AtomicExpand: Really allow incremental legalization (#108613)

Fix up 100d9b89947bb1d42af20010bb594fa4c02542fc. The iterator
fixes ended up defeating the point, since newly inserted blocks
were not visited. This never erases the current block, so we can
simply not preincrement the block iterator.

The AArch64 FP atomic tests now expand the cmpxchg in the second
round of legalization.

1 files changed, 3 insertions, 10 deletions

diff --git a/llvm/lib/CodeGen/AtomicExpandPass.cpp b/llvm/lib/CodeGen/AtomicExpandPass.cpp
index 3030584..3d4e2cb 100644
--- a/llvm/lib/CodeGen/AtomicExpandPass.cpp
+++ b/llvm/lib/CodeGen/AtomicExpandPass.cpp
@@ -351,9 +351,8 @@ bool AtomicExpandImpl::run(Function &F, const TargetMachine *TM) {
 
   bool MadeChange = false;
 
-  for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE;) {
+  for (Function::iterator BBI = F.begin(), BBE = F.end(); BBI != BBE; ++BBI) {
     BasicBlock *BB = &*BBI;
-    ++BBI;
 
     BasicBlock::reverse_iterator Next;
 
@@ -365,14 +364,8 @@ bool AtomicExpandImpl::run(Function &F, const TargetMachine *TM) {
       if (processAtomicInstr(&Inst)) {
         MadeChange = true;
 
-        // Detect control flow change and resume iteration from the original
-        // block to inspect any newly inserted blocks. This allows incremental
-        // legalization of atomicrmw and cmpxchg.
-        if (Next != E && BB != Next->getParent()) {
-          BBI = BB->getIterator();
-          BBE = F.end();
-          break;
-        }
+        // New blocks may have been inserted.
+        BBE = F.end();
       }
     }
   }