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Move the utility function UpdateTerminator() from CodePlacementOpt() into

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MachineBasicBlock so other passes can utilize it.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@86947 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jim Grosbach 2009-11-12 03:55:33 +00:00
parent 01dec0e545
commit 7707a0df5b
3 changed files with 63 additions and 62 deletions
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6
include/llvm/CodeGen/MachineBasicBlock.h
View File

@ -226,6 +226,12 @@ public:
void moveBefore(MachineBasicBlock *NewAfter);
void moveAfter(MachineBasicBlock *NewBefore);
/// updateTerminator - Update the terminator instructions in block to account
/// for changes to the layout. If the block previously used a fallthrough,
/// it may now need a branch, and if it previously used branching it may now
/// be able to use a fallthrough.
void updateTerminator();
// Machine-CFG mutators
/// addSuccessor - Add succ as a successor of this MachineBasicBlock.

64
lib/CodeGen/CodePlacementOpt.cpp
View File

@ -56,7 +56,6 @@ namespace {
MachineFunction::iterator InsertPt,
MachineFunction::iterator Begin,
MachineFunction::iterator End);
void UpdateTerminator(MachineBasicBlock *MBB);
bool EliminateUnconditionalJumpsToTop(MachineFunction &MF,
MachineLoop *L);
bool MoveDiscontiguousLoopBlocks(MachineFunction &MF,
@ -141,66 +140,9 @@ void CodePlacementOpt::Splice(MachineFunction &MF,
MF.splice(InsertPt, Begin, End);
UpdateTerminator(prior(Begin));
UpdateTerminator(OldBeginPrior);
UpdateTerminator(OldEndPrior);
}
/// UpdateTerminator - Update the terminator instructions in MBB to account
/// for changes to the layout. If the block previously used a fallthrough,
/// it may now need a branch, and if it previously used branching it may now
/// be able to use a fallthrough.
///
void CodePlacementOpt::UpdateTerminator(MachineBasicBlock *MBB) {
// A block with no successors has no concerns with fall-through edges.
if (MBB->succ_empty()) return;
MachineBasicBlock *TBB = 0, *FBB = 0;
SmallVector<MachineOperand, 4> Cond;
bool B = TII->AnalyzeBranch(*MBB, 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 (MBB->isLayoutSuccessor(TBB))
TII->RemoveBranch(*MBB);
} else {
// The block has an unconditional fallthrough. If its successor is not
// its layout successor, insert a branch.
TBB = *MBB->succ_begin();
if (!MBB->isLayoutSuccessor(TBB))
TII->InsertBranch(*MBB, 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 (MBB->isLayoutSuccessor(TBB)) {
TII->RemoveBranch(*MBB);
TII->ReverseBranchCondition(Cond);
TII->InsertBranch(*MBB, FBB, 0, Cond);
} else if (MBB->isLayoutSuccessor(FBB)) {
TII->RemoveBranch(*MBB);
TII->InsertBranch(*MBB, TBB, 0, Cond);
}
} else {
// The block has a fallthrough conditional branch.
MachineBasicBlock *MBBA = *MBB->succ_begin();
MachineBasicBlock *MBBB = *next(MBB->succ_begin());
if (MBBA == TBB) std::swap(MBBB, MBBA);
if (MBB->isLayoutSuccessor(TBB)) {
TII->RemoveBranch(*MBB);
TII->ReverseBranchCondition(Cond);
TII->InsertBranch(*MBB, MBBA, 0, Cond);
} else if (!MBB->isLayoutSuccessor(MBBA)) {
TII->RemoveBranch(*MBB);
TII->InsertBranch(*MBB, TBB, MBBA, Cond);
}
}
}
prior(Begin)->updateTerminator();
OldBeginPrior->updateTerminator();
OldEndPrior->updateTerminator();
}
/// EliminateUnconditionalJumpsToTop - Move blocks which unconditionally jump

53
lib/CodeGen/MachineBasicBlock.cpp
View File

@ -17,6 +17,7 @@
#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"
@ -242,6 +243,58 @@ void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
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)) {
TII->RemoveBranch(*this);
TII->ReverseBranchCondition(Cond);
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 = *next(succ_begin());
if (MBBA == TBB) std::swap(MBBB, MBBA);
if (isLayoutSuccessor(TBB)) {
TII->RemoveBranch(*this);
TII->ReverseBranchCondition(Cond);
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);