
Attempt to show the logic equivalence in Alive (which doesn't
currently have funnel-shift in its vocabulary AFAICT):
%shamt = zext i8 %i to i32
%m = and i32 %shamt, 31
%neg = sub i32 0, %shamt
%and4 = and i32 %neg, 31
%shl = shl i32 %v, %m
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
=>
%a = and i8 %i, 31
%shamt2 = zext i8 %a to i32
%neg2 = sub i32 0, %shamt2
%and4 = and i32 %neg2, 31
%shl = shl i32 %v, %shamt2
%shr = lshr i32 %v, %and4
%or = or i32 %shr, %shl
https://rise4fun.com/Alive/V9r
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@360605 91177308-0d34-0410-b5e6-96231b3b80d8
If they have other users we'll just end up increasing the instruction count.
We might be able to weaken this to only one of them having a single use if we can prove that the and will be removed.
Fixes PR41164.
Differential Revision: https://reviews.llvm.org/D59630
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356690 91177308-0d34-0410-b5e6-96231b3b80d8
Combine 2 fcmps that are checking for nan-ness:
and (fcmp ord X, 0), (and (fcmp ord Y, 0), Z) --> and (fcmp ord X, Y), Z
or (fcmp uno X, 0), (or (fcmp uno Y, 0), Z) --> or (fcmp uno X, Y), Z
This is an exact match for a minimal reassociation pattern.
If we want to handle this more generally that should go in
the reassociate pass and allow removing this code.
This should fix:
https://bugs.llvm.org/show_bug.cgi?id=41069
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@356471 91177308-0d34-0410-b5e6-96231b3b80d8
This bug seems to be harmless in release builds, but will cause an error in UBSAN
builds or an assertion failure in debug builds.
When it gets to this opcode comparison, it assumes both of the operands are BinaryOperators,
but the prior m_LogicalShift will also match a ConstantExpr. The cast<BinaryOperator> will
assert in a debug build, or reading an invalid value for BinaryOp from memory with
((BinaryOperator*)constantExpr)->getOpcode() will cause an error in a UBSAN build.
The test I added will fail without this change in debug/UBSAN builds, but not in release.
Patch by: @AndrewScheidecker (Andrew Scheidecker)
Differential Revision: https://reviews.llvm.org/D58049
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@353736 91177308-0d34-0410-b5e6-96231b3b80d8
to reflect the new license.
We understand that people may be surprised that we're moving the header
entirely to discuss the new license. We checked this carefully with the
Foundation's lawyer and we believe this is the correct approach.
Essentially, all code in the project is now made available by the LLVM
project under our new license, so you will see that the license headers
include that license only. Some of our contributors have contributed
code under our old license, and accordingly, we have retained a copy of
our old license notice in the top-level files in each project and
repository.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@351636 91177308-0d34-0410-b5e6-96231b3b80d8
This is matching the equivalent of the DAG expansion,
so it should never end up with worse perf than the
original code even if the target doesn't have a rotate
instruction.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@350672 91177308-0d34-0410-b5e6-96231b3b80d8
There are potential improvements to the structure of this API
raised by D54994, but remove some cosmetic blemishes before
making any functional changes.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@348149 91177308-0d34-0410-b5e6-96231b3b80d8
We should have a similar function for matching rotate and/or
funnel shift, so tidy up the related existing call.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@346871 91177308-0d34-0410-b5e6-96231b3b80d8
The original patch was committed here:
rL344609
...and reverted:
rL344612
...because it did not properly check/test data types before calling
ComputeNumSignBits().
The tests that caused bot failures for the previous commit are
over-reaching front-end tests that run the entire -O optimizer
pipeline:
Clang :: CodeGen/builtins-systemz-zvector.c
Clang :: CodeGen/builtins-systemz-zvector2.c
I've added a negative test here to ensure coverage for that case.
The new early exit check also tests the type of the 'B' parameter,
so we don't waste time on matching if either value is unsuitable.
Original commit message:
This is part of solving PR37549:
https://bugs.llvm.org/show_bug.cgi?id=37549
The patterns shown here are a special case of something
that we already convert to select. Using ComputeNumSignBits()
catches that case (but not the more complicated motivating
patterns yet).
The backend has hooks/logic to convert back to logic ops
if that's better for the target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345149 91177308-0d34-0410-b5e6-96231b3b80d8
I noticed a missing check and added it at rL344610, but there actually
are codegen tests that will fail without that, so I'll edit those and
submit a fixed patch with more tests.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344612 91177308-0d34-0410-b5e6-96231b3b80d8
This is part of solving PR37549:
https://bugs.llvm.org/show_bug.cgi?id=37549
The patterns shown here are a special case of something
that we already convert to select. Using ComputeNumSignBits()
catches that case (but not the more complicated motivating
patterns yet).
The backend has hooks/logic to convert back to logic ops
if that's better for the target.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344609 91177308-0d34-0410-b5e6-96231b3b80d8
This function will deal with more than shuffles with D50992, and I
have another potential per-element fold that could live here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@343692 91177308-0d34-0410-b5e6-96231b3b80d8
If the ~X wasn't able to simplify above the max/min, we might be able to simplify it by moving it below the max/min.
I had to modify the ~(min/max ~X, Y) transform to prevent getting stuck in a loop when we saw the new ~(max/min X, ~Y) before the ~Y had been folded away to remove the new not.
Differential Revision: https://reviews.llvm.org/D51398
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341674 91177308-0d34-0410-b5e6-96231b3b80d8
I'm probably missing some way to use m_Deferred to remove the code
duplication, but that can be a follow-up.
The improvement in demand_shrink_nsw.ll is an example of missing
the fold because the pattern matching was deficient. I didn't try
to follow the bits in that test, but Alive says it's correct:
https://rise4fun.com/Alive/ugc
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341426 91177308-0d34-0410-b5e6-96231b3b80d8
This is just a cleanup step. The TODO comments show
what is wrong with the 'and' version of the fold.
Fixing this should be part of recommitting:
rL300977
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341405 91177308-0d34-0410-b5e6-96231b3b80d8
The fold was implemented for the general case but use-limitation,
but the later constant version which didn't check uses was only
matching splat constants.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341292 91177308-0d34-0410-b5e6-96231b3b80d8
This is no-outwardly-visible-change intended, so no test.
But the code is smaller and more efficient. The check for
a 'not' op is intended to avoid the expensive value tracking
call when it should not be necessary, and it might prevent
infinite looping when we resurrect:
rL300977
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341280 91177308-0d34-0410-b5e6-96231b3b80d8
I'm assuming its easier to make sure the RHS of an XOR is all ones than it is to check for the many select patterns we have. So lets check that first. Same with the one use check.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@340321 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250):
```
signed char test(unsigned int x) { return x; }
```
`clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3`
* Old: {F6904292}
* With this patch: {F6904294}
General pattern:
X & Y
Where `Y` is checking that all the high bits (covered by a mask `4294967168`)
are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0`
Pattern can be one of:
%t = add i32 %arg, 128
%r = icmp ult i32 %t, 256
Or
%t0 = shl i32 %arg, 24
%t1 = ashr i32 %t0, 24
%r = icmp eq i32 %t1, %arg
Or
%t0 = trunc i32 %arg to i8
%t1 = sext i8 %t0 to i32
%r = icmp eq i32 %t1, %arg
This pattern is a signed truncation check.
And `X` is checking that some bit in that same mask is zero.
I.e. can be one of:
%r = icmp sgt i32 %arg, -1
Or
%t = and i32 %arg, 2147483648
%r = icmp eq i32 %t, 0
Since we are checking that all the bits in that mask are the same,
and a particular bit is zero, what we are really checking is that all the
masked bits are zero.
So this should be transformed to:
%r = icmp ult i32 %arg, 128
The transform itself ended up being rather horrible, even though i omitted some cases.
Surely there is some infrastructure that can help clean this up that i missed?
https://rise4fun.com/Alive/3Ou
The initial commit (rL339610)
was reverted, since the first assert was being triggered.
The @positive_with_extra_and test now has coverage for that case.
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: RKSimon, erichkeane, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D50465
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339621 91177308-0d34-0410-b5e6-96231b3b80d8
At least one buildbot was able to actually trigger that assert
on the top of the function. Will investigate.
This reverts commit r339610.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339612 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
This comes with `Implicit Conversion Sanitizer - integer sign change` (D50250):
```
signed char test(unsigned int x) { return x; }
```
`clang++ -fsanitize=implicit-conversion -S -emit-llvm -o - /tmp/test.cpp -O3`
* Old: {F6904292}
* With this patch: {F6904294}
General pattern:
X & Y
Where `Y` is checking that all the high bits (covered by a mask `4294967168`)
are uniform, i.e. `%arg & 4294967168` can be either `4294967168` or `0`
Pattern can be one of:
%t = add i32 %arg, 128
%r = icmp ult i32 %t, 256
Or
%t0 = shl i32 %arg, 24
%t1 = ashr i32 %t0, 24
%r = icmp eq i32 %t1, %arg
Or
%t0 = trunc i32 %arg to i8
%t1 = sext i8 %t0 to i32
%r = icmp eq i32 %t1, %arg
This pattern is a signed truncation check.
And `X` is checking that some bit in that same mask is zero.
I.e. can be one of:
%r = icmp sgt i32 %arg, -1
Or
%t = and i32 %arg, 2147483648
%r = icmp eq i32 %t, 0
Since we are checking that all the bits in that mask are the same,
and a particular bit is zero, what we are really checking is that all the
masked bits are zero.
So this should be transformed to:
%r = icmp ult i32 %arg, 128
https://rise4fun.com/Alive/3Ou
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: RKSimon, erichkeane, vsk, llvm-commits
Differential Revision: https://reviews.llvm.org/D50465
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339610 91177308-0d34-0410-b5e6-96231b3b80d8
Summary: computeKnownBits is expensive. The cases that would be detected by the computeKnownBits portion of haveNoCommonBitsSet were already handled by the earlier call to SimplifyDemandedInstructionBits.
Reviewers: spatel, lebedev.ri
Reviewed By: lebedev.ri
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D50604
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339531 91177308-0d34-0410-b5e6-96231b3b80d8
Summary:
https://rise4fun.com/Alive/IT3
Comes up in the [most ugliest] `signed int` -> `signed char` case of
`-fsanitize=implicit-conversion` (https://reviews.llvm.org/D50250)
Previously, we were stuck with `not`: {F6867736}
But now we are able to completely get rid of it: {F6867737}
(FIXME: why are we loosing the metadata? that seems wrong/strange.)
Here, we only want to do that it we will be able to completely
get rid of that 'not'.
Reviewers: spatel, craig.topper
Reviewed By: spatel
Subscribers: vsk, erichkeane, llvm-commits
Differential Revision: https://reviews.llvm.org/D50301
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@339243 91177308-0d34-0410-b5e6-96231b3b80d8
This fold was written in an odd way and tried to avoid
an endless loop by bailing out on all constants instead
of the supposedly problematic case of -1. But (X & -1)
should always be simplified before we reach here, so I'm
not sure how that is a problem.
There were no tests for the commuted patterns, so I added
those at rL338364.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338367 91177308-0d34-0410-b5e6-96231b3b80d8
The tests with constants show a missing optimization.
Analysis for adds is better than subs, so this can also
help with other transforms. And codegen is better with
adds for targets like x86 (destructive ops, no sub-from).
https://rise4fun.com/Alive/llK
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338118 91177308-0d34-0410-b5e6-96231b3b80d8
This bug was created by rL335258 because we used to always call instsimplify
after trying the associative folds. After that change it became possible
for subsequent folds to encounter unsimplified code (and potentially assert
because of it).
Instead of carrying changed state through instcombine, we can just return
immediately. This allows instsimplify to run, so we can continue assuming
that easy folds have already occurred.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@336965 91177308-0d34-0410-b5e6-96231b3b80d8
This is outwardly NFC from what I can tell, but it should be more efficient
to simplify first (despite the name, SimplifyAssociativeOrCommutative does
not actually simplify as InstSimplify does - it creates/morphs instructions).
This should make it easier to refactor duplicated code that runs for all binops.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@335258 91177308-0d34-0410-b5e6-96231b3b80d8
The bug report:
https://bugs.llvm.org/show_bug.cgi?id=36036
...requests a DAG change for this, but an IR canonicalization
probably handles most cases. If we still want to match this
pattern in the backend, there's a proposal for that too:
D47831
Alive proofs including nsw/nuw cases that were first noted in:
D46988
https://rise4fun.com/Alive/Kmp
This patch is largely copied from the existing code that was
initially added with:
D40984
...but I didn't see much gain from trying to share code.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@334137 91177308-0d34-0410-b5e6-96231b3b80d8
Review feedback from r328165. Split out just the one function from the
file that's used by Analysis. (As chandlerc pointed out, the original
change only moved the header and not the implementation anyway - which
was fine for the one function that was used (since it's a
template/inlined in the header) but not in general)
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333954 91177308-0d34-0410-b5e6-96231b3b80d8
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.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333820 91177308-0d34-0410-b5e6-96231b3b80d8
In post-commit review, Eric Christopher notes that many
new MSan warnings are being observed with this patch.
The probable reason is: if 'y' is undef here and we could
evaluate it twice and get different results.
We can't increase the number of uses of a value.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@333631 91177308-0d34-0410-b5e6-96231b3b80d8
