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https://github.com/c64scene-ar/llvm-6502.git
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add support for recursive phi translation and phi
translation of add with immediate. This allows us to optimize this function: void test(int N, double* G) { long j; G[1] = 1; for (j = 1; j < N - 1; j++) G[j+1] = G[j] + G[j+1]; } to only do one load every iteration of the loop. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@90013 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -694,17 +694,31 @@ static bool isPHITranslatable(Instruction *Inst) {
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// We can handle bitcast of a PHI, but the PHI needs to be in the same block
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// as the bitcast.
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if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst))
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// FIXME: Allow any phi translatable operand.
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if (PHINode *PN = dyn_cast<PHINode>(BC->getOperand(0)))
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if (PN->getParent() == BC->getParent())
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return true;
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// We can translate a GEP that uses a PHI in the current block for at least
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// one of its operands.
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// We can translate a GEP if all of its operands defined in this block are phi
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// translatable.
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
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for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
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if (PHINode *PN = dyn_cast<PHINode>(GEP->getOperand(i)))
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if (PN->getParent() == GEP->getParent())
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return true;
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for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i) {
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Instruction *GEPOpI = dyn_cast<Instruction>(GEP->getOperand(i));
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if (GEPOpI == 0 || GEPOpI->getParent() != Inst->getParent())
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continue;
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if (!isPHITranslatable(GEPOpI))
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return false;
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}
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return true;
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}
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if (Inst->getOpcode() == Instruction::Add &&
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isa<ConstantInt>(Inst->getOperand(1))) {
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Instruction *GEPOpI = dyn_cast<Instruction>(Inst->getOperand(0));
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if (GEPOpI == 0 || GEPOpI->getParent() != Inst->getParent())
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return true;
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return isPHITranslatable(GEPOpI);
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}
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// cerr << "MEMDEP: Could not PHI translate: " << *Pointer;
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@ -731,6 +745,7 @@ PHITranslatePointer(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
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// Handle bitcast of PHI.
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if (BitCastInst *BC = dyn_cast<BitCastInst>(Inst)) {
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// FIXME: Recurse!
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PHINode *BCPN = cast<PHINode>(BC->getOperand(0));
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Value *PHIIn = BCPN->getIncomingValueForBlock(Pred);
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@ -749,7 +764,7 @@ PHITranslatePointer(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
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return 0;
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}
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// Handle getelementptr with at least one PHI operand.
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// Handle getelementptr with at least one PHI translatable operand.
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if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Inst)) {
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SmallVector<Value*, 8> GEPOps;
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BasicBlock *CurBB = GEP->getParent();
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@ -764,8 +779,8 @@ PHITranslatePointer(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
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}
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// If the operand is a phi node, do phi translation.
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if (PHINode *PN = dyn_cast<PHINode>(GEPOp)) {
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GEPOps.push_back(PN->getIncomingValueForBlock(Pred));
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if (Value *InOp = PHITranslatePointer(GEPOp, CurBB, Pred, TD)) {
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GEPOps.push_back(InOp);
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continue;
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}
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@ -778,7 +793,6 @@ PHITranslatePointer(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
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if (Value *V = SimplifyGEPInst(&GEPOps[0], GEPOps.size(), TD))
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return V;
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// Scan to see if we have this GEP available.
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Value *APHIOp = GEPOps[0];
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for (Value::use_iterator UI = APHIOp->use_begin(), E = APHIOp->use_end();
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@ -800,6 +814,49 @@ PHITranslatePointer(Value *InVal, BasicBlock *CurBB, BasicBlock *Pred,
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return 0;
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}
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// Handle add with a constant RHS.
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if (Inst->getOpcode() == Instruction::Add &&
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isa<ConstantInt>(Inst->getOperand(1))) {
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// PHI translate the LHS.
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Value *LHS;
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Constant *RHS = cast<ConstantInt>(Inst->getOperand(1));
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Instruction *OpI = dyn_cast<Instruction>(Inst->getOperand(0));
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bool isNSW = cast<BinaryOperator>(Inst)->hasNoSignedWrap();
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bool isNUW = cast<BinaryOperator>(Inst)->hasNoUnsignedWrap();
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if (OpI == 0 || OpI->getParent() != Inst->getParent())
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LHS = Inst->getOperand(0);
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else {
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LHS = PHITranslatePointer(Inst->getOperand(0), CurBB, Pred, TD);
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if (LHS == 0)
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return 0;
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}
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// If the PHI translated LHS is an add of a constant, fold the immediates.
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if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(LHS))
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if (BOp->getOpcode() == Instruction::Add)
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if (ConstantInt *CI = dyn_cast<ConstantInt>(BOp->getOperand(1))) {
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LHS = BOp->getOperand(0);
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RHS = ConstantExpr::getAdd(RHS, CI);
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isNSW = isNUW = false;
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}
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// See if the add simplifies away.
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if (Value *Res = SimplifyAddInst(LHS, RHS, isNSW, isNUW, TD))
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return Res;
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// Otherwise, see if we have this add available somewhere.
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for (Value::use_iterator UI = LHS->use_begin(), E = LHS->use_end();
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UI != E; ++UI) {
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(*UI))
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if (BO->getOperand(0) == LHS && BO->getOperand(1) == RHS &&
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BO->getParent()->getParent() == CurBB->getParent())
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return BO;
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}
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return 0;
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}
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return 0;
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}
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@ -195,6 +195,49 @@ return:
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ret void
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}
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;void test7(int N, double* G) {
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; long j;
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; G[1] = 1;
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; for (j = 1; j < N - 1; j++)
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; G[j+1] = G[j] + G[j+1];
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;}
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; This requires phi translation of the adds.
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define void @test7(i32 %N, double* nocapture %G) nounwind ssp {
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entry:
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%0 = getelementptr inbounds double* %G, i64 1
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store double 1.000000e+00, double* %0, align 8
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%1 = add i32 %N, -1
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%2 = icmp sgt i32 %1, 1
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br i1 %2, label %bb.nph, label %return
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bb.nph:
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%tmp = sext i32 %1 to i64
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%tmp7 = add i64 %tmp, -1
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br label %bb
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bb:
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%indvar = phi i64 [ 0, %bb.nph ], [ %tmp9, %bb ]
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%tmp8 = add i64 %indvar, 2
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%scevgep = getelementptr double* %G, i64 %tmp8
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%tmp9 = add i64 %indvar, 1
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%scevgep10 = getelementptr double* %G, i64 %tmp9
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%3 = load double* %scevgep10, align 8
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%4 = load double* %scevgep, align 8
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%5 = fadd double %3, %4
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store double %5, double* %scevgep, align 8
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%exitcond = icmp eq i64 %tmp9, %tmp7
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br i1 %exitcond, label %return, label %bb
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; Should only be one load in the loop.
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; CHECK: bb:
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; CHECK: load double*
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; CHECK-NOT: load double*
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; CHECK: br i1 %exitcond
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return:
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ret void
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}
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;;; --- todo
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