Call ConstantFoldSelectInstruction() to fold cases like below
select <2 x i1><i1 true, i1 false>, <2 x i8> <i8 0, i8 1>, <2 x i8> <i8 2, i8 3>
All operands are constants and the condition has mixed true and false conditions.
Differential Revision: https://reviews.llvm.org/D38369
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This should bring signed div/rem analysis up to the same level as unsigned.
We use icmp simplification to determine when the divisor is known greater than the dividend.
Each positive test is followed by a negative test to show that we're not overstepping the boundaries of the known bits.
There are extra tests for the signed-min-value special cases.
Alive proofs:
http://rise4fun.com/Alive/WI5
Differential Revision: https://reviews.llvm.org/D37713
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As noted in PR34517, the handling of signed div/rem is not on par with
unsigned div/rem. Signed is harder to reason about, but it should be
possible to handle at least some of these using the same technique that
we use for unsigned: use icmp logic to see if there's a relationship
between the quotient and divisor.
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This removes some duplicated code and makes it easier to support signed div/rem
in a similar way if we want to do that. Note that the existing comments were not
accurate - we don't need a constant divisor to simplify; icmp simplification does
more than that. But as the added tests show, it could go even further.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312885 91177308-0d34-0410-b5e6-96231b3b80d8
These are all tests that result in a constant, so moving the tests over to where they are actually handled.
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This code is double-dead:
1. We simplify all selects with constant true/false condition in InstSimplify.
I've minimized/moved the tests to show that works as expected.
2. All remaining vector selects with a constant condition are canonicalized to
shufflevector, so we really can't see this pattern.
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This recommits r310869, with the moved files and no extra changes.
Original commit message:
This addresses a fixme in InstSimplify about using decomposeBitTest. This also fixes InstSimplify to handle ugt and ult compares too.
I've modified the interface a little to return only the APInt version of the mask that InstSimplify needs. InstCombine now has a small wrapper routine to create a Constant out of it. I've also dropped the returning of 0 since InstSimplify doesn't need that. So InstCombine creates a zero constant itself.
I also had to make decomposeBitTest support vectors since InstSimplify needs that.
As InstSimplify can't use something from the Transforms library, I've moved the CmpInstAnalysis code to the Analysis library.
Differential Revision: https://reviews.llvm.org/D36593
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310889 91177308-0d34-0410-b5e6-96231b3b80d8
Failed to add the two files that moved. And then added an extra change I didn't mean to while trying to fix that. Reverting everything.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310873 91177308-0d34-0410-b5e6-96231b3b80d8
This addresses a fixme in InstSimplify about using decomposeBitTest. This also fixes InstSimplify to handle ugt and ult compares too.
I've modified the interface a little to return only the APInt version of the mask that InstSimplify needs. InstCombine now has a small wrapper routine to create a Constant out of it. I've also dropped the returning of 0 since InstSimplify doesn't need that. So InstCombine creates a zero constant itself.
I also had to make decomposeBitTest support vectors since InstSimplify needs that.
As InstSimplify can't use something from the Transforms library, I've moved the CmpInstAnalysis code to the Analysis library.
Differential Revision: https://reviews.llvm.org/D36593
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310869 91177308-0d34-0410-b5e6-96231b3b80d8
The code in ConstantFoldGetElementPtr() assumes integers, and
therefore it crashes trying to get the integer bidwith of a vector
type (in this case <4 x i32>. I just changed the code to prevent
the folding in case of vectors and I didn't bother to generalize
as this doesn't seem to me something that really happens in
practice, but I'm willing to change the patch if you think
it's worth it.
This is hard to trigger from -instsimplify or -instcombine
only as the second instruction is dead, so the test uses loop-unroll.
Differential Revision: https://reviews.llvm.org/D35956
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Summary:
The constant folding code currently assumes that the constant expression will always be on the left and the simple null will be on the right. But that's not true at least on the path from InstSimplify.
This patch adds support to ConstantFolding to detect the reversed case.
Reviewers: spatel, dberlin, majnemer, davide, joey
Reviewed By: joey
Subscribers: joey, llvm-commits
Differential Revision: https://reviews.llvm.org/D33801
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The tests here are have operands commuted to provide more coverage. I also commuted one of the instructions in the scalar tests so the 4 tests cover the 4 commuted variations
Differential Revision: https://reviews.llvm.org/D33599
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Summary: This code was migrated from InstCombine a few years ago. InstCombine had nearby code that would move Constants to the RHS for these, but InstSimplify doesn't have such code on this path.
Reviewers: spatel, majnemer, davide
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D33473
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We already handled all of the new tests identically, but several
of those went through a lot of unnecessary processing before
getting folded.
Another motivation for grouping these cases together is that
InstCombine needs a similar fold. Currently, it handles the
'not' cases inefficiently which can lead to bugs as described
in the post-commit comments of:
https://reviews.llvm.org/D32143
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We would eventually catch these via demanded bits and computing known bits in InstCombine,
but I think it's better to handle the simple cases as soon as possible as a matter of efficiency.
This fold allows further simplifications based on distributed ops transforms. eg:
%a = lshr i8 %x, 7
%b = or i8 %a, 2
%c = and i8 %b, 1
InstSimplify can directly fold this now:
%a = lshr i8 %x, 7
Differential Revision: https://reviews.llvm.org/D33221
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Surprisingly, I don't think these are redundant for InstSimplify.
They were just misplaced as InstCombine tests.
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Summary:
Re-applying r301766 with a fix to a typo and a regression test.
The log message for r301766 was:
==================================================================================
InstructionSimplify: Canonicalize shuffle operands. NFC-ish.
Summary:
Apply canonicalization rules:
1. Input vectors with no elements selected from can be replaced with undef.
2. If only one input vector is constant it shall be the second one.
This allows constant-folding to cover more ad-hoc simplifications that
were in place and avoid duplication for RHS and LHS checks.
There are more rules we may want to add in the future when we see a
justification. e.g. mask elements that select undef elements can be
replaced with undef.
==================================================================================
Reviewers: spatel, RKSimon
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D32863
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We can simplify (or (icmp X, C1), (icmp X, C2)) to 'true' or one of the icmps in many cases.
I had to check some of these with Alive to prove to myself it's right, but everything seems
to check out. Eg, the deleted code in instcombine was completely ignoring predicates with
mismatched signedness.
This is a follow-up to:
https://reviews.llvm.org/rL301260https://reviews.llvm.org/D32143
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The sibling folds for 'and' with casts were added with https://reviews.llvm.org/rL273200.
This is a preliminary step for adding the 'or' variants for the folds added with https://reviews.llvm.org/rL301260.
The reason for the strange form with constant LHS in the 1st test is because there's another missing fold in that
case for the inverted predicate. That should be fixed when we add the ConstantRange functionality for 'or-of-icmps'
that already exists for 'and-of-icmps'.
I'm hoping to share more code for the and/or cases, so we won't have these differences. This will allow us to remove
code from InstCombine. It's also possible that we can remove some code here in InstSimplify. I think we have some
duplicated folds because patterns are not matched in a general way.
Differential Revision: https://reviews.llvm.org/D32876
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This change caused buildbot failures, apparently because we're not
passing around types that InstSimplify is used to seeing. I'm not overly
familiar with InstSimplify, so I'm reverting this until I can figure out
what exactly is wrong.
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