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[mips] Define an overloaded version of function MipsInstrInfo::AnalyzeBranchAdd.

Browse Source 
This function will be used later when the capability to search delay slot
filling instructions in successor blocks is added. No intended functionality
changes.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@176325 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Akira Hatanaka 2013-03-01 01:10:17 +00:00
parent b8bc8cc3b0
commit d0a4b60df1
2 changed files with 103 additions and 74 deletions
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162
lib/Target/Mips/MipsInstrInfo.cpp
View File

@ -93,81 +93,11 @@ bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify) const
{
bool AllowModify) const {
SmallVector<MachineInstr*, 2> BranchInstrs;
BranchType BT = AnalyzeBranch(MBB, TBB, FBB, Cond, AllowModify, BranchInstrs);
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
// Skip all the debug instructions.
while (I != REnd && I->isDebugValue())
++I;
if (I == REnd || !isUnpredicatedTerminator(&*I)) {
// If this block ends with no branches (it just falls through to its succ)
// just return false, leaving TBB/FBB null.
TBB = FBB = NULL;
return false;
}
MachineInstr *LastInst = &*I;
unsigned LastOpc = LastInst->getOpcode();
// Not an analyzable branch (must be an indirect jump).
if (!GetAnalyzableBrOpc(LastOpc))
return true;
// Get the second to last instruction in the block.
unsigned SecondLastOpc = 0;
MachineInstr *SecondLastInst = NULL;
if (++I != REnd) {
SecondLastInst = &*I;
SecondLastOpc = GetAnalyzableBrOpc(SecondLastInst->getOpcode());
// Not an analyzable branch (must be an indirect jump).
if (isUnpredicatedTerminator(SecondLastInst) && !SecondLastOpc)
return true;
}
// If there is only one terminator instruction, process it.
if (!SecondLastOpc) {
// Unconditional branch
if (LastOpc == UncondBrOpc) {
TBB = LastInst->getOperand(0).getMBB();
return false;
}
// Conditional branch
AnalyzeCondBr(LastInst, LastOpc, TBB, Cond);
return false;
}
// If we reached here, there are two branches.
// If there are three terminators, we don't know what sort of block this is.
if (++I != REnd && isUnpredicatedTerminator(&*I))
return true;
// If second to last instruction is an unconditional branch,
// analyze it and remove the last instruction.
if (SecondLastOpc == UncondBrOpc) {
// Return if the last instruction cannot be removed.
if (!AllowModify)
return true;
TBB = SecondLastInst->getOperand(0).getMBB();
LastInst->eraseFromParent();
return false;
}
// Conditional branch followed by an unconditional branch.
// The last one must be unconditional.
if (LastOpc != UncondBrOpc)
return true;
AnalyzeCondBr(SecondLastInst, SecondLastOpc, TBB, Cond);
FBB = LastInst->getOperand(0).getMBB();
return false;
return (BT == BT_None) || (BT == BT_Indirect);
}
void MipsInstrInfo::BuildCondBr(MachineBasicBlock &MBB,
@ -256,6 +186,90 @@ ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const
return false;
}
MipsInstrInfo::BranchType MipsInstrInfo::
AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB, SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify,
SmallVectorImpl<MachineInstr*> &BranchInstrs) const {
MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();
// Skip all the debug instructions.
while (I != REnd && I->isDebugValue())
++I;
if (I == REnd || !isUnpredicatedTerminator(&*I)) {
// This block ends with no branches (it just falls through to its succ).
// Leave TBB/FBB null.
TBB = FBB = NULL;
return BT_NoBranch;
}
MachineInstr *LastInst = &*I;
unsigned LastOpc = LastInst->getOpcode();
BranchInstrs.push_back(LastInst);
// Not an analyzable branch (e.g., indirect jump).
if (!GetAnalyzableBrOpc(LastOpc))
return LastInst->isIndirectBranch() ? BT_Indirect : BT_None;
// Get the second to last instruction in the block.
unsigned SecondLastOpc = 0;
MachineInstr *SecondLastInst = NULL;
if (++I != REnd) {
SecondLastInst = &*I;
SecondLastOpc = GetAnalyzableBrOpc(SecondLastInst->getOpcode());
// Not an analyzable branch (must be an indirect jump).
if (isUnpredicatedTerminator(SecondLastInst) && !SecondLastOpc)
return BT_None;
}
BranchInstrs.insert(BranchInstrs.begin(), SecondLastInst);
// If there is only one terminator instruction, process it.
if (!SecondLastOpc) {
// Unconditional branch
if (LastOpc == UncondBrOpc) {
TBB = LastInst->getOperand(0).getMBB();
return BT_Uncond;
}
// Conditional branch
AnalyzeCondBr(LastInst, LastOpc, TBB, Cond);
return BT_Cond;
}
// If we reached here, there are two branches.
// If there are three terminators, we don't know what sort of block this is.
if (++I != REnd && isUnpredicatedTerminator(&*I))
return BT_None;
// If second to last instruction is an unconditional branch,
// analyze it and remove the last instruction.
if (SecondLastOpc == UncondBrOpc) {
// Return if the last instruction cannot be removed.
if (!AllowModify)
return BT_None;
TBB = SecondLastInst->getOperand(0).getMBB();
LastInst->eraseFromParent();
BranchInstrs.pop_back();
return BT_Uncond;
}
// Conditional branch followed by an unconditional branch.
// The last one must be unconditional.
if (LastOpc != UncondBrOpc)
return BT_None;
AnalyzeCondBr(SecondLastInst, SecondLastOpc, TBB, Cond);
FBB = LastInst->getOperand(0).getMBB();
return BT_CondUncond;
}
/// Return the number of bytes of code the specified instruction may be.
unsigned MipsInstrInfo::GetInstSizeInBytes(const MachineInstr *MI) const {
switch (MI->getOpcode()) {

15
lib/Target/Mips/MipsInstrInfo.h
View File

@ -31,6 +31,15 @@ protected:
unsigned UncondBrOpc;
public:
enum BranchType {
BT_None, // Couldn't analyze branch.
BT_NoBranch, // No branches found.
BT_Uncond, // One unconditional branch.
BT_Cond, // One conditional branch.
BT_CondUncond, // A conditional branch followed by an unconditional branch.
BT_Indirect // One indirct branch.
};
explicit MipsInstrInfo(MipsTargetMachine &TM, unsigned UncondBrOpc);
static const MipsInstrInfo *create(MipsTargetMachine &TM);
@ -51,6 +60,12 @@ public:
virtual
bool ReverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const;
BranchType AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
MachineBasicBlock *&FBB,
SmallVectorImpl<MachineOperand> &Cond,
bool AllowModify,
SmallVectorImpl<MachineInstr*> &BranchInstrs) const;
virtual MachineInstr* emitFrameIndexDebugValue(MachineFunction &MF,
int FrameIx, uint64_t Offset,
const MDNode *MDPtr,