1 files changed, 18 insertions, 9 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 0aee92da0f8..6c417ba340f 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -1137,7 +1137,7 @@ private:
 /// for example 'force', means a decision has been made. So, we need to be
 /// careful NOT to add them if the user hasn't specifically asked so.
 class LoopVectorizeHints {
-  enum HintKind { HK_WIDTH, HK_UNROLL, HK_FORCE };
+  enum HintKind { HK_WIDTH, HK_UNROLL, HK_FORCE, HK_ISVECTORIZED };
 
   /// Hint - associates name and validation with the hint value.
   struct Hint {
@@ -1156,6 +1156,8 @@ class LoopVectorizeHints {
         return isPowerOf2_32(Val) && Val <= MaxInterleaveFactor;
       case HK_FORCE:
         return (Val <= 1);
+      case HK_ISVECTORIZED:
+        return (Val==0 || Val==1);
       }
       return false;
     }
@@ -1168,6 +1170,8 @@ class LoopVectorizeHints {
   /// Vectorization forced
   Hint Force;
 
+  /// Already Vectorized
+  Hint IsVectorized;
   /// Return the loop metadata prefix.
   static StringRef Prefix() { return "llvm.loop."; }
 
@@ -1187,6 +1191,7 @@ public:
               HK_WIDTH),
         Interleave("interleave.count", DisableInterleaving, HK_UNROLL),
         Force("vectorize.enable", FK_Undefined, HK_FORCE),
+        IsVectorized("isvectorized", 0, HK_ISVECTORIZED),
         PotentiallyUnsafe(false), TheLoop(L), ORE(ORE) {
     // Populate values with existing loop metadata.
     getHintsFromMetadata();
@@ -1195,14 +1200,19 @@ public:
     if (VectorizerParams::isInterleaveForced())
       Interleave.Value = VectorizerParams::VectorizationInterleave;
 
+    if (IsVectorized.Value != 1)
+      // If the vectorization width and interleaving count are both 1 then
+      // consider the loop to have been already vectorized because there's
+      // nothing more that we can do.
+      IsVectorized.Value = Width.Value == 1 && Interleave.Value == 1;
     DEBUG(if (DisableInterleaving && Interleave.Value == 1) dbgs()
           << "LV: Interleaving disabled by the pass manager\n");
   }
 
   /// Mark the loop L as already vectorized by setting the width to 1.
   void setAlreadyVectorized() {
-    Width.Value = Interleave.Value = 1;
-    Hint Hints[] = {Width, Interleave};
+    IsVectorized.Value = 1;
+    Hint Hints[] = {IsVectorized};
     writeHintsToMetadata(Hints);
   }
 
@@ -1219,9 +1229,7 @@ public:
       return false;
     }
 
-    if (getWidth() == 1 && getInterleave() == 1) {
-      // FIXME: Add a separate metadata to indicate when the loop has already
-      // been vectorized instead of setting width and count to 1.
+    if (getIsVectorized() == 1) {
       DEBUG(dbgs() << "LV: Not vectorizing: Disabled/already vectorized.\n");
       // FIXME: Add interleave.disable metadata. This will allow
       // vectorize.disable to be used without disabling the pass and errors
@@ -1230,8 +1238,8 @@ public:
                                           "AllDisabled", L->getStartLoc(),
                                           L->getHeader())
                << "loop not vectorized: vectorization and interleaving are "
-                  "explicitly disabled, or vectorize width and interleave "
-                  "count are both set to 1");
+                  "explicitly disabled, or the loop has already been "
+                  "vectorized");
       return false;
     }
 
@@ -1264,6 +1272,7 @@ public:
 
   unsigned getWidth() const { return Width.Value; }
   unsigned getInterleave() const { return Interleave.Value; }
+  unsigned getIsVectorized() const { return IsVectorized.Value; }
   enum ForceKind getForce() const { return (ForceKind)Force.Value; }
 
   /// \brief If hints are provided that force vectorization, use the AlwaysPrint
@@ -1347,7 +1356,7 @@ private:
       return;
     unsigned Val = C->getZExtValue();
 
-    Hint *Hints[] = {&Width, &Interleave, &Force};
+    Hint *Hints[] = {&Width, &Interleave, &Force, &IsVectorized};
     for (auto H : Hints) {
       if (Name == H->Name) {
         if (H->validate(Val))