diff options
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp | 22 |
1 files changed, 14 insertions, 8 deletions
diff --git a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp index e703014bb0e..e493065d590 100644 --- a/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp +++ b/llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp @@ -146,7 +146,8 @@ deleteDeadInstruction(Instruction *I, BasicBlock::iterator *BBI, /// Does this instruction write some memory? This only returns true for things /// that we can analyze with other helpers below. -static bool hasMemoryWrite(Instruction *I, const TargetLibraryInfo &TLI) { +static bool hasAnalyzableMemoryWrite(Instruction *I, + const TargetLibraryInfo &TLI) { if (isa<StoreInst>(I)) return true; if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { @@ -181,6 +182,7 @@ static bool hasMemoryWrite(Instruction *I, const TargetLibraryInfo &TLI) { /// returns true, this function and getLocForRead completely describe the memory /// operations for this instruction. static MemoryLocation getLocForWrite(Instruction *Inst, AliasAnalysis &AA) { + if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) return MemoryLocation::get(SI); @@ -208,11 +210,11 @@ static MemoryLocation getLocForWrite(Instruction *Inst, AliasAnalysis &AA) { } } -/// Return the location read by the specified "hasMemoryWrite" instruction if -/// any. +/// Return the location read by the specified "hasAnalyzableMemoryWrite" +/// instruction if any. static MemoryLocation getLocForRead(Instruction *Inst, const TargetLibraryInfo &TLI) { - assert(hasMemoryWrite(Inst, TLI) && "Unknown instruction case"); + assert(hasAnalyzableMemoryWrite(Inst, TLI) && "Unknown instruction case"); // The only instructions that both read and write are the mem transfer // instructions (memcpy/memmove). @@ -230,7 +232,7 @@ static bool isRemovable(Instruction *I) { if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) { switch (II->getIntrinsicID()) { - default: llvm_unreachable("doesn't pass 'hasMemoryWrite' predicate"); + default: llvm_unreachable("doesn't pass 'hasAnalyzableMemoryWrite' predicate"); case Intrinsic::lifetime_end: // Never remove dead lifetime_end's, e.g. because it is followed by a // free. @@ -246,6 +248,7 @@ static bool isRemovable(Instruction *I) { } } + // note: only get here for calls with analyzable writes - i.e. libcalls if (auto CS = CallSite(I)) return CS.getInstruction()->use_empty(); @@ -286,6 +289,8 @@ static bool isShortenableAtTheBeginning(Instruction *I) { /// Return the pointer that is being written to. static Value *getStoredPointerOperand(Instruction *I) { + //TODO: factor this to reuse getLocForWrite + if (StoreInst *SI = dyn_cast<StoreInst>(I)) return SI->getPointerOperand(); if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(I)) @@ -650,7 +655,8 @@ static bool handleFree(CallInst *F, AliasAnalysis *AA, MD->getPointerDependencyFrom(Loc, false, InstPt->getIterator(), BB); while (Dep.isDef() || Dep.isClobber()) { Instruction *Dependency = Dep.getInst(); - if (!hasMemoryWrite(Dependency, *TLI) || !isRemovable(Dependency)) + if (!hasAnalyzableMemoryWrite(Dependency, *TLI) || + !isRemovable(Dependency)) break; Value *DepPointer = @@ -754,7 +760,7 @@ static bool handleEndBlock(BasicBlock &BB, AliasAnalysis *AA, --BBI; // If we find a store, check to see if it points into a dead stack value. - if (hasMemoryWrite(&*BBI, *TLI) && isRemovable(&*BBI)) { + if (hasAnalyzableMemoryWrite(&*BBI, *TLI) && isRemovable(&*BBI)) { // See through pointer-to-pointer bitcasts SmallVector<Value *, 4> Pointers; GetUnderlyingObjects(getStoredPointerOperand(&*BBI), Pointers, DL); @@ -1067,7 +1073,7 @@ static bool eliminateDeadStores(BasicBlock &BB, AliasAnalysis *AA, } // Check to see if Inst writes to memory. If not, continue. - if (!hasMemoryWrite(Inst, *TLI)) + if (!hasAnalyzableMemoryWrite(Inst, *TLI)) continue; // eliminateNoopStore will update in iterator, if necessary. |
