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Implement bitfield clears

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Implement divide by negative power of two

llvm-svn: 21240
This commit is contained in:
Nate Begeman 2005-04-12 00:10:02 +00:00
parent f31b58f145
commit a154deaaff
2 changed files with 35 additions and 11 deletions
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42
lib/Target/PowerPC/PPC32ISelPattern.cpp
View File

@ -604,12 +604,13 @@ static bool IsRunOfOnes(unsigned Val, unsigned &MB, unsigned &ME) {
/// getImmediateForOpcode - This method returns a value indicating whether
/// the ConstantSDNode N can be used as an immediate to Opcode. The return
/// values are either 0, 1 or 2. 0 indicates that either N is not a
/// ConstantSDNode, or is not suitable for use by that opcode. A return value
/// of 1 indicates that the constant may be used in normal immediate form. A
/// return value of 2 indicates that the constant may be used in shifted
/// immediate form. A return value of 3 indicates that log base 2 of the
/// constant may be used. A return value of 4 indicates that the constant is
/// suitable for conversion into a magic number for integer division.
/// ConstantSDNode, or is not suitable for use by that opcode.
/// Return value codes for turning into an enum someday:
/// 1: constant may be used in normal immediate form.
/// 2: constant may be used in shifted immediate form.
/// 3: log base 2 of the constant may be used.
/// 4: constant is suitable for integer division conversion
/// 5: constant is a bitfield mask
///
static unsigned getImmediateForOpcode(SDOperand N, unsigned Opcode,
unsigned& Imm, bool U = false) {
@ -623,7 +624,13 @@ static unsigned getImmediateForOpcode(SDOperand N, unsigned Opcode,
if (v <= 32767 && v >= -32768) { Imm = v & 0xFFFF; return 1; }
if ((v & 0x0000FFFF) == 0) { Imm = v >> 16; return 2; }
break;
case ISD::AND:
case ISD::AND: {
unsigned MB, ME;
if (IsRunOfOnes(v, MB, ME)) { Imm = MB << 16 | ME & 0xFFFF; return 5; }
if (v >= 0 && v <= 65535) { Imm = v & 0xFFFF; return 1; }
if ((v & 0x0000FFFF) == 0) { Imm = v >> 16; return 2; }
break;
}
case ISD::XOR:
case ISD::OR:
if (v >= 0 && v <= 65535) { Imm = v & 0xFFFF; return 1; }
@ -639,6 +646,7 @@ static unsigned getImmediateForOpcode(SDOperand N, unsigned Opcode,
break;
case ISD::SDIV:
if ((Imm = ExactLog2(v))) { return 3; }
if ((Imm = ExactLog2(-v))) { Imm = -Imm; return 3; }
if (v <= -2 || v >= 2) { return 4; }
break;
case ISD::UDIV:
@ -695,8 +703,6 @@ static unsigned IndexedOpForOp(unsigned Opcode) {
return 0;
}
///
// Structure used to return the necessary information to codegen an SDIV as
// a multiply.
struct ms {
@ -1719,6 +1725,13 @@ unsigned ISel::SelectExpr(SDOperand N, bool Recording) {
case 2: // Shifted immediate
BuildMI(BB, PPC::ANDISo, 2, Result).addReg(Tmp1).addImm(Tmp2);
break;
case 5: // Bitfield mask
Opc = Recording ? PPC::RLWINMo : PPC::RLWINM;
Tmp3 = Tmp2 >> 16; // MB
Tmp2 &= 0xFFFF; // ME
BuildMI(BB, Opc, 4, Result).addReg(Tmp1).addImm(0)
.addImm(Tmp3).addImm(Tmp2);
break;
}
RecordSuccess = true;
return Result;
@ -1828,8 +1841,15 @@ unsigned ISel::SelectExpr(SDOperand N, bool Recording) {
case 3:
Tmp1 = MakeReg(MVT::i32);
Tmp2 = SelectExpr(N.getOperand(0));
BuildMI(BB, PPC::SRAWI, 2, Tmp1).addReg(Tmp2).addImm(Tmp3);
BuildMI(BB, PPC::ADDZE, 1, Result).addReg(Tmp1);
if ((int)Tmp3 < 0) {
unsigned Tmp4 = MakeReg(MVT::i32);
BuildMI(BB, PPC::SRAWI, 2, Tmp1).addReg(Tmp2).addImm(-Tmp3);
BuildMI(BB, PPC::ADDZE, 1, Tmp4).addReg(Tmp1);
BuildMI(BB, PPC::NEG, 1, Result).addReg(Tmp4);
} else {
BuildMI(BB, PPC::SRAWI, 2, Tmp1).addReg(Tmp2).addImm(Tmp3);
BuildMI(BB, PPC::ADDZE, 1, Result).addReg(Tmp1);
}
return Result;
// If this is a divide by constant, we can emit code using some magic
// constants to implement it as a multiply instead.

4
lib/Target/PowerPC/PowerPCInstrInfo.td
View File

@ -464,6 +464,10 @@ def RLWIMI : MForm_2<20, 0, 0, 0,
def RLWINM : MForm_2<21, 0, 0, 0,
(ops GPRC:$rA, GPRC:$rS, u5imm:$SH, u5imm:$MB, u5imm:$ME),
"rlwinm $rA, $rS, $SH, $MB, $ME">;
let Defs = [CR0] in
def RLWINMo : MForm_2<21, 1, 0, 0,
(ops GPRC:$rA, GPRC:$rS, u5imm:$SH, u5imm:$MB, u5imm:$ME),
"rlwinm. $rA, $rS, $SH, $MB, $ME">;
def RLWNM : MForm_2<23, 0, 0, 0,
(ops GPRC:$rA, GPRC:$rS, GPRC:$rB, u5imm:$MB, u5imm:$ME),
"rlwnm $rA, $rS, $rB, $MB, $ME">;