[LV] Vectorization remark for outerloop

[ABataev]

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

1049

1. Make it static?
2. Add doxygen description.

[nikolaypanchenko]

Addressed comments

[ABataev]

LG with a nit

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

1050

prepend

[fhahn]

LGTM as well, thanks for splitting this off!

[nikolaypanchenko]

fixed typo

[fhahn]

LGTM with inline comments, thanks!

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

1049

nit: In case an outer loop is vectorized, + period at end of sentence. But it would also be OK to remove the last sentence IMO.

1060

here it will use outerloop whereas above it will use outer loop. It would be good to use outer loop in both cases.

[nikolaypanchenko]

Addressed comments

[nikolaypanchenko]

@fhahn please take a look again if it's good right now

[fhahn]

LGTM, thanks!

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

void reportVectorizationInfo(const StringRef Msg, const StringRef ORETag,
                              Instruction *I) {
   LLVM_DEBUG(debugVectorizationMessage("", Msg, I));
   LoopVectorizeHints Hints(TheLoop, true /* doesn't matter */, *ORE);
   ORE->emit(
       createLVAnalysis(Hints.vectorizeAnalysisPassName(), ORETag, TheLoop, I)
       << Msg);
 }
 
+/// Report successful vectorization of the loop. In case an outer loop is
+/// vectorized, prepend "outer" to the vectorization remark.
+static void reportVectorization(OptimizationRemarkEmitter *ORE, Loop *TheLoop,
+                                VectorizationFactor VF, unsigned IC) {
+  LLVM_DEBUG(debugVectorizationMessage(
+      "Vectorizing: ", TheLoop->isInnermost() ? "innermost loop" : "outer loop",
+      nullptr));
+  StringRef LoopType = TheLoop->isInnermost() ? "" : "outer ";
+  ORE->emit([&]() {
+    return OptimizationRemark(LV_NAME, "Vectorized", TheLoop->getStartLoc(),
+                              TheLoop->getHeader())
+           << "vectorized " << LoopType << "loop (vectorization width: "
+           << ore::NV("VectorizationFactor", VF.Width)
+           << ", interleaved count: " << ore::NV("InterleaveCount", IC) << ")";
+  });
+}
+
 } // end namespace llvm
 
 #ifndef NDEBUG
 /// \return string containing a file name and a line # for the given loop.
 static std::string getDebugLocString(const Loop *L) {
   std::string Result;
   if (L) {
     raw_string_ostream OS(Result);
GeneratedRTChecks Checks(*PSE.getSE(), DT, LI, TTI,
                              F->getParent()->getDataLayout());
     InnerLoopVectorizer LB(L, PSE, LI, DT, TLI, TTI, AC, ORE, VF.Width,
                            VF.Width, 1, LVL, &CM, BFI, PSI, Checks);
     LLVM_DEBUG(dbgs() << "Vectorizing outer loop in \""
                       << L->getHeader()->getParent()->getName() << "\"\n");
     LVP.executePlan(VF.Width, 1, BestPlan, LB, DT, false);
   }
 
+  reportVectorization(ORE, L, VF, 1);
+
   // Mark the loop as already vectorized to avoid vectorizing again.
   Hints.setAlreadyVectorized();
   assert(!verifyFunction(*L->getHeader()->getParent(), &dbgs()));
   return true;
 }
 
 // Emit a remark if there are stores to floats that required a floating point
 // extension. If the vectorized loop was generated with floating point there
if (!VectorizeLoop) {
 
         // Add metadata to disable runtime unrolling a scalar loop when there
         // are no runtime checks about strides and memory. A scalar loop that is
         // rarely used is not worth unrolling.
         if (!LB.areSafetyChecksAdded())
           DisableRuntimeUnroll = true;
       }
       // Report the vectorization decision.
-      ORE->emit([&]() {
-        return OptimizationRemark(LV_NAME, "Vectorized", L->getStartLoc(),
-                                  L->getHeader())
-               << "vectorized loop (vectorization width: "
-               << NV("VectorizationFactor", VF.Width)
-               << ", interleaved count: " << NV("InterleaveCount", IC) << ")";
-      });
+      reportVectorization(ORE, L, VF, IC);
     }
 
     if (ORE->allowExtraAnalysis(LV_NAME))
       checkMixedPrecision(L, ORE);
   }
 
   std::optional<MDNode *> RemainderLoopID =
       makeFollowupLoopID(OrigLoopID, {LLVMLoopVectorizeFollowupAll,

llvm/test/Transforms/LoopVectorize/vplan-printing-outer-loop.ll

 ; REQUIRES: asserts
 
-; RUN: opt -passes=loop-vectorize -enable-vplan-native-path -debug -disable-output %s 2>&1 | FileCheck %s
+; RUN: opt -passes=loop-vectorize -pass-remarks=loop-vectorize -enable-vplan-native-path -debug -disable-output %s 2>&1 | FileCheck %s
 
 @arr2 = external global [8 x i64], align 16
 @arr = external global [8 x [8 x i64]], align 16
 
 define void @foo(i64 %n) {
 ; CHECK:      VPlan 'HCFGBuilder: Plain CFG
 ; CHECK-NEXT: {
 ; CHECK-NEXT: ir<8> = original trip-count
outer.latch:
   %outer.iv.next = add nuw nsw i64 %outer.iv, 1
   %outer.ec = icmp eq i64 %outer.iv.next, 8
   br i1 %outer.ec, label %exit, label %outer.header, !llvm.loop !1
 
 exit:
   ret void
 }
 
+; CHECK: remark: <unknown>:0:0: vectorized outer loop (vectorization width: 4, interleaved count: 1)
+
 !1 = distinct !{!1, !2, !3}
 !2 = !{!"llvm.loop.vectorize.width", i32 4}
 !3 = !{!"llvm.loop.vectorize.enable", i1 true}