David Majnemer
73059bd1f1
ConstantFold: Shifting undef by zero results in undef
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224553 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-18 23:54:43 +00:00
David Majnemer
891ec6d69f
InstSimplify: shl nsw/nuw undef, %V -> undef
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We can always choose an value for undef which might cause %V to shift
out an important bit except for one case, when %V is zero.
However, shl behaves like an identity function when the right hand side
is zero.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224405 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-17 01:54:33 +00:00
David Majnemer
c57bee5399
InstSimplify: Remove usesless %a parameter from tests
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No functional change intended.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@224016 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-11 12:56:17 +00:00
David Majnemer
ea9bcfc707
ConstantFold: an undef shift amount results in undef
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X shifted by undef results in undef because the undef value can
represent values greater than the width of the operands.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223968 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-10 21:38:05 +00:00
David Majnemer
895316336e
ConstantFold: div undef, 0 should fold to undef, not zero
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Dividing by zero yields an undefined value.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223924 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-10 09:14:55 +00:00
David Majnemer
6578f1beb1
InstSimplify: [al]shr exact undef, %X -> undef
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Exact shifts always keep the non-zero bits of their input. This means
it keeps it's undef bits.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223923 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-10 09:14:52 +00:00
David Majnemer
1297775557
InstSimplify: div %X, 0 -> undef
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We already optimized rem %X, 0 to undef, we should do the same for div.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223919 91177308-0d34-0410-b5e6-96231b3b80d8
2014-12-10 07:52:18 +00:00
Benjamin Kramer
c166623dcd
InstSimplify: Make shift, select and GEP simplifications vector-aware.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@200016 91177308-0d34-0410-b5e6-96231b3b80d8
2014-01-24 17:09:53 +00:00
Dan Gohman
abe776a794
Add tests for existing InstSimplify features.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143721 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-04 18:39:16 +00:00
Dan Gohman
71d0503157
Teach instsimplify to simplify calls to undef.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143719 91177308-0d34-0410-b5e6-96231b3b80d8
2011-11-04 18:32:42 +00:00
Dan Gohman
68c0dbc14f
Improve constant folding of undef for cmp and select operators.
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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@134223 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-01 01:03:43 +00:00
