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[SystemZ] Use zeroing form of RISBG for shift-and-AND sequences

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Extend r186072 to handle shifts and ANDs.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186073 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Richard Sandiford 2013-07-11 09:10:09 +00:00
parent b3cabb44c3
commit 261e2877eb
2 changed files with 68 additions and 7 deletions
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71
lib/Target/SystemZ/SystemZISelDAGToDAG.cpp
View File

@ -613,20 +613,81 @@ SDNode *SystemZDAGToDAGISel::tryRISBGForAND(SDNode *N) {
unsigned Start, End;
ConstantSDNode *MaskNode =
dyn_cast<ConstantSDNode>(N->getOperand(1).getNode());
if (!MaskNode
|| !isRISBGMask(MaskNode->getZExtValue(), BitSize, Start, End))
if (!MaskNode)
return 0;
SDValue Input = N->getOperand(0);
uint64_t Mask = MaskNode->getZExtValue();
if (!isRISBGMask(Mask, BitSize, Start, End)) {
APInt KnownZero, KnownOne;
CurDAG->ComputeMaskedBits(Input, KnownZero, KnownOne);
Mask |= KnownZero.getZExtValue();
if (!isRISBGMask(Mask, BitSize, Start, End))
return 0;
}
unsigned Rotate = 0;
if (Input->getOpcode() == ISD::ROTL && BitSize == 64) {
// Any 64-bit rotate left can be merged into the RISBG.
if (ConstantSDNode *CountNode =
dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
Rotate = CountNode->getZExtValue() & (BitSize - 1);
Input = Input->getOperand(0);
}
} else if (Input->getOpcode() == ISD::SHL) {
// Try to convert (and (shl X, count), mask) into
// (and (rotl X, count), mask&(~0<<count)), where the new mask
// removes bits from the original mask that are zeroed by the shl
// but that are not necessarily zero in X.
if (ConstantSDNode *CountNode =
dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
uint64_t Count = CountNode->getZExtValue();
if (Count > 0 &&
Count < BitSize &&
isRISBGMask(Mask & (allOnes(BitSize - Count) << Count),
BitSize, Start, End)) {
Rotate = Count;
Input = Input->getOperand(0);
}
}
} else if (Input->getOpcode() == ISD::SRL) {
// Try to convert (and (srl X, count), mask) into
// (and (rotl X, size-count), mask&(~0>>count)), which is similar
// to SLL above.
if (ConstantSDNode *CountNode =
dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
uint64_t Count = CountNode->getZExtValue();
if (Count > 0 &&
Count < BitSize &&
isRISBGMask(Mask & allOnes(BitSize - Count), BitSize, Start, End)) {
Rotate = 64 - Count;
Input = Input->getOperand(0);
}
}
} else if (Start <= End && Input->getOpcode() == ISD::SRA) {
// Try to convert (and (sra X, count), mask) into
// (and (rotl X, size-count), mask). The mask must not include
// any sign bits.
if (ConstantSDNode *CountNode =
dyn_cast<ConstantSDNode>(Input.getOperand(1).getNode())) {
uint64_t Count = CountNode->getZExtValue();
if (Count > 0 && Count < BitSize && Start >= 64 - (BitSize - Count)) {
Rotate = 64 - Count;
Input = Input->getOperand(0);
}
}
}
// Prefer register extensions like LLC over RSIBG.
if ((Start == 32 || Start == 48 || Start == 56) && End == 63)
if (Rotate == 0 && (Start == 32 || Start == 48 || Start == 56) && End == 63)
return 0;
SDValue Ops[5] = {
getUNDEF64(SDLoc(N)),
convertTo(SDLoc(N), MVT::i64, N->getOperand(0)),
convertTo(SDLoc(N), MVT::i64, Input),
CurDAG->getTargetConstant(Start, MVT::i32),
CurDAG->getTargetConstant(End | 128, MVT::i32),
CurDAG->getTargetConstant(0, MVT::i32)
CurDAG->getTargetConstant(Rotate, MVT::i32)
};
N = CurDAG->getMachineNode(SystemZ::RISBG, SDLoc(N), MVT::i64, Ops);
return convertTo(SDLoc(N), VT, SDValue(N, 0)).getNode();

4
test/CodeGen/SystemZ/fp-move-02.ll
View File

@ -16,7 +16,7 @@ define float @f1(i32 %a) {
; surrounding code.
define float @f2(i64 %big) {
; CHECK: f2:
; CHECK: sllg [[REGISTER:%r[0-5]]], %r2, 31
; CHECK: risbg [[REGISTER:%r[0-5]]], %r2, 0, 159, 31
; CHECK: ldgr %f0, [[REGISTER]]
%shift = lshr i64 %big, 1
%a = trunc i64 %shift to i32
@ -27,7 +27,7 @@ define float @f2(i64 %big) {
; Another example of the same thing.
define float @f3(i64 %big) {
; CHECK: f3:
; CHECK: sllg [[REGISTER:%r[0-5]]], %r2, 2
; CHECK: risbg [[REGISTER:%r[0-5]]], %r2, 0, 159, 2
; CHECK: ldgr %f0, [[REGISTER]]
%shift = ashr i64 %big, 30
%a = trunc i64 %shift to i32