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-rw-r--r--lib/Target/SystemZ/SystemZISelDAGToDAG.cpp265
-rw-r--r--test/CodeGen/SystemZ/risbg-01.ll154
2 files changed, 321 insertions, 98 deletions
diff --git a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
index 39589f6d20..149001e451 100644
--- a/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
+++ b/lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
@@ -92,6 +92,28 @@ struct SystemZAddressingMode {
}
};
+// Return a mask with Count low bits set.
+static uint64_t allOnes(unsigned int Count) {
+ return Count == 0 ? 0 : (uint64_t(1) << (Count - 1) << 1) - 1;
+}
+
+// Represents operands 2 to 5 of a ROTATE AND ... SELECTED BITS operation.
+// The operands are: Input (R2), Start (I3), End (I4) and Rotate (I5).
+// The operand value is effectively (and (rotl Input Rotate) Mask) and
+// has BitSize bits.
+struct RISBGOperands {
+ RISBGOperands(SDValue N)
+ : BitSize(N.getValueType().getSizeInBits()), Mask(allOnes(BitSize)),
+ Input(N), Start(64 - BitSize), End(63), Rotate(0) {}
+
+ unsigned BitSize;
+ uint64_t Mask;
+ SDValue Input;
+ unsigned Start;
+ unsigned End;
+ unsigned Rotate;
+};
+
class SystemZDAGToDAGISel : public SelectionDAGISel {
const SystemZTargetLowering &Lowering;
const SystemZSubtarget &Subtarget;
@@ -200,15 +222,19 @@ class SystemZDAGToDAGISel : public SelectionDAGISel {
Addr, Base, Disp, Index);
}
+ // Try to fold some of Ops.Input into other fields of Ops. Return true
+ // on success.
+ bool expandRISBG(RISBGOperands &Ops);
+
// Return an undefined i64 value.
SDValue getUNDEF64(SDLoc DL);
// Convert N to VT, if it isn't already.
SDValue convertTo(SDLoc DL, EVT VT, SDValue N);
- // Try to use RISBG to implement ISD::AND node N. Return the selected
- // node on success, otherwise return null.
- SDNode *tryRISBGForAND(SDNode *N);
+ // Try to implement AND or shift node N using RISBG with the zero flag set.
+ // Return the selected node on success, otherwise return null.
+ SDNode *tryRISBGZero(SDNode *N);
// If Op0 is null, then Node is a constant that can be loaded using:
//
@@ -546,19 +572,15 @@ static bool isStringOfOnes(uint64_t Mask, unsigned &LSB, unsigned &Length) {
return false;
}
-// Return a mask with Count low bits set.
-static uint64_t allOnes(unsigned int Count) {
- return Count == 0 ? 0 : (uint64_t(1) << (Count - 1) << 1) - 1;
-}
+// Try to update RISBG so that only the bits of Ops.Input in Mask are used.
+// Return true on success.
+static bool refineRISBGMask(RISBGOperands &RISBG, uint64_t Mask) {
+ if (RISBG.Rotate != 0)
+ Mask = (Mask << RISBG.Rotate) | (Mask >> (64 - RISBG.Rotate));
+ Mask &= RISBG.Mask;
-// Return true if RISBG can be used to extract the bits in Mask from
-// a value that has BitSize bits. Store the start and end operands
-// (I3 and I4) in Start and End if so.
-static bool isRISBGMask(uint64_t Mask, unsigned BitSize, unsigned &Start,
- unsigned &End) {
- // Reject trivial all-zero and all-one masks.
- uint64_t Used = allOnes(BitSize);
- if (Mask == 0 || Mask == Used)
+ // Reject trivial all-zero masks.
+ if (Mask == 0)
return false;
// Handle the 1+0+ or 0+1+0* cases. Start then specifies the index of
@@ -566,25 +588,127 @@ static bool isRISBGMask(uint64_t Mask, unsigned BitSize, unsigned &Start,
unsigned LSB, Length;
if (isStringOfOnes(Mask, LSB, Length))
{
- Start = 63 - (LSB + Length - 1);
- End = 63 - LSB;
+ RISBG.Mask = Mask;
+ RISBG.Start = 63 - (LSB + Length - 1);
+ RISBG.End = 63 - LSB;
return true;
}
// Handle the wrap-around 1+0+1+ cases. Start then specifies the msb
// of the low 1s and End specifies the lsb of the high 1s.
- if (isStringOfOnes(Mask ^ Used, LSB, Length))
+ if (isStringOfOnes(Mask ^ allOnes(RISBG.BitSize), LSB, Length))
{
assert(LSB > 0 && "Bottom bit must be set");
- assert(LSB + Length < BitSize && "Top bit must be set");
- Start = 63 - (LSB - 1);
- End = 63 - (LSB + Length);
+ assert(LSB + Length < RISBG.BitSize && "Top bit must be set");
+ RISBG.Mask = Mask;
+ RISBG.Start = 63 - (LSB - 1);
+ RISBG.End = 63 - (LSB + Length);
return true;
}
return false;
}
+bool SystemZDAGToDAGISel::expandRISBG(RISBGOperands &RISBG) {
+ SDValue N = RISBG.Input;
+ switch (N.getOpcode()) {
+ case ISD::AND: {
+ ConstantSDNode *MaskNode =
+ dyn_cast<ConstantSDNode>(N.getOperand(1).getNode());
+ if (!MaskNode)
+ return false;
+
+ SDValue Input = N.getOperand(0);
+ uint64_t Mask = MaskNode->getZExtValue();
+ if (!refineRISBGMask(RISBG, Mask)) {
+ // If some bits of Input are already known zeros, those bits will have
+ // been removed from the mask. See if adding them back in makes the
+ // mask suitable.
+ APInt KnownZero, KnownOne;
+ CurDAG->ComputeMaskedBits(Input, KnownZero, KnownOne);
+ Mask |= KnownZero.getZExtValue();
+ if (!refineRISBGMask(RISBG, Mask))
+ return false;
+ }
+ RISBG.Input = Input;
+ return true;
+ }
+
+ case ISD::ROTL: {
+ // Any 64-bit rotate left can be merged into the RISBG.
+ if (RISBG.BitSize != 64)
+ return false;
+ ConstantSDNode *CountNode
+ = dyn_cast<ConstantSDNode>(N.getOperand(1).getNode());
+ if (!CountNode)
+ return false;
+
+ RISBG.Rotate = (RISBG.Rotate + CountNode->getZExtValue()) & 63;
+ RISBG.Input = N.getOperand(0);
+ return true;
+ }
+
+ case ISD::SHL: {
+ // Treat (shl X, count) as (and (rotl X, count), ~0<<count).
+ ConstantSDNode *CountNode =
+ dyn_cast<ConstantSDNode>(N.getOperand(1).getNode());
+ if (!CountNode)
+ return false;
+
+ uint64_t Count = CountNode->getZExtValue();
+ if (Count < 1 ||
+ Count >= RISBG.BitSize ||
+ !refineRISBGMask(RISBG, allOnes(RISBG.BitSize - Count) << Count))
+ return false;
+
+ RISBG.Rotate = (RISBG.Rotate + Count) & 63;
+ RISBG.Input = N.getOperand(0);
+ return true;
+ }
+
+ case ISD::SRL: {
+ // Treat (srl X, count), mask) as (and (rotl X, size-count), ~0>>count),
+ // which is similar to SLL above.
+ ConstantSDNode *CountNode =
+ dyn_cast<ConstantSDNode>(N.getOperand(1).getNode());
+ if (!CountNode)
+ return false;
+
+ uint64_t Count = CountNode->getZExtValue();
+ if (Count < 1 ||
+ Count >= RISBG.BitSize ||
+ !refineRISBGMask(RISBG, allOnes(RISBG.BitSize - Count)))
+ return false;
+
+ RISBG.Rotate = (RISBG.Rotate - Count) & 63;
+ RISBG.Input = N.getOperand(0);
+ return true;
+ }
+
+ case ISD::SRA: {
+ // Treat (sra X, count) as (rotl X, size-count) as long as the top
+ // count bits from Ops.Input are ignored.
+ ConstantSDNode *CountNode =
+ dyn_cast<ConstantSDNode>(N.getOperand(1).getNode());
+ if (!CountNode)
+ return false;
+
+ uint64_t Count = CountNode->getZExtValue();
+ if (RISBG.Rotate != 0 ||
+ Count < 1 ||
+ Count >= RISBG.BitSize ||
+ RISBG.Start < 64 - (RISBG.BitSize - Count))
+ return false;
+
+ RISBG.Rotate = -Count & 63;
+ RISBG.Input = N.getOperand(0);
+ return true;
+ }
+ default:
+ return false;
+ }
+}
+
SDValue SystemZDAGToDAGISel::getUNDEF64(SDLoc DL) {
SDNode *N = CurDAG->getMachineNode(TargetOpcode::IMPLICIT_DEF, DL, MVT::i64);
return SDValue(N, 0);
@@ -607,87 +731,31 @@ SDValue SystemZDAGToDAGISel::convertTo(SDLoc DL, EVT VT, SDValue N) {
return N;
}
-SDNode *SystemZDAGToDAGISel::tryRISBGForAND(SDNode *N) {
- EVT VT = N->getValueType(0);
- unsigned BitSize = VT.getSizeInBits();
- unsigned Start, End;
- ConstantSDNode *MaskNode =
- dyn_cast<ConstantSDNode>(N->getOperand(1).getNode());
- if (!MaskNode)
+SDNode *SystemZDAGToDAGISel::tryRISBGZero(SDNode *N) {
+ RISBGOperands RISBG(SDValue(N, 0));
+ unsigned Count = 0;
+ while (expandRISBG(RISBG))
+ Count += 1;
+ // Prefer to use normal shift instructions over RISBG, since they can handle
+ // all cases and are sometimes shorter. Prefer to use RISBG for ANDs though,
+ // since it is effectively a three-operand instruction in this case,
+ // and since it can handle some masks that AND IMMEDIATE can't.
+ if (Count < (N->getOpcode() == ISD::AND ? 1 : 2))
return 0;
- SDValue Input = N->getOperand(0);
- uint64_t Mask = MaskNode->getZExtValue();
- if (!isRISBGMask(Mask, BitSize, Start, End)) {
- APInt KnownZero, KnownOne;
- CurDAG->ComputeMaskedBits(Input, KnownZero, KnownOne);
- Mask |= KnownZero.getZExtValue();
- if (!isRISBGMask(Mask, BitSize, Start, End))
- return 0;
- }
-
- unsigned Rotate = 0;
- if (Input->getOpcode() == ISD::ROTL && BitSize == 64) {
- // Any 64-bit rotate left can be merged into the RISBG.
- if (ConstantSDNode *CountNode =
- dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
- Rotate = CountNode->getZExtValue() & (BitSize - 1);
- Input = Input->getOperand(0);
- }
- } else if (Input->getOpcode() == ISD::SHL) {
- // Try to convert (and (shl X, count), mask) into
- // (and (rotl X, count), mask&(~0<<count)), where the new mask
- // removes bits from the original mask that are zeroed by the shl
- // but that are not necessarily zero in X.
- if (ConstantSDNode *CountNode =
- dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
- uint64_t Count = CountNode->getZExtValue();
- if (Count > 0 &&
- Count < BitSize &&
- isRISBGMask(Mask & (allOnes(BitSize - Count) << Count),
- BitSize, Start, End)) {
- Rotate = Count;
- Input = Input->getOperand(0);
- }
- }
- } else if (Input->getOpcode() == ISD::SRL) {
- // Try to convert (and (srl X, count), mask) into
- // (and (rotl X, size-count), mask&(~0>>count)), which is similar
- // to SLL above.
- if (ConstantSDNode *CountNode =
- dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
- uint64_t Count = CountNode->getZExtValue();
- if (Count > 0 &&
- Count < BitSize &&
- isRISBGMask(Mask & allOnes(BitSize - Count), BitSize, Start, End)) {
- Rotate = 64 - Count;
- Input = Input->getOperand(0);
- }
- }
- } else if (Start <= End && Input->getOpcode() == ISD::SRA) {
- // Try to convert (and (sra X, count), mask) into
- // (and (rotl X, size-count), mask). The mask must not include
- // any sign bits.
- if (ConstantSDNode *CountNode =
- dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
- uint64_t Count = CountNode->getZExtValue();
- if (Count > 0 && Count < BitSize && Start >= 64 - (BitSize - Count)) {
- Rotate = 64 - Count;
- Input = Input->getOperand(0);
- }
- }
- }
-
- // Prefer register extensions like LLC over RSIBG.
- if (Rotate == 0 && (Start == 32 || Start == 48 || Start == 56) && End == 63)
+ // Prefer register extensions like LLC over RISBG.
+ if (RISBG.Rotate == 0 &&
+ (RISBG.Start == 32 || RISBG.Start == 48 || RISBG.Start == 56) &&
+ RISBG.End == 63)
return 0;
+ EVT VT = N->getValueType(0);
SDValue Ops[5] = {
getUNDEF64(SDLoc(N)),
- convertTo(SDLoc(N), MVT::i64, Input),
- CurDAG->getTargetConstant(Start, MVT::i32),
- CurDAG->getTargetConstant(End | 128, MVT::i32),
- CurDAG->getTargetConstant(Rotate, MVT::i32)
+ convertTo(SDLoc(N), MVT::i64, RISBG.Input),
+ CurDAG->getTargetConstant(RISBG.Start, MVT::i32),
+ CurDAG->getTargetConstant(RISBG.End | 128, MVT::i32),
+ CurDAG->getTargetConstant(RISBG.Rotate, MVT::i32)
};
N = CurDAG->getMachineNode(SystemZ::RISBG, SDLoc(N), MVT::i64, Ops);
return convertTo(SDLoc(N), VT, SDValue(N, 0)).getNode();
@@ -778,7 +846,10 @@ SDNode *SystemZDAGToDAGISel::Select(SDNode *Node) {
break;
case ISD::AND:
- ResNode = tryRISBGForAND(Node);
+ case ISD::ROTL:
+ case ISD::SHL:
+ case ISD::SRL:
+ ResNode = tryRISBGZero(Node);
break;
case ISD::Constant:
diff --git a/test/CodeGen/SystemZ/risbg-01.ll b/test/CodeGen/SystemZ/risbg-01.ll
index f5aeaf14db..0c6826ad1f 100644
--- a/test/CodeGen/SystemZ/risbg-01.ll
+++ b/test/CodeGen/SystemZ/risbg-01.ll
@@ -1,4 +1,4 @@
-; Test sequences that can use RISBG.
+; Test sequences that can use RISBG with a zeroed first operand.
;
; RUN: llc < %s -mtriple=s390x-linux-gnu | FileCheck %s
@@ -264,3 +264,155 @@ define i64 @f23(i64 %foo) {
%and = and i64 %shr, 255
ret i64 %and
}
+
+; Test a case where the AND comes before a rotate.
+define i32 @f24(i32 %foo) {
+; CHECK-LABEL: f24:
+; CHECK: risbg [[REG:%r[0-5]]], %r2, 60, 190, 0
+; CHECK: rll %r2, [[REG]], 3
+; CHECK: br %r14
+ %and = and i32 %foo, 14
+ %parta = shl i32 %and, 3
+ %partb = lshr i32 %and, 29
+ %rotl = or i32 %parta, %partb
+ ret i32 %rotl
+}
+
+; ...and again with i64, where a single RISBG is enough.
+define i64 @f25(i64 %foo) {
+; CHECK-LABEL: f25:
+; CHECK: risbg %r2, %r2, 57, 187, 3
+; CHECK: br %r14
+ %and = and i64 %foo, 14
+ %parta = shl i64 %and, 3
+ %partb = lshr i64 %and, 61
+ %rotl = or i64 %parta, %partb
+ ret i64 %rotl
+}
+
+; Test a wrap-around case in which the rotate comes after the AND.
+define i32 @f26(i32 %foo) {
+; CHECK-LABEL: f26:
+; CHECK: risbg [[REG:%r[0-5]]], %r2, 60, 185, 0
+; CHECK: rll %r2, [[REG]], 5
+; CHECK: br %r14
+ %and = and i32 %foo, -49
+ %parta = shl i32 %and, 5
+ %partb = lshr i32 %and, 27
+ %rotl = or i32 %parta, %partb
+ ret i32 %rotl
+}
+
+; ...and again with i64, where a single RISBG is OK.
+define i64 @f27(i64 %foo) {
+; CHECK-LABEL: f27:
+; CHECK: risbg %r2, %r2, 55, 180, 5
+; CHECK: br %r14
+ %and = and i64 %foo, -49
+ %parta = shl i64 %and, 5
+ %partb = lshr i64 %and, 59
+ %rotl = or i64 %parta, %partb
+ ret i64 %rotl
+}
+
+; Test a case where the AND comes before a shift left.
+define i32 @f28(i32 %foo) {
+; CHECK-LABEL: f28:
+; CHECK: risbg %r2, %r2, 32, 173, 17
+; CHECK: br %r14
+ %and = and i32 %foo, 32766
+ %shl = shl i32 %and, 17
+ ret i32 %shl
+}
+
+; ...and again with i64.
+define i64 @f29(i64 %foo) {
+; CHECK-LABEL: f29:
+; CHECK: risbg %r2, %r2, 0, 141, 49
+; CHECK: br %r14
+ %and = and i64 %foo, 32766
+ %shl = shl i64 %and, 49
+ ret i64 %shl
+}
+
+; Test the next shift up from f28, in which the mask should get shortened.
+define i32 @f30(i32 %foo) {
+; CHECK-LABEL: f30:
+; CHECK: risbg %r2, %r2, 32, 172, 18
+; CHECK: br %r14
+ %and = and i32 %foo, 32766
+ %shl = shl i32 %and, 18
+ ret i32 %shl
+}
+
+; ...and again with i64.
+define i64 @f31(i64 %foo) {
+; CHECK-LABEL: f31:
+; CHECK: risbg %r2, %r2, 0, 140, 50
+; CHECK: br %r14
+ %and = and i64 %foo, 32766
+ %shl = shl i64 %and, 50
+ ret i64 %shl
+}
+
+; Test a wrap-around case in which the shift left comes after the AND.
+; We can't use RISBG for the shift in that case.
+define i32 @f32(i32 %foo) {
+; CHECK-LABEL: f32:
+; CHECK: sll %r2
+; CHECK: br %r14
+ %and = and i32 %foo, -7
+ %shl = shl i32 %and, 10
+ ret i32 %shl
+}
+
+; ...and again with i64.
+define i64 @f33(i64 %foo) {
+; CHECK-LABEL: f33:
+; CHECK: sllg %r2
+; CHECK: br %r14
+ %and = and i64 %foo, -7
+ %shl = shl i64 %and, 10
+ ret i64 %shl
+}
+
+; Test a case where the AND comes before a shift right.
+define i32 @f34(i32 %foo) {
+; CHECK-LABEL: f34:
+; CHECK: risbg %r2, %r2, 57, 191, 55
+; CHECK: br %r14
+ %and = and i32 %foo, 65535
+ %shl = lshr i32 %and, 9
+ ret i32 %shl
+}
+
+; ...and again with i64.
+define i64 @f35(i64 %foo) {
+; CHECK-LABEL: f35:
+; CHECK: risbg %r2, %r2, 57, 191, 55
+; CHECK: br %r14
+ %and = and i64 %foo, 65535
+ %shl = lshr i64 %and, 9
+ ret i64 %shl
+}
+
+; Test a wrap-around case where the AND comes before a shift right.
+; We can't use RISBG for the shift in that case.
+define i32 @f36(i32 %foo) {
+; CHECK-LABEL: f36:
+; CHECK: srl %r2
+; CHECK: br %r14
+ %and = and i32 %foo, -25
+ %shl = lshr i32 %and, 1
+ ret i32 %shl
+}
+
+; ...and again with i64.
+define i64 @f37(i64 %foo) {
+; CHECK-LABEL: f37:
+; CHECK: srlg %r2
+; CHECK: br %r14
+ %and = and i64 %foo, -25
+ %shl = lshr i64 %and, 1
+ ret i64 %shl
+}
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