[PATCH] D135808: [LoopInterchange] Correcting the profitability checking for vectorization

[Ramkrishnan Narayanan Komala via Phabricator via llvm-commits]

ram-NK updated this revision to Diff 469339.
ram-NK marked an inline comment as done.
ram-NK edited the summary of this revision.

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D135808/new/

https://reviews.llvm.org/D135808

Files:
  llvm/lib/Transforms/Scalar/LoopInterchange.cpp


Index: llvm/lib/Transforms/Scalar/LoopInterchange.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/LoopInterchange.cpp
+++ llvm/lib/Transforms/Scalar/LoopInterchange.cpp
@@ -1113,18 +1113,19 @@
 static bool isProfitableForVectorization(unsigned InnerLoopId,
                                          unsigned OuterLoopId,
                                          CharMatrix &DepMatrix) {
-  // TODO: Improve this heuristic to catch more cases.
-  // If the inner loop is loop independent or doesn't carry any dependency it is
-  // profitable to move this to outer position.
   for (auto &Row : DepMatrix) {
-    if (Row[InnerLoopId] != 'S' && Row[InnerLoopId] != 'I')
-      return false;
-    // TODO: We need to improve this heuristic.
+    // If the inner loop is loop independent or doesn't carry any dependency it is
+    // not profitable to move this to outer position, since we are likely able to do
+    // inner loop vectorization already.
+    if (Row[InnerLoopId] == 'I' || Row[InnerLoopId] == '=' )
+     return false;
+    // If the outer loop is not loop independent it is not not profitable to move this
+    // to inner position, since doing so would not enable inner loop parallelism.
     if (Row[OuterLoopId] != '=')
       return false;
   }
-  // If outer loop has dependence and inner loop is loop independent then it is
-  // profitable to interchange to enable parallelism.
+  // If inner loop has dependence and outer loop is loop independent then it is
+  // profitable to interchange to enable inner loop parallelism.
   // If there are no dependences, interchanging will not improve anything.
   return !DepMatrix.empty();
 }


-------------- next part --------------
A non-text attachment was scrubbed...
Name: D135808.469339.patch
Type: text/x-patch
Size: 1711 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20221020/9fc5d58c/attachment.bin>