[SCCP] Add pre-commit tests for PR76085. NFC.

Author: dtcxzyw

llvm/test/Transforms/SCCP/switch.ll

@@ -4,6 +4,8 @@
 ; Make sure we always consider the default edge executable for a switch
 ; with no cases.
 declare void @foo()
+declare i32 @g(i32)
+
 define void @test1() {
 ; CHECK-LABEL: @test1(
 ; CHECK-NEXT:    switch i32 undef, label [[D:%.*]] [
@@ -301,6 +303,73 @@ end.2:
   ret i32 20
 }
 
+define i32 @test_default_unreachable_by_dom_cond(i32 %x) {
+; CHECK-LABEL: @test_default_unreachable_by_dom_cond(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[OR_COND:%.*]] = icmp ult i32 [[X:%.*]], 4
+; CHECK-NEXT:    br i1 [[OR_COND]], label [[IF_THEN:%.*]], label [[RETURN:%.*]]
+; CHECK:       if.then:
+; CHECK-NEXT:    switch i32 [[X]], label [[SW_EPILOG:%.*]] [
+; CHECK-NEXT:      i32 0, label [[SW_BB:%.*]]
+; CHECK-NEXT:      i32 1, label [[SW_BB2:%.*]]
+; CHECK-NEXT:      i32 2, label [[SW_BB4:%.*]]
+; CHECK-NEXT:      i32 3, label [[SW_BB6:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       sw.bb:
+; CHECK-NEXT:    [[CALL:%.*]] = tail call i32 @g(i32 2)
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       sw.bb2:
+; CHECK-NEXT:    [[CALL3:%.*]] = tail call i32 @g(i32 3)
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       sw.bb4:
+; CHECK-NEXT:    [[CALL5:%.*]] = tail call i32 @g(i32 4)
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       sw.bb6:
+; CHECK-NEXT:    [[CALL7:%.*]] = tail call i32 @g(i32 5)
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       sw.epilog:
+; CHECK-NEXT:    call void @foo()
+; CHECK-NEXT:    br label [[RETURN]]
+; CHECK:       return:
+; CHECK-NEXT:    [[RETVAL_0:%.*]] = phi i32 [ [[CALL7]], [[SW_BB6]] ], [ [[CALL5]], [[SW_BB4]] ], [ [[CALL3]], [[SW_BB2]] ], [ [[CALL]], [[SW_BB]] ], [ -23, [[SW_EPILOG]] ], [ -23, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[RETVAL_0]]
+;
+entry:
+  %or.cond = icmp ult i32 %x, 4
+  br i1 %or.cond, label %if.then, label %return
+
+if.then:
+  switch i32 %x, label %sw.epilog [
+  i32 0, label %sw.bb
+  i32 1, label %sw.bb2
+  i32 2, label %sw.bb4
+  i32 3, label %sw.bb6
+  ]
+
+sw.bb:
+  %call = tail call i32 @g(i32 2)
+  br label %return
+
+sw.bb2:
+  %call3 = tail call i32 @g(i32 3)
+  br label %return
+
+sw.bb4:
+  %call5 = tail call i32 @g(i32 4)
+  br label %return
+
+sw.bb6:
+  %call7 = tail call i32 @g(i32 5)
+  br label %return
+
+sw.epilog:
+  call void @foo()
+  br label %return
+
+return:
+  %retval.0 = phi i32 [ %call7, %sw.bb6 ], [ %call5, %sw.bb4 ], [ %call3, %sw.bb2 ], [ %call, %sw.bb ], [ -23, %sw.epilog ], [ -23, %entry ]
+  ret i32 %retval.0
+}
 
 declare void @llvm.assume(i1)