LoopVectorize: convert TinyTripCountVectorThreshold constant

to a command line switch.

llvm-svn: 173837

2 files changed, 31 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
index 16eb21ef1d5..1b242c93ba1 100644
--- a/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ b/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -101,7 +101,9 @@ EnableIfConversion("enable-if-conversion", cl::init(true), cl::Hidden,
                    cl::desc("Enable if-conversion during vectorization."));
 
 /// We don't vectorize loops with a known constant trip count below this number.
-static const unsigned TinyTripCountVectorThreshold = 16;
+static cl::opt<unsigned>
+TinyTripCountVectorThreshold("vectorizer-min-trip-count", cl::init(16), cl::Hidden,
+                             cl::desc("The minimum trip count in the loops to vectorize."));
 
 /// We don't unroll loops with a known constant trip count below this number.
 static const unsigned TinyTripCountUnrollThreshold = 128;
diff --git a/llvm/test/Transforms/LoopVectorize/min-trip-count-switch.ll b/llvm/test/Transforms/LoopVectorize/min-trip-count-switch.ll
new file mode 100644
index 00000000000..186fba87d65
--- /dev/null
+++ b/llvm/test/Transforms/LoopVectorize/min-trip-count-switch.ll
@@ -0,0 +1,28 @@
+; RUN: opt < %s  -loop-vectorize -force-vector-unroll=1 -vectorizer-min-trip-count=1 -force-vector-width=4 -dce -instcombine -S | FileCheck %s
+
+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"
+
+; CHECK: <4 x float>
+define void @trivial_loop(float* nocapture %a) nounwind uwtable optsize {
+entry:
+  br label %for.body
+
+for.body:                                         ; preds = %for.body, %entry
+  %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+  %arrayidx = getelementptr inbounds float* %a, i64 %indvars.iv
+  %0 = load float* %arrayidx, align 4, !tbaa !0
+  %add = fadd float %0, 1.000000e+00
+  store float %add, float* %arrayidx, align 4, !tbaa !0
+  %indvars.iv.next = add i64 %indvars.iv, 1
+  %lftr.wideiv = trunc i64 %indvars.iv.next to i32
+  %exitcond = icmp eq i32 %lftr.wideiv, 8
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  ret void
+}
+
+!0 = metadata !{metadata !"float", metadata !1}
+!1 = metadata !{metadata !"omnipotent char", metadata !2}
+!2 = metadata !{metadata !"Simple C/C++ TBAA"}