[llvm-commits] CVS: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
Anton Korobeynikov
asl at math.spbu.ru
Tue Mar 27 04:29:29 PDT 2007
Changes in directory llvm/lib/CodeGen/SelectionDAG:
SelectionDAGISel.cpp updated: 1.395 -> 1.396
---
Log message:
Split big monster into small helpers. No functionality change.
---
Diffs of the changes: (+285 -190)
SelectionDAGISel.cpp | 475 ++++++++++++++++++++++++++++++---------------------
1 files changed, 285 insertions(+), 190 deletions(-)
Index: llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.395 llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.396
--- llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp:1.395 Mon Mar 26 19:53:36 2007
+++ llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Tue Mar 27 06:29:11 2007
@@ -384,6 +384,8 @@
/// processed at this point in the binary search tree.
CaseRange Range;
};
+
+ typedef std::vector<CaseRec> CaseRecVector;
/// The comparison function for sorting Case values.
struct CaseCmp {
@@ -496,7 +498,23 @@
void visitSwitch(SwitchInst &I);
void visitUnreachable(UnreachableInst &I) { /* noop */ }
- // Helper for visitSwitch
+ // Helpers for visitSwitch
+ void handleSmallSwitchRange(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default);
+ void handleJTSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default);
+ void handleBTSplitSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default);
+ void handleBTSmallSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default);
void visitSwitchCase(SelectionDAGISel::CaseBlock &CB);
void visitJumpTable(SelectionDAGISel::JumpTable &JT);
void visitJumpTableHeader(SelectionDAGISel::JumpTable &JT,
@@ -1208,6 +1226,265 @@
void SelectionDAGLowering::visitUnwind(UnwindInst &I) {
}
+/// handleSmaaSwitchCaseRange - Emit a series of specific tests (suitable for
+/// small case ranges).
+void SelectionDAGLowering::handleSmallSwitchRange(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default) {
+ // Get the MachineFunction which holds the current MBB. This is used when
+ // inserting any additional MBBs necessary to represent the switch.
+ MachineFunction *CurMF = CurMBB->getParent();
+
+ // Figure out which block is immediately after the current one.
+ MachineBasicBlock *NextBlock = 0;
+ MachineFunction::iterator BBI = CR.CaseBB;
+
+ Case& BackCase = *(CR.Range.second-1);
+
+ if (++BBI != CurMBB->getParent()->end())
+ NextBlock = BBI;
+
+ // TODO: If any two of the cases has the same destination, and if one value
+ // is the same as the other, but has one bit unset that the other has set,
+ // use bit manipulation to do two compares at once. For example:
+ // "if (X == 6 || X == 4)" -> "if ((X|2) == 6)"
+
+ // Rearrange the case blocks so that the last one falls through if possible.
+ if (NextBlock && Default != NextBlock && BackCase.second != NextBlock) {
+ // The last case block won't fall through into 'NextBlock' if we emit the
+ // branches in this order. See if rearranging a case value would help.
+ for (CaseItr I = CR.Range.first, E = CR.Range.second-1; I != E; ++I) {
+ if (I->second == NextBlock) {
+ std::swap(*I, BackCase);
+ break;
+ }
+ }
+ }
+
+ // Create a CaseBlock record representing a conditional branch to
+ // the Case's target mbb if the value being switched on SV is equal
+ // to C.
+ MachineBasicBlock *CurBlock = CR.CaseBB;
+ for (CaseItr I = CR.Range.first, E = CR.Range.second; I != E; ++I) {
+ MachineBasicBlock *FallThrough;
+ if (I != E-1) {
+ FallThrough = new MachineBasicBlock(CurBlock->getBasicBlock());
+ CurMF->getBasicBlockList().insert(BBI, FallThrough);
+ } else {
+ // If the last case doesn't match, go to the default block.
+ FallThrough = Default;
+ }
+
+ SelectionDAGISel::CaseBlock CB(ISD::SETEQ, SV, I->first,
+ I->second, FallThrough, CurBlock);
+
+ // If emitting the first comparison, just call visitSwitchCase to emit the
+ // code into the current block. Otherwise, push the CaseBlock onto the
+ // vector to be later processed by SDISel, and insert the node's MBB
+ // before the next MBB.
+ if (CurBlock == CurMBB)
+ visitSwitchCase(CB);
+ else
+ SwitchCases.push_back(CB);
+
+ CurBlock = FallThrough;
+ }
+}
+
+/// handleJTSwitchCase - Emit jumptable for current switch case range
+void SelectionDAGLowering::handleJTSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default) {
+ // Get the MachineFunction which holds the current MBB. This is used when
+ // inserting any additional MBBs necessary to represent the switch.
+ MachineFunction *CurMF = CurMBB->getParent();
+
+ // Figure out which block is immediately after the current one.
+ MachineBasicBlock *NextBlock = 0;
+ MachineFunction::iterator BBI = CR.CaseBB;
+
+ if (++BBI != CurMBB->getParent()->end())
+ NextBlock = BBI;
+
+ Case& FrontCase = *CR.Range.first;
+ Case& BackCase = *(CR.Range.second-1);
+ const BasicBlock *LLVMBB = CR.CaseBB->getBasicBlock();
+
+ uint64_t First = cast<ConstantInt>(FrontCase.first)->getSExtValue();
+ uint64_t Last = cast<ConstantInt>(BackCase.first)->getSExtValue();
+
+ // Create a new basic block to hold the code for loading the address
+ // of the jump table, and jumping to it. Update successor information;
+ // we will either branch to the default case for the switch, or the jump
+ // table.
+ MachineBasicBlock *JumpTableBB = new MachineBasicBlock(LLVMBB);
+ CurMF->getBasicBlockList().insert(BBI, JumpTableBB);
+ CR.CaseBB->addSuccessor(Default);
+ CR.CaseBB->addSuccessor(JumpTableBB);
+
+ // Build a vector of destination BBs, corresponding to each target
+ // of the jump table. If the value of the jump table slot corresponds to
+ // a case statement, push the case's BB onto the vector, otherwise, push
+ // the default BB.
+ std::vector<MachineBasicBlock*> DestBBs;
+ int64_t TEI = First;
+ for (CaseItr I = CR.Range.first, E = CR.Range.second; I != E; ++TEI)
+ if (cast<ConstantInt>(I->first)->getSExtValue() == TEI) {
+ DestBBs.push_back(I->second);
+ ++I;
+ } else {
+ DestBBs.push_back(Default);
+ }
+
+ // Update successor info. Add one edge to each unique successor.
+ // Vector bool would be better, but vector<bool> is really slow.
+ std::vector<unsigned char> SuccsHandled;
+ SuccsHandled.resize(CR.CaseBB->getParent()->getNumBlockIDs());
+
+ for (std::vector<MachineBasicBlock*>::iterator I = DestBBs.begin(),
+ E = DestBBs.end(); I != E; ++I) {
+ if (!SuccsHandled[(*I)->getNumber()]) {
+ SuccsHandled[(*I)->getNumber()] = true;
+ JumpTableBB->addSuccessor(*I);
+ }
+ }
+
+ // Create a jump table index for this jump table, or return an existing
+ // one.
+ unsigned JTI = CurMF->getJumpTableInfo()->getJumpTableIndex(DestBBs);
+
+ // Set the jump table information so that we can codegen it as a second
+ // MachineBasicBlock
+ SelectionDAGISel::JumpTable JT(-1UL, JTI, JumpTableBB, Default);
+ SelectionDAGISel::JumpTableHeader JTH(First, Last, SV, CR.CaseBB,
+ (CR.CaseBB == CurMBB));
+ if (CR.CaseBB == CurMBB)
+ visitJumpTableHeader(JT, JTH);
+
+ JTCases.push_back(SelectionDAGISel::JumpTableBlock(JTH, JT));
+}
+
+/// handleBTSmallSwitchCase - handle leaf in the binary comparison tree. Just
+/// emit test.
+void SelectionDAGLowering::handleBTSmallSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default) {
+ Case& FrontCase = *CR.Range.first;
+
+ // Create a CaseBlock record representing a conditional branch to
+ // the Case's target mbb if the value being switched on SV is equal
+ // to C. Otherwise, branch to default.
+ Constant *C = FrontCase.first;
+ MachineBasicBlock *Target = FrontCase.second;
+ SelectionDAGISel::CaseBlock CB(ISD::SETEQ, SV, C, Target, Default,
+ CR.CaseBB);
+
+ // If the MBB representing the leaf node is the current MBB, then just
+ // call visitSwitchCase to emit the code into the current block.
+ // Otherwise, push the CaseBlock onto the vector to be later processed
+ // by SDISel, and insert the node's MBB before the next MBB.
+ if (CR.CaseBB == CurMBB)
+ visitSwitchCase(CB);
+ else
+ SwitchCases.push_back(CB);
+}
+
+/// handleBTSplitSwitchCase - emit comparison and split binary search tree into
+/// 2 subtrees.
+void SelectionDAGLowering::handleBTSplitSwitchCase(CaseRec& CR,
+ CaseRecVector& WorkList,
+ Value* SV,
+ MachineBasicBlock* Default) {
+ // Get the MachineFunction which holds the current MBB. This is used when
+ // inserting any additional MBBs necessary to represent the switch.
+ MachineFunction *CurMF = CurMBB->getParent();
+
+ // Figure out which block is immediately after the current one.
+ MachineBasicBlock *NextBlock = 0;
+ MachineFunction::iterator BBI = CR.CaseBB;
+
+ if (++BBI != CurMBB->getParent()->end())
+ NextBlock = BBI;
+
+ Case& FrontCase = *CR.Range.first;
+ Case& BackCase = *(CR.Range.second-1);
+ const BasicBlock *LLVMBB = CR.CaseBB->getBasicBlock();
+
+ // Size is the number of Cases represented by this range.
+ unsigned Size = CR.Range.second - CR.Range.first;
+
+ uint64_t First = cast<ConstantInt>(FrontCase.first)->getSExtValue();
+ uint64_t Last = cast<ConstantInt>(BackCase.first)->getSExtValue();
+ double Density = 0;
+ CaseItr Pivot;
+
+ // Select optimal pivot, maximizing sum density of LHS and RHS. This will
+ // (heuristically) allow us to emit JumpTable's later.
+ unsigned LSize = 1;
+ unsigned RSize = Size-1;
+ for (CaseItr I = CR.Range.first, J=I+1, E = CR.Range.second;
+ J!=E; ++I, ++J, ++LSize, --RSize) {
+ uint64_t LEnd = cast<ConstantInt>(I->first)->getSExtValue();
+ uint64_t RBegin = cast<ConstantInt>(J->first)->getSExtValue();
+ double LDensity = (double)LSize / (double)((LEnd - First) + 1ULL);
+ double RDensity = (double)RSize / (double)((Last - RBegin) + 1ULL);
+ if (Density < (LDensity + RDensity)) {
+ Pivot = J;
+ Density = LDensity + RDensity;
+ }
+ }
+
+ CaseRange LHSR(CR.Range.first, Pivot);
+ CaseRange RHSR(Pivot, CR.Range.second);
+ Constant *C = Pivot->first;
+ MachineBasicBlock *FalseBB = 0, *TrueBB = 0;
+
+ // We know that we branch to the LHS if the Value being switched on is
+ // less than the Pivot value, C. We use this to optimize our binary
+ // tree a bit, by recognizing that if SV is greater than or equal to the
+ // LHS's Case Value, and that Case Value is exactly one less than the
+ // Pivot's Value, then we can branch directly to the LHS's Target,
+ // rather than creating a leaf node for it.
+ if ((LHSR.second - LHSR.first) == 1 &&
+ LHSR.first->first == CR.GE &&
+ cast<ConstantInt>(C)->getZExtValue() ==
+ (cast<ConstantInt>(CR.GE)->getZExtValue() + 1ULL)) {
+ TrueBB = LHSR.first->second;
+ } else {
+ TrueBB = new MachineBasicBlock(LLVMBB);
+ CurMF->getBasicBlockList().insert(BBI, TrueBB);
+ WorkList.push_back(CaseRec(TrueBB, C, CR.GE, LHSR));
+ }
+
+ // Similar to the optimization above, if the Value being switched on is
+ // known to be less than the Constant CR.LT, and the current Case Value
+ // is CR.LT - 1, then we can branch directly to the target block for
+ // the current Case Value, rather than emitting a RHS leaf node for it.
+ if ((RHSR.second - RHSR.first) == 1 && CR.LT &&
+ cast<ConstantInt>(RHSR.first->first)->getZExtValue() ==
+ (cast<ConstantInt>(CR.LT)->getZExtValue() - 1ULL)) {
+ FalseBB = RHSR.first->second;
+ } else {
+ FalseBB = new MachineBasicBlock(LLVMBB);
+ CurMF->getBasicBlockList().insert(BBI, FalseBB);
+ WorkList.push_back(CaseRec(FalseBB,CR.LT,C,RHSR));
+ }
+
+ // Create a CaseBlock record representing a conditional branch to
+ // the LHS node if the value being switched on SV is less than C.
+ // Otherwise, branch to LHS.
+ SelectionDAGISel::CaseBlock CB(ISD::SETLT, SV, C, TrueBB, FalseBB,
+ CR.CaseBB);
+
+ if (CR.CaseBB == CurMBB)
+ visitSwitchCase(CB);
+ else
+ SwitchCases.push_back(CB);
+}
+
void SelectionDAGLowering::visitSwitch(SwitchInst &I) {
// Figure out which block is immediately after the current one.
MachineBasicBlock *NextBlock = 0;
@@ -1245,13 +1522,8 @@
// search tree.
Value *SV = I.getOperand(0);
- // Get the MachineFunction which holds the current MBB. This is used during
- // emission of jump tables, and when inserting any additional MBBs necessary
- // to represent the switch.
- MachineFunction *CurMF = CurMBB->getParent();
-
// Push the initial CaseRec onto the worklist
- std::vector<CaseRec> WorkList;
+ CaseRecVector WorkList;
WorkList.push_back(CaseRec(CurMBB,0,0,CaseRange(Cases.begin(),Cases.end())));
while (!WorkList.empty()) {
@@ -1260,7 +1532,6 @@
WorkList.pop_back();
Case& FrontCase = *CR.Range.first;
Case& BackCase = *(CR.Range.second-1);
- const BasicBlock *LLVMBB = CR.CaseBB->getBasicBlock();
// Figure out which block is immediately after the current one.
NextBlock = 0;
@@ -1275,52 +1546,7 @@
// If the range has few cases (two or less) emit a series of specific
// tests.
if (Size < 3) {
- // TODO: If any two of the cases has the same destination, and if one value
- // is the same as the other, but has one bit unset that the other has set,
- // use bit manipulation to do two compares at once. For example:
- // "if (X == 6 || X == 4)" -> "if ((X|2) == 6)"
-
- // Rearrange the case blocks so that the last one falls through if possible.
- if (NextBlock && Default != NextBlock && BackCase.second != NextBlock) {
- // The last case block won't fall through into 'NextBlock' if we emit the
- // branches in this order. See if rearranging a case value would help.
- for (CaseItr I = CR.Range.first, E = CR.Range.second-1; I != E; ++I) {
- if (I->second == NextBlock) {
- std::swap(*I, BackCase);
- break;
- }
- }
- }
-
- // Create a CaseBlock record representing a conditional branch to
- // the Case's target mbb if the value being switched on SV is equal
- // to C.
- MachineBasicBlock *CurBlock = CR.CaseBB;
- for (CaseItr I = CR.Range.first, E = CR.Range.second; I != E; ++I) {
- MachineBasicBlock *FallThrough;
- if (I != E-1) {
- FallThrough = new MachineBasicBlock(CurBlock->getBasicBlock());
- CurMF->getBasicBlockList().insert(BBI, FallThrough);
- } else {
- // If the last case doesn't match, go to the default block.
- FallThrough = Default;
- }
-
- SelectionDAGISel::CaseBlock CB(ISD::SETEQ, SV, I->first,
- I->second, FallThrough, CurBlock);
-
- // If emitting the first comparison, just call visitSwitchCase to emit the
- // code into the current block. Otherwise, push the CaseBlock onto the
- // vector to be later processed by SDISel, and insert the node's MBB
- // before the next MBB.
- if (CurBlock == CurMBB)
- visitSwitchCase(CB);
- else
- SwitchCases.push_back(CB);
-
- CurBlock = FallThrough;
- }
-
+ handleSmallSwitchRange(CR, WorkList, SV, Default);
continue;
}
@@ -1336,56 +1562,7 @@
double Density = (double)Size / (double)((Last - First) + 1ULL);
if (Density >= 0.3125) {
- // Create a new basic block to hold the code for loading the address
- // of the jump table, and jumping to it. Update successor information;
- // we will either branch to the default case for the switch, or the jump
- // table.
- MachineBasicBlock *JumpTableBB = new MachineBasicBlock(LLVMBB);
- CurMF->getBasicBlockList().insert(BBI, JumpTableBB);
- CR.CaseBB->addSuccessor(Default);
- CR.CaseBB->addSuccessor(JumpTableBB);
-
- // Build a vector of destination BBs, corresponding to each target
- // of the jump table. If the value of the jump table slot corresponds to
- // a case statement, push the case's BB onto the vector, otherwise, push
- // the default BB.
- std::vector<MachineBasicBlock*> DestBBs;
- int64_t TEI = First;
- for (CaseItr I = CR.Range.first, E = CR.Range.second; I != E; ++TEI)
- if (cast<ConstantInt>(I->first)->getSExtValue() == TEI) {
- DestBBs.push_back(I->second);
- ++I;
- } else {
- DestBBs.push_back(Default);
- }
-
- // Update successor info. Add one edge to each unique successor.
- // Vector bool would be better, but vector<bool> is really slow.
- std::vector<unsigned char> SuccsHandled;
- SuccsHandled.resize(CR.CaseBB->getParent()->getNumBlockIDs());
-
- for (std::vector<MachineBasicBlock*>::iterator I = DestBBs.begin(),
- E = DestBBs.end(); I != E; ++I) {
- if (!SuccsHandled[(*I)->getNumber()]) {
- SuccsHandled[(*I)->getNumber()] = true;
- JumpTableBB->addSuccessor(*I);
- }
- }
-
- // Create a jump table index for this jump table, or return an existing
- // one.
- unsigned JTI = CurMF->getJumpTableInfo()->getJumpTableIndex(DestBBs);
-
- // Set the jump table information so that we can codegen it as a second
- // MachineBasicBlock
- SelectionDAGISel::JumpTable JT(-1UL, JTI, JumpTableBB, Default);
- SelectionDAGISel::JumpTableHeader JTH(First, Last, SV, CR.CaseBB,
- (CR.CaseBB == CurMBB));
- if (CR.CaseBB == CurMBB)
- visitJumpTableHeader(JT, JTH);
-
- JTCases.push_back(SelectionDAGISel::JumpTableBlock(JTH, JT));
-
+ handleJTSwitchCase(CR, WorkList, SV, Default);
continue;
}
}
@@ -1393,93 +1570,11 @@
// Emit binary tree. If Size is 1, then we are processing a leaf of the
// binary search tree. Otherwise, we need to pick a pivot, and push left
// and right ranges onto the worklist.
-
- if (Size == 1) {
- // Create a CaseBlock record representing a conditional branch to
- // the Case's target mbb if the value being switched on SV is equal
- // to C. Otherwise, branch to default.
- Constant *C = FrontCase.first;
- MachineBasicBlock *Target = FrontCase.second;
- SelectionDAGISel::CaseBlock CB(ISD::SETEQ, SV, C, Target, Default,
- CR.CaseBB);
-
- // If the MBB representing the leaf node is the current MBB, then just
- // call visitSwitchCase to emit the code into the current block.
- // Otherwise, push the CaseBlock onto the vector to be later processed
- // by SDISel, and insert the node's MBB before the next MBB.
- if (CR.CaseBB == CurMBB)
- visitSwitchCase(CB);
- else
- SwitchCases.push_back(CB);
- } else {
- uint64_t First = cast<ConstantInt>(FrontCase.first)->getSExtValue();
- uint64_t Last = cast<ConstantInt>(BackCase.first)->getSExtValue();
- double Density = 0;
- CaseItr Pivot;
-
- // Select optimal pivot, maximizing sum density of LHS and RHS. This will
- // (heuristically) allow us to emit JumpTable's later.
- unsigned LSize = 1;
- unsigned RSize = Size-1;
- for (CaseItr I = CR.Range.first, J=I+1, E = CR.Range.second;
- J!=E; ++I, ++J, ++LSize, --RSize) {
- uint64_t LEnd = cast<ConstantInt>(I->first)->getSExtValue();
- uint64_t RBegin = cast<ConstantInt>(J->first)->getSExtValue();
- double LDensity = (double)LSize / (double)((LEnd - First) + 1ULL);
- double RDensity = (double)RSize / (double)((Last - RBegin) + 1ULL);
- if (Density < (LDensity + RDensity)) {
- Pivot = J;
- Density = LDensity + RDensity;
- }
- }
-
- CaseRange LHSR(CR.Range.first, Pivot);
- CaseRange RHSR(Pivot, CR.Range.second);
- Constant *C = Pivot->first;
- MachineBasicBlock *FalseBB = 0, *TrueBB = 0;
-
- // We know that we branch to the LHS if the Value being switched on is
- // less than the Pivot value, C. We use this to optimize our binary
- // tree a bit, by recognizing that if SV is greater than or equal to the
- // LHS's Case Value, and that Case Value is exactly one less than the
- // Pivot's Value, then we can branch directly to the LHS's Target,
- // rather than creating a leaf node for it.
- if ((LHSR.second - LHSR.first) == 1 &&
- LHSR.first->first == CR.GE &&
- cast<ConstantInt>(C)->getZExtValue() ==
- (cast<ConstantInt>(CR.GE)->getZExtValue() + 1ULL)) {
- TrueBB = LHSR.first->second;
- } else {
- TrueBB = new MachineBasicBlock(LLVMBB);
- CurMF->getBasicBlockList().insert(BBI, TrueBB);
- WorkList.push_back(CaseRec(TrueBB, C, CR.GE, LHSR));
- }
-
- // Similar to the optimization above, if the Value being switched on is
- // known to be less than the Constant CR.LT, and the current Case Value
- // is CR.LT - 1, then we can branch directly to the target block for
- // the current Case Value, rather than emitting a RHS leaf node for it.
- if ((RHSR.second - RHSR.first) == 1 && CR.LT &&
- cast<ConstantInt>(RHSR.first->first)->getZExtValue() ==
- (cast<ConstantInt>(CR.LT)->getZExtValue() - 1ULL)) {
- FalseBB = RHSR.first->second;
- } else {
- FalseBB = new MachineBasicBlock(LLVMBB);
- CurMF->getBasicBlockList().insert(BBI, FalseBB);
- WorkList.push_back(CaseRec(FalseBB,CR.LT,C,RHSR));
- }
-
- // Create a CaseBlock record representing a conditional branch to
- // the LHS node if the value being switched on SV is less than C.
- // Otherwise, branch to LHS.
- SelectionDAGISel::CaseBlock CB(ISD::SETLT, SV, C, TrueBB, FalseBB,
- CR.CaseBB);
- if (CR.CaseBB == CurMBB)
- visitSwitchCase(CB);
- else
- SwitchCases.push_back(CB);
- }
+ if (Size == 1)
+ handleBTSmallSwitchCase(CR, WorkList, SV, Default);
+ else
+ handleBTSplitSwitchCase(CR, WorkList, SV, Default);
}
}
More information about the llvm-commits
mailing list