From d0a4b60df146b8c51555a752fed1530999ecbe64 Mon Sep 17 00:00:00 2001 From: Akira Hatanaka Date: Fri, 1 Mar 2013 01:10:17 +0000 Subject: [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 --- lib/Target/Mips/MipsInstrInfo.cpp | 162 +++++++++++++++++++++----------------- lib/Target/Mips/MipsInstrInfo.h | 15 ++++ 2 files changed, 103 insertions(+), 74 deletions(-) diff --git a/lib/Target/Mips/MipsInstrInfo.cpp b/lib/Target/Mips/MipsInstrInfo.cpp index 76644c1584..be08f837d5 100644 --- a/lib/Target/Mips/MipsInstrInfo.cpp +++ b/lib/Target/Mips/MipsInstrInfo.cpp @@ -93,81 +93,11 @@ bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, MachineBasicBlock *&FBB, SmallVectorImpl &Cond, - bool AllowModify) 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)) { - // 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; - } + bool AllowModify) const { + SmallVector BranchInstrs; + BranchType BT = AnalyzeBranch(MBB, TBB, FBB, Cond, AllowModify, BranchInstrs); - // 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 &Cond) const return false; } +MipsInstrInfo::BranchType MipsInstrInfo:: +AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, + MachineBasicBlock *&FBB, SmallVectorImpl &Cond, + bool AllowModify, + SmallVectorImpl &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()) { diff --git a/lib/Target/Mips/MipsInstrInfo.h b/lib/Target/Mips/MipsInstrInfo.h index aca2bc7ae9..3cd9088140 100644 --- a/lib/Target/Mips/MipsInstrInfo.h +++ b/lib/Target/Mips/MipsInstrInfo.h @@ -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 &Cond) const; + BranchType AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB, + MachineBasicBlock *&FBB, + SmallVectorImpl &Cond, + bool AllowModify, + SmallVectorImpl &BranchInstrs) const; + virtual MachineInstr* emitFrameIndexDebugValue(MachineFunction &MF, int FrameIx, uint64_t Offset, const MDNode *MDPtr, -- cgit v1.2.3