[llvm-commits] CVS: llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp
Nate Begeman
natebegeman at mac.com
Sat Aug 21 13:42:24 PDT 2004
Changes in directory llvm/lib/Target/PowerPC:
PPC32ISelSimple.cpp updated: 1.72 -> 1.73
---
Log message:
Back out branchless SetCC code. While it helped a lot in some cases, it
hurt a lot in others. Instead, improve branching version of SetCC and
Select instructions. The old code will be in CVS should we ever need to
dig it up again.
---
Diffs of the changes: (+25 -188)
Index: llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp
diff -u llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp:1.72 llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp:1.73
--- llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp:1.72 Fri Aug 20 04:56:22 2004
+++ llvm/lib/Target/PowerPC/PPC32ISelSimple.cpp Sat Aug 21 15:42:14 2004
@@ -1110,148 +1110,12 @@
if (canFoldSetCCIntoBranchOrSelect(&I))
return;
- Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
- const Type *Ty = Op0->getType();
- unsigned Class = getClassB(Ty);
- unsigned Opcode = I.getOpcode();
unsigned DestReg = getReg(I);
-
- // If the comparison type is byte, short, or int, then we can emit a
- // branchless version of the SetCC that puts 0 (false) or 1 (true) in the
- // destination register.
- if (Class <= cInt) {
- ++NumSetCC;
- MachineBasicBlock::iterator MI = BB->end();
- unsigned OpNum = getSetCCNumber(Opcode);
- unsigned Op0Reg = getReg(Op0, BB, MI);
- Op0Reg = ExtendOrClear(BB, MI, Op0Reg, Ty);
-
- // comparisons against constant zero often have shorter sequences than the
- // general case, handled below.
- ConstantInt *CI = dyn_cast<ConstantInt>(Op1);
- if (CI && CI->getRawValue() == 0) {
- switch(OpNum) {
- case 0: { // eq0
- unsigned TempReg = makeAnotherReg(Type::IntTy);
- BuildMI(*BB, MI, PPC::CNTLZW, 1, TempReg).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(TempReg).addImm(5);
- break;
- }
- case 1: { // ne0
- unsigned TempReg = makeAnotherReg(Type::IntTy);
- BuildMI(*BB, MI, PPC::ADDIC, 2, TempReg).addReg(Op0Reg).addSImm(-1);
- BuildMI(*BB, MI, PPC::SUBFE, 2, DestReg).addReg(TempReg).addReg(Op0Reg);
- break;
- }
- case 2: { // lt0, always false if unsigned
- if (Ty->isSigned())
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(Op0Reg).addImm(31);
- else
- BuildMI(*BB, MI, PPC::LI, 1, DestReg).addSImm(0);
- break;
- }
- case 3: { // ge0, always true if unsigned
- if (Ty->isSigned()) {
- unsigned TempReg = makeAnotherReg(Type::IntTy);
- BuildMI(*BB, MI, PPC::SRWI, 2, TempReg).addReg(Op0Reg).addImm(31);
- BuildMI(*BB, MI, PPC::XORI, 2, DestReg).addReg(TempReg).addImm(1);
- } else {
- BuildMI(*BB, MI, PPC::LI, 1, DestReg).addSImm(1);
- }
- break;
- }
- case 4: { // gt0, equivalent to ne0 if unsigned
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- if (Ty->isSigned()) {
- BuildMI(*BB, MI, PPC::NEG, 2, Temp1).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::ANDC, 2, Temp2).addReg(Temp1).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(Temp2).addImm(31);
- } else {
- BuildMI(*BB, MI, PPC::ADDIC, 2, Temp1).addReg(Op0Reg).addSImm(-1);
- BuildMI(*BB, MI, PPC::SUBFE, 2, DestReg).addReg(Temp1).addReg(Op0Reg);
- }
- break;
- }
- case 5: { // le0, equivalent to eq0 if unsigned
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- if (Ty->isSigned()) {
- BuildMI(*BB, MI, PPC::NEG, 2, Temp1).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::ORC, 2, Temp2).addReg(Op0Reg).addReg(Temp1);
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(Temp2).addImm(31);
- } else {
- BuildMI(*BB, MI, PPC::CNTLZW, 1, Temp1).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(Temp1).addImm(5);
- }
- break;
- }
- } // switch
- return;
- }
- unsigned Op1Reg = getReg(Op1, BB, MI);
- switch(OpNum) {
- case 0: { // eq
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- BuildMI(*BB, MI, PPC::SUBF, 2, Temp1).addReg(Op0Reg).addReg(Op1Reg);
- BuildMI(*BB, MI, PPC::CNTLZW, 1, Temp2).addReg(Temp1);
- BuildMI(*BB, MI, PPC::SRWI, 2, DestReg).addReg(Temp2).addImm(5);
- break;
- }
- case 1: { // ne
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- BuildMI(*BB, MI, PPC::SUBF, 2, Temp1).addReg(Op0Reg).addReg(Op1Reg);
- BuildMI(*BB, MI, PPC::ADDIC, 2, Temp2).addReg(Temp1).addSImm(-1);
- BuildMI(*BB, MI, PPC::SUBFE, 2, DestReg).addReg(Temp2).addReg(Temp1);
- break;
- }
- case 2:
- case 4: { // lt, gt
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- unsigned Temp3 = makeAnotherReg(Type::IntTy);
- unsigned Temp4 = makeAnotherReg(Type::IntTy);
- if (OpNum == 4) std::swap(Op0Reg, Op1Reg);
- if (Ty->isSigned()) {
- BuildMI(*BB, MI, PPC::SUBFC, 2, Temp1).addReg(Op1Reg).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::EQV, 2, Temp2).addReg(Op1Reg).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::SRWI, 2, Temp3).addReg(Temp2).addImm(31);
- BuildMI(*BB, MI, PPC::ADDZE, 1, Temp4).addReg(Temp3);
- BuildMI(*BB, MI, PPC::RLWINM, 4, DestReg).addReg(Temp4).addImm(0)
- .addImm(31).addImm(31);
- } else {
- BuildMI(*BB, MI, PPC::SUBFC, 2, Temp1).addReg(Op1Reg).addReg(Op0Reg);
- BuildMI(*BB, MI, PPC::SUBFE, 2, Temp2).addReg(Temp1).addReg(Temp1);
- BuildMI(*BB, MI, PPC::NEG, 2, DestReg).addReg(Temp2);
- }
- break;
- }
- case 3:
- case 5: { // le, ge
- unsigned Temp1 = makeAnotherReg(Type::IntTy);
- unsigned Temp2 = makeAnotherReg(Type::IntTy);
- unsigned Temp3 = makeAnotherReg(Type::IntTy);
- if (OpNum == 3) std::swap(Op0Reg, Op1Reg);
- if (Ty->isSigned()) {
- BuildMI(*BB, MI, PPC::SRWI, 2, Temp1).addReg(Op0Reg).addImm(31);
- BuildMI(*BB, MI, PPC::SRAWI, 2, Temp2).addReg(Op1Reg).addImm(31);
- BuildMI(*BB, MI, PPC::SUBFC, 2, Temp3).addReg(Op0Reg).addReg(Op1Reg);
- BuildMI(*BB, MI, PPC::ADDE, 2, DestReg).addReg(Temp2).addReg(Temp1);
- } else {
- BuildMI(*BB, MI, PPC::LI, 1, Temp2).addSImm(-1);
- BuildMI(*BB, MI, PPC::SUBFC, 2, Temp1).addReg(Op0Reg).addReg(Op1Reg);
- BuildMI(*BB, MI, PPC::SUBFZE, 1, DestReg).addReg(Temp2);
- }
- break;
- }
- } // switch
- return;
- }
- EmitComparison(Opcode, Op0, Op1, BB, BB->end());
-
+ unsigned Opcode = I.getOpcode();
unsigned PPCOpcode = getPPCOpcodeForSetCCNumber(Opcode);
+
+ // Create an iterator with which to insert the MBB for copying the false value
+ // and the MBB to hold the PHI instruction for this SetCC.
MachineBasicBlock *thisMBB = BB;
const BasicBlock *LLVM_BB = BB->getBasicBlock();
ilist<MachineBasicBlock>::iterator It = BB;
@@ -1260,32 +1124,18 @@
// thisMBB:
// ...
// cmpTY cr0, r1, r2
- // bCC copy1MBB
- // b copy0MBB
-
- // FIXME: we wouldn't need copy0MBB (we could fold it into thisMBB)
- // if we could insert other, non-terminator instructions after the
- // bCC. But MBB->getFirstTerminator() can't understand this.
- MachineBasicBlock *copy1MBB = new MachineBasicBlock(LLVM_BB);
- F->getBasicBlockList().insert(It, copy1MBB);
- BuildMI(BB, PPCOpcode, 2).addReg(PPC::CR0).addMBB(copy1MBB);
+ // %TrueValue = li 1
+ // bCC sinkMBB
+ EmitComparison(Opcode, I.getOperand(0), I.getOperand(1), BB, BB->end());
+ unsigned TrueValue = makeAnotherReg(I.getType());
+ BuildMI(BB, PPC::LI, 1, TrueValue).addSImm(1);
MachineBasicBlock *copy0MBB = new MachineBasicBlock(LLVM_BB);
- F->getBasicBlockList().insert(It, copy0MBB);
- BuildMI(BB, PPC::B, 1).addMBB(copy0MBB);
MachineBasicBlock *sinkMBB = new MachineBasicBlock(LLVM_BB);
+ BuildMI(BB, PPCOpcode, 2).addReg(PPC::CR0).addMBB(sinkMBB);
+ F->getBasicBlockList().insert(It, copy0MBB);
F->getBasicBlockList().insert(It, sinkMBB);
// Update machine-CFG edges
- BB->addSuccessor(copy1MBB);
BB->addSuccessor(copy0MBB);
-
- // copy1MBB:
- // %TrueValue = li 1
- // b sinkMBB
- BB = copy1MBB;
- unsigned TrueValue = makeAnotherReg(I.getType());
- BuildMI(BB, PPC::LI, 1, TrueValue).addSImm(1);
- BuildMI(BB, PPC::B, 1).addMBB(sinkMBB);
- // Update machine-CFG edges
BB->addSuccessor(sinkMBB);
// copy0MBB:
@@ -1298,11 +1148,11 @@
BB->addSuccessor(sinkMBB);
// sinkMBB:
- // %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, copy1MBB ]
+ // %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = sinkMBB;
BuildMI(BB, PPC::PHI, 4, DestReg).addReg(FalseValue)
- .addMBB(copy0MBB).addReg(TrueValue).addMBB(copy1MBB);
+ .addMBB(copy0MBB).addReg(TrueValue).addMBB(thisMBB);
}
void ISel::visitSelectInst(SelectInst &SI) {
@@ -1335,40 +1185,25 @@
BuildMI(*MBB, IP, PPC::CMPI, 2, PPC::CR0).addReg(CondReg).addSImm(0);
Opcode = getPPCOpcodeForSetCCNumber(Instruction::SetNE);
}
-
- // thisMBB:
- // ...
- // cmpTY cr0, r1, r2
- // bCC copy1MBB
- // b copy0MBB
+ unsigned TrueValue = getReg(TrueVal, BB, BB->end());
MachineBasicBlock *thisMBB = BB;
const BasicBlock *LLVM_BB = BB->getBasicBlock();
ilist<MachineBasicBlock>::iterator It = BB;
++It;
- // FIXME: we wouldn't need copy0MBB (we could fold it into thisMBB)
- // if we could insert other, non-terminator instructions after the
- // bCC. But MBB->getFirstTerminator() can't understand this.
- MachineBasicBlock *copy1MBB = new MachineBasicBlock(LLVM_BB);
- F->getBasicBlockList().insert(It, copy1MBB);
- BuildMI(BB, Opcode, 2).addReg(PPC::CR0).addMBB(copy1MBB);
+ // thisMBB:
+ // ...
+ // cmpTY cr0, r1, r2
+ // %TrueValue = ...
+ // bCC sinkMBB
MachineBasicBlock *copy0MBB = new MachineBasicBlock(LLVM_BB);
- F->getBasicBlockList().insert(It, copy0MBB);
- BuildMI(BB, PPC::B, 1).addMBB(copy0MBB);
MachineBasicBlock *sinkMBB = new MachineBasicBlock(LLVM_BB);
+ BuildMI(BB, Opcode, 2).addReg(PPC::CR0).addMBB(sinkMBB);
+ F->getBasicBlockList().insert(It, copy0MBB);
F->getBasicBlockList().insert(It, sinkMBB);
// Update machine-CFG edges
- BB->addSuccessor(copy1MBB);
BB->addSuccessor(copy0MBB);
-
- // copy1MBB:
- // %TrueValue = ...
- // b sinkMBB
- BB = copy1MBB;
- unsigned TrueValue = getReg(TrueVal, BB, BB->begin());
- BuildMI(BB, PPC::B, 1).addMBB(sinkMBB);
- // Update machine-CFG edges
BB->addSuccessor(sinkMBB);
// copy0MBB:
@@ -1380,12 +1215,14 @@
BB->addSuccessor(sinkMBB);
// sinkMBB:
- // %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, copy1MBB ]
+ // %Result = phi [ %FalseValue, copy0MBB ], [ %TrueValue, thisMBB ]
// ...
BB = sinkMBB;
BuildMI(BB, PPC::PHI, 4, DestReg).addReg(FalseValue)
- .addMBB(copy0MBB).addReg(TrueValue).addMBB(copy1MBB);
+ .addMBB(copy0MBB).addReg(TrueValue).addMBB(thisMBB);
+
// For a register pair representing a long value, define the second reg
+ // FIXME: Can this really be correct for selecting longs?
if (getClassB(TrueVal->getType()) == cLong)
BuildMI(BB, PPC::LI, 1, DestReg+1).addImm(0);
return;
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