Teach LegalizeTypes how to expand and promote CTLZ,

CTTZ and CTPOP.  The expansion code differs from
that in LegalizeDAG in that it chooses to take the
CTLZ/CTTZ count from the Hi/Lo part depending on
whether the Hi/Lo value is zero, not on whether
CTLZ/CTTZ of Hi/Lo returned 32 (or whatever the
width of the type is) for it.  I made this change
because the optimizers may well know that Hi/Lo
is zero and exploit it.  The promotion code for
CTTZ also differs from that in LegalizeDAG: it
uses an "or" to get the right result when the
original value is zero, rather than using a compare
and select.  This also means the value doesn't
need to be zero extended.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@47075 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2008-02-13 18:01:53 +00:00
parent 82f0a09c10
commit d462ba8539
4 changed files with 120 additions and 31 deletions

View File

@ -159,23 +159,26 @@ private:
// Result Promotion.
void PromoteResult(SDNode *N, unsigned ResNo);
SDOperand PromoteResult_UNDEF(SDNode *N);
SDOperand PromoteResult_Constant(SDNode *N);
SDOperand PromoteResult_TRUNCATE(SDNode *N);
SDOperand PromoteResult_INT_EXTEND(SDNode *N);
SDOperand PromoteResult_CTLZ(SDNode *N);
SDOperand PromoteResult_CTPOP(SDNode *N);
SDOperand PromoteResult_CTTZ(SDNode *N);
SDOperand PromoteResult_FP_ROUND(SDNode *N);
SDOperand PromoteResult_FP_TO_XINT(SDNode *N);
SDOperand PromoteResult_SETCC(SDNode *N);
SDOperand PromoteResult_INT_EXTEND(SDNode *N);
SDOperand PromoteResult_LOAD(LoadSDNode *N);
SDOperand PromoteResult_SimpleIntBinOp(SDNode *N);
SDOperand PromoteResult_SDIV(SDNode *N);
SDOperand PromoteResult_UDIV(SDNode *N);
SDOperand PromoteResult_SHL(SDNode *N);
SDOperand PromoteResult_SRA(SDNode *N);
SDOperand PromoteResult_SRL(SDNode *N);
SDOperand PromoteResult_SELECT (SDNode *N);
SDOperand PromoteResult_SELECT_CC(SDNode *N);
SDOperand PromoteResult_SETCC(SDNode *N);
SDOperand PromoteResult_SHL(SDNode *N);
SDOperand PromoteResult_SimpleIntBinOp(SDNode *N);
SDOperand PromoteResult_SRA(SDNode *N);
SDOperand PromoteResult_SRL(SDNode *N);
SDOperand PromoteResult_TRUNCATE(SDNode *N);
SDOperand PromoteResult_UDIV(SDNode *N);
SDOperand PromoteResult_UNDEF(SDNode *N);
// Operand Promotion.
bool PromoteOperand(SDNode *N, unsigned OperandNo);
SDOperand PromoteOperand_ANY_EXTEND(SDNode *N);
@ -202,18 +205,21 @@ private:
// Result Expansion.
void ExpandResult(SDNode *N, unsigned ResNo);
void ExpandResult_UNDEF (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_Constant (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_BUILD_PAIR (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_MERGE_VALUES(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_ANY_EXTEND (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_ZERO_EXTEND(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_SIGN_EXTEND(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_AssertZext (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_TRUNCATE (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_BIT_CONVERT(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_SIGN_EXTEND_INREG(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_BUILD_PAIR (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_Constant (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_CTLZ (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_CTPOP (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_CTTZ (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_LOAD (LoadSDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_MERGE_VALUES(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_SIGN_EXTEND(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_SIGN_EXTEND_INREG(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_TRUNCATE (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_UNDEF (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_ZERO_EXTEND(SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_Logical (SDNode *N, SDOperand &Lo, SDOperand &Hi);
void ExpandResult_BSWAP (SDNode *N, SDOperand &Lo, SDOperand &Hi);

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@ -82,8 +82,12 @@ void DAGTypeLegalizer::ExpandResult(SDNode *N, unsigned ResNo) {
case ISD::SHL:
case ISD::SRA:
case ISD::SRL: ExpandResult_Shift(N, Lo, Hi); break;
case ISD::CTLZ: ExpandResult_CTLZ(N, Lo, Hi); break;
case ISD::CTPOP: ExpandResult_CTPOP(N, Lo, Hi); break;
case ISD::CTTZ: ExpandResult_CTTZ(N, Lo, Hi); break;
}
// If Lo/Hi is null, the sub-method took care of registering results etc.
if (Lo.Val)
SetExpandedOp(SDOperand(N, ResNo), Lo, Hi);
@ -615,6 +619,51 @@ void DAGTypeLegalizer::ExpandResult_Shift(SDNode *N,
#endif
}
void DAGTypeLegalizer::ExpandResult_CTLZ(SDNode *N,
SDOperand &Lo, SDOperand &Hi) {
// ctlz (HiLo) -> Hi != 0 ? ctlz(Hi) : (ctlz(Lo)+32)
GetExpandedOp(N->getOperand(0), Lo, Hi);
MVT::ValueType NVT = Lo.getValueType();
SDOperand HiNotZero = DAG.getSetCC(TLI.getSetCCResultTy(), Hi,
DAG.getConstant(0, NVT), ISD::SETNE);
SDOperand LoLZ = DAG.getNode(ISD::CTLZ, NVT, Lo);
SDOperand HiLZ = DAG.getNode(ISD::CTLZ, NVT, Hi);
Lo = DAG.getNode(ISD::SELECT, NVT, HiNotZero, HiLZ,
DAG.getNode(ISD::ADD, NVT, LoLZ,
DAG.getConstant(MVT::getSizeInBits(NVT), NVT)));
Hi = DAG.getConstant(0, NVT);
}
void DAGTypeLegalizer::ExpandResult_CTPOP(SDNode *N,
SDOperand &Lo, SDOperand &Hi) {
// ctpop(HiLo) -> ctpop(Hi)+ctpop(Lo)
GetExpandedOp(N->getOperand(0), Lo, Hi);
MVT::ValueType NVT = Lo.getValueType();
Lo = DAG.getNode(ISD::ADD, NVT, DAG.getNode(ISD::CTPOP, NVT, Lo),
DAG.getNode(ISD::CTPOP, NVT, Hi));
Hi = DAG.getConstant(0, NVT);
}
void DAGTypeLegalizer::ExpandResult_CTTZ(SDNode *N,
SDOperand &Lo, SDOperand &Hi) {
// cttz (HiLo) -> Lo != 0 ? cttz(Lo) : (cttz(Hi)+32)
GetExpandedOp(N->getOperand(0), Lo, Hi);
MVT::ValueType NVT = Lo.getValueType();
SDOperand LoNotZero = DAG.getSetCC(TLI.getSetCCResultTy(), Lo,
DAG.getConstant(0, NVT), ISD::SETNE);
SDOperand LoLZ = DAG.getNode(ISD::CTTZ, NVT, Lo);
SDOperand HiLZ = DAG.getNode(ISD::CTTZ, NVT, Hi);
Lo = DAG.getNode(ISD::SELECT, NVT, LoNotZero, LoLZ,
DAG.getNode(ISD::ADD, NVT, HiLZ,
DAG.getConstant(MVT::getSizeInBits(NVT), NVT)));
Hi = DAG.getConstant(0, NVT);
}
/// ExpandShiftByConstant - N is a shift by a value that needs to be expanded,
/// and the shift amount is a constant 'Amt'. Expand the operation.

View File

@ -70,6 +70,9 @@ void DAGTypeLegalizer::PromoteResult(SDNode *N, unsigned ResNo) {
case ISD::SELECT: Result = PromoteResult_SELECT(N); break;
case ISD::SELECT_CC: Result = PromoteResult_SELECT_CC(N); break;
case ISD::CTLZ: Result = PromoteResult_CTLZ(N); break;
case ISD::CTPOP: Result = PromoteResult_CTPOP(N); break;
case ISD::CTTZ: Result = PromoteResult_CTTZ(N); break;
}
// If Result is null, the sub-method took care of registering the result.
@ -265,6 +268,38 @@ SDOperand DAGTypeLegalizer::PromoteResult_SELECT_CC(SDNode *N) {
N->getOperand(1), LHS, RHS, N->getOperand(4));
}
SDOperand DAGTypeLegalizer::PromoteResult_CTLZ(SDNode *N) {
SDOperand Op = GetPromotedOp(N->getOperand(0));
MVT::ValueType OVT = N->getValueType(0);
MVT::ValueType NVT = Op.getValueType();
// Zero extend to the promoted type and do the count there.
Op = DAG.getNode(ISD::CTLZ, NVT, DAG.getZeroExtendInReg(Op, OVT));
// Subtract off the extra leading bits in the bigger type.
return DAG.getNode(ISD::SUB, NVT, Op,
DAG.getConstant(MVT::getSizeInBits(NVT) -
MVT::getSizeInBits(OVT), NVT));
}
SDOperand DAGTypeLegalizer::PromoteResult_CTPOP(SDNode *N) {
SDOperand Op = GetPromotedOp(N->getOperand(0));
MVT::ValueType OVT = N->getValueType(0);
MVT::ValueType NVT = Op.getValueType();
// Zero extend to the promoted type and do the count there.
return DAG.getNode(ISD::CTPOP, NVT, DAG.getZeroExtendInReg(Op, OVT));
}
SDOperand DAGTypeLegalizer::PromoteResult_CTTZ(SDNode *N) {
SDOperand Op = GetPromotedOp(N->getOperand(0));
MVT::ValueType OVT = N->getValueType(0);
MVT::ValueType NVT = Op.getValueType();
// The count is the same in the promoted type except if the original
// value was zero. This can be handled by setting the bit just off
// the top of the original type.
Op = DAG.getNode(ISD::OR, NVT, Op,
// FIXME: Do this using an APINT constant.
DAG.getConstant(1UL << MVT::getSizeInBits(OVT), NVT));
return DAG.getNode(ISD::CTTZ, NVT, Op);
}
//===----------------------------------------------------------------------===//
// Operand Promotion

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@ -1,22 +1,21 @@
; RUN: llvm-as < %s | llc
@.str3 = external constant [56 x i8] ; <[56 x i8]*> [#uses=1]
@.str = internal constant [14 x i8] c"%lld %d %d %d\00"
define i32 @main() nounwind {
define i32 @main(i64 %arg) nounwind {
entry:
br label %bb30
bb30: ; preds = %bb30, %entry
%l.024 = phi i64 [ -10000, %entry ], [ 0, %bb30 ] ; <i64> [#uses=2]
%tmp37 = tail call i64 @llvm.ctlz.i64( i64 %l.024 ) ; <i64> [#uses=1]
trunc i64 %tmp37 to i32 ; <i32>:0 [#uses=1]
%tmp40 = tail call i32 (i8*, ...)* @printf( i8* noalias getelementptr ([56 x i8]* @.str3, i32 0, i32 0), i64 %l.024, i32 %0, i32 0, i32 0 ) nounwind ; <i32> [#uses=0]
br i1 false, label %bb30, label %bb9.i
bb9.i: ; preds = %bb30
%tmp37 = tail call i64 @llvm.ctlz.i64( i64 %arg ) ; <i64> [#uses=1]
%tmp47 = tail call i64 @llvm.cttz.i64( i64 %arg ) ; <i64> [#uses=1]
%tmp57 = tail call i64 @llvm.ctpop.i64( i64 %arg ) ; <i64> [#uses=1]
%tmp38 = trunc i64 %tmp37 to i32 ; <i32>:0 [#uses=1]
%tmp48 = trunc i64 %tmp47 to i32 ; <i32>:0 [#uses=1]
%tmp58 = trunc i64 %tmp57 to i32 ; <i32>:0 [#uses=1]
%tmp40 = tail call i32 (i8*, ...)* @printf( i8* noalias getelementptr ([14 x i8]* @.str, i32 0, i32 0), i64 %arg, i32 %tmp38, i32 %tmp48, i32 %tmp58 ) nounwind ; <i32> [#uses=0]
ret i32 0
}
declare i32 @printf(i8* noalias , ...) nounwind
declare i64 @llvm.ctlz.i64(i64) nounwind readnone
declare i64 @llvm.cttz.i64(i64) nounwind readnone
declare i64 @llvm.ctpop.i64(i64) nounwind readnone