SmallSet<unsigned, 4> ImpDefRegs;
MachineBasicBlock::iterator I = MBB->begin();
while (I != MBB->end()) {
- if (I->getOpcode() != TargetInstrInfo::IMPLICIT_DEF)
+ if (!I->isImplicitDef())
break;
unsigned Reg = I->getOperand(0).getReg();
ImpDefRegs.insert(Reg);
// 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());
-
- // 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));
- }
-
- // 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);
- }
- }
+ // 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);
+
+ // 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));
+ }
- // 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;
+ // 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;
+ }
+
delete RS;
return MadeChange;
}
return 0; // Empty MBB.
--I;
+ // Skip debug info so it will not affect codegen.
+ while (I->isDebugValue()) {
+ if (I==MBB->begin())
+ return 0; // MBB empty except for debug info.
+ --I;
+ }
unsigned Hash = HashMachineInstr(I);
if (I == MBB->begin() || minCommonTailLength == 1)
return Hash; // Single instr MBB.
--I;
+ while (I->isDebugValue()) {
+ if (I==MBB->begin())
+ return Hash; // MBB with single non-debug instr.
+ --I;
+ }
// Hash in the second-to-last instruction.
Hash ^= HashMachineInstr(I) << 2;
return Hash;
unsigned TailLen = 0;
while (I1 != MBB1->begin() && I2 != MBB2->begin()) {
--I1; --I2;
+ // Skip debugging pseudos; necessary to avoid changing the code.
+ while (I1->isDebugValue()) {
+ if (I1==MBB1->begin()) {
+ while (I2->isDebugValue()) {
+ if (I2==MBB2->begin())
+ // I1==DBG at begin; I2==DBG at begin
+ return TailLen;
+ --I2;
+ }
+ ++I2;
+ // I1==DBG at begin; I2==non-DBG, or first of DBGs not at begin
+ return TailLen;
+ }
+ --I1;
+ }
+ // I1==first (untested) non-DBG preceding known match
+ while (I2->isDebugValue()) {
+ if (I2==MBB2->begin()) {
+ ++I1;
+ // I1==non-DBG, or first of DBGs not at begin; I2==DBG at begin
+ return TailLen;
+ }
+ --I2;
+ }
+ // I1, I2==first (untested) non-DBGs preceding known match
if (!I1->isIdenticalTo(I2) ||
// FIXME: This check is dubious. It's used to get around a problem where
// people incorrectly expect inline asm directives to remain in the same
// relative order. This is untenable because normal compiler
// optimizations (like this one) may reorder and/or merge these
// directives.
- I1->getOpcode() == TargetInstrInfo::INLINEASM) {
+ I1->isInlineAsm()) {
++I1; ++I2;
break;
}
++TailLen;
}
+ // Back past possible debugging pseudos at beginning of block. This matters
+ // when one block differs from the other only by whether debugging pseudos
+ // are present at the beginning. (This way, the various checks later for
+ // I1==MBB1->begin() work as expected.)
+ if (I1 == MBB1->begin() && I2 != MBB2->begin()) {
+ --I2;
+ while (I2->isDebugValue()) {
+ if (I2 == MBB2->begin()) {
+ return TailLen;
+ }
+ --I2;
+ }
+ ++I2;
+ }
+ if (I2 == MBB2->begin() && I1 != MBB1->begin()) {
+ --I1;
+ while (I1->isDebugValue()) {
+ if (I1 == MBB1->begin())
+ return TailLen;
+ --I1;
+ }
+ ++I1;
+ }
return TailLen;
}
MachineBasicBlock::iterator E) {
unsigned Time = 0;
for (; I != E; ++I) {
+ if (I->isDebugValue())
+ continue;
const TargetInstrDesc &TID = I->getDesc();
if (TID.isCall())
Time += 10;
SameTails[commonTailIndex].getTailStartPos();
MachineBasicBlock *MBB = SameTails[commonTailIndex].getBlock();
+ // If the common tail includes any debug info we will take it pretty
+ // randomly from one of the inputs. Might be better to remove it?
DEBUG(dbgs() << "\nSplitting BB#" << MBB->getNumber() << ", size "
<< maxCommonTailLength);
return MadeChange;
}
+// Blocks should be considered empty if they contain only debug info;
+// else the debug info would affect codegen.
+static bool IsEmptyBlock(MachineBasicBlock *MBB) {
+ if (MBB->empty())
+ return true;
+ for (MachineBasicBlock::iterator MBBI = MBB->begin(), MBBE = MBB->end();
+ MBBI!=MBBE; ++MBBI) {
+ if (!MBBI->isDebugValue())
+ return false;
+ }
+ return true;
+}
/// IsBetterFallthrough - Return true if it would be clearly better to
/// fall-through to MBB1 than to fall through into MBB2. This has to return
// explicitly. Landing pads should not do this since the landing-pad table
// points to this block. Blocks with their addresses taken shouldn't be
// optimized away.
- if (MBB->empty() && !MBB->isLandingPad() && !MBB->hasAddressTaken()) {
+ if (IsEmptyBlock(MBB) && !MBB->isLandingPad() && !MBB->hasAddressTaken()) {
// Dead block? Leave for cleanup later.
if (MBB->pred_empty()) return MadeChange;
}
// 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;
// be 'non-branch terminators' in the block, try removing the branch and
// then seeing if the block is empty.
TII->RemoveBranch(*MBB);
-
+ // If the only things remaining in the block are debug info, remove these
+ // as well, so this will behave the same as an empty block in non-debug
+ // mode.
+ if (!MBB->empty()) {
+ bool NonDebugInfoFound = false;
+ for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end();
+ I != E; ++I) {
+ if (!I->isDebugValue()) {
+ NonDebugInfoFound = true;
+ break;
+ }
+ }
+ if (!NonDebugInfoFound)
+ // Make the block empty, losing the debug info (we could probably
+ // improve this in some cases.)
+ MBB->erase(MBB->begin(), MBB->end());
+ }
// If this block is just an unconditional branch to CurTBB, we can
// usually completely eliminate the block. The only case we cannot
// completely eliminate the block is when the block before this one
}
// 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;
projects / oota-llvm.git / blobdiff