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Teach the legalizer how to legalize FP_TO_UINT. 

Teach the legalizer to promote FP_TO_UINT to FP_TO_SINT if the wider
  FP_TO_UINT is also illegal.  This allows us on PPC to codegen
  unsigned short foo(float a) { return a; }

as:
_foo:
.LBB_foo_0:     ; entry
        fctiwz f0, f1
        stfd f0, -8(r1)
        lwz r2, -4(r1)
        rlwinm r3, r2, 0, 16, 31
        blr

instead of:
_foo:
.LBB_foo_0:     ; entry
        fctiwz f0, f1
        stfd f0, -8(r1)
        lwz r2, -4(r1)
        lis r3, ha16(.CPI_foo_0)
        lfs f0, lo16(.CPI_foo_0)(r3)
        fcmpu cr0, f1, f0
        blt .LBB_foo_2  ; entry
.LBB_foo_1:     ; entry
        fsubs f0, f1, f0
        fctiwz f0, f0
        stfd f0, -16(r1)
        lwz r2, -12(r1)
        xoris r2, r2, 32768
.LBB_foo_2:     ; entry
        rlwinm r3, r2, 0, 16, 31
        blr

llvm-svn: 22785
This commit is contained in:
Nate Begeman 2005-08-14 01:20:53 +00:00
parent 83f6b98c42
commit 36853ee1fd
1 changed files with 32 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
View File

@ -1610,7 +1610,25 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
switch (TLI.getOperationAction(Node->getOpcode(), Node->getValueType(0))){
default: assert(0 && "Unknown operation action!");
case TargetLowering::Expand:
assert(0 && "Cannot expand FP_TO*INT yet");
if (Node->getOpcode() == ISD::FP_TO_UINT) {
SDOperand True, False;
MVT::ValueType VT = Node->getOperand(0).getValueType();
MVT::ValueType NVT = Node->getValueType(0);
unsigned ShiftAmt = MVT::getSizeInBits(Node->getValueType(0))-1;
Tmp2 = DAG.getConstantFP((double)(1ULL << ShiftAmt), VT);
Tmp3 = DAG.getSetCC(TLI.getSetCCResultTy(),
Node->getOperand(0), Tmp2, ISD::SETLT);
True = DAG.getNode(ISD::FP_TO_SINT, NVT, Node->getOperand(0));
False = DAG.getNode(ISD::FP_TO_SINT, NVT,
DAG.getNode(ISD::SUB, VT, Node->getOperand(0),
Tmp2));
False = DAG.getNode(ISD::XOR, NVT, False,
DAG.getConstant(1ULL << ShiftAmt, NVT));
Result = LegalizeOp(DAG.getNode(ISD::SELECT, NVT, Tmp3, True, False));
} else {
assert(0 && "Do not know how to expand FP_TO_SINT yet!");
}
break;
case TargetLowering::Promote:
Result = PromoteLegalFP_TO_INT(Tmp1, Node->getValueType(0),
Node->getOpcode() == ISD::FP_TO_SINT);
@ -1907,7 +1925,18 @@ SDOperand SelectionDAGLegalize::PromoteOp(SDOperand Op) {
case Expand:
assert(0 && "not implemented");
}
Result = DAG.getNode(Node->getOpcode(), NVT, Tmp1);
// If we're promoting a UINT to a larger size, check to see if the new node
// will be legal. If it isn't, check to see if FP_TO_SINT is legal, since
// we can use that instead. This allows us to generate better code for
// FP_TO_UINT for small destination sizes on targets where FP_TO_UINT is not
// legal, such as PowerPC.
if (Node->getOpcode() == ISD::FP_TO_UINT &&
TargetLowering::Legal != TLI.getOperationAction(ISD::FP_TO_UINT, NVT) &&
TargetLowering::Legal == TLI.getOperationAction(ISD::FP_TO_SINT, NVT)) {
Result = DAG.getNode(ISD::FP_TO_SINT, NVT, Tmp1);
} else {
Result = DAG.getNode(Node->getOpcode(), NVT, Tmp1);
}
break;
case ISD::FABS:
@ -2078,7 +2107,7 @@ SDOperand SelectionDAGLegalize::PromoteOp(SDOperand Op) {
break;
case ISD::CTTZ:
//if Tmp1 == sizeinbits(NVT) then Tmp1 = sizeinbits(Old VT)
Tmp2 = DAG.getSetCC(MVT::i1, Tmp1,
Tmp2 = DAG.getSetCC(TLI.getSetCCResultTy(), Tmp1,
DAG.getConstant(getSizeInBits(NVT), NVT), ISD::SETEQ);
Result = DAG.getNode(ISD::SELECT, NVT, Tmp2,
DAG.getConstant(getSizeInBits(VT),NVT), Tmp1);