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83d886db3a
This builds on r217342, which added the infrastructure to compute known bits
using assumptions (@llvm.assume calls). That original commit added only a few
patterns (to catch common cases related to determining pointer alignment); this
change adds several other patterns for simple cases.
r217342 contained that, for assume(v & b = a), bits in the mask
that are known to be one, we can propagate known bits from the a to v. It also
had a known-bits transfer for assume(a = b). This patch adds:
assume(~(v & b) = a) : For those bits in the mask that are known to be one, we
can propagate inverted known bits from the a to v.
assume(v | b = a) : For those bits in b that are known to be zero, we can
propagate known bits from the a to v.
assume(~(v | b) = a): For those bits in b that are known to be zero, we can
propagate inverted known bits from the a to v.
assume(v ^ b = a) : For those bits in b that are known to be zero, we can
propagate known bits from the a to v. For those bits in
b that are known to be one, we can propagate inverted
known bits from the a to v.
assume(~(v ^ b) = a) : For those bits in b that are known to be zero, we can
propagate inverted known bits from the a to v. For those
bits in b that are known to be one, we can propagate
known bits from the a to v.
assume(v << c = a) : For those bits in a that are known, we can propagate them
to known bits in v shifted to the right by c.
assume(~(v << c) = a) : For those bits in a that are known, we can propagate
them inverted to known bits in v shifted to the right by c.
assume(v >> c = a) : For those bits in a that are known, we can propagate them
to known bits in v shifted to the right by c.
assume(~(v >> c) = a) : For those bits in a that are known, we can propagate
them inverted to known bits in v shifted to the right by c.
assume(v >=_s c) where c is non-negative: The sign bit of v is zero
assume(v >_s c) where c is at least -1: The sign bit of v is zero
assume(v <=_s c) where c is negative: The sign bit of v is one
assume(v <_s c) where c is non-positive: The sign bit of v is one
assume(v <=_u c): Transfer the known high zero bits
assume(v <_u c): Transfer the known high zero bits (if c is know to be a power
of 2, transfer one more)
A small addition to InstCombine was necessary for some of the test cases. The
problem is that when InstCombine was simplifying and, or, etc. it would fail to
check the 'do I know all of the bits' condition before checking less specific
conditions and would not fully constant-fold the result. I'm not sure how to
trigger this aside from using assumptions, so I've just included the change
here.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217343 91177308-0d34-0410-b5e6-96231b3b80d8
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| .. | ||
| ADCE | ||
| AddDiscriminators | ||
| ArgumentPromotion | ||
| AtomicExpand/ARM | ||
| BBVectorize | ||
| BranchFolding | ||
| CodeExtractor | ||
| CodeGenPrepare | ||
| ConstantHoisting | ||
| ConstantMerge | ||
| ConstProp | ||
| CorrelatedValuePropagation | ||
| DeadArgElim | ||
| DeadStoreElimination | ||
| DebugIR | ||
| EarlyCSE | ||
| FunctionAttrs | ||
| GCOVProfiling | ||
| GlobalDCE | ||
| GlobalOpt | ||
| GVN | ||
| IndVarSimplify | ||
| Inline | ||
| InstCombine | ||
| InstMerge | ||
| InstSimplify | ||
| Internalize | ||
| IPConstantProp | ||
| JumpThreading | ||
| LCSSA | ||
| LICM | ||
| LoadCombine | ||
| LoopDeletion | ||
| LoopIdiom | ||
| LoopReroll | ||
| LoopRotate | ||
| LoopSimplify | ||
| LoopStrengthReduce | ||
| LoopUnroll | ||
| LoopUnswitch | ||
| LoopVectorize | ||
| LowerAtomic | ||
| LowerExpectIntrinsic | ||
| LowerInvoke | ||
| LowerSwitch | ||
| Mem2Reg | ||
| MemCpyOpt | ||
| MergeFunc | ||
| MetaRenamer | ||
| ObjCARC | ||
| PartiallyInlineLibCalls | ||
| PhaseOrdering | ||
| PruneEH | ||
| Reassociate | ||
| Reg2Mem | ||
| SampleProfile | ||
| Scalarizer | ||
| ScalarRepl | ||
| SCCP | ||
| SeparateConstOffsetFromGEP/NVPTX | ||
| SimplifyCFG | ||
| Sink | ||
| SLPVectorizer | ||
| SROA | ||
| StripSymbols | ||
| StructurizeCFG | ||
| TailCallElim | ||
| TailDup | ||
| Util | ||