1 files changed, 36 insertions, 6 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64BranchRelaxation.cpp b/llvm/lib/Target/AArch64/AArch64BranchRelaxation.cpp
index 9d2577eed95..92130a1107c 100644
--- a/llvm/lib/Target/AArch64/AArch64BranchRelaxation.cpp
+++ b/llvm/lib/Target/AArch64/AArch64BranchRelaxation.cpp
@@ -25,7 +25,7 @@ using namespace llvm;
 #define DEBUG_TYPE "aarch64-branch-relax"
 
 STATISTIC(NumSplit, "Number of basic blocks split");
-STATISTIC(NumRelaxed, "Number of conditional branches relaxed");
+STATISTIC(NumConditionalRelaxed, "Number of conditional branches relaxed");
 
 namespace llvm {
 void initializeAArch64BranchRelaxationPass(PassRegistry &);
@@ -477,13 +477,43 @@ bool AArch64BranchRelaxation::relaxBranchInstructions() {
     if (J == MBB.end())
       continue;
 
-    MachineInstr &MI = *J;
-    if (MI.isConditionalBranch() && !isBlockInRange(MI, *getDestBlock(MI))) {
-      fixupConditionalBranch(MI);
-      ++NumRelaxed;
-      Changed = true;
+    MachineBasicBlock::iterator Next;
+    for (MachineBasicBlock::iterator J = MBB.getFirstTerminator();
+         J != MBB.end(); J = Next) {
+      Next = std::next(J);
+      MachineInstr &MI = *J;
+
+      if (MI.isConditionalBranch()) {
+        MachineBasicBlock *DestBB = getDestBlock(MI);
+        if (!isBlockInRange(MI, *DestBB)) {
+          if (Next != MBB.end() && Next->isConditionalBranch()) {
+            // If there are multiple conditional branches, this isn't an
+            // analyzable block. Split later terminators into a new block so
+            // each one will be analyzable.
+
+            MachineBasicBlock *NewBB = splitBlockBeforeInstr(*Next);
+            NewBB->transferSuccessors(&MBB);
+            MBB.addSuccessor(NewBB);
+            MBB.addSuccessor(DestBB);
+
+            // Cleanup potential unconditional branch to successor block.
+            NewBB->updateTerminator();
+            MBB.updateTerminator();
+          } else {
+            fixupConditionalBranch(MI);
+            ++NumConditionalRelaxed;
+          }
+
+          Changed = true;
+
+          // This may have modified all of the terminators, so start over.
+          Next = MBB.getFirstTerminator();
+        }
+
+      }
     }
   }
+
   return Changed;
 }