[PATCH] D123870: [LoopDeletion] Don't delete loops with blocks that have their address taken

[Arthur Eubanks via Phabricator via llvm-commits]

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Otherwise we may end up making the blockaddress invalid and passing it to other functions.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D123870

Files:
  llvm/lib/Transforms/Scalar/LoopDeletion.cpp
  llvm/test/Transforms/LoopDeletion/blockaddress.ll


Index: llvm/test/Transforms/LoopDeletion/blockaddress.ll
===================================================================
--- llvm/test/Transforms/LoopDeletion/blockaddress.ll
+++ llvm/test/Transforms/LoopDeletion/blockaddress.ll
@@ -6,11 +6,13 @@
 declare void @g(ptr)
 
 ;.
-; CHECK: @[[BA:[a-zA-Z0-9_$"\\.-]+]] = private constant ptr inttoptr (i32 1 to ptr)
+; CHECK: @[[BA:[a-zA-Z0-9_$"\\.-]+]] = private constant ptr blockaddress(@f, [[BB:%.*]])
 ;.
 define void @f() {
 ; CHECK-LABEL: @f(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    br label [[BB:%.*]]
+; CHECK:       bb:
 ; CHECK-NEXT:    br label [[BB2:%.*]]
 ; CHECK:       bb2:
 ; CHECK-NEXT:    call void @g(ptr @ba)
Index: llvm/lib/Transforms/Scalar/LoopDeletion.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopDeletion.cpp
+++ llvm/lib/Transforms/Scalar/LoopDeletion.cpp
@@ -58,6 +58,11 @@
   return LoopDeletionResult::Unmodified;
 }
 
+static bool loopHasAddressTaken(Loop *L) {
+  return any_of(L->blocks(),
+                [](BasicBlock *BB) { return BB->hasAddressTaken(); });
+}
+
 /// Determines if a loop is dead.
 ///
 /// This assumes that we've already checked for unique exit and exiting blocks,
@@ -453,6 +458,11 @@
     return LoopDeletionResult::Unmodified;
   }
 
+  if (loopHasAddressTaken(L)) {
+    LLVM_DEBUG(dbgs() << "Loop has address taken, cannot delete.\n");
+    return LoopDeletionResult::Unmodified;
+  }
+
   BasicBlock *ExitBlock = L->getUniqueExitBlock();
 
   if (ExitBlock && isLoopNeverExecuted(L)) {


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