[PATCH] D63800: [NFC][PowerPC] Improve the for loop in Early Return

[Zhang Kang via Phabricator via llvm-commits]

ZhangKang created this revision.
ZhangKang added reviewers: nemanjai, echristo, steven.zhang, hfinkel, hiraditya, jsji, efriedma.
Herald added a project: LLVM.

In `PPCEarlyReturn.cpp`

  183       for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
  184         MachineBasicBlock &B = *I++;
  185         if (processBlock(B))
  186           Changed = true;
  187       }

Above code can be improve to:

  184       for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E;) {
  185         MachineBasicBlock &B = *I++;
  186         Changed |= processBlock(B);
  187       }


https://reviews.llvm.org/D63800

Files:
  llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp


Index: llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
===================================================================
--- llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
+++ llvm/lib/Target/PowerPC/PPCEarlyReturn.cpp
@@ -179,11 +179,11 @@
       // nothing to do.
       if (MF.size() < 2)
         return Changed;
-
-      for (MachineFunction::iterator I = MF.begin(); I != MF.end();) {
+      
+      // We can't use a range-based for loop due to clobbering the iterator.
+      for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E;) {
         MachineBasicBlock &B = *I++;
-        if (processBlock(B))
-          Changed = true;
+        Changed |= processBlock(B);
       }
 
       return Changed;


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