6502/llvm-6502
1
0
Fork 0
mirror of https://github.com/c64scene-ar/llvm-6502.git synced 2024-12-13 20:32:21 +00:00
Code Issues Projects Releases Wiki Activity

Necessary changes to codegen cttz efficiently on PowerPC

Browse Source 
1. Teach LegalizeDAG how to better legalize CTTZ if the target doesn't have
   CTPOP, but does have CTLZ
2. Teach PPC32 how to do sub x, const -> add x, -const for valid consts
3. Teach PPC32 how to do and (xor a, -1) b -> andc b, a
4. Teach PPC32 that ISD::CTLZ -> PPC::CNTLZW


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21880 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-05-11 23:43:56 +00:00
parent a65640edd0
commit d7c4a4a6c0
2 changed files with 41 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -1156,15 +1156,25 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
break;
}
case ISD::CTTZ: {
// for now, we use: { return popcount(~x & (x - 1)); }
// but see also http://www.hackersdelight.org/HDcode/ntz.cc
// for now, we use: { return popcount(~x & (x - 1)); }
// unless the target has ctlz but not ctpop, in which case we use:
// { return 32 - nlz(~x & (x-1)); }
// see also http://www.hackersdelight.org/HDcode/ntz.cc
MVT::ValueType VT = Tmp1.getValueType();
Tmp2 = DAG.getConstant(~0ULL, VT);
Tmp3 = DAG.getNode(ISD::AND, VT,
DAG.getNode(ISD::XOR, VT, Tmp1, Tmp2),
DAG.getNode(ISD::SUB, VT, Tmp1,
DAG.getConstant(1, VT)));
Result = LegalizeOp(DAG.getNode(ISD::CTPOP, VT, Tmp3));
// If ISD::CTLZ is legal and CTPOP isn't, then do that instead
if (TLI.getOperationAction(ISD::CTPOP, VT) != TargetLowering::Legal &&
TLI.getOperationAction(ISD::CTLZ, VT) == TargetLowering::Legal) {
Result = LegalizeOp(DAG.getNode(ISD::SUB, VT,
DAG.getConstant(getSizeInBits(VT), VT),
DAG.getNode(ISD::CTLZ, VT, Tmp3)));
} else {
Result = LegalizeOp(DAG.getNode(ISD::CTPOP, VT, Tmp3));
}
break;
}
default:

34
lib/Target/PowerPC/PPCISelPattern.cpp
View File

@ -69,10 +69,9 @@ namespace {
setOperationAction(ISD::FCOS , MVT::f32, Expand);
setOperationAction(ISD::FSQRT, MVT::f32, Expand);
//PowerPC has these, but they are not implemented
//PowerPC does not have CTPOP or CTTZ
setOperationAction(ISD::CTPOP, MVT::i32 , Expand);
setOperationAction(ISD::CTTZ , MVT::i32 , Expand);
setOperationAction(ISD::CTLZ , MVT::i32 , Expand);
setSetCCResultContents(ZeroOrOneSetCCResult);
addLegalFPImmediate(+0.0); // Necessary for FSEL
@ -654,9 +653,13 @@ static unsigned getImmediateForOpcode(SDOperand N, unsigned Opcode,
if ((v & 0x0000FFFF) == 0) { Imm = v >> 16; return 2; }
break;
case ISD::MUL:
case ISD::SUB:
if (v <= 32767 && v >= -32768) { Imm = v & 0xFFFF; return 1; }
break;
case ISD::SUB:
// handle subtract-from separately from subtract, since subi is really addi
if (U && v <= 32767 && v >= -32768) { Imm = v & 0xFFFF; return 1; }
if (!U && v <= 32768 && v >= -32767) { Imm = (-v) & 0xFFFF; return 1; }
break;
case ISD::SETCC:
if (U && (v >= 0 && v <= 65535)) { Imm = v & 0xFFFF; return 1; }
if (!U && (v <= 32767 && v >= -32768)) { Imm = v & 0xFFFF; return 1; }
@ -1817,6 +1820,11 @@ unsigned ISel::SelectExpr(SDOperand N, bool Recording) {
}
return Result;
case ISD::CTLZ:
Tmp1 = SelectExpr(N.getOperand(0));
BuildMI(BB, PPC::CNTLZW, 1, Result).addReg(Tmp1);
return Result;
case ISD::ADD:
assert (DestType == MVT::i32 && "Only do arithmetic on i32s!");
Tmp1 = SelectExpr(N.getOperand(0));
@ -1851,6 +1859,16 @@ unsigned ISel::SelectExpr(SDOperand N, bool Recording) {
switch(getImmediateForOpcode(N.getOperand(1), opcode, Tmp2)) {
default: assert(0 && "unhandled result code");
case 0: // No immediate
// Check for andc: and, (xor a, -1), b
if (N.getOperand(0).getOpcode() == ISD::XOR &&
N.getOperand(0).getOperand(1).getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(N.getOperand(0).getOperand(1))->isAllOnesValue()) {
Tmp1 = SelectExpr(N.getOperand(0).getOperand(0));
Tmp2 = SelectExpr(N.getOperand(1));
BuildMI(BB, PPC::ANDC, 2, Result).addReg(Tmp2).addReg(Tmp1);
return Result;
}
// It wasn't and-with-complement, emit a regular and
Tmp1 = SelectExpr(N.getOperand(0));
Tmp2 = SelectExpr(N.getOperand(1));
Opc = Recording ? PPC::ANDo : PPC::AND;
@ -1976,11 +1994,15 @@ unsigned ISel::SelectExpr(SDOperand N, bool Recording) {
}
case ISD::SUB:
Tmp2 = SelectExpr(N.getOperand(1));
if (1 == getImmediateForOpcode(N.getOperand(0), opcode, Tmp1))
if (1 == getImmediateForOpcode(N.getOperand(0), opcode, Tmp1, true)) {
Tmp2 = SelectExpr(N.getOperand(1));
BuildMI(BB, PPC::SUBFIC, 2, Result).addReg(Tmp2).addSImm(Tmp1);
else {
} else if (1 == getImmediateForOpcode(N.getOperand(1), opcode, Tmp2)) {
Tmp1 = SelectExpr(N.getOperand(0));
BuildMI(BB, PPC::ADDI, 2, Result).addReg(Tmp1).addSImm(Tmp2);
} else {
Tmp1 = SelectExpr(N.getOperand(0));
Tmp2 = SelectExpr(N.getOperand(1));
BuildMI(BB, PPC::SUBF, 2, Result).addReg(Tmp2).addReg(Tmp1);
}
return Result;