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New rlwimi implementation, which is superior to the old one. There are

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still a couple missed optimizations, but we now generate all the possible
rlwimis for multiple inserts into the same bitfield.  More regression tests
to come.

llvm-svn: 28156
This commit is contained in:
Nate Begeman 2006-05-07 00:23:38 +00:00
parent 5c9c9f0eb6
commit dc94b738d0
1 changed files with 46 additions and 87 deletions
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133
lib/Target/PowerPC/PPCISelDAGToDAG.cpp
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@ -391,15 +391,7 @@ static bool isIntImmediate(SDOperand N, unsigned& Imm) {
/// SelectBitfieldInsert - turn an or of two masked values into
/// the rotate left word immediate then mask insert (rlwimi) instruction.
/// Returns true on success, false if the caller still needs to select OR.
///
/// Patterns matched:
/// 1. or shl, and 5. or and, and
/// 2. or and, shl 6. or shl, shr
/// 3. or shr, and 7. or shr, shl
/// 4. or and, shr
SDNode *PPCDAGToDAGISel::SelectBitfieldInsert(SDNode *N) {
bool IsRotate = false;
unsigned TgtMask = 0xFFFFFFFF, InsMask = 0xFFFFFFFF, SH = 0;
unsigned Value;
@ -409,89 +401,56 @@ SDNode *PPCDAGToDAGISel::SelectBitfieldInsert(SDNode *N) {
unsigned Op0Opc = Op0.getOpcode();
unsigned Op1Opc = Op1.getOpcode();
// Verify that we have the correct opcodes
if (ISD::SHL != Op0Opc && ISD::SRL != Op0Opc && ISD::AND != Op0Opc)
return false;
if (ISD::SHL != Op1Opc && ISD::SRL != Op1Opc && ISD::AND != Op1Opc)
return false;
uint64_t LKZ, LKO, RKZ, RKO;
TLI.ComputeMaskedBits(Op0, TgtMask, LKZ, LKO);
TLI.ComputeMaskedBits(Op1, TgtMask, RKZ, RKO);
// Generate Mask value for Target
if (isIntImmediate(Op0.getOperand(1), Value)) {
switch(Op0Opc) {
case ISD::SHL: TgtMask <<= Value; break;
case ISD::SRL: TgtMask >>= Value; break;
case ISD::AND: TgtMask &= Value; break;
}
} else {
return 0;
}
// Generate Mask value for Insert
if (!isIntImmediate(Op1.getOperand(1), Value))
return 0;
switch(Op1Opc) {
case ISD::SHL:
SH = Value;
InsMask <<= SH;
if (Op0Opc == ISD::SRL) IsRotate = true;
break;
case ISD::SRL:
SH = Value;
InsMask >>= SH;
SH = 32-SH;
if (Op0Opc == ISD::SHL) IsRotate = true;
break;
case ISD::AND:
InsMask &= Value;
break;
}
// If both of the inputs are ANDs and one of them has a logical shift by
// constant as its input, make that AND the inserted value so that we can
// combine the shift into the rotate part of the rlwimi instruction
bool IsAndWithShiftOp = false;
if (Op0Opc == ISD::AND && Op1Opc == ISD::AND) {
if (Op1.getOperand(0).getOpcode() == ISD::SHL ||
Op1.getOperand(0).getOpcode() == ISD::SRL) {
if (isIntImmediate(Op1.getOperand(0).getOperand(1), Value)) {
SH = Op1.getOperand(0).getOpcode() == ISD::SHL ? Value : 32 - Value;
IsAndWithShiftOp = true;
}
} else if (Op0.getOperand(0).getOpcode() == ISD::SHL ||
Op0.getOperand(0).getOpcode() == ISD::SRL) {
if (isIntImmediate(Op0.getOperand(0).getOperand(1), Value)) {
std::swap(Op0, Op1);
std::swap(TgtMask, InsMask);
SH = Op1.getOperand(0).getOpcode() == ISD::SHL ? Value : 32 - Value;
IsAndWithShiftOp = true;
// FIXME: rotrwi / rotlwi
if ((LKZ | RKZ) == 0x00000000FFFFFFFFULL) {
unsigned PInsMask = ~RKZ;
unsigned PTgtMask = ~LKZ;
// If the LHS has a foldable shift, then swap it to the RHS so that we can
// fold the shift into the insert.
if (Op0Opc == ISD::AND && Op1Opc == ISD::AND) {
if (Op0.getOperand(0).getOpcode() == ISD::SHL ||
Op0.getOperand(0).getOpcode() == ISD::SRL) {
if (Op1.getOperand(0).getOpcode() != ISD::SHL &&
Op1.getOperand(0).getOpcode() != ISD::SRL) {
std::swap(Op0, Op1);
std::swap(Op0Opc, Op1Opc);
std::swap(PInsMask, PTgtMask);
}
}
}
}
// Verify that the Target mask and Insert mask together form a full word mask
// and that the Insert mask is a run of set bits (which implies both are runs
// of set bits). Given that, Select the arguments and generate the rlwimi
// instruction.
unsigned MB, ME;
if (((TgtMask & InsMask) == 0) && isRunOfOnes(InsMask, MB, ME)) {
bool fullMask = (TgtMask ^ InsMask) == 0xFFFFFFFF;
bool Op0IsAND = Op0Opc == ISD::AND;
// Check for rotlwi / rotrwi here, a special case of bitfield insert
// where both bitfield halves are sourced from the same value.
if (IsRotate && fullMask &&
N->getOperand(0).getOperand(0) == N->getOperand(1).getOperand(0)) {
SDOperand Tmp;
Select(Tmp, N->getOperand(0).getOperand(0));
return CurDAG->getTargetNode(PPC::RLWINM, MVT::i32, Tmp,
getI32Imm(SH), getI32Imm(0), getI32Imm(31));
unsigned MB, ME;
if (isRunOfOnes(PInsMask, MB, ME)) {
SDOperand Tmp1, Tmp2, Tmp3;
bool DisjointMask = (PTgtMask ^ PInsMask) == 0xFFFFFFFF;
if ((Op1Opc == ISD::SHL || Op1Opc == ISD::SRL) &&
isIntImmediate(Op1.getOperand(1), Value)) {
Op1 = Op1.getOperand(0);
SH = (Op1Opc == ISD::SHL) ? Value : 32 - Value;
}
if (Op1Opc == ISD::AND) {
unsigned SHOpc = Op1.getOperand(0).getOpcode();
if ((SHOpc == ISD::SHL || SHOpc == ISD::SRL) &&
isIntImmediate(Op1.getOperand(0).getOperand(1), Value)) {
Op1 = Op1.getOperand(0).getOperand(0);
SH = (SHOpc == ISD::SHL) ? Value : 32 - Value;
} else {
Op1 = Op1.getOperand(0);
}
}
Tmp3 = (Op0Opc == ISD::AND && DisjointMask) ? Op0.getOperand(0) : Op0;
Select(Tmp1, Tmp3);
Select(Tmp2, Op1);
return CurDAG->getTargetNode(PPC::RLWIMI, MVT::i32, Tmp1, Tmp2,
getI32Imm(SH), getI32Imm(MB), getI32Imm(ME));
}
SDOperand Tmp1, Tmp2;
Select(Tmp1, ((Op0IsAND && fullMask) ? Op0.getOperand(0) : Op0));
Select(Tmp2, (IsAndWithShiftOp ? Op1.getOperand(0).getOperand(0)
: Op1.getOperand(0)));
return CurDAG->getTargetNode(PPC::RLWIMI, MVT::i32, Tmp1, Tmp2,
getI32Imm(SH), getI32Imm(MB), getI32Imm(ME));
}
return 0;
}