MachineFunctionPass::getAnalysisUsage(AU);
}
};
-} // namespace
+}
char BranchFolderPass::ID = 0;
char &llvm::BranchFolderPassID = BranchFolderPass::ID;
// Tail Merging of Blocks
//===----------------------------------------------------------------------===//
+/// HashMachineInstr - Compute a hash value for MI and its operands.
+static unsigned HashMachineInstr(const MachineInstr *MI) {
+ unsigned Hash = MI->getOpcode();
+ for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+ const MachineOperand &Op = MI->getOperand(i);
+
+ // Merge in bits from the operand if easy. We can't use MachineOperand's
+ // hash_code here because it's not deterministic and we sort by hash value
+ // later.
+ unsigned OperandHash = 0;
+ switch (Op.getType()) {
+ case MachineOperand::MO_Register:
+ OperandHash = Op.getReg();
+ break;
+ case MachineOperand::MO_Immediate:
+ OperandHash = Op.getImm();
+ break;
+ case MachineOperand::MO_MachineBasicBlock:
+ OperandHash = Op.getMBB()->getNumber();
+ break;
+ case MachineOperand::MO_FrameIndex:
+ case MachineOperand::MO_ConstantPoolIndex:
+ case MachineOperand::MO_JumpTableIndex:
+ OperandHash = Op.getIndex();
+ break;
+ case MachineOperand::MO_GlobalAddress:
+ case MachineOperand::MO_ExternalSymbol:
+ // Global address / external symbol are too hard, don't bother, but do
+ // pull in the offset.
+ OperandHash = Op.getOffset();
+ break;
+ default:
+ break;
+ }
+
+ Hash += ((OperandHash << 3) | Op.getType()) << (i & 31);
+ }
+ return Hash;
+}
+
/// HashEndOfMBB - Hash the last instruction in the MBB.
static unsigned HashEndOfMBB(const MachineBasicBlock *MBB) {
- auto LastInst = MBB->getLastNonDebugInstr();
- if (LastInst == MBB->end())
+ MachineBasicBlock::const_iterator I = MBB->getLastNonDebugInstr();
+ if (I == MBB->end())
return 0;
- // Hash the instruction and all operands. MachineInstrExpressionTrait ignores
- // vreg defs when computing the hash but we're post-regalloc here.
- return MachineInstrExpressionTrait::getHashValue(LastInst);
+
+ return HashMachineInstr(I);
}
/// ComputeCommonTailLength - Given two machine basic blocks, compute the number
// 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;
+ return MBB->getFirstNonDebugInstr() == MBB->end();
}
// Blocks with only debug info and branches should be considered the same
// as blocks with only branches.
static bool IsBranchOnlyBlock(MachineBasicBlock *MBB) {
- MachineBasicBlock::iterator MBBI, MBBE;
- for (MBBI = MBB->begin(), MBBE = MBB->end(); MBBI!=MBBE; ++MBBI) {
- if (!MBBI->isDebugValue())
- break;
- }
- return (MBBI->isBranch());
+ MachineBasicBlock::iterator I = MBB->getFirstNonDebugInstr();
+ assert(I != MBB->end() && "empty block!");
+ return I->isBranch();
}
/// IsBetterFallthrough - Return true if it would be clearly better to
// MBB1 doesn't, we prefer to fall through into MBB1. This allows us to
// optimize branches that branch to either a return block or an assert block
// into a fallthrough to the return.
- if (IsEmptyBlock(MBB1) || IsEmptyBlock(MBB2)) return false;
+ MachineBasicBlock::iterator MBB1I = MBB1->getLastNonDebugInstr();
+ MachineBasicBlock::iterator MBB2I = MBB2->getLastNonDebugInstr();
+ if (MBB1I == MBB1->end() || MBB2I == MBB2->end())
+ return false;
// If there is a clear successor ordering we make sure that one block
// will fall through to the next
if (MBB1->isSuccessor(MBB2)) return true;
if (MBB2->isSuccessor(MBB1)) return false;
- // Neither block consists entirely of debug info (per IsEmptyBlock check),
- // so we needn't test for falling off the beginning here.
- MachineBasicBlock::iterator MBB1I = --MBB1->end();
- while (MBB1I->isDebugValue())
- --MBB1I;
- MachineBasicBlock::iterator MBB2I = --MBB2->end();
- while (MBB2I->isDebugValue())
- --MBB2I;
return MBB2I->isCall() && !MBB1I->isCall();
}
/// getBranchDebugLoc - Find and return, if any, the DebugLoc of the branch
-/// instructions on the block. Always use the DebugLoc of the first
-/// branching instruction found unless its absent, in which case use the
-/// DebugLoc of the second if present.
+/// instructions on the block.
static DebugLoc getBranchDebugLoc(MachineBasicBlock &MBB) {
- MachineBasicBlock::iterator I = MBB.end();
- if (I == MBB.begin())
- return DebugLoc();
- --I;
- while (I->isDebugValue() && I != MBB.begin())
- --I;
- if (I->isBranch())
+ MachineBasicBlock::iterator I = MBB.getLastNonDebugInstr();
+ if (I != MBB.end() && I->isBranch())
return I->getDebugLoc();
return DebugLoc();
}
// 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 (IsEmptyBlock(MBB)) {
+ // 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
projects / oota-llvm.git / blobdiff