forked from OSchip/llvm-project
Factor a bunch of functionality related to memcpy and memset transforms out of
GVN and into its own pass. llvm-svn: 49419
This commit is contained in:
Owen Anderson
parent
8ee792d1b6
commit
ef9a6fd5c2
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@ -112,6 +112,7 @@ namespace {
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(void) llvm::createPredicateSimplifierPass();
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(void) llvm::createPredicateSimplifierPass();
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(void) llvm::createCodeGenPreparePass();
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(void) llvm::createCodeGenPreparePass();
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(void) llvm::createGVNPass();
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(void) llvm::createGVNPass();
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(void) llvm::createMemCpyOptPass();
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(void)new llvm::IntervalPartition();
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(void)new llvm::IntervalPartition();
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(void)new llvm::FindUsedTypes();
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(void)new llvm::FindUsedTypes();
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@ -303,6 +303,13 @@ FunctionPass *createGVNPREPass();
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//
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//
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FunctionPass *createGVNPass();
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FunctionPass *createGVNPass();
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//===----------------------------------------------------------------------===//
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//
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// MemCpyOpt - This pass performs optimizations related to eliminating memcpy
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// calls and/or combining multiple stores into memset's.
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//
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FunctionPass *createMemCpyOptPass();
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//===----------------------------------------------------------------------===//
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//===----------------------------------------------------------------------===//
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//
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//
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// CodeGenPrepare - This pass prepares a function for instruction selection.
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// CodeGenPrepare - This pass prepares a function for instruction selection.
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@ -42,14 +42,6 @@ using namespace llvm;
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STATISTIC(NumGVNInstr, "Number of instructions deleted");
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STATISTIC(NumGVNInstr, "Number of instructions deleted");
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STATISTIC(NumGVNLoad, "Number of loads deleted");
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STATISTIC(NumGVNLoad, "Number of loads deleted");
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STATISTIC(NumMemSetInfer, "Number of memsets inferred");
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namespace {
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cl::opt<bool>
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FormMemSet("form-memset-from-stores",
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cl::desc("Transform straight-line stores to memsets"),
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cl::init(true), cl::Hidden);
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}
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//===----------------------------------------------------------------------===//
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//===----------------------------------------------------------------------===//
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// ValueTable Class
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// ValueTable Class
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@ -668,17 +660,12 @@ namespace {
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bool processLoad(LoadInst* L,
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bool processLoad(LoadInst* L,
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DenseMap<Value*, LoadInst*> &lastLoad,
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DenseMap<Value*, LoadInst*> &lastLoad,
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SmallVectorImpl<Instruction*> &toErase);
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SmallVectorImpl<Instruction*> &toErase);
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bool processStore(StoreInst *SI, SmallVectorImpl<Instruction*> &toErase);
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bool processInstruction(Instruction* I,
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bool processInstruction(Instruction* I,
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ValueNumberedSet& currAvail,
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ValueNumberedSet& currAvail,
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DenseMap<Value*, LoadInst*>& lastSeenLoad,
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DenseMap<Value*, LoadInst*>& lastSeenLoad,
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SmallVectorImpl<Instruction*> &toErase);
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SmallVectorImpl<Instruction*> &toErase);
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bool processNonLocalLoad(LoadInst* L,
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bool processNonLocalLoad(LoadInst* L,
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SmallVectorImpl<Instruction*> &toErase);
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SmallVectorImpl<Instruction*> &toErase);
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bool processMemCpy(MemCpyInst* M, MemCpyInst* MDep,
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SmallVectorImpl<Instruction*> &toErase);
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bool performCallSlotOptzn(MemCpyInst* cpy, CallInst* C,
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SmallVectorImpl<Instruction*> &toErase);
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Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
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Value *GetValueForBlock(BasicBlock *BB, LoadInst* orig,
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DenseMap<BasicBlock*, Value*> &Phis,
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DenseMap<BasicBlock*, Value*> &Phis,
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bool top_level = false);
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bool top_level = false);
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@ -983,593 +970,6 @@ bool GVN::processLoad(LoadInst *L, DenseMap<Value*, LoadInst*> &lastLoad,
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return deletedLoad;
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return deletedLoad;
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}
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}
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/// isBytewiseValue - If the specified value can be set by repeating the same
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/// byte in memory, return the i8 value that it is represented with. This is
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/// true for all i8 values obviously, but is also true for i32 0, i32 -1,
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/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated
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/// byte store (e.g. i16 0x1234), return null.
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static Value *isBytewiseValue(Value *V) {
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// All byte-wide stores are splatable, even of arbitrary variables.
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if (V->getType() == Type::Int8Ty) return V;
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// Constant float and double values can be handled as integer values if the
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// corresponding integer value is "byteable". An important case is 0.0.
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if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
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if (CFP->getType() == Type::FloatTy)
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V = ConstantExpr::getBitCast(CFP, Type::Int32Ty);
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if (CFP->getType() == Type::DoubleTy)
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V = ConstantExpr::getBitCast(CFP, Type::Int64Ty);
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// Don't handle long double formats, which have strange constraints.
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}
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// We can handle constant integers that are power of two in size and a
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// multiple of 8 bits.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
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unsigned Width = CI->getBitWidth();
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if (isPowerOf2_32(Width) && Width > 8) {
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// We can handle this value if the recursive binary decomposition is the
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// same at all levels.
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APInt Val = CI->getValue();
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APInt Val2;
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while (Val.getBitWidth() != 8) {
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unsigned NextWidth = Val.getBitWidth()/2;
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Val2 = Val.lshr(NextWidth);
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Val2.trunc(Val.getBitWidth()/2);
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Val.trunc(Val.getBitWidth()/2);
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// If the top/bottom halves aren't the same, reject it.
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if (Val != Val2)
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return 0;
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}
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return ConstantInt::get(Val);
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}
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}
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// Conceptually, we could handle things like:
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// %a = zext i8 %X to i16
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// %b = shl i16 %a, 8
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// %c = or i16 %a, %b
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// but until there is an example that actually needs this, it doesn't seem
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// worth worrying about.
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return 0;
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}
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static int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx,
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bool &VariableIdxFound, TargetData &TD) {
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// Skip over the first indices.
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gep_type_iterator GTI = gep_type_begin(GEP);
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for (unsigned i = 1; i != Idx; ++i, ++GTI)
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/*skip along*/;
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// Compute the offset implied by the rest of the indices.
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int64_t Offset = 0;
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for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
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ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i));
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if (OpC == 0)
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return VariableIdxFound = true;
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if (OpC->isZero()) continue; // No offset.
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// Handle struct indices, which add their field offset to the pointer.
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if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
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Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
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continue;
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}
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// Otherwise, we have a sequential type like an array or vector. Multiply
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// the index by the ElementSize.
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uint64_t Size = TD.getABITypeSize(GTI.getIndexedType());
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Offset += Size*OpC->getSExtValue();
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}
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return Offset;
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}
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/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a
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/// constant offset, and return that constant offset. For example, Ptr1 might
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/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8.
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static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset,
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TargetData &TD) {
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// Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical
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// base. After that base, they may have some number of common (and
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// potentially variable) indices. After that they handle some constant
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// offset, which determines their offset from each other. At this point, we
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// handle no other case.
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GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1);
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GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2);
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if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0))
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return false;
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// Skip any common indices and track the GEP types.
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unsigned Idx = 1;
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for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx)
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if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx))
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break;
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bool VariableIdxFound = false;
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int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD);
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int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD);
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if (VariableIdxFound) return false;
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Offset = Offset2-Offset1;
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return true;
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}
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/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value.
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/// This allows us to analyze stores like:
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/// store 0 -> P+1
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/// store 0 -> P+0
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/// store 0 -> P+3
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/// store 0 -> P+2
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/// which sometimes happens with stores to arrays of structs etc. When we see
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/// the first store, we make a range [1, 2). The second store extends the range
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/// to [0, 2). The third makes a new range [2, 3). The fourth store joins the
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/// two ranges into [0, 3) which is memset'able.
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namespace {
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struct MemsetRange {
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// Start/End - A semi range that describes the span that this range covers.
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// The range is closed at the start and open at the end: [Start, End).
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int64_t Start, End;
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/// StartPtr - The getelementptr instruction that points to the start of the
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/// range.
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Value *StartPtr;
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/// Alignment - The known alignment of the first store.
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unsigned Alignment;
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/// TheStores - The actual stores that make up this range.
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SmallVector<StoreInst*, 16> TheStores;
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bool isProfitableToUseMemset(const TargetData &TD) const;
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};
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} // end anon namespace
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bool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const {
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// If we found more than 8 stores to merge or 64 bytes, use memset.
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if (TheStores.size() >= 8 || End-Start >= 64) return true;
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// Assume that the code generator is capable of merging pairs of stores
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// together if it wants to.
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if (TheStores.size() <= 2) return false;
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// If we have fewer than 8 stores, it can still be worthwhile to do this.
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// For example, merging 4 i8 stores into an i32 store is useful almost always.
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// However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the
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// memset will be split into 2 32-bit stores anyway) and doing so can
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// pessimize the llvm optimizer.
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//
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// Since we don't have perfect knowledge here, make some assumptions: assume
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// the maximum GPR width is the same size as the pointer size and assume that
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// this width can be stored. If so, check to see whether we will end up
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// actually reducing the number of stores used.
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unsigned Bytes = unsigned(End-Start);
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unsigned NumPointerStores = Bytes/TD.getPointerSize();
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// Assume the remaining bytes if any are done a byte at a time.
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unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize();
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// If we will reduce the # stores (according to this heuristic), do the
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// transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32
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// etc.
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return TheStores.size() > NumPointerStores+NumByteStores;
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}
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namespace {
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class MemsetRanges {
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/// Ranges - A sorted list of the memset ranges. We use std::list here
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/// because each element is relatively large and expensive to copy.
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std::list<MemsetRange> Ranges;
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typedef std::list<MemsetRange>::iterator range_iterator;
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TargetData &TD;
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public:
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MemsetRanges(TargetData &td) : TD(td) {}
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typedef std::list<MemsetRange>::const_iterator const_iterator;
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const_iterator begin() const { return Ranges.begin(); }
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const_iterator end() const { return Ranges.end(); }
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bool empty() const { return Ranges.empty(); }
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void addStore(int64_t OffsetFromFirst, StoreInst *SI);
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};
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} // end anon namespace
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/// addStore - Add a new store to the MemsetRanges data structure. This adds a
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/// new range for the specified store at the specified offset, merging into
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/// existing ranges as appropriate.
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void MemsetRanges::addStore(int64_t Start, StoreInst *SI) {
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int64_t End = Start+TD.getTypeStoreSize(SI->getOperand(0)->getType());
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// Do a linear search of the ranges to see if this can be joined and/or to
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// find the insertion point in the list. We keep the ranges sorted for
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// simplicity here. This is a linear search of a linked list, which is ugly,
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// however the number of ranges is limited, so this won't get crazy slow.
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range_iterator I = Ranges.begin(), E = Ranges.end();
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while (I != E && Start > I->End)
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++I;
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// We now know that I == E, in which case we didn't find anything to merge
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// with, or that Start <= I->End. If End < I->Start or I == E, then we need
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// to insert a new range. Handle this now.
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if (I == E || End < I->Start) {
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MemsetRange &R = *Ranges.insert(I, MemsetRange());
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R.Start = Start;
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R.End = End;
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R.StartPtr = SI->getPointerOperand();
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R.Alignment = SI->getAlignment();
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R.TheStores.push_back(SI);
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return;
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}
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// This store overlaps with I, add it.
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I->TheStores.push_back(SI);
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// At this point, we may have an interval that completely contains our store.
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// If so, just add it to the interval and return.
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if (I->Start <= Start && I->End >= End)
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return;
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// Now we know that Start <= I->End and End >= I->Start so the range overlaps
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// but is not entirely contained within the range.
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// See if the range extends the start of the range. In this case, it couldn't
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// possibly cause it to join the prior range, because otherwise we would have
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// stopped on *it*.
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if (Start < I->Start) {
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I->Start = Start;
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I->StartPtr = SI->getPointerOperand();
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}
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// Now we know that Start <= I->End and Start >= I->Start (so the startpoint
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// is in or right at the end of I), and that End >= I->Start. Extend I out to
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// End.
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if (End > I->End) {
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I->End = End;
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range_iterator NextI = I;;
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while (++NextI != E && End >= NextI->Start) {
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// Merge the range in.
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I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end());
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if (NextI->End > I->End)
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I->End = NextI->End;
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Ranges.erase(NextI);
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NextI = I;
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}
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}
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}
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/// processStore - When GVN is scanning forward over instructions, we look for
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/// some other patterns to fold away. In particular, this looks for stores to
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/// neighboring locations of memory. If it sees enough consequtive ones
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/// (currently 4) it attempts to merge them together into a memcpy/memset.
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bool GVN::processStore(StoreInst *SI, SmallVectorImpl<Instruction*> &toErase) {
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if (!FormMemSet) return false;
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if (SI->isVolatile()) return false;
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// There are two cases that are interesting for this code to handle: memcpy
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// and memset. Right now we only handle memset.
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// Ensure that the value being stored is something that can be memset'able a
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// byte at a time like "0" or "-1" or any width, as well as things like
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// 0xA0A0A0A0 and 0.0.
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Value *ByteVal = isBytewiseValue(SI->getOperand(0));
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if (!ByteVal)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
TargetData &TD = getAnalysis<TargetData>();
|
|
||||||
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
|
|
||||||
|
|
||||||
// Okay, so we now have a single store that can be splatable. Scan to find
|
|
||||||
// all subsequent stores of the same value to offset from the same pointer.
|
|
||||||
// Join these together into ranges, so we can decide whether contiguous blocks
|
|
||||||
// are stored.
|
|
||||||
MemsetRanges Ranges(TD);
|
|
||||||
|
|
||||||
Value *StartPtr = SI->getPointerOperand();
|
|
||||||
|
|
||||||
BasicBlock::iterator BI = SI;
|
|
||||||
for (++BI; !isa<TerminatorInst>(BI); ++BI) {
|
|
||||||
if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) {
|
|
||||||
// If the call is readnone, ignore it, otherwise bail out. We don't even
|
|
||||||
// allow readonly here because we don't want something like:
|
|
||||||
// A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A).
|
|
||||||
if (AA.getModRefBehavior(CallSite::get(BI)) ==
|
|
||||||
AliasAnalysis::DoesNotAccessMemory)
|
|
||||||
continue;
|
|
||||||
|
|
||||||
// TODO: If this is a memset, try to join it in.
|
|
||||||
|
|
||||||
break;
|
|
||||||
} else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI))
|
|
||||||
break;
|
|
||||||
|
|
||||||
// If this is a non-store instruction it is fine, ignore it.
|
|
||||||
StoreInst *NextStore = dyn_cast<StoreInst>(BI);
|
|
||||||
if (NextStore == 0) continue;
|
|
||||||
|
|
||||||
// If this is a store, see if we can merge it in.
|
|
||||||
if (NextStore->isVolatile()) break;
|
|
||||||
|
|
||||||
// Check to see if this stored value is of the same byte-splattable value.
|
|
||||||
if (ByteVal != isBytewiseValue(NextStore->getOperand(0)))
|
|
||||||
break;
|
|
||||||
|
|
||||||
// Check to see if this store is to a constant offset from the start ptr.
|
|
||||||
int64_t Offset;
|
|
||||||
if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, TD))
|
|
||||||
break;
|
|
||||||
|
|
||||||
Ranges.addStore(Offset, NextStore);
|
|
||||||
}
|
|
||||||
|
|
||||||
// If we have no ranges, then we just had a single store with nothing that
|
|
||||||
// could be merged in. This is a very common case of course.
|
|
||||||
if (Ranges.empty())
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// If we had at least one store that could be merged in, add the starting
|
|
||||||
// store as well. We try to avoid this unless there is at least something
|
|
||||||
// interesting as a small compile-time optimization.
|
|
||||||
Ranges.addStore(0, SI);
|
|
||||||
|
|
||||||
|
|
||||||
Function *MemSetF = 0;
|
|
||||||
|
|
||||||
// Now that we have full information about ranges, loop over the ranges and
|
|
||||||
// emit memset's for anything big enough to be worthwhile.
|
|
||||||
bool MadeChange = false;
|
|
||||||
for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
|
|
||||||
I != E; ++I) {
|
|
||||||
const MemsetRange &Range = *I;
|
|
||||||
|
|
||||||
if (Range.TheStores.size() == 1) continue;
|
|
||||||
|
|
||||||
// If it is profitable to lower this range to memset, do so now.
|
|
||||||
if (!Range.isProfitableToUseMemset(TD))
|
|
||||||
continue;
|
|
||||||
|
|
||||||
// Otherwise, we do want to transform this! Create a new memset. We put
|
|
||||||
// the memset right before the first instruction that isn't part of this
|
|
||||||
// memset block. This ensure that the memset is dominated by any addressing
|
|
||||||
// instruction needed by the start of the block.
|
|
||||||
BasicBlock::iterator InsertPt = BI;
|
|
||||||
|
|
||||||
if (MemSetF == 0)
|
|
||||||
MemSetF = Intrinsic::getDeclaration(SI->getParent()->getParent()
|
|
||||||
->getParent(), Intrinsic::memset_i64);
|
|
||||||
|
|
||||||
// Get the starting pointer of the block.
|
|
||||||
StartPtr = Range.StartPtr;
|
|
||||||
|
|
||||||
// Cast the start ptr to be i8* as memset requires.
|
|
||||||
const Type *i8Ptr = PointerType::getUnqual(Type::Int8Ty);
|
|
||||||
if (StartPtr->getType() != i8Ptr)
|
|
||||||
StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getNameStart(),
|
|
||||||
InsertPt);
|
|
||||||
|
|
||||||
Value *Ops[] = {
|
|
||||||
StartPtr, ByteVal, // Start, value
|
|
||||||
ConstantInt::get(Type::Int64Ty, Range.End-Range.Start), // size
|
|
||||||
ConstantInt::get(Type::Int32Ty, Range.Alignment) // align
|
|
||||||
};
|
|
||||||
Value *C = CallInst::Create(MemSetF, Ops, Ops+4, "", InsertPt);
|
|
||||||
DEBUG(cerr << "Replace stores:\n";
|
|
||||||
for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i)
|
|
||||||
cerr << *Range.TheStores[i];
|
|
||||||
cerr << "With: " << *C); C=C;
|
|
||||||
|
|
||||||
// Zap all the stores.
|
|
||||||
toErase.append(Range.TheStores.begin(), Range.TheStores.end());
|
|
||||||
++NumMemSetInfer;
|
|
||||||
MadeChange = true;
|
|
||||||
}
|
|
||||||
|
|
||||||
return MadeChange;
|
|
||||||
}
|
|
||||||
|
|
||||||
|
|
||||||
/// performCallSlotOptzn - takes a memcpy and a call that it depends on,
|
|
||||||
/// and checks for the possibility of a call slot optimization by having
|
|
||||||
/// the call write its result directly into the destination of the memcpy.
|
|
||||||
bool GVN::performCallSlotOptzn(MemCpyInst *cpy, CallInst *C,
|
|
||||||
SmallVectorImpl<Instruction*> &toErase) {
|
|
||||||
// The general transformation to keep in mind is
|
|
||||||
//
|
|
||||||
// call @func(..., src, ...)
|
|
||||||
// memcpy(dest, src, ...)
|
|
||||||
//
|
|
||||||
// ->
|
|
||||||
//
|
|
||||||
// memcpy(dest, src, ...)
|
|
||||||
// call @func(..., dest, ...)
|
|
||||||
//
|
|
||||||
// Since moving the memcpy is technically awkward, we additionally check that
|
|
||||||
// src only holds uninitialized values at the moment of the call, meaning that
|
|
||||||
// the memcpy can be discarded rather than moved.
|
|
||||||
|
|
||||||
// Deliberately get the source and destination with bitcasts stripped away,
|
|
||||||
// because we'll need to do type comparisons based on the underlying type.
|
|
||||||
Value* cpyDest = cpy->getDest();
|
|
||||||
Value* cpySrc = cpy->getSource();
|
|
||||||
CallSite CS = CallSite::get(C);
|
|
||||||
|
|
||||||
// We need to be able to reason about the size of the memcpy, so we require
|
|
||||||
// that it be a constant.
|
|
||||||
ConstantInt* cpyLength = dyn_cast<ConstantInt>(cpy->getLength());
|
|
||||||
if (!cpyLength)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// Require that src be an alloca. This simplifies the reasoning considerably.
|
|
||||||
AllocaInst* srcAlloca = dyn_cast<AllocaInst>(cpySrc);
|
|
||||||
if (!srcAlloca)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// Check that all of src is copied to dest.
|
|
||||||
TargetData& TD = getAnalysis<TargetData>();
|
|
||||||
|
|
||||||
ConstantInt* srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize());
|
|
||||||
if (!srcArraySize)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
uint64_t srcSize = TD.getABITypeSize(srcAlloca->getAllocatedType()) *
|
|
||||||
srcArraySize->getZExtValue();
|
|
||||||
|
|
||||||
if (cpyLength->getZExtValue() < srcSize)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// Check that accessing the first srcSize bytes of dest will not cause a
|
|
||||||
// trap. Otherwise the transform is invalid since it might cause a trap
|
|
||||||
// to occur earlier than it otherwise would.
|
|
||||||
if (AllocaInst* A = dyn_cast<AllocaInst>(cpyDest)) {
|
|
||||||
// The destination is an alloca. Check it is larger than srcSize.
|
|
||||||
ConstantInt* destArraySize = dyn_cast<ConstantInt>(A->getArraySize());
|
|
||||||
if (!destArraySize)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
uint64_t destSize = TD.getABITypeSize(A->getAllocatedType()) *
|
|
||||||
destArraySize->getZExtValue();
|
|
||||||
|
|
||||||
if (destSize < srcSize)
|
|
||||||
return false;
|
|
||||||
} else if (Argument* A = dyn_cast<Argument>(cpyDest)) {
|
|
||||||
// If the destination is an sret parameter then only accesses that are
|
|
||||||
// outside of the returned struct type can trap.
|
|
||||||
if (!A->hasStructRetAttr())
|
|
||||||
return false;
|
|
||||||
|
|
||||||
const Type* StructTy = cast<PointerType>(A->getType())->getElementType();
|
|
||||||
uint64_t destSize = TD.getABITypeSize(StructTy);
|
|
||||||
|
|
||||||
if (destSize < srcSize)
|
|
||||||
return false;
|
|
||||||
} else {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
// Check that src is not accessed except via the call and the memcpy. This
|
|
||||||
// guarantees that it holds only undefined values when passed in (so the final
|
|
||||||
// memcpy can be dropped), that it is not read or written between the call and
|
|
||||||
// the memcpy, and that writing beyond the end of it is undefined.
|
|
||||||
SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(),
|
|
||||||
srcAlloca->use_end());
|
|
||||||
while (!srcUseList.empty()) {
|
|
||||||
User* UI = srcUseList.back();
|
|
||||||
srcUseList.pop_back();
|
|
||||||
|
|
||||||
if (isa<GetElementPtrInst>(UI) || isa<BitCastInst>(UI)) {
|
|
||||||
for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
|
|
||||||
I != E; ++I)
|
|
||||||
srcUseList.push_back(*I);
|
|
||||||
} else if (UI != C && UI != cpy) {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
// Since we're changing the parameter to the callsite, we need to make sure
|
|
||||||
// that what would be the new parameter dominates the callsite.
|
|
||||||
DominatorTree& DT = getAnalysis<DominatorTree>();
|
|
||||||
if (Instruction* cpyDestInst = dyn_cast<Instruction>(cpyDest))
|
|
||||||
if (!DT.dominates(cpyDestInst, C))
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// In addition to knowing that the call does not access src in some
|
|
||||||
// unexpected manner, for example via a global, which we deduce from
|
|
||||||
// the use analysis, we also need to know that it does not sneakily
|
|
||||||
// access dest. We rely on AA to figure this out for us.
|
|
||||||
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
|
||||||
if (AA.getModRefInfo(C, cpy->getRawDest(), srcSize) !=
|
|
||||||
AliasAnalysis::NoModRef)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// All the checks have passed, so do the transformation.
|
|
||||||
for (unsigned i = 0; i < CS.arg_size(); ++i)
|
|
||||||
if (CS.getArgument(i) == cpySrc) {
|
|
||||||
if (cpySrc->getType() != cpyDest->getType())
|
|
||||||
cpyDest = CastInst::createPointerCast(cpyDest, cpySrc->getType(),
|
|
||||||
cpyDest->getName(), C);
|
|
||||||
CS.setArgument(i, cpyDest);
|
|
||||||
}
|
|
||||||
|
|
||||||
// Drop any cached information about the call, because we may have changed
|
|
||||||
// its dependence information by changing its parameter.
|
|
||||||
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
||||||
MD.dropInstruction(C);
|
|
||||||
|
|
||||||
// Remove the memcpy
|
|
||||||
MD.removeInstruction(cpy);
|
|
||||||
toErase.push_back(cpy);
|
|
||||||
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
|
|
||||||
/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which
|
|
||||||
/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be
|
|
||||||
/// a memcpy from X to Z (or potentially a memmove, depending on circumstances).
|
|
||||||
/// This allows later passes to remove the first memcpy altogether.
|
|
||||||
bool GVN::processMemCpy(MemCpyInst* M, MemCpyInst* MDep,
|
|
||||||
SmallVectorImpl<Instruction*> &toErase) {
|
|
||||||
// We can only transforms memcpy's where the dest of one is the source of the
|
|
||||||
// other
|
|
||||||
if (M->getSource() != MDep->getDest())
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// Second, the length of the memcpy's must be the same, or the preceeding one
|
|
||||||
// must be larger than the following one.
|
|
||||||
ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength());
|
|
||||||
ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength());
|
|
||||||
if (!C1 || !C2)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
uint64_t DepSize = C1->getValue().getZExtValue();
|
|
||||||
uint64_t CpySize = C2->getValue().getZExtValue();
|
|
||||||
|
|
||||||
if (DepSize < CpySize)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// Finally, we have to make sure that the dest of the second does not
|
|
||||||
// alias the source of the first
|
|
||||||
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
|
||||||
if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) !=
|
|
||||||
AliasAnalysis::NoAlias)
|
|
||||||
return false;
|
|
||||||
else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) !=
|
|
||||||
AliasAnalysis::NoAlias)
|
|
||||||
return false;
|
|
||||||
else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize)
|
|
||||||
!= AliasAnalysis::NoAlias)
|
|
||||||
return false;
|
|
||||||
|
|
||||||
// If all checks passed, then we can transform these memcpy's
|
|
||||||
Function* MemCpyFun = Intrinsic::getDeclaration(
|
|
||||||
M->getParent()->getParent()->getParent(),
|
|
||||||
M->getIntrinsicID());
|
|
||||||
|
|
||||||
std::vector<Value*> args;
|
|
||||||
args.push_back(M->getRawDest());
|
|
||||||
args.push_back(MDep->getRawSource());
|
|
||||||
args.push_back(M->getLength());
|
|
||||||
args.push_back(M->getAlignment());
|
|
||||||
|
|
||||||
CallInst* C = CallInst::Create(MemCpyFun, args.begin(), args.end(), "", M);
|
|
||||||
|
|
||||||
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
||||||
if (MD.getDependency(C) == MDep) {
|
|
||||||
MD.dropInstruction(M);
|
|
||||||
toErase.push_back(M);
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
|
|
||||||
MD.removeInstruction(C);
|
|
||||||
toErase.push_back(C);
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
/// processInstruction - When calculating availability, handle an instruction
|
/// processInstruction - When calculating availability, handle an instruction
|
||||||
/// by inserting it into the appropriate sets
|
/// by inserting it into the appropriate sets
|
||||||
bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
|
bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
|
||||||
|
|
@ -1578,31 +978,11 @@ bool GVN::processInstruction(Instruction *I, ValueNumberedSet &currAvail,
|
||||||
if (LoadInst* L = dyn_cast<LoadInst>(I))
|
if (LoadInst* L = dyn_cast<LoadInst>(I))
|
||||||
return processLoad(L, lastSeenLoad, toErase);
|
return processLoad(L, lastSeenLoad, toErase);
|
||||||
|
|
||||||
if (StoreInst *SI = dyn_cast<StoreInst>(I))
|
|
||||||
return processStore(SI, toErase);
|
|
||||||
|
|
||||||
// Allocations are always uniquely numbered, so we can save time and memory
|
// Allocations are always uniquely numbered, so we can save time and memory
|
||||||
// by fast failing them.
|
// by fast failing them.
|
||||||
if (isa<AllocationInst>(I))
|
if (isa<AllocationInst>(I))
|
||||||
return false;
|
return false;
|
||||||
|
|
||||||
if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) {
|
|
||||||
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
|
||||||
|
|
||||||
// The are two possible optimizations we can do for memcpy:
|
|
||||||
// a) memcpy-memcpy xform which exposes redundance for DSE
|
|
||||||
// b) call-memcpy xform for return slot optimization
|
|
||||||
Instruction* dep = MD.getDependency(M);
|
|
||||||
if (dep == MemoryDependenceAnalysis::None ||
|
|
||||||
dep == MemoryDependenceAnalysis::NonLocal)
|
|
||||||
return false;
|
|
||||||
if (MemCpyInst *MemCpy = dyn_cast<MemCpyInst>(dep))
|
|
||||||
return processMemCpy(M, MemCpy, toErase);
|
|
||||||
if (CallInst* C = dyn_cast<CallInst>(dep))
|
|
||||||
return performCallSlotOptzn(M, C, toErase);
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
unsigned num = VN.lookup_or_add(I);
|
unsigned num = VN.lookup_or_add(I);
|
||||||
|
|
||||||
// Collapse PHI nodes
|
// Collapse PHI nodes
|
||||||
|
|
|
||||||
|
|
@ -0,0 +1,769 @@
|
||||||
|
//===- MemCpyOptimizer.cpp - Optimize use of memcpy and friends -----------===//
|
||||||
|
//
|
||||||
|
// The LLVM Compiler Infrastructure
|
||||||
|
//
|
||||||
|
// This file is distributed under the University of Illinois Open Source
|
||||||
|
// License. See LICENSE.TXT for details.
|
||||||
|
//
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
//
|
||||||
|
// This pass performs various transformations related to eliminating memcpy
|
||||||
|
// calls, or transforming sets of stores into memset's.
|
||||||
|
//
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
|
||||||
|
#define DEBUG_TYPE "memcpyopt"
|
||||||
|
#include "llvm/Transforms/Scalar.h"
|
||||||
|
#include "llvm/BasicBlock.h"
|
||||||
|
#include "llvm/Constants.h"
|
||||||
|
#include "llvm/DerivedTypes.h"
|
||||||
|
#include "llvm/Function.h"
|
||||||
|
#include "llvm/IntrinsicInst.h"
|
||||||
|
#include "llvm/Instructions.h"
|
||||||
|
#include "llvm/ParameterAttributes.h"
|
||||||
|
#include "llvm/Value.h"
|
||||||
|
#include "llvm/ADT/DepthFirstIterator.h"
|
||||||
|
#include "llvm/ADT/SmallVector.h"
|
||||||
|
#include "llvm/ADT/Statistic.h"
|
||||||
|
#include "llvm/Analysis/Dominators.h"
|
||||||
|
#include "llvm/Analysis/AliasAnalysis.h"
|
||||||
|
#include "llvm/Analysis/MemoryDependenceAnalysis.h"
|
||||||
|
#include "llvm/Support/CFG.h"
|
||||||
|
#include "llvm/Support/CommandLine.h"
|
||||||
|
#include "llvm/Support/Compiler.h"
|
||||||
|
#include "llvm/Support/Debug.h"
|
||||||
|
#include "llvm/Support/GetElementPtrTypeIterator.h"
|
||||||
|
#include "llvm/Target/TargetData.h"
|
||||||
|
#include <list>
|
||||||
|
using namespace llvm;
|
||||||
|
|
||||||
|
STATISTIC(NumMemCpyInstr, "Number of memcpy instructions deleted");
|
||||||
|
STATISTIC(NumMemSetInfer, "Number of memsets inferred");
|
||||||
|
|
||||||
|
namespace {
|
||||||
|
cl::opt<bool>
|
||||||
|
FormMemSet("form-memset-from-stores",
|
||||||
|
cl::desc("Transform straight-line stores to memsets"),
|
||||||
|
cl::init(true), cl::Hidden);
|
||||||
|
}
|
||||||
|
|
||||||
|
/// isBytewiseValue - If the specified value can be set by repeating the same
|
||||||
|
/// byte in memory, return the i8 value that it is represented with. This is
|
||||||
|
/// true for all i8 values obviously, but is also true for i32 0, i32 -1,
|
||||||
|
/// i16 0xF0F0, double 0.0 etc. If the value can't be handled with a repeated
|
||||||
|
/// byte store (e.g. i16 0x1234), return null.
|
||||||
|
static Value *isBytewiseValue(Value *V) {
|
||||||
|
// All byte-wide stores are splatable, even of arbitrary variables.
|
||||||
|
if (V->getType() == Type::Int8Ty) return V;
|
||||||
|
|
||||||
|
// Constant float and double values can be handled as integer values if the
|
||||||
|
// corresponding integer value is "byteable". An important case is 0.0.
|
||||||
|
if (ConstantFP *CFP = dyn_cast<ConstantFP>(V)) {
|
||||||
|
if (CFP->getType() == Type::FloatTy)
|
||||||
|
V = ConstantExpr::getBitCast(CFP, Type::Int32Ty);
|
||||||
|
if (CFP->getType() == Type::DoubleTy)
|
||||||
|
V = ConstantExpr::getBitCast(CFP, Type::Int64Ty);
|
||||||
|
// Don't handle long double formats, which have strange constraints.
|
||||||
|
}
|
||||||
|
|
||||||
|
// We can handle constant integers that are power of two in size and a
|
||||||
|
// multiple of 8 bits.
|
||||||
|
if (ConstantInt *CI = dyn_cast<ConstantInt>(V)) {
|
||||||
|
unsigned Width = CI->getBitWidth();
|
||||||
|
if (isPowerOf2_32(Width) && Width > 8) {
|
||||||
|
// We can handle this value if the recursive binary decomposition is the
|
||||||
|
// same at all levels.
|
||||||
|
APInt Val = CI->getValue();
|
||||||
|
APInt Val2;
|
||||||
|
while (Val.getBitWidth() != 8) {
|
||||||
|
unsigned NextWidth = Val.getBitWidth()/2;
|
||||||
|
Val2 = Val.lshr(NextWidth);
|
||||||
|
Val2.trunc(Val.getBitWidth()/2);
|
||||||
|
Val.trunc(Val.getBitWidth()/2);
|
||||||
|
|
||||||
|
// If the top/bottom halves aren't the same, reject it.
|
||||||
|
if (Val != Val2)
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
return ConstantInt::get(Val);
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
// Conceptually, we could handle things like:
|
||||||
|
// %a = zext i8 %X to i16
|
||||||
|
// %b = shl i16 %a, 8
|
||||||
|
// %c = or i16 %a, %b
|
||||||
|
// but until there is an example that actually needs this, it doesn't seem
|
||||||
|
// worth worrying about.
|
||||||
|
return 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
static int64_t GetOffsetFromIndex(const GetElementPtrInst *GEP, unsigned Idx,
|
||||||
|
bool &VariableIdxFound, TargetData &TD) {
|
||||||
|
// Skip over the first indices.
|
||||||
|
gep_type_iterator GTI = gep_type_begin(GEP);
|
||||||
|
for (unsigned i = 1; i != Idx; ++i, ++GTI)
|
||||||
|
/*skip along*/;
|
||||||
|
|
||||||
|
// Compute the offset implied by the rest of the indices.
|
||||||
|
int64_t Offset = 0;
|
||||||
|
for (unsigned i = Idx, e = GEP->getNumOperands(); i != e; ++i, ++GTI) {
|
||||||
|
ConstantInt *OpC = dyn_cast<ConstantInt>(GEP->getOperand(i));
|
||||||
|
if (OpC == 0)
|
||||||
|
return VariableIdxFound = true;
|
||||||
|
if (OpC->isZero()) continue; // No offset.
|
||||||
|
|
||||||
|
// Handle struct indices, which add their field offset to the pointer.
|
||||||
|
if (const StructType *STy = dyn_cast<StructType>(*GTI)) {
|
||||||
|
Offset += TD.getStructLayout(STy)->getElementOffset(OpC->getZExtValue());
|
||||||
|
continue;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Otherwise, we have a sequential type like an array or vector. Multiply
|
||||||
|
// the index by the ElementSize.
|
||||||
|
uint64_t Size = TD.getABITypeSize(GTI.getIndexedType());
|
||||||
|
Offset += Size*OpC->getSExtValue();
|
||||||
|
}
|
||||||
|
|
||||||
|
return Offset;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// IsPointerOffset - Return true if Ptr1 is provably equal to Ptr2 plus a
|
||||||
|
/// constant offset, and return that constant offset. For example, Ptr1 might
|
||||||
|
/// be &A[42], and Ptr2 might be &A[40]. In this case offset would be -8.
|
||||||
|
static bool IsPointerOffset(Value *Ptr1, Value *Ptr2, int64_t &Offset,
|
||||||
|
TargetData &TD) {
|
||||||
|
// Right now we handle the case when Ptr1/Ptr2 are both GEPs with an identical
|
||||||
|
// base. After that base, they may have some number of common (and
|
||||||
|
// potentially variable) indices. After that they handle some constant
|
||||||
|
// offset, which determines their offset from each other. At this point, we
|
||||||
|
// handle no other case.
|
||||||
|
GetElementPtrInst *GEP1 = dyn_cast<GetElementPtrInst>(Ptr1);
|
||||||
|
GetElementPtrInst *GEP2 = dyn_cast<GetElementPtrInst>(Ptr2);
|
||||||
|
if (!GEP1 || !GEP2 || GEP1->getOperand(0) != GEP2->getOperand(0))
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Skip any common indices and track the GEP types.
|
||||||
|
unsigned Idx = 1;
|
||||||
|
for (; Idx != GEP1->getNumOperands() && Idx != GEP2->getNumOperands(); ++Idx)
|
||||||
|
if (GEP1->getOperand(Idx) != GEP2->getOperand(Idx))
|
||||||
|
break;
|
||||||
|
|
||||||
|
bool VariableIdxFound = false;
|
||||||
|
int64_t Offset1 = GetOffsetFromIndex(GEP1, Idx, VariableIdxFound, TD);
|
||||||
|
int64_t Offset2 = GetOffsetFromIndex(GEP2, Idx, VariableIdxFound, TD);
|
||||||
|
if (VariableIdxFound) return false;
|
||||||
|
|
||||||
|
Offset = Offset2-Offset1;
|
||||||
|
return true;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
/// MemsetRange - Represents a range of memset'd bytes with the ByteVal value.
|
||||||
|
/// This allows us to analyze stores like:
|
||||||
|
/// store 0 -> P+1
|
||||||
|
/// store 0 -> P+0
|
||||||
|
/// store 0 -> P+3
|
||||||
|
/// store 0 -> P+2
|
||||||
|
/// which sometimes happens with stores to arrays of structs etc. When we see
|
||||||
|
/// the first store, we make a range [1, 2). The second store extends the range
|
||||||
|
/// to [0, 2). The third makes a new range [2, 3). The fourth store joins the
|
||||||
|
/// two ranges into [0, 3) which is memset'able.
|
||||||
|
namespace {
|
||||||
|
struct MemsetRange {
|
||||||
|
// Start/End - A semi range that describes the span that this range covers.
|
||||||
|
// The range is closed at the start and open at the end: [Start, End).
|
||||||
|
int64_t Start, End;
|
||||||
|
|
||||||
|
/// StartPtr - The getelementptr instruction that points to the start of the
|
||||||
|
/// range.
|
||||||
|
Value *StartPtr;
|
||||||
|
|
||||||
|
/// Alignment - The known alignment of the first store.
|
||||||
|
unsigned Alignment;
|
||||||
|
|
||||||
|
/// TheStores - The actual stores that make up this range.
|
||||||
|
SmallVector<StoreInst*, 16> TheStores;
|
||||||
|
|
||||||
|
bool isProfitableToUseMemset(const TargetData &TD) const;
|
||||||
|
|
||||||
|
};
|
||||||
|
} // end anon namespace
|
||||||
|
|
||||||
|
bool MemsetRange::isProfitableToUseMemset(const TargetData &TD) const {
|
||||||
|
// If we found more than 8 stores to merge or 64 bytes, use memset.
|
||||||
|
if (TheStores.size() >= 8 || End-Start >= 64) return true;
|
||||||
|
|
||||||
|
// Assume that the code generator is capable of merging pairs of stores
|
||||||
|
// together if it wants to.
|
||||||
|
if (TheStores.size() <= 2) return false;
|
||||||
|
|
||||||
|
// If we have fewer than 8 stores, it can still be worthwhile to do this.
|
||||||
|
// For example, merging 4 i8 stores into an i32 store is useful almost always.
|
||||||
|
// However, merging 2 32-bit stores isn't useful on a 32-bit architecture (the
|
||||||
|
// memset will be split into 2 32-bit stores anyway) and doing so can
|
||||||
|
// pessimize the llvm optimizer.
|
||||||
|
//
|
||||||
|
// Since we don't have perfect knowledge here, make some assumptions: assume
|
||||||
|
// the maximum GPR width is the same size as the pointer size and assume that
|
||||||
|
// this width can be stored. If so, check to see whether we will end up
|
||||||
|
// actually reducing the number of stores used.
|
||||||
|
unsigned Bytes = unsigned(End-Start);
|
||||||
|
unsigned NumPointerStores = Bytes/TD.getPointerSize();
|
||||||
|
|
||||||
|
// Assume the remaining bytes if any are done a byte at a time.
|
||||||
|
unsigned NumByteStores = Bytes - NumPointerStores*TD.getPointerSize();
|
||||||
|
|
||||||
|
// If we will reduce the # stores (according to this heuristic), do the
|
||||||
|
// transformation. This encourages merging 4 x i8 -> i32 and 2 x i16 -> i32
|
||||||
|
// etc.
|
||||||
|
return TheStores.size() > NumPointerStores+NumByteStores;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
namespace {
|
||||||
|
class MemsetRanges {
|
||||||
|
/// Ranges - A sorted list of the memset ranges. We use std::list here
|
||||||
|
/// because each element is relatively large and expensive to copy.
|
||||||
|
std::list<MemsetRange> Ranges;
|
||||||
|
typedef std::list<MemsetRange>::iterator range_iterator;
|
||||||
|
TargetData &TD;
|
||||||
|
public:
|
||||||
|
MemsetRanges(TargetData &td) : TD(td) {}
|
||||||
|
|
||||||
|
typedef std::list<MemsetRange>::const_iterator const_iterator;
|
||||||
|
const_iterator begin() const { return Ranges.begin(); }
|
||||||
|
const_iterator end() const { return Ranges.end(); }
|
||||||
|
bool empty() const { return Ranges.empty(); }
|
||||||
|
|
||||||
|
void addStore(int64_t OffsetFromFirst, StoreInst *SI);
|
||||||
|
};
|
||||||
|
|
||||||
|
} // end anon namespace
|
||||||
|
|
||||||
|
|
||||||
|
/// addStore - Add a new store to the MemsetRanges data structure. This adds a
|
||||||
|
/// new range for the specified store at the specified offset, merging into
|
||||||
|
/// existing ranges as appropriate.
|
||||||
|
void MemsetRanges::addStore(int64_t Start, StoreInst *SI) {
|
||||||
|
int64_t End = Start+TD.getTypeStoreSize(SI->getOperand(0)->getType());
|
||||||
|
|
||||||
|
// Do a linear search of the ranges to see if this can be joined and/or to
|
||||||
|
// find the insertion point in the list. We keep the ranges sorted for
|
||||||
|
// simplicity here. This is a linear search of a linked list, which is ugly,
|
||||||
|
// however the number of ranges is limited, so this won't get crazy slow.
|
||||||
|
range_iterator I = Ranges.begin(), E = Ranges.end();
|
||||||
|
|
||||||
|
while (I != E && Start > I->End)
|
||||||
|
++I;
|
||||||
|
|
||||||
|
// We now know that I == E, in which case we didn't find anything to merge
|
||||||
|
// with, or that Start <= I->End. If End < I->Start or I == E, then we need
|
||||||
|
// to insert a new range. Handle this now.
|
||||||
|
if (I == E || End < I->Start) {
|
||||||
|
MemsetRange &R = *Ranges.insert(I, MemsetRange());
|
||||||
|
R.Start = Start;
|
||||||
|
R.End = End;
|
||||||
|
R.StartPtr = SI->getPointerOperand();
|
||||||
|
R.Alignment = SI->getAlignment();
|
||||||
|
R.TheStores.push_back(SI);
|
||||||
|
return;
|
||||||
|
}
|
||||||
|
|
||||||
|
// This store overlaps with I, add it.
|
||||||
|
I->TheStores.push_back(SI);
|
||||||
|
|
||||||
|
// At this point, we may have an interval that completely contains our store.
|
||||||
|
// If so, just add it to the interval and return.
|
||||||
|
if (I->Start <= Start && I->End >= End)
|
||||||
|
return;
|
||||||
|
|
||||||
|
// Now we know that Start <= I->End and End >= I->Start so the range overlaps
|
||||||
|
// but is not entirely contained within the range.
|
||||||
|
|
||||||
|
// See if the range extends the start of the range. In this case, it couldn't
|
||||||
|
// possibly cause it to join the prior range, because otherwise we would have
|
||||||
|
// stopped on *it*.
|
||||||
|
if (Start < I->Start) {
|
||||||
|
I->Start = Start;
|
||||||
|
I->StartPtr = SI->getPointerOperand();
|
||||||
|
}
|
||||||
|
|
||||||
|
// Now we know that Start <= I->End and Start >= I->Start (so the startpoint
|
||||||
|
// is in or right at the end of I), and that End >= I->Start. Extend I out to
|
||||||
|
// End.
|
||||||
|
if (End > I->End) {
|
||||||
|
I->End = End;
|
||||||
|
range_iterator NextI = I;;
|
||||||
|
while (++NextI != E && End >= NextI->Start) {
|
||||||
|
// Merge the range in.
|
||||||
|
I->TheStores.append(NextI->TheStores.begin(), NextI->TheStores.end());
|
||||||
|
if (NextI->End > I->End)
|
||||||
|
I->End = NextI->End;
|
||||||
|
Ranges.erase(NextI);
|
||||||
|
NextI = I;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
// MemCpyOpt Pass
|
||||||
|
//===----------------------------------------------------------------------===//
|
||||||
|
|
||||||
|
namespace {
|
||||||
|
|
||||||
|
class VISIBILITY_HIDDEN MemCpyOpt : public FunctionPass {
|
||||||
|
bool runOnFunction(Function &F);
|
||||||
|
public:
|
||||||
|
static char ID; // Pass identification, replacement for typeid
|
||||||
|
MemCpyOpt() : FunctionPass((intptr_t)&ID) { }
|
||||||
|
|
||||||
|
private:
|
||||||
|
// This transformation requires dominator postdominator info
|
||||||
|
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
|
||||||
|
AU.setPreservesCFG();
|
||||||
|
AU.addRequired<DominatorTree>();
|
||||||
|
AU.addRequired<MemoryDependenceAnalysis>();
|
||||||
|
AU.addRequired<AliasAnalysis>();
|
||||||
|
AU.addRequired<TargetData>();
|
||||||
|
AU.addPreserved<AliasAnalysis>();
|
||||||
|
AU.addPreserved<MemoryDependenceAnalysis>();
|
||||||
|
AU.addPreserved<TargetData>();
|
||||||
|
}
|
||||||
|
|
||||||
|
// Helper fuctions
|
||||||
|
bool processInstruction(Instruction* I,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase);
|
||||||
|
bool processStore(StoreInst *SI, SmallVectorImpl<Instruction*> &toErase);
|
||||||
|
bool processMemCpy(MemCpyInst* M, MemCpyInst* MDep,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase);
|
||||||
|
bool performCallSlotOptzn(MemCpyInst* cpy, CallInst* C,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase);
|
||||||
|
bool iterateOnFunction(Function &F);
|
||||||
|
};
|
||||||
|
|
||||||
|
char MemCpyOpt::ID = 0;
|
||||||
|
}
|
||||||
|
|
||||||
|
// createMemCpyOptPass - The public interface to this file...
|
||||||
|
FunctionPass *llvm::createMemCpyOptPass() { return new MemCpyOpt(); }
|
||||||
|
|
||||||
|
static RegisterPass<MemCpyOpt> X("memcpyopt",
|
||||||
|
"MemCpy Optimization");
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
/// processStore - When GVN is scanning forward over instructions, we look for
|
||||||
|
/// some other patterns to fold away. In particular, this looks for stores to
|
||||||
|
/// neighboring locations of memory. If it sees enough consequtive ones
|
||||||
|
/// (currently 4) it attempts to merge them together into a memcpy/memset.
|
||||||
|
bool MemCpyOpt::processStore(StoreInst *SI, SmallVectorImpl<Instruction*> &toErase) {
|
||||||
|
if (!FormMemSet) return false;
|
||||||
|
if (SI->isVolatile()) return false;
|
||||||
|
|
||||||
|
// There are two cases that are interesting for this code to handle: memcpy
|
||||||
|
// and memset. Right now we only handle memset.
|
||||||
|
|
||||||
|
// Ensure that the value being stored is something that can be memset'able a
|
||||||
|
// byte at a time like "0" or "-1" or any width, as well as things like
|
||||||
|
// 0xA0A0A0A0 and 0.0.
|
||||||
|
Value *ByteVal = isBytewiseValue(SI->getOperand(0));
|
||||||
|
if (!ByteVal)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
TargetData &TD = getAnalysis<TargetData>();
|
||||||
|
AliasAnalysis &AA = getAnalysis<AliasAnalysis>();
|
||||||
|
|
||||||
|
// Okay, so we now have a single store that can be splatable. Scan to find
|
||||||
|
// all subsequent stores of the same value to offset from the same pointer.
|
||||||
|
// Join these together into ranges, so we can decide whether contiguous blocks
|
||||||
|
// are stored.
|
||||||
|
MemsetRanges Ranges(TD);
|
||||||
|
|
||||||
|
Value *StartPtr = SI->getPointerOperand();
|
||||||
|
|
||||||
|
BasicBlock::iterator BI = SI;
|
||||||
|
for (++BI; !isa<TerminatorInst>(BI); ++BI) {
|
||||||
|
if (isa<CallInst>(BI) || isa<InvokeInst>(BI)) {
|
||||||
|
// If the call is readnone, ignore it, otherwise bail out. We don't even
|
||||||
|
// allow readonly here because we don't want something like:
|
||||||
|
// A[1] = 2; strlen(A); A[2] = 2; -> memcpy(A, ...); strlen(A).
|
||||||
|
if (AA.getModRefBehavior(CallSite::get(BI)) ==
|
||||||
|
AliasAnalysis::DoesNotAccessMemory)
|
||||||
|
continue;
|
||||||
|
|
||||||
|
// TODO: If this is a memset, try to join it in.
|
||||||
|
|
||||||
|
break;
|
||||||
|
} else if (isa<VAArgInst>(BI) || isa<LoadInst>(BI))
|
||||||
|
break;
|
||||||
|
|
||||||
|
// If this is a non-store instruction it is fine, ignore it.
|
||||||
|
StoreInst *NextStore = dyn_cast<StoreInst>(BI);
|
||||||
|
if (NextStore == 0) continue;
|
||||||
|
|
||||||
|
// If this is a store, see if we can merge it in.
|
||||||
|
if (NextStore->isVolatile()) break;
|
||||||
|
|
||||||
|
// Check to see if this stored value is of the same byte-splattable value.
|
||||||
|
if (ByteVal != isBytewiseValue(NextStore->getOperand(0)))
|
||||||
|
break;
|
||||||
|
|
||||||
|
// Check to see if this store is to a constant offset from the start ptr.
|
||||||
|
int64_t Offset;
|
||||||
|
if (!IsPointerOffset(StartPtr, NextStore->getPointerOperand(), Offset, TD))
|
||||||
|
break;
|
||||||
|
|
||||||
|
Ranges.addStore(Offset, NextStore);
|
||||||
|
}
|
||||||
|
|
||||||
|
// If we have no ranges, then we just had a single store with nothing that
|
||||||
|
// could be merged in. This is a very common case of course.
|
||||||
|
if (Ranges.empty())
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// If we had at least one store that could be merged in, add the starting
|
||||||
|
// store as well. We try to avoid this unless there is at least something
|
||||||
|
// interesting as a small compile-time optimization.
|
||||||
|
Ranges.addStore(0, SI);
|
||||||
|
|
||||||
|
|
||||||
|
Function *MemSetF = 0;
|
||||||
|
|
||||||
|
// Now that we have full information about ranges, loop over the ranges and
|
||||||
|
// emit memset's for anything big enough to be worthwhile.
|
||||||
|
bool MadeChange = false;
|
||||||
|
for (MemsetRanges::const_iterator I = Ranges.begin(), E = Ranges.end();
|
||||||
|
I != E; ++I) {
|
||||||
|
const MemsetRange &Range = *I;
|
||||||
|
|
||||||
|
if (Range.TheStores.size() == 1) continue;
|
||||||
|
|
||||||
|
// If it is profitable to lower this range to memset, do so now.
|
||||||
|
if (!Range.isProfitableToUseMemset(TD))
|
||||||
|
continue;
|
||||||
|
|
||||||
|
// Otherwise, we do want to transform this! Create a new memset. We put
|
||||||
|
// the memset right before the first instruction that isn't part of this
|
||||||
|
// memset block. This ensure that the memset is dominated by any addressing
|
||||||
|
// instruction needed by the start of the block.
|
||||||
|
BasicBlock::iterator InsertPt = BI;
|
||||||
|
|
||||||
|
if (MemSetF == 0)
|
||||||
|
MemSetF = Intrinsic::getDeclaration(SI->getParent()->getParent()
|
||||||
|
->getParent(), Intrinsic::memset_i64);
|
||||||
|
|
||||||
|
// Get the starting pointer of the block.
|
||||||
|
StartPtr = Range.StartPtr;
|
||||||
|
|
||||||
|
// Cast the start ptr to be i8* as memset requires.
|
||||||
|
const Type *i8Ptr = PointerType::getUnqual(Type::Int8Ty);
|
||||||
|
if (StartPtr->getType() != i8Ptr)
|
||||||
|
StartPtr = new BitCastInst(StartPtr, i8Ptr, StartPtr->getNameStart(),
|
||||||
|
InsertPt);
|
||||||
|
|
||||||
|
Value *Ops[] = {
|
||||||
|
StartPtr, ByteVal, // Start, value
|
||||||
|
ConstantInt::get(Type::Int64Ty, Range.End-Range.Start), // size
|
||||||
|
ConstantInt::get(Type::Int32Ty, Range.Alignment) // align
|
||||||
|
};
|
||||||
|
Value *C = CallInst::Create(MemSetF, Ops, Ops+4, "", InsertPt);
|
||||||
|
DEBUG(cerr << "Replace stores:\n";
|
||||||
|
for (unsigned i = 0, e = Range.TheStores.size(); i != e; ++i)
|
||||||
|
cerr << *Range.TheStores[i];
|
||||||
|
cerr << "With: " << *C); C=C;
|
||||||
|
|
||||||
|
// Zap all the stores.
|
||||||
|
toErase.append(Range.TheStores.begin(), Range.TheStores.end());
|
||||||
|
++NumMemSetInfer;
|
||||||
|
MadeChange = true;
|
||||||
|
}
|
||||||
|
|
||||||
|
return MadeChange;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
/// performCallSlotOptzn - takes a memcpy and a call that it depends on,
|
||||||
|
/// and checks for the possibility of a call slot optimization by having
|
||||||
|
/// the call write its result directly into the destination of the memcpy.
|
||||||
|
bool MemCpyOpt::performCallSlotOptzn(MemCpyInst *cpy, CallInst *C,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase) {
|
||||||
|
// The general transformation to keep in mind is
|
||||||
|
//
|
||||||
|
// call @func(..., src, ...)
|
||||||
|
// memcpy(dest, src, ...)
|
||||||
|
//
|
||||||
|
// ->
|
||||||
|
//
|
||||||
|
// memcpy(dest, src, ...)
|
||||||
|
// call @func(..., dest, ...)
|
||||||
|
//
|
||||||
|
// Since moving the memcpy is technically awkward, we additionally check that
|
||||||
|
// src only holds uninitialized values at the moment of the call, meaning that
|
||||||
|
// the memcpy can be discarded rather than moved.
|
||||||
|
|
||||||
|
// Deliberately get the source and destination with bitcasts stripped away,
|
||||||
|
// because we'll need to do type comparisons based on the underlying type.
|
||||||
|
Value* cpyDest = cpy->getDest();
|
||||||
|
Value* cpySrc = cpy->getSource();
|
||||||
|
CallSite CS = CallSite::get(C);
|
||||||
|
|
||||||
|
// We need to be able to reason about the size of the memcpy, so we require
|
||||||
|
// that it be a constant.
|
||||||
|
ConstantInt* cpyLength = dyn_cast<ConstantInt>(cpy->getLength());
|
||||||
|
if (!cpyLength)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Require that src be an alloca. This simplifies the reasoning considerably.
|
||||||
|
AllocaInst* srcAlloca = dyn_cast<AllocaInst>(cpySrc);
|
||||||
|
if (!srcAlloca)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Check that all of src is copied to dest.
|
||||||
|
TargetData& TD = getAnalysis<TargetData>();
|
||||||
|
|
||||||
|
ConstantInt* srcArraySize = dyn_cast<ConstantInt>(srcAlloca->getArraySize());
|
||||||
|
if (!srcArraySize)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
uint64_t srcSize = TD.getABITypeSize(srcAlloca->getAllocatedType()) *
|
||||||
|
srcArraySize->getZExtValue();
|
||||||
|
|
||||||
|
if (cpyLength->getZExtValue() < srcSize)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Check that accessing the first srcSize bytes of dest will not cause a
|
||||||
|
// trap. Otherwise the transform is invalid since it might cause a trap
|
||||||
|
// to occur earlier than it otherwise would.
|
||||||
|
if (AllocaInst* A = dyn_cast<AllocaInst>(cpyDest)) {
|
||||||
|
// The destination is an alloca. Check it is larger than srcSize.
|
||||||
|
ConstantInt* destArraySize = dyn_cast<ConstantInt>(A->getArraySize());
|
||||||
|
if (!destArraySize)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
uint64_t destSize = TD.getABITypeSize(A->getAllocatedType()) *
|
||||||
|
destArraySize->getZExtValue();
|
||||||
|
|
||||||
|
if (destSize < srcSize)
|
||||||
|
return false;
|
||||||
|
} else if (Argument* A = dyn_cast<Argument>(cpyDest)) {
|
||||||
|
// If the destination is an sret parameter then only accesses that are
|
||||||
|
// outside of the returned struct type can trap.
|
||||||
|
if (!A->hasStructRetAttr())
|
||||||
|
return false;
|
||||||
|
|
||||||
|
const Type* StructTy = cast<PointerType>(A->getType())->getElementType();
|
||||||
|
uint64_t destSize = TD.getABITypeSize(StructTy);
|
||||||
|
|
||||||
|
if (destSize < srcSize)
|
||||||
|
return false;
|
||||||
|
} else {
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
|
||||||
|
// Check that src is not accessed except via the call and the memcpy. This
|
||||||
|
// guarantees that it holds only undefined values when passed in (so the final
|
||||||
|
// memcpy can be dropped), that it is not read or written between the call and
|
||||||
|
// the memcpy, and that writing beyond the end of it is undefined.
|
||||||
|
SmallVector<User*, 8> srcUseList(srcAlloca->use_begin(),
|
||||||
|
srcAlloca->use_end());
|
||||||
|
while (!srcUseList.empty()) {
|
||||||
|
User* UI = srcUseList.back();
|
||||||
|
srcUseList.pop_back();
|
||||||
|
|
||||||
|
if (isa<GetElementPtrInst>(UI) || isa<BitCastInst>(UI)) {
|
||||||
|
for (User::use_iterator I = UI->use_begin(), E = UI->use_end();
|
||||||
|
I != E; ++I)
|
||||||
|
srcUseList.push_back(*I);
|
||||||
|
} else if (UI != C && UI != cpy) {
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
// Since we're changing the parameter to the callsite, we need to make sure
|
||||||
|
// that what would be the new parameter dominates the callsite.
|
||||||
|
DominatorTree& DT = getAnalysis<DominatorTree>();
|
||||||
|
if (Instruction* cpyDestInst = dyn_cast<Instruction>(cpyDest))
|
||||||
|
if (!DT.dominates(cpyDestInst, C))
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// In addition to knowing that the call does not access src in some
|
||||||
|
// unexpected manner, for example via a global, which we deduce from
|
||||||
|
// the use analysis, we also need to know that it does not sneakily
|
||||||
|
// access dest. We rely on AA to figure this out for us.
|
||||||
|
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
||||||
|
if (AA.getModRefInfo(C, cpy->getRawDest(), srcSize) !=
|
||||||
|
AliasAnalysis::NoModRef)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// All the checks have passed, so do the transformation.
|
||||||
|
for (unsigned i = 0; i < CS.arg_size(); ++i)
|
||||||
|
if (CS.getArgument(i) == cpySrc) {
|
||||||
|
if (cpySrc->getType() != cpyDest->getType())
|
||||||
|
cpyDest = CastInst::createPointerCast(cpyDest, cpySrc->getType(),
|
||||||
|
cpyDest->getName(), C);
|
||||||
|
CS.setArgument(i, cpyDest);
|
||||||
|
}
|
||||||
|
|
||||||
|
// Drop any cached information about the call, because we may have changed
|
||||||
|
// its dependence information by changing its parameter.
|
||||||
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
||||||
|
MD.dropInstruction(C);
|
||||||
|
|
||||||
|
// Remove the memcpy
|
||||||
|
MD.removeInstruction(cpy);
|
||||||
|
toErase.push_back(cpy);
|
||||||
|
|
||||||
|
return true;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// processMemCpy - perform simplication of memcpy's. If we have memcpy A which
|
||||||
|
/// copies X to Y, and memcpy B which copies Y to Z, then we can rewrite B to be
|
||||||
|
/// a memcpy from X to Z (or potentially a memmove, depending on circumstances).
|
||||||
|
/// This allows later passes to remove the first memcpy altogether.
|
||||||
|
bool MemCpyOpt::processMemCpy(MemCpyInst* M, MemCpyInst* MDep,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase) {
|
||||||
|
// We can only transforms memcpy's where the dest of one is the source of the
|
||||||
|
// other
|
||||||
|
if (M->getSource() != MDep->getDest())
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Second, the length of the memcpy's must be the same, or the preceeding one
|
||||||
|
// must be larger than the following one.
|
||||||
|
ConstantInt* C1 = dyn_cast<ConstantInt>(MDep->getLength());
|
||||||
|
ConstantInt* C2 = dyn_cast<ConstantInt>(M->getLength());
|
||||||
|
if (!C1 || !C2)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
uint64_t DepSize = C1->getValue().getZExtValue();
|
||||||
|
uint64_t CpySize = C2->getValue().getZExtValue();
|
||||||
|
|
||||||
|
if (DepSize < CpySize)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// Finally, we have to make sure that the dest of the second does not
|
||||||
|
// alias the source of the first
|
||||||
|
AliasAnalysis& AA = getAnalysis<AliasAnalysis>();
|
||||||
|
if (AA.alias(M->getRawDest(), CpySize, MDep->getRawSource(), DepSize) !=
|
||||||
|
AliasAnalysis::NoAlias)
|
||||||
|
return false;
|
||||||
|
else if (AA.alias(M->getRawDest(), CpySize, M->getRawSource(), CpySize) !=
|
||||||
|
AliasAnalysis::NoAlias)
|
||||||
|
return false;
|
||||||
|
else if (AA.alias(MDep->getRawDest(), DepSize, MDep->getRawSource(), DepSize)
|
||||||
|
!= AliasAnalysis::NoAlias)
|
||||||
|
return false;
|
||||||
|
|
||||||
|
// If all checks passed, then we can transform these memcpy's
|
||||||
|
Function* MemCpyFun = Intrinsic::getDeclaration(
|
||||||
|
M->getParent()->getParent()->getParent(),
|
||||||
|
M->getIntrinsicID());
|
||||||
|
|
||||||
|
std::vector<Value*> args;
|
||||||
|
args.push_back(M->getRawDest());
|
||||||
|
args.push_back(MDep->getRawSource());
|
||||||
|
args.push_back(M->getLength());
|
||||||
|
args.push_back(M->getAlignment());
|
||||||
|
|
||||||
|
CallInst* C = CallInst::Create(MemCpyFun, args.begin(), args.end(), "", M);
|
||||||
|
|
||||||
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
||||||
|
if (MD.getDependency(C) == MDep) {
|
||||||
|
MD.dropInstruction(M);
|
||||||
|
toErase.push_back(M);
|
||||||
|
return true;
|
||||||
|
}
|
||||||
|
|
||||||
|
MD.removeInstruction(C);
|
||||||
|
toErase.push_back(C);
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
|
||||||
|
/// processInstruction - When calculating availability, handle an instruction
|
||||||
|
/// by inserting it into the appropriate sets
|
||||||
|
bool MemCpyOpt::processInstruction(Instruction *I,
|
||||||
|
SmallVectorImpl<Instruction*> &toErase) {
|
||||||
|
if (StoreInst *SI = dyn_cast<StoreInst>(I))
|
||||||
|
return processStore(SI, toErase);
|
||||||
|
|
||||||
|
if (MemCpyInst* M = dyn_cast<MemCpyInst>(I)) {
|
||||||
|
MemoryDependenceAnalysis& MD = getAnalysis<MemoryDependenceAnalysis>();
|
||||||
|
|
||||||
|
// The are two possible optimizations we can do for memcpy:
|
||||||
|
// a) memcpy-memcpy xform which exposes redundance for DSE
|
||||||
|
// b) call-memcpy xform for return slot optimization
|
||||||
|
Instruction* dep = MD.getDependency(M);
|
||||||
|
if (dep == MemoryDependenceAnalysis::None ||
|
||||||
|
dep == MemoryDependenceAnalysis::NonLocal)
|
||||||
|
return false;
|
||||||
|
if (MemCpyInst *MemCpy = dyn_cast<MemCpyInst>(dep))
|
||||||
|
return processMemCpy(M, MemCpy, toErase);
|
||||||
|
if (CallInst* C = dyn_cast<CallInst>(dep))
|
||||||
|
return performCallSlotOptzn(M, C, toErase);
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
|
||||||
|
return false;
|
||||||
|
}
|
||||||
|
|
||||||
|
// MemCpyOpt::runOnFunction - This is the main transformation entry point for a
|
||||||
|
// function.
|
||||||
|
//
|
||||||
|
bool MemCpyOpt::runOnFunction(Function& F) {
|
||||||
|
|
||||||
|
bool changed = false;
|
||||||
|
bool shouldContinue = true;
|
||||||
|
|
||||||
|
while (shouldContinue) {
|
||||||
|
shouldContinue = iterateOnFunction(F);
|
||||||
|
changed |= shouldContinue;
|
||||||
|
}
|
||||||
|
|
||||||
|
return changed;
|
||||||
|
}
|
||||||
|
|
||||||
|
|
||||||
|
// MemCpyOpt::iterateOnFunction - Executes one iteration of GVN
|
||||||
|
bool MemCpyOpt::iterateOnFunction(Function &F) {
|
||||||
|
bool changed_function = false;
|
||||||
|
|
||||||
|
DominatorTree &DT = getAnalysis<DominatorTree>();
|
||||||
|
|
||||||
|
SmallVector<Instruction*, 8> toErase;
|
||||||
|
|
||||||
|
// Top-down walk of the dominator tree
|
||||||
|
for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
|
||||||
|
E = df_end(DT.getRootNode()); DI != E; ++DI) {
|
||||||
|
|
||||||
|
BasicBlock* BB = DI->getBlock();
|
||||||
|
for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
|
||||||
|
BI != BE;) {
|
||||||
|
changed_function |= processInstruction(BI, toErase);
|
||||||
|
if (toErase.empty()) {
|
||||||
|
++BI;
|
||||||
|
continue;
|
||||||
|
}
|
||||||
|
|
||||||
|
// If we need some instructions deleted, do it now.
|
||||||
|
NumMemCpyInstr += toErase.size();
|
||||||
|
|
||||||
|
// Avoid iterator invalidation.
|
||||||
|
bool AtStart = BI == BB->begin();
|
||||||
|
if (!AtStart)
|
||||||
|
--BI;
|
||||||
|
|
||||||
|
for (SmallVector<Instruction*, 4>::iterator I = toErase.begin(),
|
||||||
|
E = toErase.end(); I != E; ++I)
|
||||||
|
(*I)->eraseFromParent();
|
||||||
|
|
||||||
|
if (AtStart)
|
||||||
|
BI = BB->begin();
|
||||||
|
else
|
||||||
|
++BI;
|
||||||
|
|
||||||
|
toErase.clear();
|
||||||
|
}
|
||||||
|
}
|
||||||
|
|
||||||
|
return changed_function;
|
||||||
|
}
|
||||||
|
|
@ -1,4 +1,4 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn -dse | llvm-dis | grep {call.*initialize} | not grep memtmp
|
; RUN: llvm-as < %s | opt -memcpyopt -dse | llvm-dis | grep {call.*initialize} | not grep memtmp
|
||||||
; PR2077
|
; PR2077
|
||||||
|
|
||||||
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
|
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32"
|
||||||
|
|
@ -1,4 +1,4 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn | llvm-dis | not grep {call.*memcpy.}
|
; RUN: llvm-as < %s | opt -memcpyopt | llvm-dis | not grep {call.*memcpy.}
|
||||||
%a = type { i32 }
|
%a = type { i32 }
|
||||||
%b = type { float }
|
%b = type { float }
|
||||||
|
|
||||||
|
|
@ -0,0 +1,3 @@
|
||||||
|
load_lib llvm.exp
|
||||||
|
|
||||||
|
RunLLVMTests [lsort [glob -nocomplain $srcdir/$subdir/*.{ll,llx,c,cpp,tr}]]
|
||||||
|
|
@ -1,5 +1,5 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn -form-memset-from-stores | llvm-dis | not grep store
|
; RUN: llvm-as < %s | opt -memcpyopt -form-memset-from-stores | llvm-dis | not grep store
|
||||||
; RUN: llvm-as < %s | opt -gvn -form-memset-from-stores | llvm-dis | grep {call.*llvm.memset}
|
; RUN: llvm-as < %s | opt -memcpyopt -form-memset-from-stores | llvm-dis | grep {call.*llvm.memset}
|
||||||
|
|
||||||
; All the stores in this example should be merged into a single memset.
|
; All the stores in this example should be merged into a single memset.
|
||||||
|
|
||||||
|
|
@ -1,5 +1,5 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn -form-memset-from-stores | llvm-dis | not grep store
|
; RUN: llvm-as < %s | opt -memcpyopt -form-memset-from-stores | llvm-dis | not grep store
|
||||||
; RUN: llvm-as < %s | opt -gvn -form-memset-from-stores | llvm-dis | grep {call.*llvm.memset} | count 3
|
; RUN: llvm-as < %s | opt -memcpyopt -form-memset-from-stores | llvm-dis | grep {call.*llvm.memset} | count 3
|
||||||
|
|
||||||
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
||||||
target triple = "i386-apple-darwin8"
|
target triple = "i386-apple-darwin8"
|
||||||
|
|
@ -1,4 +1,4 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn -dse | llvm-dis | grep {call.*memcpy} | count 1
|
; RUN: llvm-as < %s | opt -memcpyopt -dse | llvm-dis | grep {call.*memcpy} | count 1
|
||||||
|
|
||||||
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
||||||
target triple = "i686-apple-darwin9"
|
target triple = "i686-apple-darwin9"
|
||||||
|
|
@ -1,4 +1,4 @@
|
||||||
; RUN: llvm-as < %s | opt -gvn | llvm-dis | not grep {call.*memcpy}
|
; RUN: llvm-as < %s | opt -memcpyopt | llvm-dis | not grep {call.*memcpy}
|
||||||
|
|
||||||
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:128:128"
|
||||||
target triple = "i686-apple-darwin9"
|
target triple = "i686-apple-darwin9"
|
||||||
|
|
@ -169,6 +169,7 @@ void Optimize(Module* M) {
|
||||||
addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
|
addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
|
||||||
|
|
||||||
addPass(Passes, createLICMPass()); // Hoist loop invariants
|
addPass(Passes, createLICMPass()); // Hoist loop invariants
|
||||||
|
addPass(Passes, createMemCpyOptPass()); // Remove dead memcpy's
|
||||||
addPass(Passes, createGVNPass()); // Remove redundancies
|
addPass(Passes, createGVNPass()); // Remove redundancies
|
||||||
addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
|
addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
|
||||||
|
|
||||||
|
|
|
||||||
|
|
@ -282,6 +282,7 @@ void AddStandardCompilePasses(PassManager &PM) {
|
||||||
addPass(PM, createIndVarSimplifyPass()); // Canonicalize indvars
|
addPass(PM, createIndVarSimplifyPass()); // Canonicalize indvars
|
||||||
addPass(PM, createLoopUnrollPass()); // Unroll small loops
|
addPass(PM, createLoopUnrollPass()); // Unroll small loops
|
||||||
addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
|
addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
|
||||||
|
addPass(PM, createMemCpyOptPass()); // Remove unneeded memcpy's
|
||||||
addPass(PM, createGVNPass()); // Remove redundancies
|
addPass(PM, createGVNPass()); // Remove redundancies
|
||||||
addPass(PM, createSCCPPass()); // Constant prop with SCCP
|
addPass(PM, createSCCPPass()); // Constant prop with SCCP
|
||||||
|
|
||||||
|
|
|
||||||
Loading…
Reference in New Issue