[SLP][NFC]Add a test for reducing same values, NFC.

llvm/test/Transforms/SLPVectorizer/X86/reduction-same-vals.ll

@@ -0,0 +1,49 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -S -slp-vectorizer < %s | FileCheck %s
+
+define i64 @test() {
+; CHECK-LABEL: @test(
+; CHECK-NEXT:  bb1:
+; CHECK-NEXT:    br label [[BB3:%.*]]
+; CHECK:       bb2:
+; CHECK-NEXT:    br label [[BB3]]
+; CHECK:       bb3:
+; CHECK-NEXT:    [[TMP:%.*]] = phi i32 [ 0, [[BB2:%.*]] ], [ 0, [[BB1:%.*]] ]
+; CHECK-NEXT:    [[TMP4:%.*]] = phi i32 [ 0, [[BB2]] ], [ 0, [[BB1]] ]
+; CHECK-NEXT:    [[TMP5:%.*]] = mul i32 [[TMP]], [[TMP4]]
+; CHECK-NEXT:    [[TMP6:%.*]] = mul i32 [[TMP5]], [[TMP4]]
+; CHECK-NEXT:    [[TMP7:%.*]] = mul i32 [[TMP6]], [[TMP4]]
+; CHECK-NEXT:    [[TMP8:%.*]] = mul i32 [[TMP7]], [[TMP4]]
+; CHECK-NEXT:    [[TMP9:%.*]] = mul i32 [[TMP8]], [[TMP4]]
+; CHECK-NEXT:    [[TMP10:%.*]] = mul i32 [[TMP9]], [[TMP4]]
+; CHECK-NEXT:    [[TMP11:%.*]] = mul i32 [[TMP10]], [[TMP4]]
+; CHECK-NEXT:    [[TMP12:%.*]] = mul i32 [[TMP11]], [[TMP4]]
+; CHECK-NEXT:    [[TMP13:%.*]] = mul i32 [[TMP12]], [[TMP4]]
+; CHECK-NEXT:    [[TMP14:%.*]] = mul i32 [[TMP13]], [[TMP4]]
+; CHECK-NEXT:    [[TMP15:%.*]] = mul i32 [[TMP14]], [[TMP4]]
+; CHECK-NEXT:    [[TMP65:%.*]] = sext i32 [[TMP15]] to i64
+; CHECK-NEXT:    ret i64 [[TMP65]]
+;
+bb1:
+  br label %bb3
+
+bb2:
+  br label %bb3
+
+bb3:
+  %tmp = phi i32 [ 0, %bb2 ], [ 0, %bb1 ]
+  %tmp4 = phi i32 [ 0, %bb2 ], [ 0, %bb1 ]
+  %tmp5 = mul i32 %tmp, %tmp4
+  %tmp6 = mul i32 %tmp5, %tmp4
+  %tmp7 = mul i32 %tmp6, %tmp4
+  %tmp8 = mul i32 %tmp7, %tmp4
+  %tmp9 = mul i32 %tmp8, %tmp4
+  %tmp10 = mul i32 %tmp9, %tmp4
+  %tmp11 = mul i32 %tmp10, %tmp4
+  %tmp12 = mul i32 %tmp11, %tmp4
+  %tmp13 = mul i32 %tmp12, %tmp4
+  %tmp14 = mul i32 %tmp13, %tmp4
+  %tmp15 = mul i32 %tmp14, %tmp4
+  %tmp65 = sext i32 %tmp15 to i64
+  ret i64 %tmp65
+}