diff options
| -rw-r--r-- | llvm/include/llvm/Analysis/Loads.h | 19 | ||||
| -rw-r--r-- | llvm/lib/Analysis/Lint.cpp | 5 | ||||
| -rw-r--r-- | llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp | 7 | ||||
| -rw-r--r-- | llvm/lib/Transforms/Scalar/JumpThreading.cpp | 7 |
4 files changed, 11 insertions, 27 deletions
diff --git a/llvm/include/llvm/Analysis/Loads.h b/llvm/include/llvm/Analysis/Loads.h index 3107a765992..698b665a93f 100644 --- a/llvm/include/llvm/Analysis/Loads.h +++ b/llvm/include/llvm/Analysis/Loads.h @@ -29,28 +29,15 @@ class MDNode; bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom, unsigned Align); -/// DEF_MAX_INSTS_TO_SCAN - the default number of maximum instructions -/// to scan in the block, used by FindAvailableLoadedValue(). -/// FindAvailableLoadedValue() was introduced in r60148, to improve jump -/// threading in part by eliminating partially redundant loads. -/// At that point, the value of MaxInstsToScan was already set to '6' -/// without documented explanation. -/// FIXME: Ask r60148 author for details, and complete this documentation. -/// NOTE: As of now, every use of FindAvailableLoadedValue() uses this default -/// value of '6'. -#ifndef DEF_MAX_INSTS_TO_SCAN -#define DEF_MAX_INSTS_TO_SCAN 6 -#endif - /// FindAvailableLoadedValue - Scan the ScanBB block backwards (starting at /// the instruction before ScanFrom) checking to see if we have the value at /// the memory address *Ptr locally available within a small number of /// instructions. If the value is available, return it. /// -/// If not, return the iterator for the last validated instruction that the +/// If not, return the iterator for the last validated instruction that the /// value would be live through. If we scanned the entire block and didn't /// find something that invalidates *Ptr or provides it, ScanFrom would be -/// left at begin() and this returns null. ScanFrom could also be left +/// left at begin() and this returns null. ScanFrom could also be left /// /// MaxInstsToScan specifies the maximum instructions to scan in the block. /// If it is set to 0, it will scan the whole block. You can also optionally @@ -61,7 +48,7 @@ bool isSafeToLoadUnconditionally(Value *V, Instruction *ScanFrom, /// is found, it is left unmodified. Value *FindAvailableLoadedValue(Value *Ptr, BasicBlock *ScanBB, BasicBlock::iterator &ScanFrom, - unsigned MaxInstsToScan = DEF_MAX_INSTS_TO_SCAN, + unsigned MaxInstsToScan = 6, AliasAnalysis *AA = nullptr, AAMDNodes *AATags = nullptr); diff --git a/llvm/lib/Analysis/Lint.cpp b/llvm/lib/Analysis/Lint.cpp index 4928e45f892..0f5599e8204 100644 --- a/llvm/lib/Analysis/Lint.cpp +++ b/llvm/lib/Analysis/Lint.cpp @@ -829,9 +829,8 @@ Value *Lint::findValueImpl(Value *V, bool OffsetOk, for (;;) { if (!VisitedBlocks.insert(BB).second) break; - if (Value *U = - FindAvailableLoadedValue(L->getPointerOperand(), - BB, BBI, DEF_MAX_INSTS_TO_SCAN, AA)) + if (Value *U = FindAvailableLoadedValue(L->getPointerOperand(), + BB, BBI, 6, AA)) return findValueImpl(U, OffsetOk, Visited); if (BBI != BB->begin()) break; BB = BB->getUniquePredecessor(); diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp index 32d3f80d15e..3c70f442647 100644 --- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp +++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp @@ -750,9 +750,8 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { // separated by a few arithmetic operations. BasicBlock::iterator BBI = &LI; AAMDNodes AATags; - if (Value *AvailableVal = - FindAvailableLoadedValue(Op, LI.getParent(), BBI, - DEF_MAX_INSTS_TO_SCAN, AA, &AATags)) { + if (Value *AvailableVal = FindAvailableLoadedValue(Op, LI.getParent(), BBI, + 6, AA, &AATags)) { if (LoadInst *NLI = dyn_cast<LoadInst>(AvailableVal)) { unsigned KnownIDs[] = { LLVMContext::MD_tbaa, @@ -823,7 +822,7 @@ Instruction *InstCombiner::visitLoadInst(LoadInst &LI) { } // load (select (cond, null, P)) -> load P - if (isa<ConstantPointerNull>(SI->getOperand(1)) && + if (isa<ConstantPointerNull>(SI->getOperand(1)) && LI.getPointerAddressSpace() == 0) { LI.setOperand(0, SI->getOperand(2)); return &LI; diff --git a/llvm/lib/Transforms/Scalar/JumpThreading.cpp b/llvm/lib/Transforms/Scalar/JumpThreading.cpp index d3b9a34ba39..f71376827a4 100644 --- a/llvm/lib/Transforms/Scalar/JumpThreading.cpp +++ b/llvm/lib/Transforms/Scalar/JumpThreading.cpp @@ -769,7 +769,7 @@ bool JumpThreading::ProcessBlock(BasicBlock *BB) { // If we're branching on a conditional, LVI might be able to determine // it's value at the branch instruction. We only handle comparisons // against a constant at this time. - // TODO: This should be extended to handle switches as well. + // TODO: This should be extended to handle switches as well. BranchInst *CondBr = dyn_cast<BranchInst>(BB->getTerminator()); Constant *CondConst = dyn_cast<Constant>(CondCmp->getOperand(1)); if (CondBr && CondConst && CondBr->isConditional()) { @@ -877,7 +877,7 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) { BasicBlock::iterator BBIt = LI; if (Value *AvailableVal = - FindAvailableLoadedValue(LoadedPtr, LoadBB, BBIt)) { + FindAvailableLoadedValue(LoadedPtr, LoadBB, BBIt, 6)) { // If the value if the load is locally available within the block, just use // it. This frequently occurs for reg2mem'd allocas. //cerr << "LOAD ELIMINATED:\n" << *BBIt << *LI << "\n"; @@ -922,8 +922,7 @@ bool JumpThreading::SimplifyPartiallyRedundantLoad(LoadInst *LI) { // Scan the predecessor to see if the value is available in the pred. BBIt = PredBB->end(); AAMDNodes ThisAATags; - Value *PredAvailable = FindAvailableLoadedValue(LoadedPtr, PredBB, BBIt, - DEF_MAX_INSTS_TO_SCAN, + Value *PredAvailable = FindAvailableLoadedValue(LoadedPtr, PredBB, BBIt, 6, nullptr, &ThisAATags); if (!PredAvailable) { OneUnavailablePred = PredBB; |
