Rearrange handling of jump tables. Highlights:
1. MachineJumpTableInfo is now created lazily for a function the first time
it actually makes a jump table instead of for every function.
2. The encoding of jump table entries is now described by the
MachineJumpTableInfo::JTEntryKind enum. This enum is determined by the
TLI::getJumpTableEncoding() hook, instead of by lots of code scattered
throughout the compiler that "knows" that jump table entries are always
32-bits in pic mode (for example).
3. The size and alignment of jump table entries is now calculated based on
their kind, instead of at machinefunction creation time.
Future work includes using the EntryKind in more places in the compiler,
eliminating other logic that "knows" the layout of jump tables in various
situations.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@94470 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index 024a252..19cb41d 100644
--- a/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -498,8 +498,9 @@
OutStreamer.SwitchSection(ReadOnlySection);
JTInDiffSection = true;
}
-
- EmitAlignment(Log2_32(MJTI->getAlignment()));
+
+ unsigned EntrySize = MJTI->getEntrySize(*TM.getTargetData());
+ EmitAlignment(Log2_32(MJTI->getEntryAlignment(*TM.getTargetData())));
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
const std::vector<MachineBasicBlock*> &JTBBs = JT[i].MBBs;
@@ -528,7 +529,6 @@
if (!IsPic) {
// In non-pic mode, the entries in the jump table are direct references
// to the basic blocks.
- unsigned EntrySize = MJTI->getEntrySize();
for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
MCSymbol *MBBSym = GetMBBSymbol(JTBBs[ii]->getNumber());
OutStreamer.EmitValue(MCSymbolRefExpr::Create(MBBSym, OutContext),
@@ -566,7 +566,8 @@
Val = MCBinaryExpr::CreateSub(Val, JTI, OutContext);
}
- OutStreamer.EmitValue(Val, MJTI->getEntrySize(), /*addrspace*/0);
+ unsigned EntrySize = MJTI->getEntrySize(*TM.getTargetData());
+ OutStreamer.EmitValue(Val, EntrySize, /*addrspace*/0);
}
diff --git a/lib/CodeGen/BranchFolding.cpp b/lib/CodeGen/BranchFolding.cpp
index 92849d3..4f76aac 100644
--- a/lib/CodeGen/BranchFolding.cpp
+++ b/lib/CodeGen/BranchFolding.cpp
@@ -206,53 +206,56 @@
// See if any jump tables have become mergable or dead as the code generator
// did its thing.
MachineJumpTableInfo *JTI = MF.getJumpTableInfo();
+ if (JTI == 0) {
+ delete RS;
+ return MadeChange;
+ }
+
const std::vector<MachineJumpTableEntry> &JTs = JTI->getJumpTables();
- if (!JTs.empty()) {
- // Figure out how these jump tables should be merged.
- std::vector<unsigned> JTMapping;
- JTMapping.reserve(JTs.size());
+ // Figure out how these jump tables should be merged.
+ std::vector<unsigned> JTMapping;
+ JTMapping.reserve(JTs.size());
- // We always keep the 0th jump table.
- JTMapping.push_back(0);
+ // We always keep the 0th jump table.
+ JTMapping.push_back(0);
- // Scan the jump tables, seeing if there are any duplicates. Note that this
- // is N^2, which should be fixed someday.
- for (unsigned i = 1, e = JTs.size(); i != e; ++i) {
- if (JTs[i].MBBs.empty())
- JTMapping.push_back(i);
- else
- JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
- }
+ // Scan the jump tables, seeing if there are any duplicates. Note that this
+ // is N^2, which should be fixed someday.
+ for (unsigned i = 1, e = JTs.size(); i != e; ++i) {
+ if (JTs[i].MBBs.empty())
+ JTMapping.push_back(i);
+ else
+ JTMapping.push_back(JTI->getJumpTableIndex(JTs[i].MBBs));
+ }
- // If a jump table was merge with another one, walk the function rewriting
- // references to jump tables to reference the new JT ID's. Keep track of
- // whether we see a jump table idx, if not, we can delete the JT.
- BitVector JTIsLive(JTs.size());
- for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
- BB != E; ++BB) {
- for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
- I != E; ++I)
- for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
- MachineOperand &Op = I->getOperand(op);
- if (!Op.isJTI()) continue;
- unsigned NewIdx = JTMapping[Op.getIndex()];
- Op.setIndex(NewIdx);
+ // If a jump table was merge with another one, walk the function rewriting
+ // references to jump tables to reference the new JT ID's. Keep track of
+ // whether we see a jump table idx, if not, we can delete the JT.
+ BitVector JTIsLive(JTs.size());
+ for (MachineFunction::iterator BB = MF.begin(), E = MF.end();
+ BB != E; ++BB) {
+ for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
+ I != E; ++I)
+ for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
+ MachineOperand &Op = I->getOperand(op);
+ if (!Op.isJTI()) continue;
+ unsigned NewIdx = JTMapping[Op.getIndex()];
+ Op.setIndex(NewIdx);
- // Remember that this JT is live.
- JTIsLive.set(NewIdx);
- }
- }
-
- // Finally, remove dead jump tables. This happens either because the
- // indirect jump was unreachable (and thus deleted) or because the jump
- // table was merged with some other one.
- for (unsigned i = 0, e = JTIsLive.size(); i != e; ++i)
- if (!JTIsLive.test(i)) {
- JTI->RemoveJumpTable(i);
- MadeChange = true;
+ // Remember that this JT is live.
+ JTIsLive.set(NewIdx);
}
}
+ // Finally, remove dead jump tables. This happens either because the
+ // indirect jump was unreachable (and thus deleted) or because the jump
+ // table was merged with some other one.
+ for (unsigned i = 0, e = JTIsLive.size(); i != e; ++i)
+ if (!JTIsLive.test(i)) {
+ JTI->RemoveJumpTable(i);
+ MadeChange = true;
+ }
+
delete RS;
return MadeChange;
}
@@ -957,7 +960,8 @@
}
// If MBB was the target of a jump table, update jump tables to go to the
// fallthrough instead.
- MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, FallThrough);
+ if (MachineJumpTableInfo *MJTI = MF.getJumpTableInfo())
+ MJTI->ReplaceMBBInJumpTables(MBB, FallThrough);
MadeChange = true;
}
return MadeChange;
@@ -1191,7 +1195,8 @@
}
// Change any jumptables to go to the new MBB.
- MF.getJumpTableInfo()->ReplaceMBBInJumpTables(MBB, CurTBB);
+ if (MachineJumpTableInfo *MJTI = MF.getJumpTableInfo())
+ MJTI->ReplaceMBBInJumpTables(MBB, CurTBB);
if (DidChange) {
++NumBranchOpts;
MadeChange = true;
diff --git a/lib/CodeGen/MachineFunction.cpp b/lib/CodeGen/MachineFunction.cpp
index 1e3e314..bea0445 100644
--- a/lib/CodeGen/MachineFunction.cpp
+++ b/lib/CodeGen/MachineFunction.cpp
@@ -96,15 +96,7 @@
MachineConstantPool(TM.getTargetData());
Alignment = TM.getTargetLowering()->getFunctionAlignment(F);
- // Set up jump table.
- const TargetData &TD = *TM.getTargetData();
- bool IsPic = TM.getRelocationModel() == Reloc::PIC_;
- unsigned EntrySize = IsPic ? 4 : TD.getPointerSize();
- unsigned TyAlignment = IsPic ?
- TD.getABITypeAlignment(Type::getInt32Ty(F->getContext()))
- : TD.getPointerABIAlignment();
- JumpTableInfo = new (Allocator.Allocate<MachineJumpTableInfo>())
- MachineJumpTableInfo(EntrySize, TyAlignment);
+ JumpTableInfo = 0;
}
MachineFunction::~MachineFunction() {
@@ -121,9 +113,23 @@
}
FrameInfo->~MachineFrameInfo(); Allocator.Deallocate(FrameInfo);
ConstantPool->~MachineConstantPool(); Allocator.Deallocate(ConstantPool);
- JumpTableInfo->~MachineJumpTableInfo(); Allocator.Deallocate(JumpTableInfo);
+
+ if (JumpTableInfo) {
+ JumpTableInfo->~MachineJumpTableInfo();
+ Allocator.Deallocate(JumpTableInfo);
+ }
}
+/// getOrCreateJumpTableInfo - Get the JumpTableInfo for this function, if it
+/// does already exist, allocate one.
+MachineJumpTableInfo *MachineFunction::
+getOrCreateJumpTableInfo(unsigned EntryKind) {
+ if (JumpTableInfo) return JumpTableInfo;
+
+ JumpTableInfo = new (Allocator.Allocate<MachineJumpTableInfo>())
+ MachineJumpTableInfo((MachineJumpTableInfo::JTEntryKind)EntryKind);
+ return JumpTableInfo;
+}
/// RenumberBlocks - This discards all of the MachineBasicBlock numbers and
/// recomputes them. This guarantees that the MBB numbers are sequential,
@@ -311,7 +317,8 @@
FrameInfo->print(*this, OS);
// Print JumpTable Information
- JumpTableInfo->print(OS);
+ if (JumpTableInfo)
+ JumpTableInfo->print(OS);
// Print Constant Pool
ConstantPool->print(OS);
@@ -528,6 +535,37 @@
// MachineJumpTableInfo implementation
//===----------------------------------------------------------------------===//
+/// getEntrySize - Return the size of each entry in the jump table.
+unsigned MachineJumpTableInfo::getEntrySize(const TargetData &TD) const {
+ // The size of a jump table entry is 4 bytes unless the entry is just the
+ // address of a block, in which case it is the pointer size.
+ switch (getEntryKind()) {
+ case MachineJumpTableInfo::EK_BlockAddress:
+ return TD.getPointerSize();
+ case MachineJumpTableInfo::EK_GPRel32BlockAddress:
+ case MachineJumpTableInfo::EK_LabelDifference32:
+ return 4;
+ }
+ assert(0 && "Unknown jump table encoding!");
+ return ~0;
+}
+
+/// getEntryAlignment - Return the alignment of each entry in the jump table.
+unsigned MachineJumpTableInfo::getEntryAlignment(const TargetData &TD) const {
+ // The alignment of a jump table entry is the alignment of int32 unless the
+ // entry is just the address of a block, in which case it is the pointer
+ // alignment.
+ switch (getEntryKind()) {
+ case MachineJumpTableInfo::EK_BlockAddress:
+ return TD.getPointerABIAlignment();
+ case MachineJumpTableInfo::EK_GPRel32BlockAddress:
+ case MachineJumpTableInfo::EK_LabelDifference32:
+ return TD.getABIIntegerTypeAlignment(32);
+ }
+ assert(0 && "Unknown jump table encoding!");
+ return ~0;
+}
+
/// getJumpTableIndex - Create a new jump table entry in the jump table info
/// or return an existing one.
///
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 1c83869..12a4b31 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -2816,9 +2816,12 @@
SDValue Index = Node->getOperand(2);
EVT PTy = TLI.getPointerTy();
- MachineFunction &MF = DAG.getMachineFunction();
- unsigned EntrySize = MF.getJumpTableInfo()->getEntrySize();
- Index= DAG.getNode(ISD::MUL, dl, PTy,
+
+ const TargetData &TD = *TLI.getTargetData();
+ unsigned EntrySize =
+ DAG.getMachineFunction().getJumpTableInfo()->getEntrySize(TD);
+
+ Index = DAG.getNode(ISD::MUL, dl, PTy,
Index, DAG.getConstant(EntrySize, PTy));
SDValue Addr = DAG.getNode(ISD::ADD, dl, PTy, Index, Table);
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 23c7059..dddf385 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -1733,8 +1733,8 @@
std::vector<MachineBasicBlock*> DestBBs;
APInt TEI = First;
for (CaseItr I = CR.Range.first, E = CR.Range.second; I != E; ++TEI) {
- const APInt& Low = cast<ConstantInt>(I->Low)->getValue();
- const APInt& High = cast<ConstantInt>(I->High)->getValue();
+ const APInt &Low = cast<ConstantInt>(I->Low)->getValue();
+ const APInt &High = cast<ConstantInt>(I->High)->getValue();
if (Low.sle(TEI) && TEI.sle(High)) {
DestBBs.push_back(I->BB);
@@ -1757,7 +1757,9 @@
// Create a jump table index for this jump table, or return an existing
// one.
- unsigned JTI = CurMF->getJumpTableInfo()->getJumpTableIndex(DestBBs);
+ unsigned JTEncoding = TLI.getJumpTableEncoding();
+ unsigned JTI = CurMF->getOrCreateJumpTableInfo(JTEncoding)
+ ->getJumpTableIndex(DestBBs);
// Set the jump table information so that we can codegen it as a second
// MachineBasicBlock
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 5b00adb..966c817 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -21,6 +21,7 @@
#include "llvm/GlobalVariable.h"
#include "llvm/DerivedTypes.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Support/ErrorHandling.h"
@@ -793,6 +794,22 @@
return TD->getCallFrameTypeAlignment(Ty);
}
+/// getJumpTableEncoding - Return the entry encoding for a jump table in the
+/// current function. The returned value is a member of the
+/// MachineJumpTableInfo::JTEntryKind enum.
+unsigned TargetLowering::getJumpTableEncoding() const {
+ // In non-pic modes, just use the address of a block.
+ if (getTargetMachine().getRelocationModel() != Reloc::PIC_)
+ return MachineJumpTableInfo::EK_BlockAddress;
+
+ // In PIC mode, if the target supports a GPRel32 directive, use it.
+ if (getTargetMachine().getMCAsmInfo()->getGPRel32Directive() != 0)
+ return MachineJumpTableInfo::EK_GPRel32BlockAddress;
+
+ // Otherwise, use a label difference.
+ return MachineJumpTableInfo::EK_LabelDifference32;
+}
+
SDValue TargetLowering::getPICJumpTableRelocBase(SDValue Table,
SelectionDAG &DAG) const {
if (usesGlobalOffsetTable())