#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetInstrDesc.h"
+#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/LeakDetector.h"
#include "llvm/Support/raw_ostream.h"
os << " %reg" << RegNo;
}
+StringRef MachineBasicBlock::getName() const {
+ if (const BasicBlock *LBB = getBasicBlock())
+ return LBB->getName();
+ else
+ return "(null)";
+}
+
void MachineBasicBlock::print(raw_ostream &OS) const {
const MachineFunction *MF = getParent();
if (!MF) {
getParent()->splice(++BBI, this);
}
+void MachineBasicBlock::updateTerminator() {
+ const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
+ // A block with no successors has no concerns with fall-through edges.
+ if (this->succ_empty()) return;
+
+ MachineBasicBlock *TBB = 0, *FBB = 0;
+ SmallVector<MachineOperand, 4> Cond;
+ bool B = TII->AnalyzeBranch(*this, TBB, FBB, Cond);
+ (void) B;
+ assert(!B && "UpdateTerminators requires analyzable predecessors!");
+ if (Cond.empty()) {
+ if (TBB) {
+ // The block has an unconditional branch. If its successor is now
+ // its layout successor, delete the branch.
+ if (isLayoutSuccessor(TBB))
+ TII->RemoveBranch(*this);
+ } else {
+ // The block has an unconditional fallthrough. If its successor is not
+ // its layout successor, insert a branch.
+ TBB = *succ_begin();
+ if (!isLayoutSuccessor(TBB))
+ TII->InsertBranch(*this, TBB, 0, Cond);
+ }
+ } else {
+ if (FBB) {
+ // The block has a non-fallthrough conditional branch. If one of its
+ // successors is its layout successor, rewrite it to a fallthrough
+ // conditional branch.
+ if (isLayoutSuccessor(TBB)) {
+ if (TII->ReverseBranchCondition(Cond))
+ return;
+ TII->RemoveBranch(*this);
+ TII->InsertBranch(*this, FBB, 0, Cond);
+ } else if (isLayoutSuccessor(FBB)) {
+ TII->RemoveBranch(*this);
+ TII->InsertBranch(*this, TBB, 0, Cond);
+ }
+ } else {
+ // The block has a fallthrough conditional branch.
+ MachineBasicBlock *MBBA = *succ_begin();
+ MachineBasicBlock *MBBB = *llvm::next(succ_begin());
+ if (MBBA == TBB) std::swap(MBBB, MBBA);
+ if (isLayoutSuccessor(TBB)) {
+ if (TII->ReverseBranchCondition(Cond)) {
+ // We can't reverse the condition, add an unconditional branch.
+ Cond.clear();
+ TII->InsertBranch(*this, MBBA, 0, Cond);
+ return;
+ }
+ TII->RemoveBranch(*this);
+ TII->InsertBranch(*this, MBBA, 0, Cond);
+ } else if (!isLayoutSuccessor(MBBA)) {
+ TII->RemoveBranch(*this);
+ TII->InsertBranch(*this, TBB, MBBA, Cond);
+ }
+ }
+ }
+}
void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
Successors.push_back(succ);
bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
MachineFunction::const_iterator I(this);
- return next(I) == MachineFunction::const_iterator(MBB);
+ return llvm::next(I) == MachineFunction::const_iterator(MBB);
+}
+
+bool MachineBasicBlock::canFallThrough() {
+ MachineBasicBlock *TBB = 0, *FBB = 0;
+ SmallVector<MachineOperand, 4> Cond;
+ const TargetInstrInfo *TII = getParent()->getTarget().getInstrInfo();
+ bool BranchUnAnalyzable = TII->AnalyzeBranch(*this, TBB, FBB, Cond, true);
+
+ MachineFunction::iterator Fallthrough = this;
+ ++Fallthrough;
+ // If FallthroughBlock is off the end of the function, it can't fall through.
+ if (Fallthrough == getParent()->end())
+ return false;
+
+ // If FallthroughBlock isn't a successor, no fallthrough is possible.
+ if (!isSuccessor(Fallthrough))
+ return false;
+
+ // If we couldn't analyze the branch, examine the last instruction.
+ // If the block doesn't end in a known control barrier, assume fallthrough
+ // is possible. The isPredicable check is needed because this code can be
+ // called during IfConversion, where an instruction which is normally a
+ // Barrier is predicated and thus no longer an actual control barrier. This
+ // is over-conservative though, because if an instruction isn't actually
+ // predicated we could still treat it like a barrier.
+ if (BranchUnAnalyzable)
+ return empty() || !back().getDesc().isBarrier() ||
+ back().getDesc().isPredicable();
+
+ // If there is no branch, control always falls through.
+ if (TBB == 0) return true;
+
+ // If there is some explicit branch to the fallthrough block, it can obviously
+ // reach, even though the branch should get folded to fall through implicitly.
+ if (MachineFunction::iterator(TBB) == Fallthrough ||
+ MachineFunction::iterator(FBB) == Fallthrough)
+ return true;
+
+ // If it's an unconditional branch to some block not the fall through, it
+ // doesn't fall through.
+ if (Cond.empty()) return false;
+
+ // Otherwise, if it is conditional and has no explicit false block, it falls
+ // through.
+ return FBB == 0;
}
/// removeFromParent - This method unlinks 'this' from the containing function,
bool MadeChange = false;
bool AddedFallThrough = false;
- MachineFunction::iterator FallThru = next(MachineFunction::iterator(this));
+ MachineFunction::iterator FallThru =
+ llvm::next(MachineFunction::iterator(this));
// If this block ends with a conditional branch that falls through to its
// successor, set DestB as the successor.
}
return MadeChange;
}
+
+void llvm::WriteAsOperand(raw_ostream &OS, const MachineBasicBlock *MBB,
+ bool t) {
+ OS << "BB#" << MBB->getNumber();
+}