[LV] Add test showing missing debug location on VPScalarIVStepsRecipe.

Author: fhahn

llvm/test/Transforms/LoopVectorize/debugloc.ll

@@ -171,6 +171,43 @@ exit:
   ret void
 }
 
+define void @test_scalar_steps(ptr nocapture %a, ptr noalias %b, i64 %size) !dbg !39 {
+; CHECK-LABEL: define void @test_scalar_steps(
+; CHECK:       vector.body:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, %vector.ph ], [ [[INDEX_NEXT:%.*]], %vector.body ]
+; CHECK-NEXT:    [[OFFSET_IDX:%.*]] = mul i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP6:%.*]] = add i64 [[OFFSET_IDX]], 0
+; CHECK-NOT:     !dbg
+; CHECK-NEXT:    [[TMP7:%.*]] = add i64 [[OFFSET_IDX]], 2
+; CHECK-NEXT:    [[TMP8:%.*]] = getelementptr inbounds i32, ptr [[A:%.*]], i64 [[TMP6]]
+; CHECK-NEXT:    [[TMP9:%.*]] = getelementptr inbounds i32, ptr [[A]], i64 [[TMP7]]
+; CHECK-NEXT:    [[TMP10:%.*]] = getelementptr inbounds i32, ptr [[B:%.*]], i64 [[TMP6]]
+; CHECK-NEXT:    [[TMP11:%.*]] = getelementptr inbounds i32, ptr [[B]], i64 [[TMP7]]
+; CHECK-NEXT:    [[TMP12:%.*]] = load i32, ptr [[TMP8]], align 4
+; CHECK-NEXT:    [[TMP13:%.*]] = load i32, ptr [[TMP9]], align 4
+; CHECK-NEXT:    store i32 [[TMP12]], ptr [[TMP10]], align 4
+; CHECK-NEXT:    store i32 [[TMP13]], ptr [[TMP11]], align 4
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i64 [[INDEX]], 2
+; CHECK-NEXT:    [[TMP20:%.*]] = icmp eq i64 [[INDEX_NEXT]], %n.vec
+; CHECK-NEXT:    br i1 [[TMP20]], label %middle.block, label %vector.body
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i64 [ 0, %entry ], [ %iv.next, %loop ], !dbg !41
+  %arrayidx.1 = getelementptr inbounds i32, ptr %a, i64 %iv
+  %arrayidx.2 = getelementptr inbounds i32, ptr %b, i64 %iv
+  %l.1 = load i32, ptr %arrayidx.1, align 4
+  store i32 %l.1, ptr %arrayidx.2
+  %iv.next = add i64 %iv, 2
+  %exitcond = icmp ne i64 %iv.next, %size
+  br i1 %exitcond, label %loop, label %exit
+
+exit:
+  ret void
+}
+
 ; CHECK: ![[LOC2]] = !DILocation(line: 3
 ; CHECK: ![[BR_LOC]] = !DILocation(line: 5,
 ; CHECK: ![[LOC1]] = !DILocation(line: 6
@@ -223,3 +260,6 @@ declare void @llvm.dbg.value(metadata, metadata, metadata)
 !36 = distinct !DILexicalBlock(scope: !35, file: !5, line: 137, column: 2)
 !37 = !DILocation(line: 430, column: 44, scope: !36)
 !38 = !DILocation(line: 540, column: 44, scope: !36)
+!39 = distinct !DISubprogram(name: "test_scalar_Steps", line: 3, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: true, unit: !0, scopeLine: 3, file: !5, scope: !6, type: !7, retainedNodes: !12)
+!40 = distinct !DILexicalBlock(scope: !39, file: !5, line: 137, column: 2)
+!41 = !DILocation(line: 650, column: 44, scope: !40)