[llvm] r270773 - [MBB] Early exit to reduce indentation, per coding guidelines. NFC.

[Chad Rosier via llvm-commits]

Author: mcrosier
Date: Wed May 25 16:53:46 2016
New Revision: 270773

URL: http://llvm.org/viewvc/llvm-project?rev=270773&view=rev
Log:
[MBB] Early exit to reduce indentation, per coding guidelines. NFC.

Modified:
    llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp

Modified: llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp?rev=270773&r1=270772&r2=270773&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp (original)
+++ llvm/trunk/lib/CodeGen/MachineBasicBlock.cpp Wed May 25 16:53:46 2016
@@ -404,7 +404,8 @@ void MachineBasicBlock::moveAfter(Machin
 void MachineBasicBlock::updateTerminator() {
   const TargetInstrInfo *TII = getParent()->getSubtarget().getInstrInfo();
   // A block with no successors has no concerns with fall-through edges.
-  if (this->succ_empty()) return;
+  if (this->succ_empty())
+    return;
 
   MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
   SmallVector<MachineOperand, 4> Cond;
@@ -414,14 +415,14 @@ void MachineBasicBlock::updateTerminator
   assert(!B && "UpdateTerminators requires analyzable predecessors!");
   if (Cond.empty()) {
     if (TBB) {
-      // The block has an unconditional branch. If its successor is now
-      // its layout successor, delete the branch.
+      // The block has an unconditional branch. If its successor is now its
+      // layout successor, delete the branch.
       if (isLayoutSuccessor(TBB))
         TII->RemoveBranch(*this);
     } else {
-      // The block has an unconditional fallthrough. If its successor is not
-      // its layout successor, insert a branch. First we have to locate the
-      // only non-landing-pad successor, as that is the fallthrough block.
+      // The block has an unconditional fallthrough. If its successor is not its
+      // layout successor, insert a branch. First we have to locate the only
+      // non-landing-pad successor, as that is the fallthrough block.
       for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
         if ((*SI)->isEHPad())
           continue;
@@ -429,8 +430,8 @@ void MachineBasicBlock::updateTerminator
         TBB = *SI;
       }
 
-      // If there is no non-landing-pad successor, the block has no
-      // fall-through edges to be concerned with.
+      // If there is no non-landing-pad successor, the block has no fall-through
+      // edges to be concerned with.
       if (!TBB)
         return;
 
@@ -439,61 +440,63 @@ void MachineBasicBlock::updateTerminator
       if (!isLayoutSuccessor(TBB))
         TII->InsertBranch(*this, TBB, nullptr, Cond, DL);
     }
-  } else {
-    if (FBB) {
-      // The block has a non-fallthrough conditional branch. If one of its
-      // successors is its layout successor, rewrite it to a fallthrough
-      // conditional branch.
-      if (isLayoutSuccessor(TBB)) {
-        if (TII->ReverseBranchCondition(Cond))
-          return;
-        TII->RemoveBranch(*this);
-        TII->InsertBranch(*this, FBB, nullptr, Cond, DL);
-      } else if (isLayoutSuccessor(FBB)) {
-        TII->RemoveBranch(*this);
-        TII->InsertBranch(*this, TBB, nullptr, Cond, DL);
-      }
-    } else {
-      // Walk through the successors and find the successor which is not
-      // a landing pad and is not the conditional branch destination (in TBB)
-      // as the fallthrough successor.
-      MachineBasicBlock *FallthroughBB = nullptr;
-      for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
-        if ((*SI)->isEHPad() || *SI == TBB)
-          continue;
-        assert(!FallthroughBB && "Found more than one fallthrough successor.");
-        FallthroughBB = *SI;
-      }
-      if (!FallthroughBB && canFallThrough()) {
-        // We fallthrough to the same basic block as the conditional jump
-        // targets. Remove the conditional jump, leaving unconditional
-        // fallthrough.
-        // FIXME: This does not seem like a reasonable pattern to support, but
-        // it has been seen in the wild coming out of degenerate ARM test cases.
-        TII->RemoveBranch(*this);
+    return;
+  }
 
-        // Finally update the unconditional successor to be reached via a branch
-        // if it would not be reached by fallthrough.
-        if (!isLayoutSuccessor(TBB))
-          TII->InsertBranch(*this, TBB, nullptr, Cond, DL);
+  if (FBB) {
+    // The block has a non-fallthrough conditional branch. If one of its
+    // successors is its layout successor, rewrite it to a fallthrough
+    // conditional branch.
+    if (isLayoutSuccessor(TBB)) {
+      if (TII->ReverseBranchCondition(Cond))
         return;
-      }
+      TII->RemoveBranch(*this);
+      TII->InsertBranch(*this, FBB, nullptr, Cond, DL);
+    } else if (isLayoutSuccessor(FBB)) {
+      TII->RemoveBranch(*this);
+      TII->InsertBranch(*this, TBB, nullptr, Cond, DL);
+    }
+    return;
+  }
 
-      // The block has a fallthrough conditional branch.
-      if (isLayoutSuccessor(TBB)) {
-        if (TII->ReverseBranchCondition(Cond)) {
-          // We can't reverse the condition, add an unconditional branch.
-          Cond.clear();
-          TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, DL);
-          return;
-        }
-        TII->RemoveBranch(*this);
-        TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, DL);
-      } else if (!isLayoutSuccessor(FallthroughBB)) {
-        TII->RemoveBranch(*this);
-        TII->InsertBranch(*this, TBB, FallthroughBB, Cond, DL);
-      }
+  // Walk through the successors and find the successor which is not a landing
+  // pad and is not the conditional branch destination (in TBB) as the
+  // fallthrough successor.
+  MachineBasicBlock *FallthroughBB = nullptr;
+  for (succ_iterator SI = succ_begin(), SE = succ_end(); SI != SE; ++SI) {
+    if ((*SI)->isEHPad() || *SI == TBB)
+      continue;
+    assert(!FallthroughBB && "Found more than one fallthrough successor.");
+    FallthroughBB = *SI;
+  }
+
+  if (!FallthroughBB && canFallThrough()) {
+    // We fallthrough to the same basic block as the conditional jump targets.
+    // Remove the conditional jump, leaving unconditional fallthrough.
+    // FIXME: This does not seem like a reasonable pattern to support, but it
+    // has been seen in the wild coming out of degenerate ARM test cases.
+    TII->RemoveBranch(*this);
+
+    // Finally update the unconditional successor to be reached via a branch if
+    // it would not be reached by fallthrough.
+    if (!isLayoutSuccessor(TBB))
+      TII->InsertBranch(*this, TBB, nullptr, Cond, DL);
+    return;
+  }
+
+  // The block has a fallthrough conditional branch.
+  if (isLayoutSuccessor(TBB)) {
+    if (TII->ReverseBranchCondition(Cond)) {
+      // We can't reverse the condition, add an unconditional branch.
+      Cond.clear();
+      TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, DL);
+      return;
     }
+    TII->RemoveBranch(*this);
+    TII->InsertBranch(*this, FallthroughBB, nullptr, Cond, DL);
+  } else if (!isLayoutSuccessor(FallthroughBB)) {
+    TII->RemoveBranch(*this);
+    TII->InsertBranch(*this, TBB, FallthroughBB, Cond, DL);
   }
 }