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https://github.com/c64scene-ar/llvm-6502.git
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Generalize createSCEV to be able to form SCEV expressions from
ConstantExprs. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52615 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dan Gohman
parent
17f1972c77
commit
6c459a28ec
@ -1704,118 +1704,125 @@ SCEVHandle ScalarEvolutionsImpl::createSCEV(Value *V) {
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if (!isa<IntegerType>(V->getType()))
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return SE.getUnknown(V);
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if (Instruction *I = dyn_cast<Instruction>(V)) {
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switch (I->getOpcode()) {
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case Instruction::Add:
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return SE.getAddExpr(getSCEV(I->getOperand(0)),
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getSCEV(I->getOperand(1)));
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case Instruction::Mul:
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return SE.getMulExpr(getSCEV(I->getOperand(0)),
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getSCEV(I->getOperand(1)));
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case Instruction::UDiv:
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return SE.getUDivExpr(getSCEV(I->getOperand(0)),
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getSCEV(I->getOperand(1)));
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case Instruction::Sub:
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return SE.getMinusSCEV(getSCEV(I->getOperand(0)),
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getSCEV(I->getOperand(1)));
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case Instruction::Or:
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// If the RHS of the Or is a constant, we may have something like:
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// X*4+1 which got turned into X*4|1. Handle this as an Add so loop
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// optimizations will transparently handle this case.
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//
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// In order for this transformation to be safe, the LHS must be of the
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// form X*(2^n) and the Or constant must be less than 2^n.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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SCEVHandle LHS = getSCEV(I->getOperand(0));
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const APInt &CIVal = CI->getValue();
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if (GetMinTrailingZeros(LHS) >=
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(CIVal.getBitWidth() - CIVal.countLeadingZeros()))
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return SE.getAddExpr(LHS, getSCEV(I->getOperand(1)));
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}
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break;
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case Instruction::Xor:
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// If the RHS of the xor is a signbit, then this is just an add.
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// Instcombine turns add of signbit into xor as a strength reduction step.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(I->getOperand(1))) {
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if (CI->getValue().isSignBit())
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return SE.getAddExpr(getSCEV(I->getOperand(0)),
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getSCEV(I->getOperand(1)));
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else if (CI->isAllOnesValue())
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return SE.getNotSCEV(getSCEV(I->getOperand(0)));
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}
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break;
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unsigned Opcode = Instruction::UserOp1;
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if (Instruction *I = dyn_cast<Instruction>(V))
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Opcode = I->getOpcode();
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else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V))
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Opcode = CE->getOpcode();
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else
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return SE.getUnknown(V);
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case Instruction::Shl:
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// Turn shift left of a constant amount into a multiply.
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if (ConstantInt *SA = dyn_cast<ConstantInt>(I->getOperand(1))) {
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uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
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Constant *X = ConstantInt::get(
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APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
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return SE.getMulExpr(getSCEV(I->getOperand(0)), getSCEV(X));
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}
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break;
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case Instruction::Trunc:
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return SE.getTruncateExpr(getSCEV(I->getOperand(0)), I->getType());
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case Instruction::ZExt:
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return SE.getZeroExtendExpr(getSCEV(I->getOperand(0)), I->getType());
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case Instruction::SExt:
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return SE.getSignExtendExpr(getSCEV(I->getOperand(0)), I->getType());
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case Instruction::BitCast:
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// BitCasts are no-op casts so we just eliminate the cast.
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if (I->getType()->isInteger() &&
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I->getOperand(0)->getType()->isInteger())
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return getSCEV(I->getOperand(0));
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break;
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case Instruction::PHI:
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return createNodeForPHI(cast<PHINode>(I));
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case Instruction::Select:
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// This could be a smax or umax that was lowered earlier.
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// Try to recover it.
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if (ICmpInst *ICI = dyn_cast<ICmpInst>(I->getOperand(0))) {
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Value *LHS = ICI->getOperand(0);
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Value *RHS = ICI->getOperand(1);
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switch (ICI->getPredicate()) {
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case ICmpInst::ICMP_SLT:
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case ICmpInst::ICMP_SLE:
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std::swap(LHS, RHS);
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// fall through
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case ICmpInst::ICMP_SGT:
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case ICmpInst::ICMP_SGE:
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if (LHS == I->getOperand(1) && RHS == I->getOperand(2))
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return SE.getSMaxExpr(getSCEV(LHS), getSCEV(RHS));
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else if (LHS == I->getOperand(2) && RHS == I->getOperand(1))
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// -smax(-x, -y) == smin(x, y).
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return SE.getNegativeSCEV(SE.getSMaxExpr(
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SE.getNegativeSCEV(getSCEV(LHS)),
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SE.getNegativeSCEV(getSCEV(RHS))));
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break;
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case ICmpInst::ICMP_ULT:
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case ICmpInst::ICMP_ULE:
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std::swap(LHS, RHS);
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// fall through
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case ICmpInst::ICMP_UGT:
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case ICmpInst::ICMP_UGE:
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if (LHS == I->getOperand(1) && RHS == I->getOperand(2))
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return SE.getUMaxExpr(getSCEV(LHS), getSCEV(RHS));
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else if (LHS == I->getOperand(2) && RHS == I->getOperand(1))
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// ~umax(~x, ~y) == umin(x, y)
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return SE.getNotSCEV(SE.getUMaxExpr(SE.getNotSCEV(getSCEV(LHS)),
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SE.getNotSCEV(getSCEV(RHS))));
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break;
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default:
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break;
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}
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}
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default: // We cannot analyze this expression.
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break;
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User *U = cast<User>(V);
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switch (Opcode) {
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case Instruction::Add:
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return SE.getAddExpr(getSCEV(U->getOperand(0)),
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getSCEV(U->getOperand(1)));
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case Instruction::Mul:
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return SE.getMulExpr(getSCEV(U->getOperand(0)),
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getSCEV(U->getOperand(1)));
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case Instruction::UDiv:
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return SE.getUDivExpr(getSCEV(U->getOperand(0)),
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getSCEV(U->getOperand(1)));
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case Instruction::Sub:
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return SE.getMinusSCEV(getSCEV(U->getOperand(0)),
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getSCEV(U->getOperand(1)));
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case Instruction::Or:
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// If the RHS of the Or is a constant, we may have something like:
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// X*4+1 which got turned into X*4|1. Handle this as an Add so loop
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// optimizations will transparently handle this case.
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//
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// In order for this transformation to be safe, the LHS must be of the
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// form X*(2^n) and the Or constant must be less than 2^n.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
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SCEVHandle LHS = getSCEV(U->getOperand(0));
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const APInt &CIVal = CI->getValue();
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if (GetMinTrailingZeros(LHS) >=
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(CIVal.getBitWidth() - CIVal.countLeadingZeros()))
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return SE.getAddExpr(LHS, getSCEV(U->getOperand(1)));
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}
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break;
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case Instruction::Xor:
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// If the RHS of the xor is a signbit, then this is just an add.
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// Instcombine turns add of signbit into xor as a strength reduction step.
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if (ConstantInt *CI = dyn_cast<ConstantInt>(U->getOperand(1))) {
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if (CI->getValue().isSignBit())
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return SE.getAddExpr(getSCEV(U->getOperand(0)),
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getSCEV(U->getOperand(1)));
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else if (CI->isAllOnesValue())
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return SE.getNotSCEV(getSCEV(U->getOperand(0)));
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}
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break;
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case Instruction::Shl:
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// Turn shift left of a constant amount into a multiply.
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if (ConstantInt *SA = dyn_cast<ConstantInt>(U->getOperand(1))) {
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uint32_t BitWidth = cast<IntegerType>(V->getType())->getBitWidth();
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Constant *X = ConstantInt::get(
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APInt(BitWidth, 1).shl(SA->getLimitedValue(BitWidth)));
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return SE.getMulExpr(getSCEV(U->getOperand(0)), getSCEV(X));
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}
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break;
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case Instruction::Trunc:
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return SE.getTruncateExpr(getSCEV(U->getOperand(0)), U->getType());
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case Instruction::ZExt:
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return SE.getZeroExtendExpr(getSCEV(U->getOperand(0)), U->getType());
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case Instruction::SExt:
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return SE.getSignExtendExpr(getSCEV(U->getOperand(0)), U->getType());
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case Instruction::BitCast:
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// BitCasts are no-op casts so we just eliminate the cast.
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if (U->getType()->isInteger() &&
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U->getOperand(0)->getType()->isInteger())
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return getSCEV(U->getOperand(0));
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break;
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case Instruction::PHI:
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return createNodeForPHI(cast<PHINode>(U));
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case Instruction::Select:
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// This could be a smax or umax that was lowered earlier.
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// Try to recover it.
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if (ICmpInst *ICI = dyn_cast<ICmpInst>(U->getOperand(0))) {
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Value *LHS = ICI->getOperand(0);
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Value *RHS = ICI->getOperand(1);
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switch (ICI->getPredicate()) {
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case ICmpInst::ICMP_SLT:
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case ICmpInst::ICMP_SLE:
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std::swap(LHS, RHS);
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// fall through
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case ICmpInst::ICMP_SGT:
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case ICmpInst::ICMP_SGE:
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if (LHS == U->getOperand(1) && RHS == U->getOperand(2))
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return SE.getSMaxExpr(getSCEV(LHS), getSCEV(RHS));
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else if (LHS == U->getOperand(2) && RHS == U->getOperand(1))
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// -smax(-x, -y) == smin(x, y).
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return SE.getNegativeSCEV(SE.getSMaxExpr(
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SE.getNegativeSCEV(getSCEV(LHS)),
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SE.getNegativeSCEV(getSCEV(RHS))));
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break;
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case ICmpInst::ICMP_ULT:
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case ICmpInst::ICMP_ULE:
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std::swap(LHS, RHS);
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// fall through
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case ICmpInst::ICMP_UGT:
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case ICmpInst::ICMP_UGE:
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if (LHS == U->getOperand(1) && RHS == U->getOperand(2))
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return SE.getUMaxExpr(getSCEV(LHS), getSCEV(RHS));
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else if (LHS == U->getOperand(2) && RHS == U->getOperand(1))
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// ~umax(~x, ~y) == umin(x, y)
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return SE.getNotSCEV(SE.getUMaxExpr(SE.getNotSCEV(getSCEV(LHS)),
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SE.getNotSCEV(getSCEV(RHS))));
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break;
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default:
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break;
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}
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}
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default: // We cannot analyze this expression.
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break;
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}
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return SE.getUnknown(V);
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