Introduce runtime unrolling disable matadata and use it to mark the scalar loop from vectorization.

Runtime unrolling is an expensive optimization which can bring benefit
only if the loop is hot and iteration number is relatively large enough.
For some loops, we know they are not worth to be runtime unrolled.
The scalar loop from vectorization is one of the cases.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@231631 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 37 insertions, 2 deletions

diff --git a/test/Transforms/LoopUnroll/runtime-loop.ll b/test/Transforms/LoopUnroll/runtime-loop.ll
index 3bec939178a..9e78edfb25e 100644
--- a/test/Transforms/LoopUnroll/runtime-loop.ll
+++ b/test/Transforms/LoopUnroll/runtime-loop.ll
@@ -113,6 +113,39 @@ for.end:                                          ; preds = %for.cond.for.end_cr
   ret i16 %res.0.lcssa
 }
 
+; Test run-time unrolling disable metadata.
+; CHECK: for.body:
+; CHECK-NOT: for.body.prol:
+
+define zeroext i16 @test2(i16* nocapture %p, i32 %len) nounwind uwtable readonly {
+entry:
+  %cmp2 = icmp eq i32 %len, 0
+  br i1 %cmp2, label %for.end, label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %p.addr.05 = phi i16* [ %incdec.ptr, %for.body ], [ %p, %entry ]
+  %len.addr.04 = phi i32 [ %sub, %for.body ], [ %len, %entry ]
+  %res.03 = phi i32 [ %add, %for.body ], [ 0, %entry ]
+  %incdec.ptr = getelementptr inbounds i16, i16* %p.addr.05, i64 1
+  %0 = load i16, i16* %p.addr.05, align 2
+  %conv = zext i16 %0 to i32
+  %add = add i32 %conv, %res.03
+  %sub = add nsw i32 %len.addr.04, -2
+  %cmp = icmp eq i32 %sub, 0
+  br i1 %cmp, label %for.cond.for.end_crit_edge, label %for.body, !llvm.loop !0
+
+for.cond.for.end_crit_edge:                       ; preds = %for.body
+  %phitmp = trunc i32 %add to i16
+  br label %for.end
+
+for.end:                                          ; preds = %for.cond.for.end_crit_edge, %entry
+  %res.0.lcssa = phi i16 [ %phitmp, %for.cond.for.end_crit_edge ], [ 0, %entry ]
+  ret i16 %res.0.lcssa
+}
+
+!0 = distinct !{!0, !1}
+!1 = !{!"llvm.loop.unroll.runtime.disable"}
+
 ; CHECK: !0 = distinct !{!0, !1}
 ; CHECK: !1 = !{!"llvm.loop.unroll.disable"}
 
diff --git a/test/Transforms/LoopVectorize/X86/already-vectorized.ll b/test/Transforms/LoopVectorize/X86/already-vectorized.ll
index 248d6dc90bd..c400c76461b 100644
--- a/test/Transforms/LoopVectorize/X86/already-vectorized.ll
+++ b/test/Transforms/LoopVectorize/X86/already-vectorized.ll
@@ -42,5 +42,6 @@ for.end:                                          ; preds = %for.body
 ; CHECK: [[vect]] = distinct !{[[vect]], [[width:![0-9]+]], [[unroll:![0-9]+]]}
 ; CHECK: [[width]] = !{!"llvm.loop.vectorize.width", i32 1}
 ; CHECK: [[unroll]] = !{!"llvm.loop.interleave.count", i32 1}
-; CHECK: [[scalar]] = distinct !{[[scalar]], [[width]], [[unroll]]}
+; CHECK: [[scalar]] = distinct !{[[scalar]], [[runtime_unroll:![0-9]+]], [[width]], [[unroll]]}
+; CHECK: [[runtime_unroll]] = !{!"llvm.loop.unroll.runtime.disable"}
 
diff --git a/test/Transforms/LoopVectorize/vectorize-once.ll b/test/Transforms/LoopVectorize/vectorize-once.ll
index 5d0e96b2c5a..9a912503996 100644
--- a/test/Transforms/LoopVectorize/vectorize-once.ll
+++ b/test/Transforms/LoopVectorize/vectorize-once.ll
@@ -71,7 +71,8 @@ attributes #0 = { nounwind readonly ssp uwtable "fp-contract-model"="standard" "
 ; CHECK: !0 = distinct !{!0, !1, !2}
 ; CHECK: !1 = !{!"llvm.loop.vectorize.width", i32 1}
 ; CHECK: !2 = !{!"llvm.loop.interleave.count", i32 1}
-; CHECK: !3 = distinct !{!3, !1, !2}
+; CHECK: !3 = distinct !{!3, !4, !1, !2}
+; CHECK: !4 = !{!"llvm.loop.unroll.runtime.disable"}
 
 !0 = !{!0, !1}
 !1 = !{!"llvm.loop.vectorize.width", i32 1}