[llvm] ce24524 - [Test] Add test for unreachable backedge with duplicating predecessors

[Max Kazantsev via llvm-commits]

Author: Max Kazantsev
Date: 2021-05-25T12:43:31+07:00
New Revision: ce245246043d3c4f12515b2c773ed6c9174345b5

URL: https://github.com/llvm/llvm-project/commit/ce245246043d3c4f12515b2c773ed6c9174345b5
DIFF: https://github.com/llvm/llvm-project/commit/ce245246043d3c4f12515b2c773ed6c9174345b5.diff

LOG: [Test] Add test for unreachable backedge with duplicating predecessors

Added: 
    

Modified: 
    llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll

Removed: 
    


################################################################################
diff  --git a/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll b/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
index b42f7f4359e86..1cb98be580cd1 100644
--- a/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
+++ b/llvm/test/Transforms/LoopDeletion/eval_first_iteration.ll
@@ -271,3 +271,69 @@ done:                                             ; preds = %backedge
 failure:
   unreachable
 }
+
+; TODO: We can break the backedge here.
+define i32 @test_multiple_pred(i32 %limit) {
+; CHECK-LABEL: @test_multiple_pred(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[LOOP_GUARD:%.*]] = icmp sgt i32 [[LIMIT:%.*]], 0
+; CHECK-NEXT:    br i1 [[LOOP_GUARD]], label [[LOOP_PREHEADER:%.*]], label [[FAILURE:%.*]]
+; CHECK:       loop.preheader:
+; CHECK-NEXT:    br label [[LOOP:%.*]]
+; CHECK:       loop:
+; CHECK-NEXT:    [[SUM:%.*]] = phi i32 [ [[SUM_NEXT:%.*]], [[BACKEDGE:%.*]] ], [ 0, [[LOOP_PREHEADER]] ]
+; CHECK-NEXT:    [[SUB:%.*]] = sub i32 [[LIMIT]], [[SUM]]
+; CHECK-NEXT:    [[IS_POSITIVE:%.*]] = icmp sgt i32 [[SUB]], 0
+; CHECK-NEXT:    br i1 [[IS_POSITIVE]], label [[IF_TRUE:%.*]], label [[IF_FALSE:%.*]]
+; CHECK:       if.true:
+; CHECK-NEXT:    switch i32 [[LIMIT]], label [[FAILURE_LOOPEXIT:%.*]] [
+; CHECK-NEXT:    i32 100, label [[BACKEDGE]]
+; CHECK-NEXT:    i32 200, label [[BACKEDGE]]
+; CHECK-NEXT:    ]
+; CHECK:       if.false:
+; CHECK-NEXT:    br label [[BACKEDGE]]
+; CHECK:       backedge:
+; CHECK-NEXT:    [[MERGE_PHI:%.*]] = phi i32 [ 0, [[IF_FALSE]] ], [ [[SUB]], [[IF_TRUE]] ], [ [[SUB]], [[IF_TRUE]] ]
+; CHECK-NEXT:    [[SUM_NEXT]] = add i32 [[SUM]], [[MERGE_PHI]]
+; CHECK-NEXT:    [[LOOP_COND:%.*]] = icmp ne i32 [[SUM_NEXT]], [[LIMIT]]
+; CHECK-NEXT:    br i1 [[LOOP_COND]], label [[LOOP]], label [[DONE:%.*]]
+; CHECK:       done:
+; CHECK-NEXT:    [[SUM_NEXT_LCSSA:%.*]] = phi i32 [ [[SUM_NEXT]], [[BACKEDGE]] ]
+; CHECK-NEXT:    ret i32 [[SUM_NEXT_LCSSA]]
+; CHECK:       failure.loopexit:
+; CHECK-NEXT:    br label [[FAILURE]]
+; CHECK:       failure:
+; CHECK-NEXT:    unreachable
+;
+entry:
+  %loop_guard = icmp sgt i32 %limit, 0
+  br i1 %loop_guard, label %loop, label %failure
+
+loop:                                             ; preds = %backedge, %entry
+  %sum = phi i32 [ 0, %entry ], [ %sum.next, %backedge ]
+  %sub = sub i32 %limit, %sum
+  %is.positive = icmp sgt i32 %sub, 0
+  br i1 %is.positive, label %if.true, label %if.false
+
+if.true:
+  switch i32 %limit, label %failure [
+  i32 100, label %backedge
+  i32 200, label %backedge
+  ]
+
+if.false:                                         ; preds = %loop
+  br label %backedge
+
+backedge:
+  %merge.phi = phi i32 [ 0, %if.false ], [ %sub, %if.true ], [ %sub, %if.true ]
+  %sum.next = add i32 %sum, %merge.phi
+  %loop.cond = icmp ne i32 %sum.next, %limit
+  br i1 %loop.cond, label %loop, label %done
+
+done:                                             ; preds = %backedge
+  %sum.next.lcssa = phi i32 [ %sum.next, %backedge ]
+  ret i32 %sum.next.lcssa
+
+failure:
+  unreachable
+}