Mark vector loops as already vectorized

Make sure we mark all loops (scalar and vector) when vectorizing,
so that we don't try to vectorize them anymore. Also, set unroll
to 1, since this is what we check for on early exit.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@193349 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -801,6 +801,7 @@ struct LoopVectorizeHints {
         Vals.push_back(LoopID->getOperand(i));
 
     Vals.push_back(createHint(Context, Twine(Prefix(), "width").str(), Width));
+    Vals.push_back(createHint(Context, Twine(Prefix(), "unroll").str(), 1));
 
     MDNode *NewLoopID = MDNode::get(Context, Vals);
     // Set operand 0 to refer to the loop id itself.
@@ -1785,6 +1786,9 @@ InnerLoopVectorizer::createEmptyLoop(LoopVectorizationLegality *Legal) {
   LoopExitBlock = ExitBlock;
   LoopVectorBody = VecBody;
   LoopScalarBody = OldBasicBlock;
+
+  LoopVectorizeHints Hints(Lp, true);
+  Hints.setAlreadyVectorized(Lp);
 }
 
 /// This function returns the identity element (or neutral element) for

test/Transforms/LoopVectorize/already-vectorized.ll

@@ -0,0 +1,46 @@
+; RUN: opt < %s -debug-only=loop-vectorize -O3 -S 2>&1 | FileCheck %s
+; REQUIRES: asserts
+; We want to make sure that we don't even try to vectorize loops again
+; The vectorizer used to mark the un-vectorized loop only as already vectorized
+; thus, trying to vectorize the vectorized loop again
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@a = external global [255 x i32]
+
+; Function Attrs: nounwind readonly uwtable
+define i32 @vect() {
+; CHECK: LV: Checking a loop in "vect"
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+; We need to make sure we did vectorize the loop
+; CHECK: LV: Found a loop: for.body
+; CHECK: LV: We can vectorize this loop!
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %red.05 = phi i32 [ 0, %entry ], [ %add, %for.body ]
+  %arrayidx = getelementptr inbounds [255 x i32]* @a, i64 0, i64 %indvars.iv
+  %0 = load i32* %arrayidx, align 4
+  %add = add nsw i32 %0, %red.05
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv.next, 255
+  br i1 %exitcond, label %for.end, label %for.body
+
+; If it did, we have two loops:
+; CHECK: vector.body:
+; CHECK: br {{.*}} label %vector.body, !llvm.loop [[vect:![0-9]+]]
+; CHECK: for.body:
+; CHECK: br {{.*}} label %for.body, !llvm.loop [[scalar:![0-9]+]]
+
+for.end:                                          ; preds = %for.body
+  ret i32 %add
+}
+
+; Now, we check for the Hint metadata
+; CHECK: [[vect]] = metadata !{metadata [[vect]], metadata [[width:![0-9]+]], metadata [[unroll:![0-9]+]]}
+; CHECK: [[width]] = metadata !{metadata !"llvm.vectorizer.width", i32 1}
+; CHECK: [[unroll]] = metadata !{metadata !"llvm.vectorizer.unroll", i32 1}
+; CHECK: [[scalar]] = metadata !{metadata [[scalar]], metadata [[width]], metadata [[unroll]]}
+

test/Transforms/LoopVectorize/vectorize-once.ll

@@ -68,9 +68,10 @@ _ZSt10accumulateIPiiET0_T_S2_S1_.exit:            ; preds = %for.body.i, %entry
 
 attributes #0 = { nounwind readonly ssp uwtable "fp-contract-model"="standard" "no-frame-pointer-elim" "no-frame-pointer-elim-non-leaf" "realign-stack" "relocation-model"="pic" "ssp-buffers-size"="8" }
 
-; CHECK: !0 = metadata !{metadata !0, metadata !1}
+; CHECK: !0 = metadata !{metadata !0, metadata !1, metadata !2}
 ; CHECK: !1 = metadata !{metadata !"llvm.vectorizer.width", i32 1}
-; CHECK: !2 = metadata !{metadata !2, metadata !1}
+; CHECK: !2 = metadata !{metadata !"llvm.vectorizer.unroll", i32 1}
+; CHECK: !3 = metadata !{metadata !3, metadata !1, metadata !2}
 
 !0 = metadata !{metadata !0, metadata !1}
 !1 = metadata !{metadata !"llvm.vectorizer.width", i32 1}