diff options
Diffstat (limited to 'lib/Transforms/Scalar/InstructionCombining.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 38 |
1 files changed, 31 insertions, 7 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 5dfd4472bb..23db4bb058 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -259,7 +259,8 @@ namespace { Instruction *FoldFCmp_IntToFP_Cst(FCmpInst &I, Instruction *LHSI, Constant *RHSC); Instruction *FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, - GlobalVariable *GV, CmpInst &ICI); + GlobalVariable *GV, CmpInst &ICI, + ConstantInt *AndCst = 0); Instruction *visitFCmpInst(FCmpInst &I); Instruction *visitICmpInst(ICmpInst &I); Instruction *visitICmpInstWithCastAndCast(ICmpInst &ICI); @@ -6022,9 +6023,12 @@ Instruction *InstCombiner::FoldFCmp_IntToFP_Cst(FCmpInst &I, /// where GV is a global variable with a constant initializer. Try to simplify /// this into some simple computation that does not need the load. For example /// we can optimize "icmp eq (load (gep "foo", 0, i)), 0" into "icmp eq i, 3". +/// +/// If AndCst is non-null, then the loaded value is masked with that constant +/// before doing the comparison. This handles cases like "A[i]&4 == 0". Instruction *InstCombiner:: FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, - CmpInst &ICI) { + CmpInst &ICI, ConstantInt *AndCst) { // There are many forms of this optimization we can handle, for now, just do // the simple index into a single-dimensional array. @@ -6070,9 +6074,13 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, // Scan the array and see if one of our patterns matches. Constant *CompareRHS = cast<Constant>(ICI.getOperand(1)); for (unsigned i = 0, e = Init->getNumOperands(); i != e; ++i) { + Constant *Elt = Init->getOperand(i); + + // If the element is masked, handle it. + if (AndCst) Elt = ConstantExpr::getAnd(Elt, AndCst); + // Find out if the comparison would be true or false for the i'th element. - Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), - Init->getOperand(i), + Constant *C = ConstantFoldCompareInstOperands(ICI.getPredicate(), Elt, CompareRHS, TD); // If the result is undef for this element, ignore it. if (isa<UndefValue>(C)) { @@ -6236,7 +6244,6 @@ FoldCmpLoadFromIndexedGlobal(GetElementPtrInst *GEP, GlobalVariable *GV, return new ICmpInst(ICmpInst::ICMP_NE, V, ConstantInt::get(Ty, 0)); } - // TODO: A[i]&4 == 0 // TODO: GEP 0, i, 4 return 0; @@ -6333,7 +6340,7 @@ Instruction *InstCombiner::visitFCmpInst(FCmpInst &I) { !cast<LoadInst>(LHSI)->isVolatile()) if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) return Res; - //errs() << "NOT HANDLED: " << *GV << "\n"; + //errs() << "NOT HANDLED FP: " << *GV << "\n"; //errs() << "\t" << *GEP << "\n"; //errs() << "\t " << I << "\n\n\n"; } @@ -6719,6 +6726,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { break; case Instruction::Load: + // Try to optimize things like "A[i] > 4" to index computations. if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(LHSI->getOperand(0))) { if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) @@ -6726,7 +6734,7 @@ Instruction *InstCombiner::visitICmpInst(ICmpInst &I) { !cast<LoadInst>(LHSI)->isVolatile()) if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV, I)) return Res; - //errs() << "NOT HANDLED: " << *GV << "\n"; + //errs() << "NOT HANDLED INT: " << *GV << "\n"; //errs() << "\t" << *GEP << "\n"; //errs() << "\t " << I << "\n\n\n"; } @@ -7382,6 +7390,22 @@ Instruction *InstCombiner::visitICmpInstWithInstAndIntCst(ICmpInst &ICI, return &ICI; } } + + // Try to optimize things like "A[i]&42 == 0" to index computations. + if (LoadInst *LI = dyn_cast<LoadInst>(LHSI->getOperand(0))) { + if (GetElementPtrInst *GEP = + dyn_cast<GetElementPtrInst>(LI->getOperand(0))) + if (GlobalVariable *GV = dyn_cast<GlobalVariable>(GEP->getOperand(0))) + if (GV->isConstant() && GV->hasDefinitiveInitializer() && + !LI->isVolatile() && isa<ConstantInt>(LHSI->getOperand(1))) { + ConstantInt *C = cast<ConstantInt>(LHSI->getOperand(1)); + if (Instruction *Res = FoldCmpLoadFromIndexedGlobal(GEP, GV,ICI, C)) + return Res; + //errs() << "NOT HANDLED INT: " << *GV << "\n"; + //errs() << "\t" << *GEP << "\n"; + //errs() << "\t " << I << "\n\n\n"; + } + } break; case Instruction::Or: { |