1 files changed, 74 insertions, 0 deletions
diff --git a/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll b/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll
new file mode 100644
index 00000000000..7b6e91a742b
--- /dev/null
+++ b/llvm/test/Transforms/IndVarSimplify/exit_value_test2.ll
@@ -0,0 +1,74 @@
+; PR23538
+; RUN: opt < %s -indvars -loop-deletion -S | FileCheck %s
+
+; Check IndVarSimplify should not replace exit value because or else
+; udiv will be introduced by expand and the cost will be high.
+
+declare void @_Z3mixRjj(i32* dereferenceable(4), i32)
+declare void @llvm.lifetime.start.p0i8(i64, i8* nocapture)
+declare void @llvm.lifetime.end.p0i8(i64, i8* nocapture)
+
+define i32 @_Z3fooPKcjj(i8* nocapture readonly %s, i32 %len, i32 %c) {
+; CHECK-LABEL: @_Z3fooPKcjj(
+; CHECK-NOT: udiv
+entry:
+  %a = alloca i32, align 4
+  %tmp = bitcast i32* %a to i8*
+  call void @llvm.lifetime.start.p0i8(i64 4, i8* %tmp)
+  store i32 -1640531527, i32* %a, align 4
+  %cmp8 = icmp ugt i32 %len, 11
+  br i1 %cmp8, label %while.body.lr.ph, label %while.end
+
+while.body.lr.ph:                                 ; preds = %entry
+  br label %while.body
+
+while.body:                                       ; preds = %while.body, %while.body.lr.ph
+  %keylen.010 = phi i32 [ %len, %while.body.lr.ph ], [ %sub, %while.body ]
+  %s.addr.09 = phi i8* [ %s, %while.body.lr.ph ], [ %add.ptr, %while.body ]
+  %tmp1 = bitcast i8* %s.addr.09 to i32*
+  %tmp2 = load i32, i32* %tmp1, align 4
+  %shl.i = shl i32 %tmp2, 1
+  %and.i = and i32 %shl.i, 16843008
+  %tmp3 = load i32, i32* %a, align 4
+  %sub.i = add i32 %tmp3, %tmp2
+  %add = sub i32 %sub.i, %and.i
+  store i32 %add, i32* %a, align 4
+  %add.ptr = getelementptr inbounds i8, i8* %s.addr.09, i64 12
+  %sub = add i32 %keylen.010, -12
+  %cmp = icmp ugt i32 %sub, 11
+  br i1 %cmp, label %while.body, label %while.cond.while.end_crit_edge
+
+while.cond.while.end_crit_edge:                   ; preds = %while.body
+  %sub.lcssa = phi i32 [ %sub, %while.body ]
+  br label %while.end
+
+while.end:                                        ; preds = %while.cond.while.end_crit_edge, %entry
+  %keylen.0.lcssa = phi i32 [ %sub.lcssa, %while.cond.while.end_crit_edge ], [ %len, %entry ]
+  call void @_Z3mixRjj(i32* dereferenceable(4) %a, i32 %keylen.0.lcssa)
+  %tmp4 = load i32, i32* %a, align 4
+  call void @llvm.lifetime.end.p0i8(i64 4, i8* %tmp)
+  ret i32 %tmp4
+}
+
+define i32 @zero_backedge_count_test(i32 %unknown_init, i32* %unknown_mem) {
+; CHECK-LABEL: @zero_backedge_count_test(
+entry:
+  br label %loop
+
+loop:
+  %iv = phi i32 [ 0, %entry], [ %iv.inc, %loop ]
+  %unknown_phi = phi i32 [ %unknown_init, %entry ], [ %unknown_next, %loop ]
+  %iv.inc = add i32 %iv, 1
+  %be_taken = icmp ne i32 %iv.inc, 1
+  %unknown_next = load volatile i32, i32* %unknown_mem
+  br i1 %be_taken, label %loop, label %leave
+
+leave:
+; We can fold %unknown_phi even though the backedge value for it is completely
+; unknown, since we can prove that the loop's backedge taken count is 0.
+
+; CHECK: leave:
+; CHECK: ret i32 %unknown_init
+  %exit_val = phi i32 [ %unknown_phi, %loop ]
+  ret i32 %exit_val
+}