Reduce indentation by early detection of 'continue'. No functionality change.

llvm-svn: 157348

diff --git a/llvm/lib/CodeGen/BranchFolding.cpp b/llvm/lib/CodeGen/BranchFolding.cpp
index c7f2d64..dc786a2 100644 (file)
--- a/llvm/lib/CodeGen/BranchFolding.cpp
+++ b/llvm/lib/CodeGen/BranchFolding.cpp
@@ -819,10 +819,8 @@ bool BranchFolder::TryTailMergeBlocks(MachineBasicBlock *SuccBB,
 }
 
 bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
-
-  if (!EnableTailMerge) return false;
-
   bool MadeChange = false;
+  if (!EnableTailMerge) return MadeChange;
 
   // First find blocks with no successors.
   MergePotentials.clear();
@@ -839,6 +837,7 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
   if (MergePotentials.size() == TailMergeThreshold)
     for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
       TriedMerging.insert(MergePotentials[i].getBlock());
+
   // See if we can do any tail merging on those.
   if (MergePotentials.size() >= 2)
     MadeChange |= TryTailMergeBlocks(NULL, NULL);
@@ -864,88 +863,97 @@ bool BranchFolder::TailMergeBlocks(MachineFunction &MF) {
 
   for (MachineFunction::iterator I = llvm::next(MF.begin()), E = MF.end();
        I != E; ++I) {
-    if (I->pred_size() >= 2) {
-      SmallPtrSet<MachineBasicBlock *, 8> UniquePreds;
-      MachineBasicBlock *IBB = I;
-      MachineBasicBlock *PredBB = prior(I);
-      MergePotentials.clear();
-      for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
-                                            E2 = I->pred_end();
-           P != E2 && MergePotentials.size() < TailMergeThreshold; ++P) {
-        MachineBasicBlock *PBB = *P;
-        if (TriedMerging.count(PBB))
-          continue;
-        // Skip blocks that loop to themselves, can't tail merge these.
-        if (PBB == IBB)
-          continue;
-        // Visit each predecessor only once.
-        if (!UniquePreds.insert(PBB))
-          continue;
-        // Skip blocks which may jump to a landing pad. Can't tail merge these.
-        if (PBB->getLandingPadSuccessor())
-          continue;
-        MachineBasicBlock *TBB = 0, *FBB = 0;
-        SmallVector<MachineOperand, 4> 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);
-          if (!Cond.empty() && TBB == IBB) {
-            if (TII->ReverseBranchCondition(NewCond))
+    if (I->pred_size() >= 2) continue;
+    SmallPtrSet<MachineBasicBlock *, 8> UniquePreds;
+    MachineBasicBlock *IBB = I;
+    MachineBasicBlock *PredBB = prior(I);
+    MergePotentials.clear();
+    for (MachineBasicBlock::pred_iterator P = I->pred_begin(),
+           E2 = I->pred_end();
+         P != E2 && MergePotentials.size() < TailMergeThreshold; ++P) {
+      MachineBasicBlock *PBB = *P;
+      if (TriedMerging.count(PBB))
+        continue;
+
+      // Skip blocks that loop to themselves, can't tail merge these.
+      if (PBB == IBB)
+        continue;
+
+      // Visit each predecessor only once.
+      if (!UniquePreds.insert(PBB))
+        continue;
+
+      // Skip blocks which may jump to a landing pad. Can't tail merge these.
+      if (PBB->getLandingPadSuccessor())
+        continue;
+
+      MachineBasicBlock *TBB = 0, *FBB = 0;
+      SmallVector<MachineOperand, 4> 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);
+        if (!Cond.empty() && TBB == IBB) {
+          if (TII->ReverseBranchCondition(NewCond))
+            continue;
+          // This is the QBB case described above
+          if (!FBB)
+            FBB = llvm::next(MachineFunction::iterator(PBB));
+        }
+
+        // Failing case: the only way IBB can be reached from PBB is via
+        // exception handling.  Happens for landing pads.  Would be nice to have
+        // a bit in the edge so we didn't have to do all this.
+        if (IBB->isLandingPad()) {
+          MachineFunction::iterator IP = PBB;  IP++;
+          MachineBasicBlock *PredNextBB = NULL;
+          if (IP != MF.end())
+            PredNextBB = IP;
+          if (TBB == NULL) {
+            if (IBB != PredNextBB)      // fallthrough
+              continue;
+          } else if (FBB) {
+            if (TBB != IBB && FBB != IBB)   // cbr then ubr
+              continue;
+          } else if (Cond.empty()) {
+            if (TBB != IBB)               // ubr
+              continue;
+          } else {
+            if (TBB != IBB && IBB != PredNextBB)  // cbr
               continue;
-            // This is the QBB case described above
-            if (!FBB)
-              FBB = llvm::next(MachineFunction::iterator(PBB));
-          }
-          // Failing case:  the only way IBB can be reached from PBB is via
-          // exception handling.  Happens for landing pads.  Would be nice
-          // to have a bit in the edge so we didn't have to do all this.
-          if (IBB->isLandingPad()) {
-            MachineFunction::iterator IP = PBB;  IP++;
-            MachineBasicBlock *PredNextBB = NULL;
-            if (IP != MF.end())
-              PredNextBB = IP;
-            if (TBB == NULL) {
-              if (IBB != PredNextBB)      // fallthrough
-                continue;
-            } else if (FBB) {
-              if (TBB != IBB && FBB != IBB)   // cbr then ubr
-                continue;
-            } else if (Cond.empty()) {
-              if (TBB != IBB)               // ubr
-                continue;
-            } else {
-              if (TBB != IBB && IBB != PredNextBB)  // cbr
-                continue;
-            }
-          }
-          // Remove the unconditional branch at the end, if any.
-          if (TBB && (Cond.empty() || FBB)) {
-            DebugLoc dl;  // FIXME: this is nowhere
-            TII->RemoveBranch(*PBB);
-            if (!Cond.empty())
-              // reinsert conditional branch only, for now
-              TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond, dl);
           }
-          MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(PBB), *P));
         }
+
+        // Remove the unconditional branch at the end, if any.
+        if (TBB && (Cond.empty() || FBB)) {
+          DebugLoc dl;  // FIXME: this is nowhere
+          TII->RemoveBranch(*PBB);
+          if (!Cond.empty())
+            // reinsert conditional branch only, for now
+            TII->InsertBranch(*PBB, (TBB == IBB) ? FBB : TBB, 0, NewCond, dl);
+        }
+
+        MergePotentials.push_back(MergePotentialsElt(HashEndOfMBB(PBB), *P));
       }
-      // If this is a large problem, avoid visiting the same basic blocks
-      // multiple times.
-      if (MergePotentials.size() == TailMergeThreshold)
-        for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
-          TriedMerging.insert(MergePotentials[i].getBlock());
-      if (MergePotentials.size() >= 2)
-        MadeChange |= TryTailMergeBlocks(IBB, PredBB);
-      // Reinsert an unconditional branch if needed.
-      // The 1 below can occur as a result of removing blocks in
-      // TryTailMergeBlocks.
-      PredBB = prior(I);     // this may have been changed in TryTailMergeBlocks
-      if (MergePotentials.size() == 1 &&
-          MergePotentials.begin()->getBlock() != PredBB)
-        FixTail(MergePotentials.begin()->getBlock(), IBB, TII);
     }
+
+    // If this is a large problem, avoid visiting the same basic blocks multiple
+    // times.
+    if (MergePotentials.size() == TailMergeThreshold)
+      for (unsigned i = 0, e = MergePotentials.size(); i != e; ++i)
+        TriedMerging.insert(MergePotentials[i].getBlock());
+
+    if (MergePotentials.size() >= 2)
+      MadeChange |= TryTailMergeBlocks(IBB, PredBB);
+
+    // Reinsert an unconditional branch if needed. The 1 below can occur as a
+    // result of removing blocks in TryTailMergeBlocks.
+    PredBB = prior(I);     // this may have been changed in TryTailMergeBlocks
+    if (MergePotentials.size() == 1 &&
+        MergePotentials.begin()->getBlock() != PredBB)
+      FixTail(MergePotentials.begin()->getBlock(), IBB, TII);
   }
+
   return MadeChange;
 }