Turns out AnalyzeBranch can modify the mbb being analyzed. This is a nasty

suprise to some callers, e.g. register coalescer. For now, add an parameter
that tells AnalyzeBranch whether it's safe to modify the mbb. A better
solution is out there, but I don't have time to deal with it right now.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@64124 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetInstrInfo.h

@@ -195,9 +195,13 @@ public:
   /// Note that RemoveBranch and InsertBranch must be implemented to support
   /// cases where this method returns success.
   ///
+  /// If AllowModify is true, then this routine is allowed to modify the basic
+  /// block (e.g. delete instructions after the unconditional branch).
+  ///
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const {
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify = false) const {
     return true;
   }
   

lib/CodeGen/BranchFolding.cpp

@@ -191,7 +191,7 @@ bool BranchFolder::runOnMachineFunction(MachineFunction &MF) {
   for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; I++) {
     MachineBasicBlock *MBB = I, *TBB = 0, *FBB = 0;
     SmallVector<MachineOperand, 4> Cond;
-    if (!TII->AnalyzeBranch(*MBB, TBB, FBB, Cond))
+    if (!TII->AnalyzeBranch(*MBB, TBB, FBB, Cond, true))
       EverMadeChange |= MBB->CorrectExtraCFGEdges(TBB, FBB, !Cond.empty());
     EverMadeChange |= OptimizeImpDefsBlock(MBB);
   }
@@ -434,7 +434,7 @@ static void FixTail(MachineBasicBlock* CurMBB, MachineBasicBlock *SuccBB,
   MachineBasicBlock *TBB = 0, *FBB = 0;
   SmallVector<MachineOperand, 4> Cond;
   if (I != MF->end() &&
-      !TII->AnalyzeBranch(*CurMBB, TBB, FBB, Cond)) {
+      !TII->AnalyzeBranch(*CurMBB, TBB, FBB, Cond, true)) {
     MachineBasicBlock *NextBB = I;
     if (TBB == NextBB && !Cond.empty() && !FBB) {
       if (!TII->ReverseBranchCondition(Cond)) {
@@ -711,7 +711,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
           continue;
         MachineBasicBlock *TBB = 0, *FBB = 0;
         SmallVector<MachineOperand, 4> Cond;
-        if (!TII->AnalyzeBranch(*PBB, TBB, FBB, Cond)) {
+        if (!TII->AnalyzeBranch(*PBB, TBB, FBB, Cond, true)) {
           // Failing case:  IBB is the target of a cbr, and
           // we cannot reverse the branch.
           SmallVector<MachineOperand, 4> NewCond(Cond);
@@ -845,7 +845,7 @@ bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB,
 bool BranchFolder::CanFallThrough(MachineBasicBlock *CurBB) {
   MachineBasicBlock *TBB = 0, *FBB = 0;
   SmallVector<MachineOperand, 4> Cond;
-  bool CurUnAnalyzable = TII->AnalyzeBranch(*CurBB, TBB, FBB, Cond);
+  bool CurUnAnalyzable = TII->AnalyzeBranch(*CurBB, TBB, FBB, Cond, true);
   return CanFallThrough(CurBB, CurUnAnalyzable, TBB, FBB, Cond);
 }
 
@@ -910,7 +910,7 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
   MachineBasicBlock *PriorTBB = 0, *PriorFBB = 0;
   SmallVector<MachineOperand, 4> PriorCond;
   bool PriorUnAnalyzable =
-    TII->AnalyzeBranch(PrevBB, PriorTBB, PriorFBB, PriorCond);
+    TII->AnalyzeBranch(PrevBB, PriorTBB, PriorFBB, PriorCond, true);
   if (!PriorUnAnalyzable) {
     // If the CFG for the prior block has extra edges, remove them.
     MadeChange |= PrevBB.CorrectExtraCFGEdges(PriorTBB, PriorFBB,
@@ -1023,7 +1023,7 @@ void BranchFolder::OptimizeBlock(MachineBasicBlock *MBB) {
   // Analyze the branch in the current block.
   MachineBasicBlock *CurTBB = 0, *CurFBB = 0;
   SmallVector<MachineOperand, 4> CurCond;
-  bool CurUnAnalyzable = TII->AnalyzeBranch(*MBB, CurTBB, CurFBB, CurCond);
+  bool CurUnAnalyzable= TII->AnalyzeBranch(*MBB, CurTBB, CurFBB, CurCond, true);
   if (!CurUnAnalyzable) {
     // If the CFG for the prior block has extra edges, remove them.
     MadeChange |= MBB->CorrectExtraCFGEdges(CurTBB, CurFBB, !CurCond.empty());

lib/Target/ARM/ARMInstrInfo.cpp

@@ -335,7 +335,8 @@ ARMInstrInfo::convertToThreeAddress(MachineFunction::iterator &MFI,
 // Branch analysis.
 bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
                                  MachineBasicBlock *&FBB,
-                                 SmallVectorImpl<MachineOperand> &Cond) const {
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -385,7 +386,8 @@ bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
       (LastOpc == ARM::B || LastOpc == ARM::tB)) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 
@@ -396,7 +398,8 @@ bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
        SecondLastOpc == ARM::BR_JTadd || SecondLastOpc==ARM::tBR_JTr) &&
       (LastOpc == ARM::B || LastOpc == ARM::tB)) {
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return true;
   } 
 

lib/Target/ARM/ARMInstrInfo.h

@@ -172,7 +172,8 @@ public:
   // Branch analysis.
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const;
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify) const;
   virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const;
   virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                                 MachineBasicBlock *FBB,

lib/Target/Alpha/AlphaInstrInfo.cpp

@@ -321,8 +321,9 @@ static unsigned AlphaRevCondCode(unsigned Opcode) {
 
 // Branch analysis.
 bool AlphaInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
-                                 MachineBasicBlock *&FBB,
+                                   MachineBasicBlock *&FBB,
-                                 SmallVectorImpl<MachineOperand> &Cond) const {
+                                   SmallVectorImpl<MachineOperand> &Cond,
+                                   bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -373,7 +374,8 @@ bool AlphaInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TB
       LastInst->getOpcode() == Alpha::BR) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 

lib/Target/Alpha/AlphaInstrInfo.h

@@ -83,7 +83,8 @@ public:
   
   bool AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
                      MachineBasicBlock *&FBB,
-                     SmallVectorImpl<MachineOperand> &Cond) const;
+                     SmallVectorImpl<MachineOperand> &Cond,
+                     bool AllowModify) const;
   unsigned RemoveBranch(MachineBasicBlock &MBB) const;
   void insertNoop(MachineBasicBlock &MBB, 
                   MachineBasicBlock::iterator MI) const;

lib/Target/CellSPU/SPUInstrInfo.cpp

@@ -524,7 +524,8 @@ SPUInstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
 bool
 SPUInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                             MachineBasicBlock *&FBB,
-                            SmallVectorImpl<MachineOperand> &Cond) const {
+                            SmallVectorImpl<MachineOperand> &Cond,
+                            bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -575,7 +576,8 @@ SPUInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
   if (isUncondBranch(SecondLastInst) && isUncondBranch(LastInst)) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 

lib/Target/CellSPU/SPUInstrInfo.h

@@ -100,7 +100,8 @@ namespace llvm {
 
     virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                                MachineBasicBlock *&FBB,
-                               SmallVectorImpl<MachineOperand> &Cond) const;
+                               SmallVectorImpl<MachineOperand> &Cond,
+                               bool AllowModify) const;
 
     virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const;
 

lib/Target/Mips/MipsInstrInfo.cpp

@@ -453,7 +453,8 @@ Mips::CondCode Mips::GetOppositeBranchCondition(Mips::CondCode CC)
 bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, 
                                   MachineBasicBlock *&TBB,
                                   MachineBasicBlock *&FBB,
-                                  SmallVectorImpl<MachineOperand> &Cond) const 
+                                  SmallVectorImpl<MachineOperand> &Cond,
+                                  bool AllowModify) const 
 {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
@@ -525,7 +526,8 @@ bool MipsInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
   if ((SecondLastOpc == Mips::J) && (LastOpc == Mips::J)) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 

lib/Target/Mips/MipsInstrInfo.h

@@ -166,7 +166,8 @@ public:
   /// Branch Analysis
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const;
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify) const;
   virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const;
   virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                                 MachineBasicBlock *FBB,

lib/Target/PowerPC/PPCInstrInfo.cpp

@@ -204,7 +204,8 @@ void PPCInstrInfo::insertNoop(MachineBasicBlock &MBB,
 // Branch analysis.
 bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
                                  MachineBasicBlock *&FBB,
-                                 SmallVectorImpl<MachineOperand> &Cond) const {
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -253,7 +254,8 @@ bool PPCInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
       LastInst->getOpcode() == PPC::B) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 

lib/Target/PowerPC/PPCInstrInfo.h

@@ -104,7 +104,8 @@ public:
   // Branch analysis.
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const;
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify) const;
   virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const;
   virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                                 MachineBasicBlock *FBB,

lib/Target/X86/X86InstrInfo.cpp

@@ -1488,7 +1488,8 @@ static bool isBrAnalysisUnpredicatedTerminator(const MachineInstr *MI,
 bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, 
                                  MachineBasicBlock *&TBB,
                                  MachineBasicBlock *&FBB,
-                                 SmallVectorImpl<MachineOperand> &Cond) const {
+                                 SmallVectorImpl<MachineOperand> &Cond,
+                                 bool AllowModify) const {
   // Start from the bottom of the block and work up, examining the
   // terminator instructions.
   MachineBasicBlock::iterator I = MBB.end();
@@ -1504,6 +1505,11 @@ bool X86InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,
       return true;
     // Handle unconditional branches.
     if (I->getOpcode() == X86::JMP) {
+      if (!AllowModify) {
+        TBB = I->getOperand(0).getMBB();
+        return false;
+      }
+
       // If the block has any instructions after a JMP, delete them.
       while (next(I) != MBB.end())
         next(I)->eraseFromParent();

lib/Target/X86/X86InstrInfo.h

@@ -323,7 +323,8 @@ public:
   virtual bool isUnpredicatedTerminator(const MachineInstr* MI) const;
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const;
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify) const;
   virtual unsigned RemoveBranch(MachineBasicBlock &MBB) const;
   virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                                 MachineBasicBlock *FBB,

lib/Target/XCore/XCoreInstrInfo.cpp

@@ -228,8 +228,9 @@ static inline XCore::CondCode GetOppositeBranchCondition(XCore::CondCode CC)
 ///
 bool
 XCoreInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
-                           MachineBasicBlock *&FBB,
+                              MachineBasicBlock *&FBB,
-                           SmallVectorImpl<MachineOperand> &Cond) const {
+                              SmallVectorImpl<MachineOperand> &Cond,
+                              bool AllowModify) const {
   // If the block has no terminators, it just falls into the block after it.
   MachineBasicBlock::iterator I = MBB.end();
   if (I == MBB.begin() || !isUnpredicatedTerminator(--I))
@@ -288,7 +289,8 @@ XCoreInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
       IsBRU(LastInst->getOpcode())) {
     TBB = SecondLastInst->getOperand(0).getMBB();
     I = LastInst;
-    I->eraseFromParent();
+    if (AllowModify)
+      I->eraseFromParent();
     return false;
   }
 

lib/Target/XCore/XCoreInstrInfo.h

@@ -56,7 +56,8 @@ public:
   
   virtual bool AnalyzeBranch(MachineBasicBlock &MBB, MachineBasicBlock *&TBB,
                              MachineBasicBlock *&FBB,
-                             SmallVectorImpl<MachineOperand> &Cond) const;
+                             SmallVectorImpl<MachineOperand> &Cond,
+                             bool AllowModify) const;
   
   virtual unsigned InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
                              MachineBasicBlock *FBB,