[llvm] c066ff1 - [LoopUtils] Updated deleteDeadLoop() to handle loop nest.

[Whitney Tsang via llvm-commits]

Author: Whitney Tsang
Date: 2019-12-17T01:06:14Z
New Revision: c066ff11d84a7797503ad5a44c4129136926dc85

URL: https://github.com/llvm/llvm-project/commit/c066ff11d84a7797503ad5a44c4129136926dc85
DIFF: https://github.com/llvm/llvm-project/commit/c066ff11d84a7797503ad5a44c4129136926dc85.diff

LOG: [LoopUtils] Updated deleteDeadLoop() to handle loop nest.

Reviewer: kariddi, sanjoy, reames, Meinersbur, bmahjour, etiotto,
kbarton
Reviewed By: Meinersbur
Subscribers: mgorny, hiraditya, llvm-commits
Tag: LLVM
Differential Revision: https://reviews.llvm.org/D70939

Added: 
    

Modified: 
    llvm/lib/Transforms/Utils/LoopUtils.cpp
    llvm/unittests/Transforms/Utils/CMakeLists.txt

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index 68ef0fe40714..2340e8c72e10 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -673,7 +673,18 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT = nullptr,
       LI->removeBlock(BB);
 
     // The last step is to update LoopInfo now that we've eliminated this loop.
-    LI->erase(L);
+    // Note: LoopInfo::erase remove the given loop and relink its subloops with
+    // its parent. While removeLoop/removeChildLoop remove the given loop but
+    // not relink its subloops, which is what we want.
+    if (Loop *ParentLoop = L->getParentLoop()) {
+      Loop::iterator I = find(ParentLoop->begin(), ParentLoop->end(), L);
+      assert(I != ParentLoop->end() && "Couldn't find loop");
+      ParentLoop->removeChildLoop(I);
+    } else {
+      Loop::iterator I = find(LI->begin(), LI->end(), L);
+      assert(I != LI->end() && "Couldn't find loop");
+      LI->removeLoop(I);
+    }
   }
 }
 

diff  --git a/llvm/unittests/Transforms/Utils/CMakeLists.txt b/llvm/unittests/Transforms/Utils/CMakeLists.txt
index 5a8204cb86ac..424f09025ea2 100644
--- a/llvm/unittests/Transforms/Utils/CMakeLists.txt
+++ b/llvm/unittests/Transforms/Utils/CMakeLists.txt
@@ -15,6 +15,7 @@ add_llvm_unittest(UtilsTests
   FunctionComparatorTest.cpp
   IntegerDivisionTest.cpp
   LocalTest.cpp
+  LoopUtilsTest.cpp
   SizeOptsTest.cpp
   SSAUpdaterBulkTest.cpp
   UnrollLoopTest.cpp