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Avoid zero extend bit test operands to pointer type if all the masks fit in 

the original type of the switch statement key.
rdar://8781238

llvm-svn: 122935
This commit is contained in:
Evan Cheng 2011-01-06 01:02:44 +00:00
parent 3b949bcaf3
commit ac730dd2d1
4 changed files with 72 additions and 24 deletions
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52
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
View File

@ -1615,12 +1615,28 @@ void SelectionDAGBuilder::visitBitTestHeader(BitTestBlock &B,
Sub, DAG.getConstant(B.Range, VT),
ISD::SETUGT);
SDValue ShiftOp = DAG.getZExtOrTrunc(Sub, getCurDebugLoc(),
TLI.getPointerTy());
// Determine the type of the test operands.
bool UsePtrType = false;
if (!TLI.isTypeLegal(VT))
UsePtrType = true;
else {
for (unsigned i = 0, e = B.Cases.size(); i != e; ++i)
if ((uint64_t)((int64_t)B.Cases[i].Mask >> VT.getSizeInBits()) + 1 >= 2) {
// Switch table case range are encoded into series of masks.
// Just use pointer type, it's guaranteed to fit.
UsePtrType = true;
break;
}
}
if (UsePtrType) {
VT = TLI.getPointerTy();
Sub = DAG.getZExtOrTrunc(Sub, getCurDebugLoc(), VT);
}
B.Reg = FuncInfo.CreateReg(TLI.getPointerTy());
B.RegVT = VT;
B.Reg = FuncInfo.CreateReg(VT);
SDValue CopyTo = DAG.getCopyToReg(getControlRoot(), getCurDebugLoc(),
B.Reg, ShiftOp);
B.Reg, Sub);
// Set NextBlock to be the MBB immediately after the current one, if any.
// This is used to avoid emitting unnecessary branches to the next block.
@ -1646,36 +1662,34 @@ void SelectionDAGBuilder::visitBitTestHeader(BitTestBlock &B,
}
/// visitBitTestCase - this function produces one "bit test"
void SelectionDAGBuilder::visitBitTestCase(MachineBasicBlock* NextMBB,
void SelectionDAGBuilder::visitBitTestCase(BitTestBlock &BB,
MachineBasicBlock* NextMBB,
unsigned Reg,
BitTestCase &B,
MachineBasicBlock *SwitchBB) {
SDValue ShiftOp = DAG.getCopyFromReg(getControlRoot(), getCurDebugLoc(), Reg,
TLI.getPointerTy());
EVT VT = BB.RegVT;
SDValue ShiftOp = DAG.getCopyFromReg(getControlRoot(), getCurDebugLoc(),
Reg, VT);
SDValue Cmp;
if (CountPopulation_64(B.Mask) == 1) {
// Testing for a single bit; just compare the shift count with what it
// would need to be to shift a 1 bit in that position.
Cmp = DAG.getSetCC(getCurDebugLoc(),
TLI.getSetCCResultType(ShiftOp.getValueType()),
TLI.getSetCCResultType(VT),
ShiftOp,
DAG.getConstant(CountTrailingZeros_64(B.Mask),
TLI.getPointerTy()),
DAG.getConstant(CountTrailingZeros_64(B.Mask), VT),
ISD::SETEQ);
} else {
// Make desired shift
SDValue SwitchVal = DAG.getNode(ISD::SHL, getCurDebugLoc(),
TLI.getPointerTy(),
DAG.getConstant(1, TLI.getPointerTy()),
ShiftOp);
SDValue SwitchVal = DAG.getNode(ISD::SHL, getCurDebugLoc(), VT,
DAG.getConstant(1, VT), ShiftOp);
// Emit bit tests and jumps
SDValue AndOp = DAG.getNode(ISD::AND, getCurDebugLoc(),
TLI.getPointerTy(), SwitchVal,
DAG.getConstant(B.Mask, TLI.getPointerTy()));
VT, SwitchVal, DAG.getConstant(B.Mask, VT));
Cmp = DAG.getSetCC(getCurDebugLoc(),
TLI.getSetCCResultType(AndOp.getValueType()),
AndOp, DAG.getConstant(0, TLI.getPointerTy()),
TLI.getSetCCResultType(VT),
AndOp, DAG.getConstant(0, VT),
ISD::SETNE);
}
@ -2219,7 +2233,7 @@ bool SelectionDAGBuilder::handleBitTestsSwitchCase(CaseRec& CR,
}
BitTestBlock BTB(lowBound, cmpRange, SV,
-1U, (CR.CaseBB == SwitchBB),
-1U, MVT::Other, (CR.CaseBB == SwitchBB),
CR.CaseBB, Default, BTC);
if (CR.CaseBB == SwitchBB)

8
llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.h
View File

@ -258,15 +258,16 @@ private:
struct BitTestBlock {
BitTestBlock(APInt F, APInt R, const Value* SV,
unsigned Rg, bool E,
unsigned Rg, EVT RgVT, bool E,
MachineBasicBlock* P, MachineBasicBlock* D,
const BitTestInfo& C):
First(F), Range(R), SValue(SV), Reg(Rg), Emitted(E),
First(F), Range(R), SValue(SV), Reg(Rg), RegVT(RgVT), Emitted(E),
Parent(P), Default(D), Cases(C) { }
APInt First;
APInt Range;
const Value *SValue;
unsigned Reg;
EVT RegVT;
bool Emitted;
MachineBasicBlock *Parent;
MachineBasicBlock *Default;
@ -435,7 +436,8 @@ public:
void visitSwitchCase(CaseBlock &CB,
MachineBasicBlock *SwitchBB);
void visitBitTestHeader(BitTestBlock &B, MachineBasicBlock *SwitchBB);
void visitBitTestCase(MachineBasicBlock* NextMBB,
void visitBitTestCase(BitTestBlock &BB,
MachineBasicBlock* NextMBB,
unsigned Reg,
BitTestCase &B,
MachineBasicBlock *SwitchBB);

6
llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
View File

@ -1017,12 +1017,14 @@ SelectionDAGISel::FinishBasicBlock() {
FuncInfo->InsertPt = FuncInfo->MBB->end();
// Emit the code
if (j+1 != ej)
SDB->visitBitTestCase(SDB->BitTestCases[i].Cases[j+1].ThisBB,
SDB->visitBitTestCase(SDB->BitTestCases[i],
SDB->BitTestCases[i].Cases[j+1].ThisBB,
SDB->BitTestCases[i].Reg,
SDB->BitTestCases[i].Cases[j],
FuncInfo->MBB);
else
SDB->visitBitTestCase(SDB->BitTestCases[i].Default,
SDB->visitBitTestCase(SDB->BitTestCases[i],
SDB->BitTestCases[i].Default,
SDB->BitTestCases[i].Reg,
SDB->BitTestCases[i].Cases[j],
FuncInfo->MBB);

30
llvm/test/CodeGen/X86/switch-bt.ll
View File

@ -49,3 +49,33 @@ sw.epilog: ; preds = %sw.default, %sw.bb4
}
declare void @foo(i32)
; Don't zero extend the test operands to pointer type if it can be avoided.
; rdar://8781238
define void @test2(i32 %x) nounwind ssp {
; CHECK: test2:
; CHECK: cmpl $6
; CHECK: ja
; CHECK-NEXT: movl $91
; CHECK-NOT: movl
; CHECK-NEXT: btl
; CHECK-NEXT: jb
entry:
switch i32 %x, label %if.end [
i32 6, label %if.then
i32 4, label %if.then
i32 3, label %if.then
i32 1, label %if.then
i32 0, label %if.then
]
if.then: ; preds = %entry, %entry, %entry, %entry, %entry
tail call void @bar() nounwind
ret void
if.end: ; preds = %entry
ret void
}
declare void @bar()