Replace all weight-based interfaces in MBB with probability-based interfaces, and update all uses of old interfaces.

The patch in http://reviews.llvm.org/D13745 is broken into four parts:

1. New interfaces without functional changes (http://reviews.llvm.org/D13908).
2. Use new interfaces in SelectionDAG, while in other passes treat probabilities
as weights (http://reviews.llvm.org/D14361).
3. Use new interfaces in all other passes.
4. Remove old interfaces.

This patch is 3+4 above. In this patch, MBB won't provide weight-based
interfaces any more, which are totally replaced by probability-based ones.
The interface addSuccessor() is redesigned so that the default probability is
unknown. We allow unknown probabilities but don't allow using it together
with known probabilities in successor list. That is to say, we either have a
list of successors with all known probabilities, or all unknown
probabilities. In the latter case, we assume each successor has 1/N
probability where N is the number of successors. An assertion checks if the
user is attempting to add a successor with the disallowed mixed use as stated
above. This can help us catch many misuses.

All uses of weight-based interfaces are now updated to use probability-based
ones.


Differential revision: http://reviews.llvm.org/D14973

llvm-svn: 254348

5 files changed, 7 insertions, 13 deletions

diff --git a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
index f1b38301790..cdbd1209215 100644
--- a/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDILCFGStructurizer.cpp
@@ -1570,8 +1570,7 @@ void AMDGPUCFGStructurizer::mergeLooplandBlock(MachineBasicBlock *DstBlk,
 
   insertInstrBefore(DstBlk, AMDGPU::WHILELOOP, DebugLoc());
   insertInstrEnd(DstBlk, AMDGPU::ENDLOOP, DebugLoc());
-  DstBlk->addSuccessor(LandMBB);
-  DstBlk->removeSuccessor(DstBlk);
+  DstBlk->replaceSuccessor(DstBlk, LandMBB);
 }
 
 
@@ -1666,8 +1665,7 @@ AMDGPUCFGStructurizer::cloneBlockForPredecessor(MachineBasicBlock *MBB,
   replaceInstrUseOfBlockWith(PredMBB, MBB, CloneMBB);
   //srcBlk, oldBlk, newBlk
 
-  PredMBB->removeSuccessor(MBB);
-  PredMBB->addSuccessor(CloneMBB);
+  PredMBB->replaceSuccessor(MBB, CloneMBB);
 
   // add all successor to cloneBlk
   cloneSuccessorList(CloneMBB, MBB);
diff --git a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
index 0bf2d374df6..e89757c19ec 100644
--- a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
+++ b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp
@@ -2274,8 +2274,7 @@ adjustJTTargetBlockForward(MachineBasicBlock *BB, MachineBasicBlock *JTBB) {
 
   // Update the CFG.
   NewBB->addSuccessor(BB);
-  JTBB->removeSuccessor(BB);
-  JTBB->addSuccessor(NewBB);
+  JTBB->replaceSuccessor(BB, NewBB);
 
   ++NumJTInserted;
   return NewBB;
diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
index 0cc41812d71..e8f3ab65bdb 100644
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -7346,7 +7346,7 @@ void ARMTargetLowering::EmitSjLjDispatchBlock(MachineInstr *MI,
       }
     }
 
-    BB->addSuccessor(DispatchBB);
+    BB->addSuccessor(DispatchBB, BranchProbability::getZero());
 
     // Find the invoke call and mark all of the callee-saved registers as
     // 'implicit defined' so that they're spilled. This prevents code from
diff --git a/llvm/lib/Target/Hexagon/HexagonCFGOptimizer.cpp b/llvm/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
index 96bb6175080..efafdd00728 100644
--- a/llvm/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonCFGOptimizer.cpp
@@ -186,13 +186,11 @@ bool HexagonCFGOptimizer::runOnMachineFunction(MachineFunction &Fn) {
 
             if (case1 || case2) {
               InvertAndChangeJumpTarget(MI, UncondTarget);
-              MBB->removeSuccessor(JumpAroundTarget);
-              MBB->addSuccessor(UncondTarget);
+              MBB->replaceSuccessor(JumpAroundTarget, UncondTarget);
 
               // Remove the unconditional branch in LayoutSucc.
               LayoutSucc->erase(LayoutSucc->begin());
-              LayoutSucc->removeSuccessor(UncondTarget);
-              LayoutSucc->addSuccessor(JumpAroundTarget);
+              LayoutSucc->replaceSuccessor(UncondTarget, JumpAroundTarget);
 
               // This code performs the conversion for case 2, which moves
               // the block to the fall-thru case (BB3 in the code above).
diff --git a/llvm/lib/Target/Mips/MipsLongBranch.cpp b/llvm/lib/Target/Mips/MipsLongBranch.cpp
index d09843ed0e5..e75858a181e 100644
--- a/llvm/lib/Target/Mips/MipsLongBranch.cpp
+++ b/llvm/lib/Target/Mips/MipsLongBranch.cpp
@@ -262,8 +262,7 @@ void MipsLongBranch::expandToLongBranch(MBBInfo &I) {
       static_cast<const MipsInstrInfo *>(Subtarget.getInstrInfo());
 
   MF->insert(FallThroughMBB, LongBrMBB);
-  MBB->removeSuccessor(TgtMBB);
-  MBB->addSuccessor(LongBrMBB);
+  MBB->replaceSuccessor(TgtMBB, LongBrMBB);
 
   if (IsPIC) {
     MachineBasicBlock *BalTgtMBB = MF->CreateMachineBasicBlock(BB);