[llvm] [llvm] Issues found PVS studio static analyzer. LoopUnrollAndJam.cpp (PR #170162)

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llvmbot wrote:


<!--LLVM PR SUMMARY COMMENT-->

@llvm/pr-subscribers-llvm-transforms

Author: Bala_Bhuvan_Varma (Bhuvan1527)

<details>
<summary>Changes</summary>

Minor misoptimization. The PVS-Studio warning: V791 The initial value of the index in the nested loop equals 'I'. Perhaps, 'I + 1' should be used instead. LoopUnrollAndJam.cpp 793

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Full diff: https://github.com/llvm/llvm-project/pull/170162.diff


1 Files Affected:

- (modified) llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp (+1-1) 


``````````diff
diff --git a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
index 1e614bd29ee6e..663e45e89c5da 100644
--- a/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUnrollAndJam.cpp
@@ -789,7 +789,7 @@ checkDependencies(Loop &Root, const BasicBlockSet &SubLoopBlocks,
 
     size_t NumInsts = CurrentLoadsAndStores.size();
     for (size_t I = 0; I < NumInsts; ++I) {
-      for (size_t J = I; J < NumInsts; ++J) {
+      for (size_t J = I + 1; J < NumInsts; ++J) {
         if (!checkDependency(CurrentLoadsAndStores[I], CurrentLoadsAndStores[J],
                              LoopDepth, CurLoopDepth, true, DI))
           return false;

``````````

</details>


https://github.com/llvm/llvm-project/pull/170162