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Teach the legalizer how to promote SINT_TO_FP to a wider SINT_TO_FP that

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the target natively supports.  This eliminates some special-case code from
the x86 backend and generates better code as well.

For an i8 to f64 conversion, before & after:

_x87 before:
        subl $2, %esp
        movb 6(%esp), %al
        movsbw %al, %ax
        movw %ax, (%esp)
        filds (%esp)
        addl $2, %esp
        ret

_x87 after:
        subl $2, %esp
        movsbw 6(%esp), %ax
        movw %ax, (%esp)
        filds (%esp)
        addl $2, %esp
        ret

_sse before:
        subl $12, %esp
        movb 16(%esp), %al
        movsbl %al, %eax
        cvtsi2sd %eax, %xmm0
        addl $12, %esp
        ret

_sse after:
        subl $12, %esp
        movsbl 16(%esp), %eax
        cvtsi2sd %eax, %xmm0
        addl $12, %esp
        ret


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22452 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Nate Begeman
2005-07-16 02:02:34 +00:00
parent 11cefd926a
commit 5a8441ea3f
2 changed files with 39 additions and 54 deletions
Download Patch File Download Diff File Expand all files Collapse all files

28
lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
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@@ -126,7 +126,8 @@ private:
SDOperand Source);
SDOperand ExpandLegalUINT_TO_FP(SDOperand LegalOp, MVT::ValueType DestVT);
SDOperand PromoteLegalUINT_TO_FP(SDOperand LegalOp, MVT::ValueType DestVT);
SDOperand PromoteLegalINT_TO_FP(SDOperand LegalOp, MVT::ValueType DestVT,
bool isSigned);
bool ExpandShift(unsigned Opc, SDOperand Op, SDOperand Amt,
SDOperand &Lo, SDOperand &Hi);
@@ -197,8 +198,9 @@ SDOperand SelectionDAGLegalize::ExpandLegalUINT_TO_FP(SDOperand Op0,
/// we promote it. At this point, we know that the result and operand types are
/// legal for the target, and that there is a legal UINT_TO_FP or SINT_TO_FP
/// operation that takes a larger input.
SDOperand SelectionDAGLegalize::PromoteLegalUINT_TO_FP(SDOperand LegalOp,
MVT::ValueType DestVT) {
SDOperand SelectionDAGLegalize::PromoteLegalINT_TO_FP(SDOperand LegalOp,
MVT::ValueType DestVT,
bool isSigned) {
// First step, figure out the appropriate *INT_TO_FP operation to use.
MVT::ValueType NewInTy = LegalOp.getValueType();
@@ -221,6 +223,7 @@ SDOperand SelectionDAGLegalize::PromoteLegalUINT_TO_FP(SDOperand LegalOp,
break;
}
if (OpToUse) break;
if (isSigned) continue;
// If the target supports UINT_TO_FP of this type, use it.
switch (TLI.getOperationAction(ISD::UINT_TO_FP, NewInTy)) {
@@ -244,7 +247,8 @@ SDOperand SelectionDAGLegalize::PromoteLegalUINT_TO_FP(SDOperand LegalOp,
// Okay, we found the operation and type to use. Zero extend our input to the
// desired type then run the operation on it.
return DAG.getNode(OpToUse, DestVT,
DAG.getNode(ISD::ZERO_EXTEND, NewInTy, LegalOp));
DAG.getNode(isSigned ? ISD::SIGN_EXTEND : ISD::ZERO_EXTEND,
NewInTy, LegalOp));
}
void SelectionDAGLegalize::LegalizeDAG() {
@@ -1438,18 +1442,24 @@ SDOperand SelectionDAGLegalize::LegalizeOp(SDOperand Op) {
switch (getTypeAction(Node->getOperand(0).getValueType())) {
case Legal:
//still made need to expand if the op is illegal, but the types are legal
if (Node->getOpcode() == ISD::UINT_TO_FP) {
if (Node->getOpcode() == ISD::UINT_TO_FP ||
Node->getOpcode() == ISD::SINT_TO_FP) {
bool isSigned = Node->getOpcode() == ISD::SINT_TO_FP;
switch (TLI.getOperationAction(Node->getOpcode(),
Node->getOperand(0).getValueType())) {
default: assert(0 && "Unknown operation action!");
case TargetLowering::Expand:
Result = ExpandLegalUINT_TO_FP(LegalizeOp(Node->getOperand(0)),
Node->getValueType(0));
if (!isSigned)
Result = ExpandLegalUINT_TO_FP(LegalizeOp(Node->getOperand(0)),
Node->getValueType(0));
else
assert(0 && "Legalize cannot Expand SINT_TO_FP yet");
AddLegalizedOperand(Op, Result);
return Result;
case TargetLowering::Promote:
Result = PromoteLegalUINT_TO_FP(LegalizeOp(Node->getOperand(0)),
Node->getValueType(0));
Result = PromoteLegalINT_TO_FP(LegalizeOp(Node->getOperand(0)),
Node->getValueType(0),
isSigned);
AddLegalizedOperand(Op, Result);
return Result;
case TargetLowering::Legal: