================
@@ -8695,6 +8730,83 @@ SDValue SystemZTargetLowering::combineSETCC(
}
static bool combineCCMask(SDValue &CCReg, int &CCValid, int &CCMask) {
+ // CCMask for ICmp is equal to 0, 1, 2 or 3.
+ const auto CCMaskForICmpEQCCVal = [](unsigned CC) {
+ assert(CC < 4 && "CC out of range");
+ return 1 << (3 - CC);
+ };
+ // Convert CCVal to CCMask based on CCMask and update it.
+ const auto convertCCValToCCMask = [&](int CCVal) {
+ bool Invert = false;
+ if (CCMask == SystemZ::CCMASK_CMP_NE)
+ Invert = !Invert;
+ if (CCMask == SystemZ::CCMASK_CMP_EQ || CCMask == SystemZ::CCMASK_CMP_NE) {
+ CCMask = CCMaskForICmpEQCCVal(CCVal);
+ if (Invert)
+ CCMask ^= SystemZ::CCMASK_ANY;
+ return true;
+ } else if (CCMask == SystemZ::CCMASK_CMP_LT) {
+ // CC in range [0, CCVal).
+ CCMask = ((~0U << (4 - CCVal)) & SystemZ::CCMASK_ANY);
+ return true;
+ } else if (CCMask == SystemZ::CCMASK_CMP_GT) {
+ // CC in range (CCVal, 3].
+ CCMask = (~(~0U << (3 - CCVal))) & SystemZ::CCMASK_ANY;
+ return true;
+ }
+ return false;
+ };
+ // Check (SRL (IPM (CC))) and update CCReg to combine.
+ const auto isSRL_IPM_CCSequence = [&CCReg](SDNode *N) {
+ if (!N || N->getOpcode() != ISD::SRL)
+ return false;
+ auto *SRLCount = dyn_cast<ConstantSDNode>(N->getOperand(1));
+ if (!SRLCount || SRLCount->getZExtValue() != SystemZ::IPM_CC)
+ return false;
+ auto *IPM = N->getOperand(0).getNode();
+ if (!IPM || IPM->getOpcode() != SystemZISD::IPM)
+ return false;
+ CCReg = IPM->getOperand(0);
+ return true;
+ };
+
+ auto *CCNode = CCReg.getNode();
+ if (!CCNode)
+ return false;
+
+ // Check (SRL (IPM)) pattern and update CCReg if true.
+ if (isSRL_IPM_CCSequence(CCNode))
+ return true;
+
+ // Combine CCMASK_TM with select_ccmask.
+ if (CCNode->getOpcode() == SystemZISD::SELECT_CCMASK) {
----------------
uweigand wrote:
Why restrict this to SELECT_CCMASK? If the transformation is correct for
SELECT_CCMASK, it must also be correct for BR_CCMASK.
https://github.com/llvm/llvm-project/pull/125970
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