[LV] Hint at the new loop distribution pragma in optimization remark

When we encounter unsafe memory dependencies, loop distribution could
help.

Even though, the diagnostics is in LAA, it's only currently emitted in
the vectorizer.

llvm-svn: 268987

1 files changed, 6 insertions, 2 deletions

diff --git a/llvm/lib/Analysis/LoopAccessAnalysis.cpp b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
index 6b1c5f22aa3..cb7ee1cb246 100644
--- a/llvm/lib/Analysis/LoopAccessAnalysis.cpp
+++ b/llvm/lib/Analysis/LoopAccessAnalysis.cpp
@@ -1694,8 +1694,12 @@ void LoopAccessInfo::analyzeLoop(const ValueToValueMap &Strides) {
                  << (PtrRtChecking.Need ? "" : " don't")
                  << " need runtime memory checks.\n");
   else {
-    emitAnalysis(LoopAccessReport() <<
-                 "unsafe dependent memory operations in loop");
+    emitAnalysis(
+        LoopAccessReport()
+        << "unsafe dependent memory operations in loop. Use "
+           "#pragma loop distribute(enable) to allow loop distribution "
+           "to attempt to isolate the offending operations into a separate "
+           "loop");
     DEBUG(dbgs() << "LAA: unsafe dependent memory operations in loop\n");
   }
 }