diff options
Diffstat (limited to 'lib/Analysis/DataStructure/DataStructureOpt.cpp')
| -rw-r--r-- | lib/Analysis/DataStructure/DataStructureOpt.cpp | 17 |
1 files changed, 16 insertions, 1 deletions
diff --git a/lib/Analysis/DataStructure/DataStructureOpt.cpp b/lib/Analysis/DataStructure/DataStructureOpt.cpp index ad5b8947ed..297979a72a 100644 --- a/lib/Analysis/DataStructure/DataStructureOpt.cpp +++ b/lib/Analysis/DataStructure/DataStructureOpt.cpp @@ -14,6 +14,8 @@ namespace { Statistic<> NumGlobalsConstanted("ds-opt", "Number of globals marked constant"); + Statistic<> + NumGlobalsIsolated("ds-opt", "Number of globals with references dropped"); class DSOpt : public Pass { TDDataStructures *TD; @@ -60,8 +62,21 @@ bool DSOpt::OptimizeGlobals(Module &M) { // can delete it. We don't ACTUALLY want to delete the global, just // remove anything that references the global: later passes will take // care of nuking it. - I->replaceAllUsesWith(Constant::getNullValue((Type*)I->getType())); + if (!I->use_empty()) { + I->replaceAllUsesWith(Constant::getNullValue((Type*)I->getType())); + ++NumGlobalsIsolated; + } } else if (GNode && GNode->isComplete()) { + + // If the node has not been read or written, and it is not externally + // visible, kill any references to it so it can be DCE'd. + if (!GNode->isModified() && !GNode->isRead() &&I->hasInternalLinkage()){ + if (!I->use_empty()) { + I->replaceAllUsesWith(Constant::getNullValue((Type*)I->getType())); + ++NumGlobalsIsolated; + } + } + // We expect that there will almost always be a node for this global. // If there is, and the node doesn't have the M bit set, we can set the // 'constant' bit on the global. |