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| author | Dan Gohman <gohman@apple.com> | 2010-12-10 20:47:03 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2010-12-10 20:47:03 +0000 |
| commit | 3bd5e52676681914f2cb2767da2d6ef8c168cf73 (patch) | |
| tree | 6577fcc5850825d01ff83722035cda9a65e1c0aa /lib/Analysis | |
| parent | 6ce219ec64088fc4ee550afbb6cd30621fbba27e (diff) | |
| download | external_llvm-3bd5e52676681914f2cb2767da2d6ef8c168cf73.zip external_llvm-3bd5e52676681914f2cb2767da2d6ef8c168cf73.tar.gz external_llvm-3bd5e52676681914f2cb2767da2d6ef8c168cf73.tar.bz2 | |
Implement PartialAlias checking in BasicAA.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121520 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Analysis')
| -rw-r--r-- | lib/Analysis/BasicAliasAnalysis.cpp | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/lib/Analysis/BasicAliasAnalysis.cpp b/lib/Analysis/BasicAliasAnalysis.cpp index 3ab18fd..17a502e 100644 --- a/lib/Analysis/BasicAliasAnalysis.cpp +++ b/lib/Analysis/BasicAliasAnalysis.cpp @@ -857,6 +857,17 @@ BasicAliasAnalysis::aliasGEP(const GEPOperator *GEP1, uint64_t V1Size, if (GEP1BaseOffset == 0 && GEP1VariableIndices.empty()) return MustAlias; + // If there is a difference betwen the pointers, but the difference is + // less than the size of the associated memory object, then we know + // that the objects are partially overlapping. + if (GEP1BaseOffset != 0 && GEP1VariableIndices.empty()) { + if (GEP1BaseOffset >= 0 ? + (V2Size != UnknownSize && (uint64_t)GEP1BaseOffset < V2Size) : + (V1Size != UnknownSize && -(uint64_t)GEP1BaseOffset < V1Size && + GEP1BaseOffset != INT64_MIN)) + return PartialAlias; + } + // If we have a known constant offset, see if this offset is larger than the // access size being queried. If so, and if no variable indices can remove // pieces of this constant, then we know we have a no-alias. For example, |