diff options
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/SCCP.cpp | 16 |
1 files changed, 15 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/SCCP.cpp b/lib/Transforms/Scalar/SCCP.cpp index 8d06690f2a..5a0f62083e 100644 --- a/lib/Transforms/Scalar/SCCP.cpp +++ b/lib/Transforms/Scalar/SCCP.cpp @@ -1918,6 +1918,14 @@ bool IPSCCP::runOnModule(Module &M) { // all call uses with the inferred value. This means we don't need to bother // actually returning anything from the function. Replace all return // instructions with return undef. + // + // Do this in two stages: first identify the functions we should process, then + // actually zap their returns. This is important because we can only do this + // the address of the function isn't taken. In cases where a return is the + // last use of a function, the order of processing functions would affect + // whether we other functions are optimizable. + SmallVector<ReturnInst*, 8> ReturnsToZap; + // TODO: Process multiple value ret instructions also. const DenseMap<Function*, LatticeVal> &RV = Solver.getTrackedRetVals(); for (DenseMap<Function*, LatticeVal>::const_iterator I = RV.begin(), @@ -1933,7 +1941,13 @@ bool IPSCCP::runOnModule(Module &M) { for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) if (!isa<UndefValue>(RI->getOperand(0))) - RI->setOperand(0, UndefValue::get(F->getReturnType())); + ReturnsToZap.push_back(RI); + } + + // Zap all returns which we've identified as zap to change. + for (unsigned i = 0, e = ReturnsToZap.size(); i != e; ++i) { + Function *F = ReturnsToZap[i]->getParent()->getParent(); + ReturnsToZap[i]->setOperand(0, UndefValue::get(F->getReturnType())); } // If we infered constant or undef values for globals variables, we can delete |