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Implement SDIV by power of 2 as srawi/addze rather than load imm, divw

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@21091 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman 2005-04-05 00:15:08 +00:00
parent 93075ec0a5
commit 80196b1331
1 changed files with 24 additions and 0 deletions
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24
lib/Target/PowerPC/PPCISelPattern.cpp
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@ -485,6 +485,18 @@ public:
void SelectBranchCC(SDOperand N);
};
/// ExactLog2 - This function solves for (Val == 1 << (N-1)) and returns N. It
/// returns zero when the input is not exactly a power of two.
static unsigned ExactLog2(unsigned Val) {
if (Val == 0 || (Val & (Val-1))) return 0;
unsigned Count = 0;
while (Val != 1) {
Val >>= 1;
++Count;
}
return Count;
}
/// canUseAsImmediateForOpcode - 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
@ -520,6 +532,9 @@ static unsigned canUseAsImmediateForOpcode(SDOperand N, unsigned Opcode,
if (U && (v >= 0 && v <= 65535)) { Imm = v & 0xFFFF; return 1; }
if (!U && (v <= 32767 && v >= -32768)) { Imm = v & 0xFFFF; return 1; }
break;
case ISD::SDIV:
if (0 != ExactLog2(v)) { Imm = ExactLog2(v); return 1; }
break;
}
return 0;
}
@ -790,6 +805,7 @@ unsigned ISel::SelectExprFP(SDOperand N, unsigned Result)
N.getOperand(0).Val->hasOneUse() &&
ISD::MUL == N.getOperand(0).getOperand(0).getOpcode() &&
N.getOperand(0).getOperand(0).Val->hasOneUse()) {
++FusedFP; // Statistic
Tmp1 = SelectExpr(N.getOperand(0).getOperand(0).getOperand(0));
Tmp2 = SelectExpr(N.getOperand(0).getOperand(0).getOperand(1));
Tmp3 = SelectExpr(N.getOperand(0).getOperand(1));
@ -800,6 +816,7 @@ unsigned ISel::SelectExprFP(SDOperand N, unsigned Result)
N.getOperand(0).Val->hasOneUse() &&
ISD::MUL == N.getOperand(0).getOperand(0).getOpcode() &&
N.getOperand(0).getOperand(0).Val->hasOneUse()) {
++FusedFP; // Statistic
Tmp1 = SelectExpr(N.getOperand(0).getOperand(0).getOperand(0));
Tmp2 = SelectExpr(N.getOperand(0).getOperand(0).getOperand(1));
Tmp3 = SelectExpr(N.getOperand(0).getOperand(1));
@ -1385,6 +1402,13 @@ unsigned ISel::SelectExpr(SDOperand N) {
case ISD::SDIV:
case ISD::UDIV:
if (1 == canUseAsImmediateForOpcode(N.getOperand(1), opcode, Tmp3)) {
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);
return Result;
}
Tmp1 = SelectExpr(N.getOperand(0));
Tmp2 = SelectExpr(N.getOperand(1));
Opc = (ISD::UDIV == opcode) ? PPC::DIVWU : PPC::DIVW;