[mips] Define an overloaded version of function MipsInstrInfo::AnalyzeBranchAdd.
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
diff --git a/lib/Target/Mips/MipsInstrInfo.cpp b/lib/Target/Mips/MipsInstrInfo.cpp
index 76644c1..be08f83 100644
--- a/lib/Target/Mips/MipsInstrInfo.cpp
+++ b/lib/Target/Mips/MipsInstrInfo.cpp
@@ -93,81 +93,11 @@
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 @@
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()) {