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https://github.com/capstone-engine/llvm-capstone.git
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[SystemZ] Make more use of TMHH
This originally came about after noticing that InstCombine turns some of the TMHH (icmp (and...), ...) tests into plain comparisons. Since there is no instruction to compare with a 64-bit immediate, TMHH is generally better than an ordered comparison for the cases that it can handle. llvm-svn: 197238
This commit is contained in:
Richard Sandiford
parent
680385830f
commit
c3dc44781b
@ -1440,47 +1440,75 @@ static void adjustForTestUnderMask(SelectionDAG &DAG, Comparison &C) {
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uint64_t CmpVal = ConstOp1->getZExtValue();
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// Check whether the nonconstant input is an AND with a constant mask.
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if (C.Op0.getOpcode() != ISD::AND)
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return;
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SDValue AndOp0 = C.Op0.getOperand(0);
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SDValue AndOp1 = C.Op0.getOperand(1);
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ConstantSDNode *Mask = dyn_cast<ConstantSDNode>(AndOp1.getNode());
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if (!Mask)
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return;
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uint64_t MaskVal = Mask->getZExtValue();
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Comparison NewC(C);
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uint64_t MaskVal;
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ConstantSDNode *Mask = 0;
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if (C.Op0.getOpcode() == ISD::AND) {
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NewC.Op0 = C.Op0.getOperand(0);
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NewC.Op1 = C.Op0.getOperand(1);
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Mask = dyn_cast<ConstantSDNode>(NewC.Op1);
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if (!Mask)
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return;
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MaskVal = Mask->getZExtValue();
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} else {
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// There is no instruction to compare with a 64-bit immediate
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// so use TMHH instead if possible. We need an unsigned ordered
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// comparison with an i64 immediate.
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if (NewC.Op0.getValueType() != MVT::i64 ||
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NewC.CCMask == SystemZ::CCMASK_CMP_EQ ||
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NewC.CCMask == SystemZ::CCMASK_CMP_NE ||
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NewC.ICmpType == SystemZICMP::SignedOnly)
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return;
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// Convert LE and GT comparisons into LT and GE.
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if (NewC.CCMask == SystemZ::CCMASK_CMP_LE ||
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NewC.CCMask == SystemZ::CCMASK_CMP_GT) {
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if (CmpVal == uint64_t(-1))
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return;
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CmpVal += 1;
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NewC.CCMask ^= SystemZ::CCMASK_CMP_EQ;
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}
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// If the low N bits of Op1 are zero than the low N bits of Op0 can
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// be masked off without changing the result.
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MaskVal = -(CmpVal & -CmpVal);
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NewC.ICmpType = SystemZICMP::UnsignedOnly;
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}
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// Check whether the combination of mask, comparison value and comparison
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// type are suitable.
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unsigned BitSize = C.Op0.getValueType().getSizeInBits();
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unsigned BitSize = NewC.Op0.getValueType().getSizeInBits();
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unsigned NewCCMask, ShiftVal;
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if (C.ICmpType != SystemZICMP::SignedOnly &&
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AndOp0.getOpcode() == ISD::SHL &&
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isSimpleShift(AndOp0, ShiftVal) &&
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(NewCCMask = getTestUnderMaskCond(BitSize, C.CCMask, MaskVal >> ShiftVal,
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if (NewC.ICmpType != SystemZICMP::SignedOnly &&
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NewC.Op0.getOpcode() == ISD::SHL &&
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isSimpleShift(NewC.Op0, ShiftVal) &&
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(NewCCMask = getTestUnderMaskCond(BitSize, NewC.CCMask,
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MaskVal >> ShiftVal,
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CmpVal >> ShiftVal,
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SystemZICMP::Any))) {
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AndOp0 = AndOp0.getOperand(0);
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AndOp1 = DAG.getConstant(MaskVal >> ShiftVal, AndOp0.getValueType());
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} else if (C.ICmpType != SystemZICMP::SignedOnly &&
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AndOp0.getOpcode() == ISD::SRL &&
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isSimpleShift(AndOp0, ShiftVal) &&
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(NewCCMask = getTestUnderMaskCond(BitSize, C.CCMask,
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NewC.Op0 = NewC.Op0.getOperand(0);
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MaskVal >>= ShiftVal;
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} else if (NewC.ICmpType != SystemZICMP::SignedOnly &&
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NewC.Op0.getOpcode() == ISD::SRL &&
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isSimpleShift(NewC.Op0, ShiftVal) &&
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(NewCCMask = getTestUnderMaskCond(BitSize, NewC.CCMask,
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MaskVal << ShiftVal,
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CmpVal << ShiftVal,
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SystemZICMP::UnsignedOnly))) {
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AndOp0 = AndOp0.getOperand(0);
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AndOp1 = DAG.getConstant(MaskVal << ShiftVal, AndOp0.getValueType());
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NewC.Op0 = NewC.Op0.getOperand(0);
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MaskVal <<= ShiftVal;
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} else {
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NewCCMask = getTestUnderMaskCond(BitSize, C.CCMask, MaskVal, CmpVal,
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C.ICmpType);
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NewCCMask = getTestUnderMaskCond(BitSize, NewC.CCMask, MaskVal, CmpVal,
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NewC.ICmpType);
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if (!NewCCMask)
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return;
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}
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// Go ahead and make the change.
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C.Opcode = SystemZISD::TM;
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C.Op0 = AndOp0;
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C.Op1 = AndOp1;
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C.Op0 = NewC.Op0;
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if (Mask && Mask->getZExtValue() == MaskVal)
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C.Op1 = SDValue(Mask, 0);
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else
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C.Op1 = DAG.getConstant(MaskVal, C.Op0.getValueType());
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C.CCValid = SystemZ::CCMASK_TM;
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C.CCMask = NewCCMask;
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}
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@ -232,3 +232,112 @@ store:
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exit:
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ret void
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}
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; Check a case where TMHH can be used to implement a ult comparison.
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define void @f13(i64 %a) {
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; CHECK-LABEL: f13:
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; CHECK: tmhh %r2, 49152
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; CHECK: jno {{\.L.*}}
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; CHECK: br %r14
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entry:
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%cmp = icmp ult i64 %a, 13835058055282163712
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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; And again with ule.
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define void @f14(i64 %a) {
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; CHECK-LABEL: f14:
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; CHECK: tmhh %r2, 49152
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; CHECK: jno {{\.L.*}}
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; CHECK: br %r14
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entry:
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%cmp = icmp ule i64 %a, 13835058055282163711
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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; And again with ugt.
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define void @f15(i64 %a) {
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; CHECK-LABEL: f15:
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; CHECK: tmhh %r2, 49152
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; CHECK: jo {{\.L.*}}
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; CHECK: br %r14
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entry:
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%cmp = icmp ugt i64 %a, 13835058055282163711
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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; And again with uge.
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define void @f16(i64 %a) {
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; CHECK-LABEL: f16:
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; CHECK: tmhh %r2, 49152
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; CHECK: jo {{\.L.*}}
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; CHECK: br %r14
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entry:
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%cmp = icmp uge i64 %a, 13835058055282163712
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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; Decrease the constant from f13 to make TMHH invalid.
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define void @f17(i64 %a) {
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; CHECK-LABEL: f17:
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; CHECK-NOT: tmhh
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; CHECK: llihh {{%r[0-5]}}, 49151
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; CHECK-NOT: tmhh
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; CHECK: br %r14
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entry:
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%cmp = icmp ult i64 %a, 13834776580305453056
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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; Check that we don't use TMHH just to test the top bit.
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define void @f18(i64 %a) {
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; CHECK-LABEL: f18:
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; CHECK-NOT: tmhh
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; CHECK: cgijhe %r2, 0,
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; CHECK: br %r14
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entry:
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%cmp = icmp ult i64 %a, 9223372036854775808
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br i1 %cmp, label %exit, label %store
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store:
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store i32 1, i32 *@g
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br label %exit
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exit:
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ret void
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}
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