[PATCH] D23073: [LoopVectorize] Change comment for isOutOfScope in collectLoopUniforms, NFC

[Wei Mi via llvm-commits]

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Update comment for isOutOfScope. 
Add a testcase for uniform value being used out of scope.

Repository:
  rL LLVM

https://reviews.llvm.org/D23073

Files:
  lib/Transforms/Vectorize/LoopVectorize.cpp
  test/Transforms/LoopVectorize/X86/uniform-phi.ll

Index: test/Transforms/LoopVectorize/X86/uniform-phi.ll
===================================================================
--- test/Transforms/LoopVectorize/X86/uniform-phi.ll
+++ test/Transforms/LoopVectorize/X86/uniform-phi.ll
@@ -48,3 +48,30 @@
 for.end:
   ret void
 }
+
+; CHECK-LABEL: goo
+; Check %indvars.iv and %indvars.iv.next are uniform instructions even if they are used outside of loop.
+; CHECK-DAG: LV: Found uniform instruction:   %indvars.iv = phi i64 [ 0, %entry ], [ %indvars.iv.next, %for.body ]
+; CHECK-DAG: LV: Found uniform instruction:   %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+; CHECK-DAG: LV: Found uniform instruction:   %exitcond = icmp eq i64 %indvars.iv, 1599
+
+define i64 @goo(float* noalias nocapture %a, float* noalias nocapture readonly %b) #0 {
+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, float* %b, i64 %indvars.iv
+  %tmp0 = load float, float* %arrayidx, align 4
+  %add = fadd float %tmp0, 1.000000e+00
+  %arrayidx5 = getelementptr inbounds float, float* %a, i64 %indvars.iv
+  store float %add, float* %arrayidx5, align 4
+  %indvars.iv.next = add nuw nsw i64 %indvars.iv, 1
+  %exitcond = icmp eq i64 %indvars.iv, 1599
+  br i1 %exitcond, label %for.end, label %for.body
+
+for.end:                                          ; preds = %for.body
+  %retval = add i64 %indvars.iv, %indvars.iv.next
+  ret i64 %retval
+}
+
Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -4946,10 +4946,11 @@
 
 void LoopVectorizationLegality::collectLoopUniforms() {
   // We now know that the loop is vectorizable!
-  // Collect variables that will remain uniform after vectorization.
+  // Collect variables inside the loop that will remain uniform after
+  // vectorization.
 
-  // If V is not an instruction inside the current loop, it is a Value
-  // outside of the scope which we are interesting in.
+  // Global value, param or instruction outside of current loop are out of
+  // scope.
   auto isOutOfScope = [&](Value *V) -> bool {
     Instruction *I = dyn_cast<Instruction>(V);
     return (!I || !TheLoop->contains(I));


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