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Implement Transforms/InstCombine/hoist_instr.ll
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30234 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -1330,14 +1330,31 @@ static Instruction *FoldOpIntoSelect(Instruction &Op, SelectInst *SI,
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Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
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PHINode *PN = cast<PHINode>(I.getOperand(0));
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unsigned NumPHIValues = PN->getNumIncomingValues();
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if (!PN->hasOneUse() || NumPHIValues == 0 ||
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!isa<Constant>(PN->getIncomingValue(0))) return 0;
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if (!PN->hasOneUse() || NumPHIValues == 0) return 0;
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// Check to see if all of the operands of the PHI are constants. If not, we
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// cannot do the transformation.
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for (unsigned i = 1; i != NumPHIValues; ++i)
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if (!isa<Constant>(PN->getIncomingValue(i)))
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return 0;
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// Check to see if all of the operands of the PHI are constants. If there is
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// one non-constant value, remember the BB it is. If there is more than one
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// bail out.
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BasicBlock *NonConstBB = 0;
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for (unsigned i = 0; i != NumPHIValues; ++i)
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if (!isa<Constant>(PN->getIncomingValue(i))) {
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if (NonConstBB) return 0; // More than one non-const value.
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NonConstBB = PN->getIncomingBlock(i);
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// If the incoming non-constant value is in I's block, we have an infinite
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// loop.
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if (NonConstBB == I.getParent())
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return 0;
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}
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// If there is exactly one non-constant value, we can insert a copy of the
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// operation in that block. However, if this is a critical edge, we would be
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// inserting the computation one some other paths (e.g. inside a loop). Only
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// do this if the pred block is unconditionally branching into the phi block.
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if (NonConstBB) {
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BranchInst *BI = dyn_cast<BranchInst>(NonConstBB->getTerminator());
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if (!BI || !BI->isUnconditional()) return 0;
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}
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// Okay, we can do the transformation: create the new PHI node.
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PHINode *NewPN = new PHINode(I.getType(), I.getName());
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@ -1349,17 +1366,40 @@ Instruction *InstCombiner::FoldOpIntoPhi(Instruction &I) {
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if (I.getNumOperands() == 2) {
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Constant *C = cast<Constant>(I.getOperand(1));
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for (unsigned i = 0; i != NumPHIValues; ++i) {
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Constant *InV = cast<Constant>(PN->getIncomingValue(i));
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NewPN->addIncoming(ConstantExpr::get(I.getOpcode(), InV, C),
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PN->getIncomingBlock(i));
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Value *InV;
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if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
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InV = ConstantExpr::get(I.getOpcode(), InC, C);
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} else {
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assert(PN->getIncomingBlock(i) == NonConstBB);
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if (BinaryOperator *BO = dyn_cast<BinaryOperator>(&I))
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InV = BinaryOperator::create(BO->getOpcode(),
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PN->getIncomingValue(i), C, "phitmp",
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NonConstBB->getTerminator());
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else if (ShiftInst *SI = dyn_cast<ShiftInst>(&I))
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InV = new ShiftInst(SI->getOpcode(),
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PN->getIncomingValue(i), C, "phitmp",
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NonConstBB->getTerminator());
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else
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assert(0 && "Unknown binop!");
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WorkList.push_back(cast<Instruction>(InV));
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}
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NewPN->addIncoming(InV, PN->getIncomingBlock(i));
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}
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} else {
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assert(isa<CastInst>(I) && "Unary op should be a cast!");
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const Type *RetTy = I.getType();
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for (unsigned i = 0; i != NumPHIValues; ++i) {
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Constant *InV = cast<Constant>(PN->getIncomingValue(i));
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NewPN->addIncoming(ConstantExpr::getCast(InV, RetTy),
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PN->getIncomingBlock(i));
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Value *InV;
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if (Constant *InC = dyn_cast<Constant>(PN->getIncomingValue(i))) {
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InV = ConstantExpr::getCast(InC, RetTy);
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} else {
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assert(PN->getIncomingBlock(i) == NonConstBB);
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InV = new CastInst(PN->getIncomingValue(i), I.getType(), "phitmp",
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NonConstBB->getTerminator());
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WorkList.push_back(cast<Instruction>(InV));
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}
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NewPN->addIncoming(InV, PN->getIncomingBlock(i));
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}
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}
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return ReplaceInstUsesWith(I, NewPN);
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