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1cc7eb0b48
Currently, BasicAA does not exploit information about value ranges of indexes. For example, consider the 2 pointers %a = %base and %b = %base + %stride below, assuming they are used to access 4 elements. If we know that %stride >= 4, we know the accesses do not alias. If %stride is a constant, BasicAA currently gets that. But if the >= 4 constraint is encoded using an assume, it misses the NoAlias. This patch extends DecomposedGEP to include an additional MinOtherOffset field, which tracks the constant offset similar to the existing OtherOffset, which the difference that it also includes non-negative lower bounds on the range of the index value. When checking if the distance between 2 accesses exceeds the access size, we can use this improved bound. For now this is limited to using non-negative lower bounds for indices, as this conveniently skips cases where we do not have a useful lower bound (because it is not constrained). We potential miss out in cases where the lower bound is constrained but negative, but that can be exploited in the future. Reviewers: sanjoy, hfinkel, reames, asbirlea Reviewed By: asbirlea Differential Revision: https://reviews.llvm.org/D76194 |
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| .. | ||
| AliasSet | ||
| AssumptionCache | ||
| BasicAA | ||
| BlockFrequencyInfo | ||
| BranchProbabilityInfo | ||
| CallGraph | ||
| CFLAliasAnalysis | ||
| ConstantFolding | ||
| CostModel | ||
| DDG | ||
| Delinearization | ||
| DemandedBits | ||
| DependenceAnalysis | ||
| DivergenceAnalysis | ||
| DominanceFrontier | ||
| Dominators | ||
| GlobalsModRef | ||
| IVUsers | ||
| LazyCallGraph | ||
| LazyValueAnalysis | ||
| LegacyDivergenceAnalysis | ||
| Lint | ||
| LoopAccessAnalysis | ||
| LoopCacheAnalysis/PowerPC | ||
| LoopInfo | ||
| LoopNestAnalysis | ||
| MemoryDependenceAnalysis | ||
| MemorySSA | ||
| MustExecute | ||
| PhiValues | ||
| PostDominators | ||
| ProfileSummary | ||
| RegionInfo | ||
| ScalarEvolution | ||
| ScopedNoAliasAA | ||
| StackSafetyAnalysis | ||
| TypeBasedAliasAnalysis | ||
| ValueTracking | ||
| alias-analysis-uses.ll | ||