[LV] Improve a test, regen with UTC (#151947)

Author: artagnon

llvm/test/Transforms/LoopVectorize/pr36983-multiple-lcssa.ll

@@ -0,0 +1,53 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --check-globals none --version 5
+; RUN: opt -passes=loop-vectorize -S %s | FileCheck %s
+
+; There could be more than one LCSSA PHIs in loop exit block.
+define i16 @duplicate_lcssa(i16 %val) {
+; CHECK-LABEL: define i16 @duplicate_lcssa(
+; CHECK-SAME: i16 [[VAL:%.*]]) {
+; CHECK-NEXT:  [[ENTRY:.*]]:
+; CHECK-NEXT:    br i1 false, label %[[SCALAR_PH:.*]], label %[[VECTOR_PH:.*]]
+; CHECK:       [[VECTOR_PH]]:
+; CHECK-NEXT:    br label %[[VECTOR_BODY:.*]]
+; CHECK:       [[VECTOR_BODY]]:
+; CHECK-NEXT:    [[INDEX:%.*]] = phi i32 [ 0, %[[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_IND:%.*]] = phi <4 x i16> [ <i16 0, i16 -1, i16 -2, i16 -3>, %[[VECTOR_PH]] ], [ [[VEC_IND_NEXT:%.*]], %[[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[TMP0:%.*]] = sub nsw <4 x i16> [[VEC_IND]], splat (i16 1)
+; CHECK-NEXT:    [[INDEX_NEXT]] = add nuw i32 [[INDEX]], 4
+; CHECK-NEXT:    [[VEC_IND_NEXT]] = add <4 x i16> [[VEC_IND]], splat (i16 -4)
+; CHECK-NEXT:    [[TMP1:%.*]] = icmp eq i32 [[INDEX_NEXT]], 65536
+; CHECK-NEXT:    br i1 [[TMP1]], label %[[MIDDLE_BLOCK:.*]], label %[[VECTOR_BODY]], !llvm.loop [[LOOP0:![0-9]+]]
+; CHECK:       [[MIDDLE_BLOCK]]:
+; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT_FOR_PHI:%.*]] = extractelement <4 x i16> [[TMP0]], i32 2
+; CHECK-NEXT:    [[VECTOR_RECUR_EXTRACT_FOR_PHI1:%.*]] = extractelement <4 x i16> [[TMP0]], i32 2
+; CHECK-NEXT:    br label %[[EXIT:.*]]
+; CHECK:       [[SCALAR_PH]]:
+; CHECK-NEXT:    [[BC_RESUME_VAL:%.*]] = phi i16 [ 0, %[[ENTRY]] ]
+; CHECK-NEXT:    [[SCALAR_RECUR_INIT:%.*]] = phi i16 [ [[VAL]], %[[ENTRY]] ]
+; CHECK-NEXT:    br label %[[LOOP:.*]]
+; CHECK:       [[LOOP]]:
+; CHECK-NEXT:    [[IV:%.*]] = phi i16 [ [[BC_RESUME_VAL]], %[[SCALAR_PH]] ], [ [[IV_NEXT:%.*]], %[[LOOP]] ]
+; CHECK-NEXT:    [[RES:%.*]] = phi i16 [ [[SCALAR_RECUR_INIT]], %[[SCALAR_PH]] ], [ [[IV_NEXT]], %[[LOOP]] ]
+; CHECK-NEXT:    [[IV_NEXT]] = sub nsw i16 [[IV]], 1
+; CHECK-NEXT:    [[EXIT_COND:%.*]] = icmp ne i16 [[IV_NEXT]], 0
+; CHECK-NEXT:    br i1 [[EXIT_COND]], label %[[LOOP]], label %[[EXIT]], !llvm.loop [[LOOP3:![0-9]+]]
+; CHECK:       [[EXIT]]:
+; CHECK-NEXT:    [[LCSSA_1:%.*]] = phi i16 [ [[RES]], %[[LOOP]] ], [ [[VECTOR_RECUR_EXTRACT_FOR_PHI]], %[[MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    [[LCSSA_2:%.*]] = phi i16 [ [[RES]], %[[LOOP]] ], [ [[VECTOR_RECUR_EXTRACT_FOR_PHI1]], %[[MIDDLE_BLOCK]] ]
+; CHECK-NEXT:    ret i16 [[LCSSA_2]]
+;
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i16 [ 0, %entry ], [ %iv.next, %loop ]
+  %res = phi i16 [ %val, %entry ], [ %iv.next, %loop ]
+  %iv.next = sub nsw i16 %iv, 1
+  %exit.cond = icmp ne i16 %iv.next, 0
+  br i1 %exit.cond, label %loop, label %exit
+
+exit:
+  %lcssa.1 = phi i16 [ %res, %loop ]
+  %lcssa.2 = phi i16 [ %res, %loop ]
+  ret i16 %lcssa.2
+}