From fc605ac12cd2035f6d096b53cbb2033e24bdc092 Mon Sep 17 00:00:00 2001 From: Sebastian Pop Date: Fri, 21 Feb 2014 18:15:07 +0000 Subject: fail delinearization when the size of subscripts differs Because the delinearization is not a global analysis pass, it will compute the delinearization independently of knowledge about the way the delinearization happened for other data accesses to the same array: the dependence analysis will only trigger the delinearization on a tuple of access functions, and thus delinearization may compute different subscripts sizes for a same array. When that happens the safest is to discard the delinearized information. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@201866 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Analysis/DependenceAnalysis.cpp | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) (limited to 'lib/Analysis/DependenceAnalysis.cpp') diff --git a/lib/Analysis/DependenceAnalysis.cpp b/lib/Analysis/DependenceAnalysis.cpp index b74140db2c..6f9effa127 100644 --- a/lib/Analysis/DependenceAnalysis.cpp +++ b/lib/Analysis/DependenceAnalysis.cpp @@ -3193,10 +3193,23 @@ DependenceAnalysis::tryDelinearize(const SCEV *SrcSCEV, const SCEV *DstSCEV, DstAR->delinearize(*SE, DstSubscripts, DstSizes); int size = SrcSubscripts.size(); + // Fail when there is only a subscript: that's a linearized access function. + if (size < 2) + return false; + int dstSize = DstSubscripts.size(); - if (size != dstSize || size < 2) + // Fail when the number of subscripts in Src and Dst differ. + if (size != dstSize) return false; + // Fail when the size of any of the subscripts in Src and Dst differs: the + // dependence analysis assumes that elements in the same array have same size. + // SCEV delinearization does not have a context based on which it would decide + // globally the size of subscripts that would best fit all the array accesses. + for (int i = 0; i < size; ++i) + if (SrcSizes[i] != DstSizes[i]) + return false; + #ifndef NDEBUG DEBUG(errs() << "\nSrcSubscripts: "); for (int i = 0; i < size; i++) -- cgit v1.2.3