[PowerPC] Eliminate integer compare instructions - vol. 2
This patch builds upon https://reviews.llvm.org/rL302810 to add
handling for bitwise logical operations in general purpose registers.
The idea is to keep the values in GPRs as long as possible - only
extracting them to a condition register bit when no further operations
are to be done.
Differential Revision: https://reviews.llvm.org/D31851
llvm-svn: 304282
diff --git a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
index 5fa7b2c..25991e5 100644
--- a/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelDAGToDAG.cpp
@@ -77,6 +77,11 @@
"Number of sign extensions for compare inputs added.");
STATISTIC(ZeroExtensionsAdded,
"Number of zero extensions for compare inputs added.");
+STATISTIC(NumLogicOpsOnComparison,
+ "Number of logical ops on i1 values calculated in GPR.");
+STATISTIC(OmittedForNonExtendUses,
+ "Number of compares not eliminated as they have non-extending uses.");
+
// FIXME: Remove this once the bug has been fixed!
cl::opt<bool> ANDIGlueBug("expose-ppc-andi-glue-bug",
cl::desc("expose the ANDI glue bug on PPC"), cl::Hidden);
@@ -275,6 +280,8 @@
bool trySETCC(SDNode *N);
bool tryEXTEND(SDNode *N);
+ bool tryLogicOpOfCompares(SDNode *N);
+ SDValue computeLogicOpInGPR(SDValue LogicOp);
SDValue signExtendInputIfNeeded(SDValue Input);
SDValue zeroExtendInputIfNeeded(SDValue Input);
SDValue addExtOrTrunc(SDValue NatWidthRes, ExtOrTruncConversion Conv);
@@ -2501,6 +2508,11 @@
return true;
}
+// Is this opcode a bitwise logical operation?
+static bool isLogicOp(unsigned Opc) {
+ return Opc == ISD::AND || Opc == ISD::OR || Opc == ISD::XOR;
+}
+
/// If this node is a sign/zero extension of an integer comparison,
/// it can usually be computed in GPR's rather than using comparison
/// instructions and ISEL. We only do this on 64-bit targets for now
@@ -2513,13 +2525,20 @@
N->getOpcode() == ISD::SIGN_EXTEND) &&
"Expecting a zero/sign extend node!");
- if (N->getOperand(0).getOpcode() != ISD::SETCC)
+ SDValue WideRes;
+ // If we are zero-extending the result of a logical operation on i1
+ // values, we can keep the values in GPRs.
+ if (isLogicOp(N->getOperand(0).getOpcode()) &&
+ N->getOperand(0).getValueType() == MVT::i1 &&
+ N->getOpcode() == ISD::ZERO_EXTEND)
+ WideRes = computeLogicOpInGPR(N->getOperand(0));
+ else if (N->getOperand(0).getOpcode() != ISD::SETCC)
return false;
-
- SDValue WideRes =
- getSETCCInGPR(N->getOperand(0),
- N->getOpcode() == ISD::SIGN_EXTEND ?
- SetccInGPROpts::SExtOrig : SetccInGPROpts::ZExtOrig);
+ else
+ WideRes =
+ getSETCCInGPR(N->getOperand(0),
+ N->getOpcode() == ISD::SIGN_EXTEND ?
+ SetccInGPROpts::SExtOrig : SetccInGPROpts::ZExtOrig);
if (!WideRes)
return false;
@@ -2540,6 +2559,159 @@
return true;
}
+// Lower a logical operation on i1 values into a GPR sequence if possible.
+// The result can be kept in a GPR if requested.
+// Three types of inputs can be handled:
+// - SETCC
+// - TRUNCATE
+// - Logical operation (AND/OR/XOR)
+// There is also a special case that is handled (namely a complement operation
+// achieved with xor %a, -1).
+SDValue PPCDAGToDAGISel::computeLogicOpInGPR(SDValue LogicOp) {
+ assert(isLogicOp(LogicOp.getOpcode()) &&
+ "Can only handle logic operations here.");
+ assert(LogicOp.getValueType() == MVT::i1 &&
+ "Can only handle logic operations on i1 values here.");
+ SDLoc dl(LogicOp);
+ SDValue LHS, RHS;
+
+ // Special case: xor %a, -1
+ bool IsBitwiseNegation = isBitwiseNot(LogicOp);
+
+ // Produces a GPR sequence for each operand of the binary logic operation.
+ // For SETCC, it produces the respective comparison, for TRUNCATE it truncates
+ // the value in a GPR and for logic operations, it will recursively produce
+ // a GPR sequence for the operation.
+ auto getLogicOperand = [&] (SDValue Operand) -> SDValue {
+ unsigned OperandOpcode = Operand.getOpcode();
+ if (OperandOpcode == ISD::SETCC)
+ return getSETCCInGPR(Operand, SetccInGPROpts::ZExtOrig);
+ else if (OperandOpcode == ISD::TRUNCATE) {
+ SDValue InputOp = Operand.getOperand(0);
+ EVT InVT = InputOp.getValueType();
+ return
+ SDValue(CurDAG->getMachineNode(InVT == MVT::i32 ? PPC::RLDICL_32 :
+ PPC::RLDICL, dl, InVT, InputOp,
+ getI64Imm(0, dl), getI64Imm(63, dl)), 0);
+ } else if (isLogicOp(OperandOpcode))
+ return computeLogicOpInGPR(Operand);
+ return SDValue();
+ };
+ LHS = getLogicOperand(LogicOp.getOperand(0));
+ RHS = getLogicOperand(LogicOp.getOperand(1));
+
+ // If a GPR sequence can't be produced for the LHS we can't proceed.
+ // Not producing a GPR sequence for the RHS is only a problem if this isn't
+ // a bitwise negation operation.
+ if (!LHS || (!RHS && !IsBitwiseNegation))
+ return SDValue();
+
+ NumLogicOpsOnComparison++;
+
+ // We will use the inputs as 64-bit values.
+ if (LHS.getValueType() == MVT::i32)
+ LHS = addExtOrTrunc(LHS, ExtOrTruncConversion::Ext);
+ if (!IsBitwiseNegation && RHS.getValueType() == MVT::i32)
+ RHS = addExtOrTrunc(RHS, ExtOrTruncConversion::Ext);
+
+ unsigned NewOpc;
+ switch (LogicOp.getOpcode()) {
+ default: llvm_unreachable("Unknown logic operation.");
+ case ISD::AND: NewOpc = PPC::AND8; break;
+ case ISD::OR: NewOpc = PPC::OR8; break;
+ case ISD::XOR: NewOpc = PPC::XOR8; break;
+ }
+
+ if (IsBitwiseNegation) {
+ RHS = getI64Imm(1, dl);
+ NewOpc = PPC::XORI8;
+ }
+
+ return SDValue(CurDAG->getMachineNode(NewOpc, dl, MVT::i64, LHS, RHS), 0);
+
+}
+
+/// Try performing logical operations on results of comparisons in GPRs.
+/// It is typically preferred from a performance perspective over performing
+/// the operations on individual bits in the CR. We only do this on 64-bit
+/// targets for now as the code is specialized for 64-bit (it uses 64-bit
+/// instructions and assumes 64-bit registers).
+bool PPCDAGToDAGISel::tryLogicOpOfCompares(SDNode *N) {
+ if (TM.getOptLevel() == CodeGenOpt::None || !TM.isPPC64())
+ return false;
+ if (N->getValueType(0) != MVT::i1)
+ return false;
+ assert(isLogicOp(N->getOpcode()) &&
+ "Expected a logic operation on setcc results.");
+ SDValue LoweredLogical = computeLogicOpInGPR(SDValue(N, 0));
+ if (!LoweredLogical)
+ return false;
+
+ SDLoc dl(N);
+ bool IsBitwiseNegate = LoweredLogical.getMachineOpcode() == PPC::XORI8;
+ unsigned SubRegToExtract = IsBitwiseNegate ? PPC::sub_eq : PPC::sub_gt;
+ SDValue CR0Reg = CurDAG->getRegister(PPC::CR0, MVT::i32);
+ SDValue LHS = LoweredLogical.getOperand(0);
+ SDValue RHS = LoweredLogical.getOperand(1);
+ SDValue WideOp;
+ SDValue OpToConvToRecForm;
+
+ // Look through any 32-bit to 64-bit implicit extend nodes to find the opcode
+ // that is input to the XORI.
+ if (IsBitwiseNegate &&
+ LoweredLogical.getOperand(0).getMachineOpcode() == PPC::INSERT_SUBREG)
+ OpToConvToRecForm = LoweredLogical.getOperand(0).getOperand(1);
+ else if (IsBitwiseNegate)
+ // If the input to the XORI isn't an extension, that's what we're after.
+ OpToConvToRecForm = LoweredLogical.getOperand(0);
+ else
+ // If this is not an XORI, it is a reg-reg logical op and we can convert it
+ // to record-form.
+ OpToConvToRecForm = LoweredLogical;
+
+ // Get the record-form version of the node we're looking to use to get the
+ // CR result from.
+ uint16_t NonRecOpc = OpToConvToRecForm.getMachineOpcode();
+ int NewOpc = PPCInstrInfo::getRecordFormOpcode(NonRecOpc);
+
+ // Convert the right node to record-form. This is either the logical we're
+ // looking at or it is the input node to the negation (if we're looking at
+ // a bitwise negation).
+ if (NewOpc != -1 && IsBitwiseNegate) {
+ // The input to the XORI has a record-form. Use it.
+ assert(LoweredLogical.getConstantOperandVal(1) == 1 &&
+ "Expected a PPC::XORI8 only for bitwise negation.");
+ // Emit the record-form instruction.
+ std::vector<SDValue> Ops;
+ for (int i = 0, e = OpToConvToRecForm.getNumOperands(); i < e; i++)
+ Ops.push_back(OpToConvToRecForm.getOperand(i));
+
+ WideOp =
+ SDValue(CurDAG->getMachineNode(NewOpc, dl,
+ OpToConvToRecForm.getValueType(),
+ MVT::Glue, Ops), 0);
+ } else {
+ assert((NewOpc != -1 || !IsBitwiseNegate) &&
+ "No record form available for AND8/OR8/XOR8?");
+ WideOp =
+ SDValue(CurDAG->getMachineNode(NewOpc == -1 ? PPC::ANDIo8 : NewOpc, dl,
+ MVT::i64, MVT::Glue, LHS, RHS), 0);
+ }
+
+ // Select this node to a single bit from CR0 set by the record-form node
+ // just created. For bitwise negation, use the EQ bit which is the equivalent
+ // of negating the result (i.e. it is a bit set when the result of the
+ // operation is zero).
+ SDValue SRIdxVal =
+ CurDAG->getTargetConstant(SubRegToExtract, dl, MVT::i32);
+ SDValue CRBit =
+ SDValue(CurDAG->getMachineNode(TargetOpcode::EXTRACT_SUBREG, dl,
+ MVT::i1, CR0Reg, SRIdxVal,
+ WideOp.getValue(1)), 0);
+ ReplaceNode(N, CRBit.getNode());
+ return true;
+}
+
/// If the value isn't guaranteed to be sign-extended to 64-bits, extend it.
/// Useful when emitting comparison code for 32-bit values without using
/// the compare instruction (which only considers the lower 32-bits).
@@ -2677,6 +2849,31 @@
}
}
+/// Does this SDValue have any uses for which keeping the value in a GPR is
+/// appropriate. This is meant to be used on values that have type i1 since
+/// it is somewhat meaningless to ask if values of other types can be kept in
+/// GPR's.
+static bool allUsesExtend(SDValue Compare, SelectionDAG *CurDAG) {
+ assert(Compare.getOpcode() == ISD::SETCC &&
+ "An ISD::SETCC node required here.");
+
+ // For values that have a single use, the caller should obviously already have
+ // checked if that use is an extending use. We check the other uses here.
+ if (Compare.hasOneUse())
+ return true;
+ // We want the value in a GPR if it is being extended, used for a select, or
+ // used in logical operations.
+ for (auto CompareUse : Compare.getNode()->uses())
+ if (CompareUse->getOpcode() != ISD::SIGN_EXTEND &&
+ CompareUse->getOpcode() != ISD::ZERO_EXTEND &&
+ CompareUse->getOpcode() != ISD::SELECT &&
+ !isLogicOp(CompareUse->getOpcode())) {
+ OmittedForNonExtendUses++;
+ return false;
+ }
+ return true;
+}
+
/// Returns an equivalent of a SETCC node but with the result the same width as
/// the inputs. This can nalso be used for SELECT_CC if either the true or false
/// values is a power of two while the other is zero.
@@ -2686,6 +2883,11 @@
Compare.getOpcode() == ISD::SELECT_CC) &&
"An ISD::SETCC node required here.");
+ // Don't convert this comparison to a GPR sequence because there are uses
+ // of the i1 result (i.e. uses that require the result in the CR).
+ if ((Compare.getOpcode() == ISD::SETCC) && !allUsesExtend(Compare, CurDAG))
+ return SDValue();
+
SDValue LHS = Compare.getOperand(0);
SDValue RHS = Compare.getOperand(1);
@@ -2906,6 +3108,9 @@
}
case ISD::AND: {
+ if (tryLogicOpOfCompares(N))
+ return;
+
unsigned Imm, Imm2, SH, MB, ME;
uint64_t Imm64;
@@ -3025,6 +3230,9 @@
if (tryBitfieldInsert(N))
return;
+ if (tryLogicOpOfCompares(N))
+ return;
+
short Imm;
if (N->getOperand(0)->getOpcode() == ISD::FrameIndex &&
isIntS16Immediate(N->getOperand(1), Imm)) {
@@ -3042,6 +3250,11 @@
// Other cases are autogenerated.
break;
}
+ case ISD::XOR: {
+ if (tryLogicOpOfCompares(N))
+ return;
+ break;
+ }
case ISD::ADD: {
short Imm;
if (N->getOperand(0)->getOpcode() == ISD::FrameIndex &&
diff --git a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
index 165970f..295590b 100644
--- a/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
+++ b/llvm/lib/Target/PowerPC/PPCInstr64Bit.td
@@ -735,12 +735,12 @@
"rldicl $rA, $rS, $SH, $MBE", IIC_IntRotateDI,
[]>, isPPC64;
// End fast-isel.
-let isCodeGenOnly = 1 in
-def RLDICL_32 : MDForm_1<30, 0,
- (outs gprc:$rA),
- (ins gprc:$rS, u6imm:$SH, u6imm:$MBE),
- "rldicl $rA, $rS, $SH, $MBE", IIC_IntRotateDI,
- []>, isPPC64;
+let Interpretation64Bit = 1, isCodeGenOnly = 1 in
+defm RLDICL_32 : MDForm_1r<30, 0,
+ (outs gprc:$rA),
+ (ins gprc:$rS, u6imm:$SH, u6imm:$MBE),
+ "rldicl", "$rA, $rS, $SH, $MBE", IIC_IntRotateDI,
+ []>, isPPC64;
defm RLDICR : MDForm_1r<30, 1,
(outs g8rc:$rA), (ins g8rc:$rS, u6imm:$SH, u6imm:$MBE),
"rldicr", "$rA, $rS, $SH, $MBE", IIC_IntRotateDI,
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
index fd6785e..f3c68c4 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
@@ -1983,3 +1983,7 @@
return &PPC::VSRCRegClass;
return RC;
}
+
+int PPCInstrInfo::getRecordFormOpcode(unsigned Opcode) {
+ return PPC::getRecordFormOpcode(Opcode);
+}
diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.h b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
index b30d09e..8dd4dbb 100644
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.h
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.h
@@ -290,6 +290,7 @@
return Reg >= PPC::V0 && Reg <= PPC::V31;
}
const TargetRegisterClass *updatedRC(const TargetRegisterClass *RC) const;
+ static int getRecordFormOpcode(unsigned Opcode);
};
}