[clang] [llvm] Add support for flag output operand "=@cc" for SystemZ. (PR #125970)
Ulrich Weigand via cfe-commits
cfe-commits at lists.llvm.org
Mon Aug 11 01:46:37 PDT 2025
================
@@ -8702,61 +8738,264 @@ SDValue SystemZTargetLowering::combineSETCC(
return SDValue();
}
+static SmallSet<int, 4> convertCCMaskToCCValsSet(int Mask) {
+ SmallSet<int, 4> CCVals;
+ size_t Pos = 0;
+ while (Mask) {
+ if (Mask & 0x1)
+ CCVals.insert(3 - Pos);
+ Mask >>= 1;
+ ++Pos;
+ }
+ return CCVals;
+}
+
+static std::pair<SDValue, int> findCCUse(const SDValue &Val) {
+ auto *N = Val.getNode();
+ if (!N)
+ return {Val, SystemZ::CCMASK_NONE};
+ if (isa<ConstantSDNode>(Val))
+ return std::make_pair(SDValue(), SystemZ::CCMASK_NONE);
+ else if (N->getOpcode() == ISD::CopyFromReg && N->getNumOperands() > 1) {
+ if (auto *RN = cast<RegisterSDNode>(N->getOperand(1))) {
+ if (RN->getReg() == SystemZ::CC)
+ return {Val, SystemZ::CCMASK_ANY};
+ }
+ } else if (N->getOpcode() == SystemZISD::IPM)
+ return std::make_pair(N->getOperand(0), SystemZ::CCMASK_ANY);
+ else if (N->getOpcode() == ISD::SRL)
+ return findCCUse(N->getOperand(0));
+ else if (N->getOpcode() == SystemZISD::ICMP)
+ return findCCUse(N->getOperand(0));
+ else if (N->getOpcode() == SystemZISD::TM)
+ return findCCUse(N->getOperand(0));
+ else if (N->getOpcode() == SystemZISD::SELECT_CCMASK) {
+ SDValue SelectCCReg = N->getOperand(4);
+ auto [OpCC, OpCCValid] = findCCUse(SelectCCReg);
+ auto *OpCCNode = OpCC.getNode();
+ if (OpCCNode && OpCCNode != SelectCCReg.getNode())
+ return std::make_pair(OpCC, OpCCValid);
+ auto *CCValid = dyn_cast<ConstantSDNode>(N->getOperand(2));
+ if (CCValid)
+ return std::make_pair(SelectCCReg, CCValid->getZExtValue());
+ } else if (N->getOpcode() == ISD::ADD || N->getOpcode() == ISD::AND ||
+ N->getOpcode() == ISD::OR || N->getOpcode() == ISD::XOR ||
+ N->getOpcode() == ISD::AND) {
+ auto [Op0CC, Op0CCValid] = findCCUse(N->getOperand(0));
+ if (isa<ConstantSDNode>(N->getOperand(1)))
+ return std::make_pair(Op0CC, Op0CCValid);
+ auto [Op1CC, Op1CCValid] = findCCUse(N->getOperand(1));
+ auto *N0 = Op0CC.getNode(), *N1 = Op1CC.getNode();
+ if (N0 && N1 && N0 == N1 && Op0CCValid == Op1CCValid)
+ return std::make_pair(Op0CC, Op0CCValid);
+ }
+ return {SDValue(), SystemZ::CCMASK_ANY};
+}
+
+static bool combineCCMask(SDValue &CCReg, int &CCValid, int &CCMask);
+
+static SmallVector<int, 4> simplifyAssumingCCVal(SDValue &Val, SDValue &CC) {
+ const auto isValidBinaryOperation = [](const SDValue &Op, SDValue &Op0,
+ SDValue &Op1, unsigned &Opcode) {
+ auto *N = Op.getNode();
+ if (!N)
+ return false;
+ Opcode = N->getOpcode();
+ if (Opcode != ISD::ADD && Opcode != ISD::AND && Opcode != ISD::OR &&
+ Opcode != ISD::XOR)
+ return false;
+ Op0 = N->getOperand(0);
+ Op1 = N->getOperand(1);
+ return true;
+ };
+ auto *C = dyn_cast<ConstantSDNode>(Val);
+ if (C) {
+ int ConstVal = C->getZExtValue();
+ return {ConstVal, ConstVal, ConstVal, ConstVal};
+ }
+ auto *N = Val.getNode(), *CCNode = CC.getNode();
+ if (!N || !CCNode)
+ return {};
+ if (N == CCNode)
+ return {0, 1, 2, 3};
+ if (N->getOpcode() == SystemZISD::IPM) {
+ SDValue IPMOp0 = N->getOperand(0);
+ auto &&CCVals = simplifyAssumingCCVal(IPMOp0, CC);
+ if (CCVals.empty())
+ return CCVals;
+ auto ShiftAmount = SystemZ::IPM_CC;
+ std::for_each(CCVals.begin(), CCVals.end(),
+ [&ShiftAmount](auto &V) { V <<= ShiftAmount; });
+ return CCVals;
+ }
+ if (N->getOpcode() == ISD::SRL) {
+ SDValue Op0 = N->getOperand(0);
+ auto *SRLCount = dyn_cast<ConstantSDNode>(N->getOperand(1));
+ if (!SRLCount)
+ return {};
+ auto SRLCountVal = SRLCount->getZExtValue();
+ auto &&CCVals = simplifyAssumingCCVal(Op0, CC);
+ if (CCVals.empty())
+ return CCVals;
+ std::for_each(CCVals.begin(), CCVals.end(),
+ [SRLCountVal](auto &V) { V >>= SRLCountVal; });
+ return CCVals;
+ }
+ DenseMap<unsigned, std::function<int(int, int)>> BinaryOPS = {
+ {ISD::ADD, [](int Op1, int Op2) { return Op1 + Op2; }},
+ {ISD::AND, [](int Op1, int Op2) { return Op1 & Op2; }},
+ {ISD::OR, [](int Op1, int Op2) { return Op1 | Op2; }},
+ {ISD::XOR, [](int Op1, int Op2) { return Op1 ^ Op2; }},
+ };
+ if (N->getOpcode() == SystemZISD::SELECT_CCMASK) {
+ SDValue TrueVal = N->getOperand(0), FalseVal = N->getOperand(1);
+ auto *TrueOp = TrueVal.getNode();
+ auto *FalseOp = FalseVal.getNode();
+ auto *CCValid = dyn_cast<ConstantSDNode>(N->getOperand(2));
+ auto *CCMask = dyn_cast<ConstantSDNode>(N->getOperand(3));
+ if (!TrueOp || !FalseOp || !CCValid || !CCMask)
+ return {};
+
+ int CCValidVal = CCValid->getZExtValue();
+ int CCMaskVal = CCMask->getZExtValue();
+ auto [Op0CC, Op0CCValid] = findCCUse(TrueVal);
+ auto &&TrueVals =
+ simplifyAssumingCCVal(TrueVal, Op0CC == SDValue() ? CC : Op0CC);
+ auto [Op1CC, Op1CCValid] = findCCUse(FalseVal);
+ auto &&FalseVals =
+ simplifyAssumingCCVal(FalseVal, Op1CC == SDValue() ? CC : Op1CC);
+ SDValue SelectCCReg = N->getOperand(4);
+ auto [Op4CC, Op4CCValid] = findCCUse(SelectCCReg);
+ auto Op4CCNode = Op4CC.getNode();
+ if (Op4CCNode && Op4CCNode == CCNode && Op4CCNode != SelectCCReg.getNode())
+ combineCCMask(SelectCCReg, CCValidVal, CCMaskVal);
+ SmallVector<int, 4> CCVals;
+ auto CCMaskValsSet = convertCCMaskToCCValsSet(CCMaskVal);
+ auto CCValidValsSet = convertCCMaskToCCValsSet(CCValidVal);
+ for (auto &CCVal : {0, 1, 2, 3})
+ CCVals.emplace_back(
+ (CCMaskValsSet.count(CCVal) && CCValidValsSet.count(CCVal))
+ ? TrueVals[CCVal]
+ : FalseVals[CCVal]);
+ return CCVals;
+ }
+ SDValue Op0, Op1;
+ unsigned Opcode;
+ if (isValidBinaryOperation(Val, Op0, Op1, Opcode)) {
+ auto &&CC0Vals = simplifyAssumingCCVal(Op0, CC);
+ auto &&CC1Vals = simplifyAssumingCCVal(Op1, CC);
+ SmallVector<int, 4> CCVals;
+ for (auto CCVal : {0, 1, 2, 3})
+ CCVals.emplace_back(BinaryOPS[Opcode](CC0Vals[CCVal], CC1Vals[CCVal]));
+ return CCVals;
+ }
+ return {};
+}
+
static bool combineCCMask(SDValue &CCReg, int &CCValid, int &CCMask) {
// We have a SELECT_CCMASK or BR_CCMASK comparing the condition code
// set by the CCReg instruction using the CCValid / CCMask masks,
- // If the CCReg instruction is itself a ICMP testing the condition
+ // If the CCReg instruction is itself a ICMP / TM testing the condition
// code set by some other instruction, see whether we can directly
// use that condition code.
-
- // Verify that we have an ICMP against some constant.
- if (CCValid != SystemZ::CCMASK_ICMP)
- return false;
- auto *ICmp = CCReg.getNode();
- if (ICmp->getOpcode() != SystemZISD::ICMP)
- return false;
- auto *CompareLHS = ICmp->getOperand(0).getNode();
- auto *CompareRHS = dyn_cast<ConstantSDNode>(ICmp->getOperand(1));
- if (!CompareRHS)
+ auto *CCNode = CCReg.getNode();
+ if (!CCNode)
return false;
-
- // Optimize the case where CompareLHS is a SELECT_CCMASK.
- if (CompareLHS->getOpcode() == SystemZISD::SELECT_CCMASK) {
- // Verify that we have an appropriate mask for a EQ or NE comparison.
- bool Invert = false;
- if (CCMask == SystemZ::CCMASK_CMP_NE)
- Invert = !Invert;
- else if (CCMask != SystemZ::CCMASK_CMP_EQ)
+ if (CCNode->getOpcode() == SystemZISD::TM) {
+ if (CCValid != SystemZ::CCMASK_TM)
return false;
-
- // Verify that the ICMP compares against one of select values.
- auto *TrueVal = dyn_cast<ConstantSDNode>(CompareLHS->getOperand(0));
- if (!TrueVal)
+ if ((CCMask != SystemZ::CCMASK_TM_SOME_1) &&
+ (CCMask != SystemZ::CCMASK_TM_ALL_0))
return false;
- auto *FalseVal = dyn_cast<ConstantSDNode>(CompareLHS->getOperand(1));
- if (!FalseVal)
+ SDValue Op0 = CCNode->getOperand(0);
+ SDValue Op1 = CCNode->getOperand(1);
+ auto [Op0CC, Op0CCValid] = findCCUse(Op0);
+ if (Op0CC == SDValue())
return false;
- if (CompareRHS->getAPIntValue() == FalseVal->getAPIntValue())
- Invert = !Invert;
- else if (CompareRHS->getAPIntValue() != TrueVal->getAPIntValue())
+ int TMConstVal;
+ auto *N = dyn_cast<ConstantSDNode>(Op1);
+ if (N) {
+ TMConstVal = N->getZExtValue();
+ if ((TMConstVal != (1 << SystemZ::IPM_CC)) && (TMConstVal != 1))
+ return false;
----------------
uweigand wrote:
This should likewise not be necessary if we fully implement TM semantics.
https://github.com/llvm/llvm-project/pull/125970
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