Merge pull request eclipse-omr#7250 from jdmpapin/fix18803

Don't version BNDCHK based on an IV if the loop test is backwards
dsouzai · Feb 9, 2024 · 92e1304 · 92e1304
2 parents ac0dab2 + 2ad3b1c
commit 92e1304
Showing 1 changed file with 15 additions and 0 deletions.
diff --git a/compiler/optimizer/LoopVersioner.cpp b/compiler/optimizer/LoopVersioner.cpp
@@ -7475,6 +7475,8 @@ void TR_LoopVersioner::buildBoundCheckComparisonsTree(
             else
                incrementI = incrementJ;
 
+            bool isIncreasingI = incrementI > 0; // check before taking abs just below
+
             if (incrementI < 0)
                incrementI = -incrementI;
             if (incrementJ < 0)
@@ -7488,6 +7490,19 @@ void TR_LoopVersioner::buildBoundCheckComparisonsTree(
             if (reverseBranch)
                stayInLoopOp = stayInLoopOp.getOpCodeForReverseBranch();
 
+            if (isIncreasingI == stayInLoopOp.isCompareTrueIfGreater())
+               {
+               dumpOptDetails(
+                  comp(),
+                  "Abandon versioning bound check because while condition %s "
+                  "is incompatible with %s loop driving IV\n",
+                  stayInLoopOp.getName(),
+                  isIncreasingI ? "an increasing" : "a decreasing");
+
+               nextTree = nextTree->getNextElement();
+               continue;
+               }
+
             bool strict = !stayInLoopOp.isCompareTrueIfEqual();
             if (strict)
                {